1. Introduzione

Questo documento elenca i requisiti che devono essere soddisfatti affinché i dispositivi siano compatibili con Android 7.1.

L'uso di "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" e "OPTIONAL" è conforme a IETF standard definito in RFC2119 .

Come utilizzato in questo documento, un "implementatore del dispositivo" o "implementatore" è una persona o un'organizzazione che sviluppa una soluzione hardware/software con Android 7.1. Una “implementazione del dispositivo” o “implementazione” è la soluzione hardware/software così sviluppata.

Per essere considerate compatibili con Android 7.1, le implementazioni del dispositivo DEVONO soddisfare i requisiti presentati nella presente Definizione di compatibilità, inclusi eventuali documenti incorporati tramite riferimento.

Laddove questa definizione o i test software descritti nella sezione 10 siano silenziosi, ambigui o incompleti, è responsabilità dell'implementatore del dispositivo garantire la compatibilità con le implementazioni esistenti.

Per questo motivo, il progetto Android Open Source è sia l'implementazione di riferimento che quella preferita di Android. Agli implementatori dei dispositivi SI RACCOMANDA FORTEMENTE di basare le proprie implementazioni nella massima misura possibile sul codice sorgente "upstream" disponibile dal progetto Android Open Source. Sebbene alcuni componenti possano ipoteticamente essere sostituiti con implementazioni alternative, SI CONSIGLIA FORTEMENTE di non seguire questa pratica, poiché superare i test del software diventerà sostanzialmente più difficile. È responsabilità dell'implementatore garantire la piena compatibilità comportamentale con l'implementazione Android standard, inclusa e oltre la Compatibility Test Suite. Infine, si noti che alcune sostituzioni e modifiche di componenti sono esplicitamente vietate da questo documento.

Molte delle risorse collegate in questo documento derivano direttamente o indirettamente dall'SDK di Android e saranno funzionalmente identiche alle informazioni contenute nella documentazione dell'SDK. In tutti i casi in cui la presente Definizione di compatibilità o la Suite di test di compatibilità non sono d'accordo con la documentazione dell'SDK, la documentazione dell'SDK è considerata autorevole. Tutti i dettagli tecnici forniti nelle risorse collegate in questo documento sono considerati, per inclusione, parte della presente Definizione di compatibilità.

2. Tipi di dispositivi

Sebbene il progetto Android Open Source sia stato utilizzato nell'implementazione di una varietà di tipi di dispositivi e fattori di forma, molti aspetti dell'architettura e dei requisiti di compatibilità sono stati ottimizzati per i dispositivi portatili. A partire da Android 5.0, il progetto Android Open Source mira ad abbracciare una più ampia varietà di tipi di dispositivi come descritto in questa sezione.

Il dispositivo portatile Android si riferisce a un'implementazione del dispositivo Android che viene generalmente utilizzata tenendolo in mano, come lettori mp3, telefoni e tablet. Implementazioni del dispositivo portatile Android:

• DEVE avere un touchscreen incorporato nel dispositivo.
• DEVE avere una fonte di alimentazione che garantisca mobilità, come una batteria.

Per dispositivo Android Television si intende un'implementazione del dispositivo Android che costituisce un'interfaccia di intrattenimento per la fruizione di media digitali, film, giochi, app e/o TV in diretta per utenti seduti a circa tre metri di distanza (un'interfaccia utente "appoggiata allo schienale" o "interfaccia utente da 10 piedi") "). Dispositivi TV Android:

• DEVE avere uno schermo incorporato OPPURE includere una porta di uscita video, come VGA, HDMI o una porta wireless per il display.
• DEVE dichiarare le funzionalità android.software.leanback e android.hardware.type.television.

Per dispositivo Android Watch si intende un'implementazione del dispositivo Android destinata ad essere indossata sul corpo, magari al polso, e:

• DEVE avere uno schermo con una lunghezza diagonale fisica compresa tra 1,1 e 2,5 pollici.
• DEVE dichiarare la funzionalità android.hardware.type.watch.
• DEVE supportare uiMode = UI_MODE_TYPE_WATCH .

L'implementazione di Android Automotive si riferisce a un'unità principale del veicolo che esegue Android come sistema operativo per parte o tutte le funzionalità del sistema e/o di infotainment. Implementazioni Android Automotive:

• DEVE avere uno schermo con lunghezza diagonale fisica pari o superiore a 6 pollici.
• DEVE dichiarare la funzionalità android.hardware.type.automotive.
• DEVE supportare uiMode = UI_MODE_TYPE_CAR .
• Le implementazioni di Android Automotive DEVONO supportare tutte le API pubbliche nello spazio dei nomi android.car.* .

Tutte le implementazioni di dispositivi Android che non rientrano in nessuno dei tipi di dispositivi sopra indicati DEVONO comunque soddisfare tutti i requisiti presenti in questo documento per essere compatibili con Android 7.1, a meno che il requisito non sia esplicitamente descritto come applicabile solo a uno specifico tipo di dispositivo Android sopra.

2.1 Configurazioni del dispositivo

Questo è un riepilogo delle principali differenze nella configurazione hardware in base al tipo di dispositivo. (Le celle vuote indicano un "MAGGIO"). Non tutte le configurazioni sono trattate in questa tabella; vedere le sezioni hardware pertinenti per maggiori dettagli.

3. Software

3.1. Compatibilità API gestita

L'ambiente di esecuzione del bytecode Dalvik gestito è il veicolo principale per le applicazioni Android. L'API (Application Programming Interface) Android è l'insieme di interfacce della piattaforma Android esposte alle applicazioni in esecuzione nell'ambiente di runtime gestito. Le implementazioni del dispositivo DEVONO fornire implementazioni complete, inclusi tutti i comportamenti documentati, di qualsiasi API documentata esposta dall'SDK di Android o di qualsiasi API decorata con il marcatore "@SystemApi" nel codice sorgente Android upstream.

Le implementazioni del dispositivo DEVONO supportare/preservare tutte le classi, i metodi e gli elementi associati contrassegnati dall'annotazione TestApi (@TestApi).

Le implementazioni del dispositivo NON DEVONO omettere alcuna API gestita, alterare le interfacce o le firme API, deviare dal comportamento documentato o includere no-op, tranne dove specificamente consentito dalla presente Definizione di compatibilità.

Questa definizione di compatibilità consente di omettere dalle implementazioni del dispositivo alcuni tipi di hardware per i quali Android include API. In questi casi, le API DEVONO essere ancora presenti e comportarsi in modo ragionevole. Vedere la sezione 7 per i requisiti specifici per questo scenario.

3.1.1. Estensioni Android

Android include il supporto per l'estensione delle API gestite mantenendo la stessa versione a livello API. Le implementazioni dei dispositivi Android DEVONO precaricare l'implementazione AOSP sia della libreria condivisa ExtShared che dei servizi ExtServices con versioni superiori o uguali alle versioni minime consentite per ciascun livello API. Ad esempio, le implementazioni dei dispositivi Android 7.0 che eseguono il livello API 24 DEVONO includere almeno la versione 1.

3.2. Compatibilità API soft

Oltre alle API gestite della sezione 3.1 , Android include anche una significativa API "soft" solo in fase di runtime, sotto forma di intenti, autorizzazioni e aspetti simili delle applicazioni Android che non possono essere applicati in fase di compilazione dell'applicazione.

3.2.1. Autorizzazioni

Gli implementatori del dispositivo DEVONO supportare e applicare tutte le costanti di autorizzazione come documentato dalla pagina di riferimento delle autorizzazioni . Tieni presente che la sezione 9 elenca i requisiti aggiuntivi relativi al modello di sicurezza Android.

3.2.2. Costruisci parametri

Le API Android includono una serie di costanti nella classe android.os.Build destinate a descrivere il dispositivo corrente. Per fornire valori coerenti e significativi tra le implementazioni del dispositivo, la tabella seguente include ulteriori restrizioni sui formati di questi valori a cui le implementazioni del dispositivo DEVONO conformarsi.

3.2.3. Compatibilità degli intenti

3.2.3.1. Intenti dell'applicazione principale

Gli intenti Android consentono ai componenti dell'applicazione di richiedere funzionalità da altri componenti Android. Il progetto Android upstream include un elenco di applicazioni considerate applicazioni Android principali, che implementa diversi modelli di intenti per eseguire azioni comuni. Le principali applicazioni Android sono:

• Orologio da tavolo
• Navigatore
• Calendario
• Contatti
• Galleria
• Ricerca globale
• Lanciatore
• Musica
• Impostazioni

Le implementazioni del dispositivo DEVONO includere le applicazioni Android principali, a seconda dei casi, o un componente che implementa gli stessi modelli di intenti definiti da tutti i componenti Attività o Servizio di queste applicazioni Android principali esposte ad altre applicazioni, implicitamente o esplicitamente, tramite l'attributo android:exported .

3.2.3.2. Risoluzione dell'intento

Poiché Android è una piattaforma estensibile, le implementazioni del dispositivo DEVONO consentire che ogni modello di intent a cui si fa riferimento nella sezione 3.2.3.1 venga sovrascritto da applicazioni di terze parti. L'implementazione open source Android upstream lo consente per impostazione predefinita; gli implementatori del dispositivo NON DEVONO attribuire privilegi speciali all'utilizzo di questi modelli di intenti da parte delle applicazioni di sistema, né impedire ad applicazioni di terze parti di vincolarsi e assumere il controllo di questi modelli. Questo divieto include specificamente, ma non è limitato alla disabilitazione dell'interfaccia utente "Scelta" che consente all'utente di selezionare tra più applicazioni che gestiscono tutte lo stesso modello di intenti.

Le implementazioni del dispositivo DEVONO fornire un'interfaccia utente affinché gli utenti possano modificare l'attività predefinita per gli intenti.

Tuttavia, le implementazioni del dispositivo POSSONO fornire attività predefinite per modelli URI specifici (ad esempio http://play.google.com) quando l'attività predefinita fornisce un attributo più specifico per l'URI dei dati. Ad esempio, un modello di filtro di intenti che specifica l'URI dei dati "http://www.android.com" è più specifico del modello di intenti principale del browser per "http://".

Android include anche un meccanismo che consente alle app di terze parti di dichiarare un comportamento di collegamento delle app predefinito autorevole per determinati tipi di intenti URI Web. Quando tali dichiarazioni autorevoli vengono definite nei modelli di filtro degli intenti di un'app, le implementazioni del dispositivo:

• DEVE tentare di convalidare eventuali filtri di intenti eseguendo i passaggi di convalida definiti nella specifica Digital Asset Links implementata dal Package Manager nel progetto Android Open Source upstream.
• DEVE tentare la convalida dei filtri di intenti durante l'installazione dell'applicazione e impostare tutti i filtri di intenti UIR convalidati con successo come gestori di app predefiniti per i relativi UIR.
• PUÒ impostare filtri di intenti URI specifici come gestori di app predefiniti per i loro URI, se vengono verificati con successo ma altri filtri URI candidati falliscono la verifica. Se un'implementazione del dispositivo fa ciò, DEVE fornire le sovrascritture del modello per URI appropriate all'utente nel menu delle impostazioni.
• DEVE fornire all'utente i controlli Collegamenti app per app nelle Impostazioni come segue:
  • L'utente DEVE essere in grado di sovrascrivere in modo olistico il comportamento predefinito dei collegamenti dell'app affinché un'app sia: sempre aperta, chiedi sempre o non aprire mai, che deve applicarsi allo stesso modo a tutti i filtri di intenti dell'URI candidato.
  • L'utente DEVE essere in grado di vedere un elenco dei filtri di intenti URI candidati.
  • L'implementazione del dispositivo PUÒ fornire all'utente la possibilità di sovrascrivere filtri di intenti URI candidati specifici che sono stati verificati con successo, in base al filtro per intent.
  • L'implementazione del dispositivo DEVE fornire agli utenti la possibilità di visualizzare e sovrascrivere filtri di intenti URI candidati specifici se l'implementazione del dispositivo consente ad alcuni filtri di intenti URI candidati di riuscire nella verifica mentre altri possono fallire.

3.2.3.3. Spazi dei nomi di intenti

Le implementazioni del dispositivo NON DEVONO includere alcun componente Android che rispetti qualsiasi nuovo intento o modello di intento di trasmissione utilizzando un'AZIONE, una CATEGORIA o un'altra stringa chiave nell'Android. o com.android. spazio dei nomi. Gli implementatori del dispositivo NON DEVONO includere componenti Android che rispettano nuovi intenti o modelli di intenti di trasmissione utilizzando un'AZIONE, una CATEGORIA o un'altra stringa chiave in uno spazio pacchetto appartenente a un'altra organizzazione. Gli implementatori del dispositivo NON DEVONO alterare o estendere nessuno dei modelli di intenti utilizzati dalle app principali elencate nella sezione 3.2.3.1 . Le implementazioni dei dispositivi POSSONO includere modelli di intenti che utilizzano spazi dei nomi chiaramente e ovviamente associati alla propria organizzazione. Questo divieto è analogo a quello specificato per le classi del linguaggio Java nella sezione 3.6 .

3.2.3.4. Intenti di trasmissione

Le applicazioni di terze parti si affidano alla piattaforma per trasmettere determinati intenti per notificare loro cambiamenti nell'ambiente hardware o software. I dispositivi compatibili con Android DEVONO trasmettere gli intenti di trasmissione pubblica in risposta agli eventi di sistema appropriati. Gli intenti di trasmissione sono descritti nella documentazione dell'SDK.

3.2.3.5. Impostazioni predefinite dell'app

Android include impostazioni che forniscono agli utenti un modo semplice per selezionare le applicazioni predefinite, ad esempio per la schermata Home o gli SMS. Laddove opportuno, le implementazioni del dispositivo DEVONO fornire un menu di impostazioni simile ed essere compatibili con il modello di filtro intent e i metodi API descritti nella documentazione dell'SDK come di seguito.

Implementazioni del dispositivo:

• DEVE rispettare l'intento android.settings.HOME_SETTINGS di mostrare un menu di impostazioni dell'app predefinito per la schermata principale, se l'implementazione del dispositivo riporta android.software.home_screen.
• DEVE fornire un menu di impostazioni che chiamerà l'intento android.provider.Telephony.ACTION_CHANGE_DEFAULT per mostrare una finestra di dialogo per modificare l'applicazione SMS predefinita, se l'implementazione del dispositivo riporta android.hardware.telephony.
• DEVE rispettare l'intento android.settings.NFC_PAYMENT_SETTINGS di mostrare un menu di impostazioni dell'app predefinito per Tocca e paga, se l'implementazione del dispositivo riporta android.hardware.nfc.hce.
• DEVE rispettare l'intento android.telecom.action.CHANGE_DEFAULT_DIALER di mostrare una finestra di dialogo per consentire all'utente di modificare l'applicazione Telefono predefinita, se l'implementazione del dispositivo riporta android.hardware.telephony .
• DEVE rispettare l'intento android.settings.ACTION_VOICE_INPUT_SETTINGS quando il dispositivo supporta VoiceInteractionService e mostrare un menu di impostazioni dell'app predefinito per l'input vocale e l'assistenza.

3.3. Compatibilità API nativa

La compatibilità del codice nativo è impegnativa. Per questo motivo, agli implementatori del dispositivo SI RACCOMANDA FORTEMENTE di utilizzare le implementazioni delle librerie elencate di seguito dal progetto Android Open Source upstream.

3.3.1. Interfacce binarie dell'applicazione

Il bytecode Dalvik gestito può richiamare il codice nativo fornito nel file .apk dell'applicazione come file ELF .so compilato per l'architettura hardware del dispositivo appropriata. Poiché il codice nativo dipende fortemente dalla tecnologia del processore sottostante, Android definisce una serie di interfacce binarie applicative (ABI) nell'NDK di Android. Le implementazioni del dispositivo DEVONO essere compatibili con uno o più ABI definiti e DEVONO implementare la compatibilità con Android NDK, come di seguito.

Se l'implementazione di un dispositivo include il supporto per un'ABI Android, essa:

• DEVE includere il supporto per il codice in esecuzione nell'ambiente gestito per richiamare il codice nativo, utilizzando la semantica JNI (Java Native Interface) standard.
• DEVE essere compatibile con il codice sorgente (ovvero compatibile con l'intestazione) e compatibile con il codice binario (per ABI) con ciascuna libreria richiesta nell'elenco seguente.
• DEVE supportare l'equivalente ABI a 32 bit se è supportata una qualsiasi ABI a 64 bit.
• DEVE riportare accuratamente l'Application Binary Interface (ABI) nativa supportata dal dispositivo, tramite i parametri android.os.Build.SUPPORTED_ABIS, android.os.Build.SUPPORTED_32_BIT_ABIS e android.os.Build.SUPPORTED_64_BIT_ABIS, ciascuno un elenco separato da virgole di ABI ordinati dal più al meno preferito.
• DEVE riportare, tramite i parametri di cui sopra, solo gli ABI documentati e descritti nell'ultima versione della documentazione di gestione ABI di NDK di Android e DEVE includere il supporto per l'estensione Advanced SIMD (nota anche come NEON).
• DOVREBBE essere creato utilizzando il codice sorgente e i file di intestazione disponibili nel progetto Android Open Source upstream

Tieni presente che le versioni future di Android NDK potrebbero introdurre il supporto per ABI aggiuntivi. Se l'implementazione di un dispositivo non è compatibile con un'ABI predefinita esistente, NON DEVE segnalare il supporto per alcuna ABI.

Le seguenti API di codice nativo DEVONO essere disponibili per le app che includono codice nativo:

• libandroid.so (supporto attività Android nativo)
• libc (libreria C)
• libcamera2ndk.so
• libdl (linker dinamico)
• libEGL.so (gestione superficie OpenGL nativa)
• libGLESv1_CM.so (OpenGL ES 1.x)
• libGLESv2.so (OpenGL ES 2.0)
• libGLESv3.so (OpenGL ES 3.x)
• libicui18n.so
• libicuuc.so
• libjnigraphics.so
• liblog (registrazione Android)
• libmediandk.so (supporto API multimediali native)
• libm (libreria matematica)
• libOpenMAXAL.so (supporto OpenMAX AL 1.0.1)
• libOpenSLES.so (supporto audio OpenSL ES 1.0.1)
• libRS.so
• libstdc++ (supporto minimo per C++)
• libvulkan.so (Vulkan)
• libz (compressione Zlib)
• Interfaccia JNI
• Supporto per OpenGL, come descritto di seguito

Per le librerie native sopra elencate, l'implementazione del dispositivo NON DEVE aggiungere o rimuovere le funzioni pubbliche.

Le librerie native non elencate sopra ma implementate e fornite in AOSP poiché le librerie di sistema sono riservate e NON DEVONO essere esposte ad app di terze parti destinate al livello API 24 o superiore.

Le implementazioni del dispositivo POSSONO aggiungere librerie non AOSP ed esporle direttamente come API ad app di terze parti, ma le librerie aggiuntive DOVREBBERO essere in /vendor/lib o /vendor/lib64 e DEVONO essere elencate in /vendor/etc/public.libraries.txt .

Tieni presente che le implementazioni del dispositivo DEVONO includere libGLESv3.so e, a loro volta, DEVONO esportare tutti i simboli di funzione OpenGL ES 3.1 e Android Extension Pack come definito nella versione NDK android-24. Anche se devono essere presenti tutti i simboli, devono essere completamente implementate solo le funzioni corrispondenti per le versioni e le estensioni OpenGL ES effettivamente supportate dal dispositivo.

3.3.1.1. Biblioteche grafiche

Vulkan è un'API multipiattaforma a basso costo per grafica 3D ad alte prestazioni. Le implementazioni dei dispositivi, anche se non includono il supporto delle API Vulkan, DEVONO soddisfare i seguenti requisiti:

• DEVE sempre fornire una libreria nativa denominata libvulkan.so che esporta i simboli di funzione per l'API Vulkan 1.0 principale nonché le estensioni VK_KHR_surface , VK_KHR_android_surface e VK_KHR_swapchain .

Implementazioni del dispositivo, se include il supporto delle API Vulkan:

• DEVE segnalare uno o più VkPhysicalDevices tramite la chiamata vkEnumeratePhysicalDevices .
• Ciascun VkPhysicalDevices elencato DEVE implementare completamente l'API Vulkan 1.0.
• DEVE segnalare i flag di funzionalità PackageManager#FEATURE_VULKAN_HARDWARE_LEVEL e PackageManager#FEATURE_VULKAN_HARDWARE_VERSION corretti.
• È NECESSARIO enumerare i livelli, contenuti nelle librerie native denominate libVkLayer*.so nella directory della libreria nativa del pacchetto dell'applicazione, tramite le funzioni vkEnumerateInstanceLayerProperties e vkEnumerateDeviceLayerProperties in libvulkan.so
• NON DEVE enumerare i livelli forniti dalle librerie esterne al pacchetto dell'applicazione o fornire altri modi per tracciare o intercettare l'API Vulkan, a meno che l'applicazione non abbia l'attributo android:debuggable=”true” .

Implementazioni del dispositivo, se non incluso il supporto delle API Vulkan:

• DEVE segnalare 0 VkPhysicalDevices tramite la chiamata vkEnumeratePhysicalDevices .
• NON DEVE dichiarare nessuno dei flag di funzionalità Vulkan PackageManager#FEATURE_VULKAN_HARDWARE_LEVEL e PackageManager#FEATURE_VULKAN_HARDWARE_VERSION .

3.3.2. Compatibilità del codice nativo ARM a 32 bit

L'architettura ARMv8 depreca diverse operazioni della CPU, comprese alcune operazioni utilizzate nel codice nativo esistente. Sui dispositivi ARM a 64 bit, le seguenti operazioni deprecate DEVONO rimanere disponibili per il codice ARM nativo a 32 bit, tramite il supporto nativo della CPU o tramite l'emulazione software:

• Istruzioni SWP e SWPB
• Istruzione SETEND
• Operazioni con barriera CP15ISB, CP15DSB e CP15DMB

Le versioni legacy di Android NDK utilizzavano /proc/cpuinfo per scoprire le funzionalità della CPU dal codice nativo ARM a 32 bit. Per compatibilità con le applicazioni create utilizzando questo NDK, i dispositivi DEVONO includere le seguenti righe in /proc/cpuinfo quando viene letto dalle applicazioni ARM a 32 bit:

• "Caratteristiche: ", seguito da un elenco di eventuali funzionalità opzionali della CPU ARMv7 supportate dal dispositivo.
• "Architettura CPU: ", seguito da un numero intero che descrive l'architettura ARM supportata più elevata del dispositivo (ad esempio, "8" per i dispositivi ARMv8).

Questi requisiti si applicano solo quando /proc/cpuinfo viene letto da applicazioni ARM a 32 bit. I dispositivi NON DOVREBBERO alterare /proc/cpuinfo quando letti da applicazioni ARM o non ARM a 64 bit.

3.4. Compatibilità Web

3.4.1. Compatibilità WebView

La funzionalità della piattaforma android.software.webview DEVE essere segnalata su qualsiasi dispositivo che fornisce un'implementazione completa dell'API android.webkit.WebView e NON DEVE essere segnalata su dispositivi senza un'implementazione completa dell'API. L'implementazione Android Open Source utilizza il codice del progetto Chromium per implementare android.webkit.WebView . Poiché non è possibile sviluppare una suite di test completa per un sistema di rendering web, gli implementatori del dispositivo DEVONO utilizzare la specifica build upstream di Chromium nell'implementazione WebView. Nello specifico:

• Le implementazioni del dispositivo android.webkit.WebView DEVONO essere basate sulla build Chromium del progetto Android Open Source upstream per Android 7.1. Questa build include un insieme specifico di funzionalità e correzioni di sicurezza per WebView.

• La stringa dello user agent riportata da WebView DEVE essere in questo formato:

  Mozilla/5.0 (Linux; Android $(VERSION); $(MODEL) Build/$(BUILD); wv) AppleWebKit/537.36 (KHTML, come Gecko) Versione/4.0 $(CHROMIUM_VER) Mobile Safari/537.36

  • Il valore della stringa $(VERSION) DEVE essere uguale al valore di android.os.Build.VERSION.RELEASE.
  • Il valore della stringa $(MODEL) DEVE essere uguale al valore di android.os.Build.MODEL.
  • Il valore della stringa $(BUILD) DEVE essere uguale al valore di android.os.Build.ID.
  • Il valore della stringa $(CHROMIUM_VER) DEVE essere la versione di Chromium nel progetto Android Open Source upstream.
  • Le implementazioni del dispositivo POSSONO omettere Mobile nella stringa dell'agente utente.

Il componente WebView DOVREBBE includere il supporto per quante più funzionalità HTML5 possibili e, se supporta la funzionalità, DOVREBBE essere conforme alle specifiche HTML5 .

3.4.2. Compatibilità del browser

Il browser autonomo PUÒ essere basato su una tecnologia browser diversa da WebKit. Tuttavia, anche se viene utilizzata un'applicazione browser alternativa, il componente android.webkit.WebView fornito alle applicazioni di terze parti DEVE essere basato su WebKit, come descritto nella sezione 3.4.1 .

Le implementazioni POSSONO fornire una stringa dell'agente utente personalizzata nell'applicazione browser autonoma.

L'applicazione del browser standalone (in base all'applicazione del browser Webkit a monte o di una sostituzione di terze parti) dovrebbe includere il supporto per il maggior numero possibile di HTML5 . Minimamente, le implementazioni del dispositivo devono supportare ciascuna di queste API associate a HTML5:

• Cache dell'applicazione/operazione offline
• <Video> Tag
• geolocalizzazione

Inoltre, le implementazioni del dispositivo devono supportare l' API WebStorage HTML5/W3C e dovrebbero supportare l' API INDICEDDB HTML5/W3C. Si noti che poiché gli organi di sviluppo di sviluppo web stanno passando per favorire IndexEDDB su WebStorage, IndexEDDB dovrebbe diventare un componente richiesto in una versione futura di Android.

3.5. Compatibilità comportamentale API

I comportamenti di ciascuno dei tipi API (gestiti, soft, nativi e web) devono essere coerenti con l'implementazione preferita del progetto open source Android a monte. Alcune aree specifiche di compatibilità sono:

• I dispositivi non devono cambiare il comportamento o la semantica di un intento standard.
• I dispositivi non devono alterare la semantica del ciclo di vita o del ciclo di vita di un particolare tipo di componente di sistema (come servizio, attività, contentProvider, ecc.).
• I dispositivi non devono modificare la semantica di un'autorizzazione standard.

L'elenco di cui sopra non è completo. La suite di test di compatibilità (CTS) verifica parti significative della piattaforma per la compatibilità comportamentale, ma non tutte. È responsabilità dell'implementatore garantire la compatibilità comportamentale con il progetto open source Android. Per questo motivo, gli implementatori di dispositivi dovrebbero utilizzare il codice sorgente disponibile tramite il progetto open source Android ove possibile, piuttosto che reimplementare parti significative del sistema.

3.6. Spazi dei nomi API

Android segue le convenzioni dello spazio dei nomi del pacchetto e della classe definite dal linguaggio di programmazione Java. Per garantire la compatibilità con applicazioni di terze parti, gli implementari del dispositivo non devono apportare modifiche proibite (vedi sotto) a questi spazi dei nomi dei pacchetti:

• Giava.*
• Javax.*
• sole.*
• Android.*
• com.android.*

Le modifiche proibite includono :

• Le implementazioni del dispositivo non devono modificare le API esposte pubblicamente sulla piattaforma Android modificando qualsiasi metodo o firme di classe o rimuovendo le classi o i campi di classe.
• Gli implementari del dispositivo possono modificare l'implementazione sottostante delle API, ma tali modifiche non devono influire sul comportamento dichiarato e la firma in lingua Java di qualsiasi API esposta pubblicamente.
• Gli implementari del dispositivo non devono aggiungere elementi esposti pubblicamente (come classi o interfacce o campi o metodi per classi o interfacce esistenti) alle API sopra.

Un "elemento esposto pubblicamente" è qualsiasi costrutto che non è decorato con il marcatore "@Hide" utilizzato nel codice sorgente Android a monte. In altre parole, gli implementari del dispositivo non devono esporre nuove API o alterare le API esistenti negli spazi dei nomi sopra indicati. Gli implementatori di dispositivi possono apportare modifiche solo interne, ma tali modifiche non devono essere pubblicizzate o altrimenti esposte agli sviluppatori.

Gli implementatori di dispositivi possono aggiungere API personalizzate, ma tali API non devono essere in uno spazio dei nomi di proprietà o riferirsi a un'altra organizzazione. Ad esempio, gli implementatori di dispositivi non devono aggiungere API al COM.Google.* O spazio dei nomi simile: solo Google può farlo. Allo stesso modo, Google non deve aggiungere API agli spazi dei nomi di altre società. Inoltre, se un'implementazione del dispositivo include API personalizzate al di fuori dello spazio dei nomi Android standard, quelle API devono essere confezionate in una libreria condivisa Android in modo che solo le app che le usano esplicitamente (tramite il meccanismo <usi-library>) siano influenzate dall'utilizzo di memoria di tali API.

Se un implementatore del dispositivo propone di migliorare uno degli spazi dei nomi dei pacchetti sopra (ad esempio aggiungendo nuove funzionalità utili a un'API esistente o aggiungendo una nuova API), l'implementatore dovrebbe visitare fonte.android.com e iniziare il processo per contribuire alle modifiche e Codice, secondo le informazioni su quel sito.

Si noti che le restrizioni sopra corrispondono alle convenzioni standard per la denominazione delle API nel linguaggio di programmazione Java; Questa sezione mira semplicemente a rafforzare tali convenzioni e renderle vincolanti attraverso l'inclusione in questa definizione di compatibilità.

3.7. Compatibilità di runtime

Le implementazioni del dispositivo devono supportare la specifica e la semantica Dalvik Executable (DEX) e la semantica Dalvik Bytecode . Gli implementatori di dispositivi dovrebbero utilizzare l'ART, l'implementazione a monte del formato eseguibile Dalvik e il sistema di gestione dei pacchetti dell'implementazione di riferimento.

Le implementazioni del dispositivo devono configurare i runtimes Dalvik per allocare la memoria in conformità con la piattaforma Android a monte e, come specificato dalla tabella seguente. (Vedere la sezione 7.1.1 per le dimensioni dello schermo e le definizioni della densità dello schermo.) Si noti che i valori di memoria specificati di seguito sono considerati valori minimi e le implementazioni del dispositivo possono allocare più memoria per applicazione.

3.8. Compatibilità dell'interfaccia utente

3.8.1. Launcher (schermata principale)

Android include un'applicazione di lancio (schermata iniziale) e supporto per applicazioni di terze parti per sostituire il lancio del dispositivo (schermata iniziale). Le implementazioni del dispositivo che consentono alle applicazioni di terze parti di sostituire la schermata domestica del dispositivo devono dichiarare la funzionalità della piattaforma Android.Software.home_screen.

3.8.2. Widget

Android definisce un tipo di componente e un corrispondente API e ciclo di vita che consente alle applicazioni di esporre un "appwidget" all'utente finale, una funzionalità che si consiglia vivamente di essere supportata sulle implementazioni del dispositivo portatile. Le implementazioni del dispositivo che supportano i widget di incorporamento nella schermata principale devono soddisfare i seguenti requisiti e dichiarare il supporto per la funzionalità della piattaforma Android.Software.App_Widgets.

• I lanciatori del dispositivo devono includere il supporto integrato per AppWidgets ed esporre le accessi delle interfacce utente per aggiungere, configurare, visualizzare e rimuovere AppWidget direttamente all'interno del lanciatore.
• Le implementazioni del dispositivo devono essere in grado di rendere i widget di 4 x 4 nella dimensione della griglia standard. Vedere le linee guida per la progettazione del widget app nella documentazione SDK Android per i dettagli.
• Le implementazioni del dispositivo che includono il supporto per la schermata di blocco possono supportare i widget dell'applicazione sulla schermata di blocco.

3.8.3. Notifiche

Android include API che consentono agli sviluppatori di avvisare gli utenti di eventi notevoli utilizzando le funzionalità hardware e software del dispositivo.

Alcune API consentono alle applicazioni di eseguire notifiche o attirare l'attenzione usando l'hardware: in particolare il suono, le vibrazioni e la luce. Le implementazioni del dispositivo devono supportare le notifiche che utilizzano funzionalità hardware, come descritto nella documentazione SDK e nella misura possibile con l'hardware di implementazione del dispositivo. Ad esempio, se un'implementazione del dispositivo include un vibratore, deve implementare correttamente le API di vibrazione. Se un'implementazione del dispositivo manca di hardware, le API corrispondenti devono essere implementate come no-op. Questo comportamento è ulteriormente dettagliato nella Sezione 7 .

Inoltre, l'implementazione deve rendere correttamente tutte le risorse (icone, file di animazione ecc.) Previsto nelle API o nella Guida allo stile delle icone della barra dello stato/sistema, che nel caso di un dispositivo televisivo Android include la possibilità di non visualizzare il notifiche. Gli implementatori di dispositivi possono fornire un'esperienza utente alternativa per le notifiche rispetto a quella fornita dall'implementazione open source Android di riferimento; Tuttavia, tali sistemi di notifica alternativa devono supportare le risorse di notifica esistenti, come sopra.

Android include supporto per varie notifiche, come:

• Notifiche ricche . Viste interattive per le notifiche in corso.
• Notifiche heads-up . Visualizzazioni interattive Gli utenti possono agire o liquidare senza lasciare l'app corrente.
• Notifiche a schermo di blocco . Notifiche mostrate su una schermata di blocco con controllo granulare sulla visibilità.

Le implementazioni del dispositivo Android, quando tali notifiche sono rese visibili, devono eseguire correttamente notifiche ricche e heads-up e includere il titolo/nome, icona, testo come documentato nelle API Android .

Android include API di servizio di listener di notifica che consentono alle app (una volta abilitate esplicitamente dall'utente) di ricevere una copia di tutte le notifiche quando vengono pubblicate o aggiornate. Le implementazioni del dispositivo devono inviare correttamente e prontamente le notifiche nella loro interalità a tutti questi servizi di ascoltatore installati e abilitati per gli utenti, inclusi tutti i metadati collegati all'oggetto di notifica.

Le implementazioni del dispositivo portatile devono supportare i comportamenti di aggiornamento, rimozione, risposta e raggruppamento delle notifiche come descritto in questa sezione .

Inoltre, le implementazioni del dispositivo portatile devono fornire:

• La capacità di controllare le notifiche direttamente nell'ombra di notifica.
• La convenienza visiva per attivare il pannello di controllo nell'ombra di notifica.
• La possibilità di bloccare, disattivare e ripristinare la preferenza di notifica da un pacchetto, sia nel pannello di controllo in linea che nell'app Impostazioni.

Tutte e 6 le sottoclassi dirette della Notification.Style class deve essere supportata come descritto nei documenti SDK .

Le implementazioni del dispositivo che supportano la funzione DND (non disturb) devono soddisfare i seguenti requisiti:

• Deve implementare un'attività che risponderebbe all'intento action_notification_policy_access_settings , che per le implementazioni con UI_MODE_TYPE_Normal deve essere un'attività in cui l'utente può concedere o negare l'accesso all'app alle configurazioni della politica DND.
• Deve, per quando l'implementazione del dispositivo ha fornito un mezzo per l'utente per concedere o negare le app di terze parti per accedere alla configurazione del criterio DND, visualizzare le regole DND automatiche create dalle applicazioni insieme alle regole create dall'utente e predefinite.
• Deve onorare i valori suppressedVisualEffects passati lungo la NotificationManager.Policy e se un'app ha impostato uno qualsiasi degli effetti SUPPRESED_EFFECT_SCREEN_OFF o SUPPREMED_EFFECT_SCREEN_ON, dovrebbe indicare all'utente che gli effetti visivi sono soppressi nel menu delle impostazioni DND.

3.8.4. Ricerca

Android include API che consentono agli sviluppatori di incorporare la ricerca nelle loro applicazioni ed esporre i dati della loro applicazione nella ricerca del sistema globale. In generale, questa funzionalità è costituita da una singola interfaccia utente a livello di sistema che consente agli utenti di inserire query, visualizzare i suggerimenti come utilizzano gli utenti e visualizzare i risultati. Le API Android consentono agli sviluppatori di riutilizzare questa interfaccia per fornire la ricerca all'interno delle proprie app e consentono agli sviluppatori di fornire risultati all'interfaccia utente di ricerca globale comune.

Le implementazioni del dispositivo Android dovrebbero includere la ricerca globale, una singola interfaccia utente di ricerca condivisa a livello di sistema in grado di suggerimenti in tempo reale in risposta all'input dell'utente. Le implementazioni del dispositivo dovrebbero implementare le API che consentono agli sviluppatori di riutilizzare questa interfaccia utente per fornire la ricerca all'interno delle proprie applicazioni. Le implementazioni del dispositivo che implementano l'interfaccia di ricerca globale devono implementare le API che consentono alle applicazioni di terze parti di aggiungere suggerimenti alla casella di ricerca quando viene eseguita in modalità di ricerca globale. Se non vengono installate applicazioni di terze parti che utilizzino questa funzionalità, il comportamento predefinito dovrebbe essere quello di visualizzare i risultati e i suggerimenti dei motori di ricerca Web.

Le implementazioni di dispositivi Android dovrebbero e le implementazioni automobilistiche Android devono implementare un assistente sul dispositivo per gestire l' azione di assistenza .

Android include anche le API di assistenza per consentire alle applicazioni di eleggere quante informazioni sul contesto attuale sono condivise con l'assistente sul dispositivo. Le implementazioni del dispositivo a supporto dell'azione assist devono indicare chiaramente all'utente finale quando il contesto viene condiviso visualizzando una luce bianca attorno ai bordi dello schermo. Per garantire una chiara visibilità all'utente finale, l'indicazione deve soddisfare o superare la durata e la luminosità dell'implementazione del progetto open source Android.

Questa indicazione può essere disabilitata per impostazione predefinita per le app preinstallate utilizzando l'API Assist and Voice InteractionService, se tutti i seguenti requisiti sono soddisfatti:

• L'app preinstallata deve richiedere che il contesto sia condiviso solo quando l'utente ha invocato l'app con uno dei seguenti mezzi e l'app è in esecuzione in primo piano:

  • Invocazione hotword
  • Input del tasto di navigazione/pulsante/gesto

• L'implementazione del dispositivo deve fornire una convenienza per abilitare l'indicazione, a meno di due navigazioni da (il menu delle impostazioni di input vocale predefinito e delle impostazioni dell'app Assistant) sezione 3.2.3.5 .

3.8.5. Toast

Le applicazioni possono utilizzare l' API "Toast" per visualizzare corde non moodali brevi all'utente finale che scompaiono dopo un breve periodo di tempo. Le implementazioni del dispositivo devono visualizzare brindisi dalle applicazioni agli utenti finali in un modo ad alta visibilità.

3.8.6. Temi

Android fornisce "temi" come meccanismo per le applicazioni per applicare stili in un'intera attività o applicazione.

Android include una famiglia a tema "Holo" come insieme di stili definiti per gli sviluppatori di applicazioni se vogliono abbinare l' aspetto del tema Holo come definito dall'SDK Android. Le implementazioni del dispositivo non devono alterare nessuno degli attributi del tema Holo esposti alle applicazioni.

Android include una famiglia di temi "materiale" come insieme di stili definiti per gli sviluppatori di applicazioni da utilizzare se vogliono abbinare l'aspetto e la sensazione del tema del design attraverso l'ampia varietà di diversi tipi di dispositivi Android. Le implementazioni del dispositivo devono supportare la famiglia del tema "materiale" e non devono alterare nessuno degli attributi tematici materiali o le loro attività esposte alle applicazioni.

Android include anche una famiglia a tema "dispositivo predefinito" come insieme di stili definiti per gli sviluppatori di applicazioni da utilizzare se vogliono abbinare l'aspetto del tema del dispositivo come definito dall'implementatore del dispositivo. Le implementazioni del dispositivo possono modificare gli attributi del tema predefinito del dispositivo esposti alle applicazioni.

Android supporta un tema variante con barre di sistema traslucide, che consente agli sviluppatori di applicazioni di riempire l'area dietro lo stato e la barra di navigazione con il loro contenuto dell'app. Per abilitare un'esperienza di sviluppatore coerente in questa configurazione, è importante che lo stile dell'icona della barra di stato sia mantenuto tra diverse implementazioni del dispositivo. Pertanto, le implementazioni del dispositivo Android devono utilizzare il bianco per le icone di stato del sistema (come la potenza del segnale e il livello della batteria) e le notifiche emesse dal sistema, a meno che l'icona non indicasse uno stato problematico o un'app richieda una barra di stato della luce utilizzando la flag System_Ui_Flag_light_Status_Bar. Quando un'app richiede una barra di stato della luce, le implementazioni del dispositivo Android devono modificare il colore delle icone di stato del sistema in nero (per i dettagli, fare riferimento a R.style ).

3.8.7. Sfondi animati

Android definisce un tipo di componente e un corrispondente API e ciclo di vita che consente alle applicazioni di esporre uno o più "sfondi vivi" all'utente finale. Gli sfondi dal vivo sono animazioni, motivi o immagini simili con capacità di input limitate che vengono visualizzate come sfondo, dietro altre applicazioni.

L'hardware è considerato in grado di eseguire sfondi vivi in ​​modo affidabile se può eseguire tutti gli sfondi vivi, senza limiti alla funzionalità, a un frame rate ragionevole senza effetti avversi su altre applicazioni. Se le limitazioni nell'hardware causano crash di sfondi e/o applicazioni, malfunzionamento, consumano CPU eccessiva o batteria o eseguono una velocità di frame inaccettabilmente bassa, l'hardware è considerato incapace di eseguire sfondo in tempo reale. Ad esempio, alcuni sfondi in diretta possono utilizzare un contesto OpenGL 2.0 o 3.x per rendere i loro contenuti. Lo sfondo in diretta non si eseguerà in modo affidabile su hardware che non supporta più contesti OpenGL perché l'uso del sfondo in diretta di un contesto OpenGL può essere in conflitto con altre applicazioni che utilizzano anche un contesto OpenGL.

Implementazioni del dispositivo in grado di eseguire sfondi in diretta in modo affidabile come descritto sopra, dovrebbero implementare sfondi in diretta e, se implementati, devono segnalare il flag di funzionalità della piattaforma Android.Software.live_wallpaper.

3.8.8. Commutazione dell'attività

Il codice sorgente Android upstream include la schermata Panoramica , un'interfaccia utente a livello di sistema per la commutazione delle attività e la visualizzazione di attività e attività di recente accessibile utilizzando un'immagine in miniatura dello stato grafico dell'applicazione nel momento in cui l'utente ha lasciato l'ultima volta l'applicazione. Le implementazioni del dispositivo tra cui il tasto di navigazione della funzione Recents, come dettagliato nella Sezione 7.2.3 , possono modificare l'interfaccia ma devono soddisfare i seguenti requisiti:

• Deve supportare almeno fino a 20 attività visualizzate.
• Dovrebbe almeno visualizzare il titolo di 4 attività alla volta.
• Deve implementare il comportamento di blocco dello schermo e fornire all'utente un menu Impostazioni per attivare la funzione.
• Dovrebbe visualizzare il colore di evidenziazione, l'icona, il titolo dello schermo in recenti.
• Dovrebbe visualizzare una convenienza di chiusura ("X") ma può ritardare fino a quando l'utente non interagisce con gli schermi.
• Dovrebbe implementare un collegamento per passare facilmente all'attività precedente
• Può visualizzare recenti affiliati come gruppo che si muove insieme.
• Dovrebbe attivare l'azione a switch veloce tra le due app utilizzate più di recente, quando il tasto della funzione dei recenti viene sfruttato due volte.
• Dovrebbe attivare la modalità multiwindow a schermo diviso, se supportato, quando il tasto dei recenti viene premuto a lungo.

Le implementazioni del dispositivo sono fortemente consigliate di utilizzare l'interfaccia utente Android a monte (o un'interfaccia basata su miniatura simile) per la schermata Panoramica.

3.8.9. Gestione degli ingressi

Android include il supporto per la gestione delle input e il supporto per i redattori di metodi di input di terze parti. Le implementazioni del dispositivo che consentono agli utenti di utilizzare metodi di input di terze parti sul dispositivo devono dichiarare la funzionalità della piattaforma Android.Software.input_Methods e supportare API IME come definito nella documentazione SDK Android.

Le implementazioni del dispositivo che dichiarano la funzione Android.Software.input_Methods devono fornire un meccanismo accessibile dall'utente per aggiungere e configurare i metodi di input di terze parti. Le implementazioni del dispositivo devono visualizzare l'interfaccia Impostazioni in risposta all'intento Android.settings.input_method_settings.

3.8.10. Controllo multimediale della schermata di blocco

L'API client di controllo remoto è deprecata da Android 5.0 a favore del modello di notifica multimediale che consente alle applicazioni multimediali di integrarsi con i controlli di riproduzione visualizzati sulla schermata di blocco. Le implementazioni del dispositivo che supportano una schermata di blocco, a meno che un automobile Android o l'implementazione di orologi, debbano visualizzare le notifiche della schermata di blocco incluso il modello di notifica multimediale.

3.8.11. Screen Savers (precedentemente sogni)

Android include il supporto per InteractiveScreensavers , precedentemente indicato come sogni. Screen Savers consentono agli utenti di interagire con le applicazioni quando un dispositivo collegato a una fonte di alimentazione è inattivo o attratto in un dock da scrivania. I dispositivi di orologi Android possono implementare screen salvavers, ma altri tipi di implementazioni dei dispositivi dovrebbero includere il supporto per le sceneggiatori e fornire un'opzione Impostazioni per gli utenti di configurare Screen Savers in risposta all'intento android.settings.DREAM_SETTINGS .

3.8.12. Posizione

Quando un dispositivo ha un sensore hardware (ad es. GPS) in grado di fornire le coordinate di posizione, le modalità di posizione devono essere visualizzate nel menu di posizione all'interno delle impostazioni.

3.8.13. Unicode e carattere

Android include il supporto per i caratteri emoji definiti in Unicode 9.0 . Tutte le implementazioni del dispositivo devono essere in grado di rendere questi caratteri emoji nel glifo a colori e quando le implementazioni di dispositivi Android includono un IME, dovrebbero fornire un metodo di input all'utente per questi caratteri emoji.

I dispositivi portatile Android dovrebbero supportare il tono della pelle e i diversi emoji familiari come specificato nel rapporto tecnico Unicode #51 .

Android include il supporto per il carattere roboto 2 con pesi diversi-san-serif-sottile, sans-serif-lughip, sans-serif-medio, sans-serif-n-n-n-n-n-n-n-n-n-n-n-n-n-n-n-black, sans-serif condensato, sans-serif-light-light- Devono essere tutti inclusi per le lingue disponibili sul dispositivo e per la copertura piena di Unicode 7.0 di latino, greco e cirillico, tra cui le gamme latine estese A, B, C e D e tutti glifi nel blocco dei simboli di valuta di Unicode 7.0.

3.8.14. Multi-finestre

Un'implementazione del dispositivo può scegliere di non implementare alcuna modalità multi-finestra, ma se ha la capacità di visualizzare più attività contemporaneamente, deve implementare tali modalità multi-finestre in conformità con i comportamenti dell'applicazione e le API descritte in Android SDK Multi-Window Modalità Supporto documentazione e soddisfare i seguenti requisiti:

• Le applicazioni possono indicare se sono in grado di operare in modalità multi-Window nel file AndroidManifest.xml, esplicitamente tramite android:resizeableActivity o implicitamente avendo il TargetSdkVersion> 24. App che imposta esplicitamente questo attributo su falso nel loro manifest deve non essere lanciato in modalità multi-finestra. Le app che non impostano l'attributo nel loro file manifest (TargetSdkVersion <24) possono essere lanciate in modalità multi-finestra, ma il sistema deve fornire avvertimento che l'app potrebbe non funzionare come previsto in modalità multi-finestra.
• Le implementazioni del dispositivo non devono offrire modalità a schermo diviso o a forma libera se sia l'altezza e la larghezza dello schermo sono inferiori a 440 dp.
• Le implementazioni del dispositivo con dimensioni dello schermo xlarge dovrebbero supportare la modalità Freeform.
• Le implementazioni di dispositivi televisivi Android devono supportare la modalità multi-finestra Modalità Picture-In-Picture (PIP) e posizionare la finestra multipla PIP nell'angolo in alto a destra quando PIP è acceso.
• Le implementazioni del dispositivo con il supporto multi-finestra in modalità PIP devono allocare almeno 240x135 DP per la finestra PIP.
• Se la modalità Multi-Window PIP è supportata, il tasto KeyEvent.KEYCODE_WINDOW deve essere utilizzato per controllare la finestra PIP; Altrimenti, la chiave deve essere disponibile per l'attività in primo piano.

3.9. Amministrazione del dispositivo

Android include funzionalità che consentono alle applicazioni consapevoli della sicurezza di eseguire funzioni di amministrazione dei dispositivi a livello di sistema, come l'applicazione di politiche di password o l'esecuzione di una pulizia remota, attraverso l' API di amministrazione dei dispositivi Android ]. Le implementazioni del dispositivo devono fornire un'implementazione della classe DevicePolicyManager . Le implementazioni del dispositivo che supportano una schermata di blocco sicure devono implementare l'intera gamma di politiche di amministrazione dei dispositivi definiti nella documentazione SDK Android e segnalare la funzionalità della piattaforma Android.Software.device_admin.

3.9.1 Provuzione dei dispositivi

3.9.1.1 Provuzione del proprietario del dispositivo

Se un'implementazione del dispositivo dichiara la funzione android.software.device_admin , deve implementare l' applicazione dell'app del proprietario del dispositivo di un'applicazione DPC Client Clicy (DEVICE COLLICE) come indicato di seguito:

• Quando l'implementazione del dispositivo non ha ancora dati utente configurati, IT:
  • Deve segnalare true per DevicePolicyManager.isProvisioningAllowed(ACTION_PROVISION_MANAGED_DEVICE) .
  • È necessario iscrivere l'applicazione DPC come app per il proprietario del dispositivo in risposta all'intento android.app.action.PROVISION_MANAGED_DEVICE .
  • È necessario iscrivere l'applicazione DPC come app per il proprietario del dispositivo se il dispositivo dichiara il supporto NFC di comunicazione a campo vicino () tramite il flag di funzionalità android.hardware.nfc e riceve un messaggio NFC contenente un record con tipo mime MIME_TYPE_PROVISIONING_NFC .
• Quando l'implementazione del dispositivo ha dati utente, IT:
  • Deve segnalare false per DevicePolicyManager.isProvisioningAllowed(ACTION_PROVISION_MANAGED_DEVICE) .
  • Non deve più iscrivere alcuna applicazione DPC come app del proprietario del dispositivo.

Le implementazioni del dispositivo possono avere un'applicazione preinstallata che esegue le funzioni di amministrazione del dispositivo, ma questa applicazione non deve essere impostata come app per il proprietario del dispositivo senza consenso esplicito o azione da parte dell'utente o dell'amministratore del dispositivo.

3.9.1.2 Produzione del profilo gestito

Se un'implementazione del dispositivo dichiara Android.Software.Managed_users, deve essere possibile iscrivere un'applicazione DPC (Disposition Policy Controller) come proprietario di un nuovo profilo gestito .

Il processo di provisioning del profilo gestito (il flusso avviato da Android.app.action.provision_managed_profile ) l'esperienza utente deve allinearsi con l'implementazione AOSP.

Le implementazioni del dispositivo devono fornire le seguenti prezzi degli utenti all'interno dell'interfaccia utente delle impostazioni per indicare all'utente quando una particolare funzione di sistema è stata disabilitata dal controller dei criteri del dispositivo (DPC):

• Un'icona coerente o altra convenienza degli utenti (ad esempio l'icona APS -Aosp a monte) da rappresentare quando una particolare impostazione è limitata da un amministratore del dispositivo.
• Un breve messaggio di spiegazione, come previsto dall'amministratore del dispositivo tramite setShortSupportMessage .
• L'icona dell'applicazione DPC.

3.9.2 Supporto del profilo gestito

I dispositivi capaci di profilo gestito sono quei dispositivi che:

• Dichiarare Android.Software.device_admin (vedere la sezione 3.9 Amministrazione dei dispositivi ).
• Non sono dispositivi a bassa RAM (vedere la Sezione 7.6.1 ).
• Assegnare l'archiviazione interna (non rimovibile) come archiviazione condivisa (vedere la Sezione 7.6.2 ).

I dispositivi capaci di profilo gestito devono:

• Dichiarare il flag di funzionalità della piattaforma android.software.managed_users .
• Supporto profili gestiti tramite le API android.app.admin.DevicePolicyManager .
• Consentire la creazione di un solo profilo gestito .
• Utilizzare un badge Icon (simile al badge di lavoro a monte AOSP) per rappresentare le applicazioni e i widget gestiti e altri elementi dell'interfaccia utente badge come recenti e notifiche.
• Visualizza un'icona di notifica (simile al badge di lavoro a monte AOSP) per indicare quando l'utente è all'interno di un'applicazione del profilo gestito.
• Visualizza un brindisi che indica che l'utente è nel profilo gestito se e quando il dispositivo si sveglia (action_user_present) e l'applicazione in primo piano è all'interno del profilo gestito.
• Laddove esista un profilo gestito, mostra una convenienza visiva nell'intento "scelta" per consentire all'utente di inoltrare l'intento dal profilo gestito all'utente primario o viceversa, se abilitato dal controller della politica del dispositivo.
• Laddove esiste un profilo gestito, esponi le seguenti convenzioni utente sia per l'utente principale che per il profilo gestito:
  • Contabilità separata per batteria, posizione, dati mobili e utilizzo di archiviazione per l'utente primario e il profilo gestito.
  • Gestione indipendente delle applicazioni VPN installate all'interno dell'utente primario o del profilo gestito.
  • Gestione indipendente delle applicazioni installate all'interno dell'utente primario o del profilo gestito.
  • Gestione indipendente degli account all'interno dell'utente primario o del profilo gestito.
• Assicurarsi che il dialer preinstallato, i contatti e le applicazioni di messaggistica possano cercare e cercare le informazioni sui chiamanti dal profilo gestito (se esiste) insieme a quelli del profilo primario, se il controller del criterio del dispositivo lo consente. Quando i contatti del profilo gestito vengono visualizzati nel registro delle chiamate preinstallate, l'interfaccia utente, in corso e le notifiche di chiamata, i contatti e le app di messaggistica mancati, devono essere tagliati con lo stesso badge utilizzato per indicare le applicazioni del profilo gestito.
• Deve garantire che soddisfi tutti i requisiti di sicurezza applicabili per un dispositivo con più utenti abilitati (vedere la sezione 9.5 ), anche se il profilo gestito non viene conteggiato come un altro utente oltre all'utente primario.
• Supportare la possibilità di specificare una schermata di blocco separata che soddisfa i seguenti requisiti per concedere l'accesso alle app in esecuzione in un profilo gestito.
  • Le implementazioni del dispositivo devono onorare DevicePolicyManager.ACTION_SET_NEW_PASSWORD Intent e mostrare un'interfaccia per configurare una credenziale di schermata di blocco separata per il profilo gestito.
  • Le credenziali della schermata di blocco del profilo gestito devono utilizzare gli stessi meccanismi di archiviazione e gestione delle credenziali del profilo genitore, come documentato nel sito del progetto Open Source Android
  • Le politiche della password DPC devono essere applicate solo alle credenziali della schermata di blocco del profilo gestito se non convocate l'istanza DevicePolicyManager restituita da GetParentProfileInstance .

3.10. Accessibilità

Android fornisce un livello di accessibilità che aiuta gli utenti con disabilità per navigare più facilmente i propri dispositivi. Inoltre, Android fornisce API a piattaforma che consentono alle implementazioni del servizio di accessibilità di ricevere callback per eventi utente e di sistema e generare meccanismi di feedback alternativi, come la navigazione text-to-speech, tattili e navigazione trackball/D-PAD.

Le implementazioni del dispositivo includono i seguenti requisiti:

• Le implementazioni automobilistiche Android dovrebbero fornire un'implementazione del framework di accessibilità Android coerente con l'implementazione di Android predefinita.
• Le implementazioni dei dispositivi (Android Automotive escluse) devono fornire un'implementazione del framework di accessibilità Android coerente con l'implementazione di Android predefinita.
• Le implementazioni dei dispositivi (escluse Android Automotive) devono supportare le implementazioni del servizio di accessibilità di terze parti tramite le API Android.AccessibilityService .
• Le implementazioni del dispositivo (Android Automotive escluse) devono generare accessibilità e consegnare questi eventi a tutte le accessibilità registrate Implementazioni in modo coerente con l'implementazione di Android predefinita

• Le implementazioni del dispositivo (dispositivi di orologi Android Automotive e Android senza esclusi output audio), devono fornire un meccanismo ad accesso utente per abilitare e disabilitare i servizi di accessibilità e devono visualizzare questa interfaccia in risposta a Android.Provider.settings.Action_Accessibility_Settings IntenT.

• Le implementazioni di dispositivi Android con output audio sono fortemente raccomandate per fornire implementazioni dei servizi di accessibilità sul dispositivo comparabili o superando la funzionalità del talkback ** e lo switch Access Accessibility Services (https://github.com/google/talkback).

• I dispositivi di watch Android con output audio dovrebbero fornire implementazioni di un servizio di accessibilità sul dispositivo comparabile o superando la funzionalità del servizio di accessibilità di Talkback (https://github.com/google/talkback).
• Le implementazioni del dispositivo dovrebbero fornire un meccanismo nel flusso di configurazione fuori dalla scatola per gli utenti per consentire i servizi di accessibilità pertinenti, nonché le opzioni per regolare le dimensioni del carattere, le dimensioni del display e i gesti di ingrandimento.

** Per le lingue supportate da text-to-speech.

Inoltre, si noti che se è presente un servizio di accessibilità precaricato, deve essere un'app a conoscenza dell'avvio diretto {DirectbootaWare} se il dispositivo ha un'archiviazione crittografata utilizzando la crittografia basata su file (FBE).

3.11. Da testo a voce

Android include API che consentono alle applicazioni di utilizzare i servizi TEX-to-Speech (TTS) e consente ai fornitori di servizi di fornire implementazioni dei servizi TTS. Device implementations reporting the feature android.hardware.audio.output MUST meet these requirements related to the Android TTS framework .

Android Automotive implementations:

• MUST support the Android TTS framework APIs.
• MAY support installation of third-party TTS engines. If supported, partners MUST provide a user-accessible interface that allows the user to select a TTS engine for use at system level.

All other device implementations:

• MUST support the Android TTS framework APIs and SHOULD include a TTS engine supporting the languages available on the device. Note that the upstream Android open source software includes a full-featured TTS engine implementation.
• MUST support installation of third-party TTS engines.
• MUST provide a user-accessible interface that allows users to select a TTS engine for use at the system level.

3.12. TV Input Framework

The Android Television Input Framework (TIF) simplifies the delivery of live content to Android Television devices. TIF provides a standard API to create input modules that control Android Television devices. Android Television device implementations MUST support TV Input Framework.

Device implementations that support TIF MUST declare the platform feature android.software.live_tv.

3.12.1. Applicazione televisiva

Any device implementation that declares support for Live TV MUST have an installed TV application (TV App). The Android Open Source Project provides an implementation of the TV App.

The TV App MUST provide facilities to install and use TV Channels and meet the following requirements:

• Device implementations MUST allow third-party TIF-based inputs ( third-party inputs ) to be installed and managed.
• Device implementations MAY provide visual separation between pre-installed TIF-based inputs (installed inputs) and third-party inputs.
• Device implementations MUST NOT display the third-party inputs more than a single navigation action away from the TV App (ie expanding a list of third-party inputs from the TV App).

3.12.1.1. Guida elettronica ai programmi

Android Television device implementations MUST show an informational and interactive overlay, which MUST include an electronic program guide (EPG) generated from the values in the TvContract.Programs fields. The EPG MUST meet the following requirements:

• The EPG MUST display information from all installed inputs and third-party inputs.
• The EPG MAY provide visual separation between the installed inputs and third-party inputs.
• The EPG is STRONGLY RECOMMENDED to display installed inputs and third-party inputs with equal prominence. The EPG MUST NOT display the third-party inputs more than a single navigation action away from the installed inputs on the EPG.
• On channel change, device implementations MUST display EPG data for the currently playing program.

3.12.1.2. Navigazione

The TV App MUST allow navigation for the following functions via the D-pad, Back, and Home keys on the Android Television device's input device(s) (ie remote control, remote control application, or game controller):

• Changing TV channels
• Opening EPG
• Configuring and tuning to third-party TIF-based inputs
• Opening Settings menu

The TV App SHOULD pass key events to HDMI inputs through CEC.

3.12.1.3. TV input app linking

Android Television device implementations MUST support TV input app linking , which allows all inputs to provide activity links from the current activity to another activity (ie a link from live programming to related content). The TV App MUST show TV input app linking when it is provided.

3.12.1.4. Tempo di spostamento

Android Television device implementations MUST support time shifting, which allows the user to pause and resume live content. Device implementations MUST provide the user a way to pause and resume the currently playing program, if time shifting for that program is available .

3.12.1.5. Registrazione televisiva

Android Television device implementations are STRONGLY RECOMMENDED to support TV recording. If the TV input supports recording, the EPG MAY provide a way to record a program if the recording of such a program is not prohibited . Device implementations SHOULD provide a user interface to play recorded programs.

3.13. Impostazioni rapide

Android device implementations SHOULD include a Quick Settings UI component that allow quick access to frequently used or urgently needed actions.

Android includes the quicksettings API allowing third party apps to implement tiles that can be added by the user alongside the system-provided tiles in the Quick Settings UI component. If a device implementation has a Quick Settings UI component, it:

• MUST allow the user to add or remove tiles from a third-party app to Quick Settings.
• MUST NOT automatically add a tile from a third-party app directly to Quick Settings.
• MUST display all the user-added tiles from third-party apps alongside the system-provided quick setting tiles.

3.14. Vehicle UI APIs

3.14.1. Vehicle Media UI

Any device implementation that declares automotive support MUST include a UI framework to support third-party apps consuming the MediaBrowser and MediaSession APIs.

The UI framework supporting third-party apps that depend on MediaBrowser and MediaSession has the following visual requirements:

• MUST display MediaItem icons and notification icons unaltered.
• MUST display those items as described by MediaSession, eg, metadata, icons, imagery.
• MUST show app title.
• MUST have drawer to present MediaBrowser hierarchy.

4. Application Packaging Compatibility

Device implementations MUST install and run Android “.apk” files as generated by the “aapt” tool included in the official Android SDK . For this reason device implementations SHOULD use the reference implementation's package management system.

The package manager MUST support verifying “.apk” files using the APK Signature Scheme v2 and JAR signing .

Devices implementations MUST NOT extend either the .apk , Android Manifest , Dalvik bytecode , or RenderScript bytecode formats in such a way that would prevent those files from installing and running correctly on other compatible devices.

Device implementations MUST NOT allow apps other than the current "installer of record" for the package to silently uninstall the app without any prompt, as documented in the SDK for the DELETE_PACKAGE permission. The only exceptions are the system package verifier app handling PACKAGE_NEEDS_VERIFICATION intent and the storage manager app handling ACTION_MANAGE_STORAGE intent.

5. Multimedia Compatibility

5.1. Media Codecs

Device implementations—

• MUST support the core media formats specified in the Android SDK documentation, except where explicitly permitted in this document.

• MUST support the media formats, encoders, decoders, file types, and container formats defined in the tables below and reported via MediaCodecList .

• MUST also be able to decode all profiles reported in its CamcorderProfile

• MUST be able to decode all formats it can encode. This includes all bitstreams that its encoders generate.

Codecs SHOULD aim for minimum codec latency, in other words, codecs—

• SHOULD NOT consume and store input buffers and return input buffers only once processed
• SHOULD NOT hold onto decoded buffers for longer than as specified by the standard (eg SPS).
• SHOULD NOT hold onto encoded buffers longer than required by the GOP structure.

All of the codecs listed in the table below are provided as software implementations in the preferred Android implementation from the Android Open Source Project.

Please note that neither Google nor the Open Handset Alliance make any representation that these codecs are free from third-party patents. Those intending to use this source code in hardware or software products are advised that implementations of this code, including in open source software or shareware, may require patent licenses from the relevant patent holders.

5.1.1. Codec audio

1 Required for device implementations that define android.hardware.microphone but optional for Android Watch device implementations.

2 Recording or playback MAY be performed in mono or stereo, but the decoding of AAC input buffers of multichannel streams (ie more than two channels) to PCM through the default AAC audio decoder in the android.media.MediaCodec API, the following MUST be supportato:

• decoding is performed without downmixing (eg a 5.0 AAC stream must be decoded to five channels of PCM, a 5.1 AAC stream must be decoded to six channels of PCM),
• dynamic range metadata, as defined in "Dynamic Range Control (DRC)" in ISO/IEC 14496-3, and the android.media.MediaFormat DRC keys to configure the dynamic range-related behaviors of the audio decoder. The AAC DRC keys were introduced in API 21,and are: KEY_AAC_DRC_ATTENUATION_FACTOR, KEY_AAC_DRC_BOOST_FACTOR, KEY_AAC_DRC_HEAVY_COMPRESSION, KEY_AAC_DRC_TARGET_REFERENCE_LEVEL and KEY_AAC_ENCODED_TARGET_LEVEL

3 Required for Android Handheld device implementations.

4 Required for device implementations that define android.hardware.microphone, including Android Watch device implementations.

5.1.2. Image Codecs

5.1.3. Codec video

• Codecs advertising HDR profile support MUST support HDR static metadata parsing and handling.

• If a media codec advertises intra refresh support, then it MUST support the refresh periods in the range of 10 - 60 frames and accurately operate within 20% of configured refresh period.

• Video codecs MUST support output and input bytebuffer sizes that accommodate the largest feasible compressed and uncompressed frame as dictated by the standard and configuration but also not overallocate.

• Video encoders and decoders MUST support YUV420 flexible color format (COLOR_FormatYUV420Flexible).

1 Required for device implementations that include camera hardware and define android.hardware.camera or android.hardware.camera.front.

2 Required for device implementations except Android Watch devices.

3 For acceptable quality of web video streaming and video-conference services, device implementations SHOULD use a hardware VP8 codec that meets the requirements .

4 Device implementations SHOULD support writing Matroska WebM files.

5 STRONGLY RECOMMENDED for Android Automotive, optional for Android Watch, and required for all other device types.

6 Applies only to Android Television device implementations.

5.2. Codifica video

H.264, VP8, VP9 and HEVC video encoders—

• MUST support dynamically configurable bitrates.
• SHOULD support variable frame rates, where video encoder SHOULD determine instantaneous frame duration based on the timestamps of input buffers, and allocate its bit bucket based on that frame duration.

H.263 and MPEG-4 video encoder SHOULD support dynamically configurable bitrates.

All video encoders SHOULD meet the following bitrate targets over two sliding windows:

• It SHOULD be not more than ~15% over the bitrate between intraframe (I-frame) intervals.
• It SHOULD be not more than ~100% over the bitrate over a sliding window of 1 second.

5.2.1. H.263

Android device implementations with H.263 encoders MUST support Baseline Profile Level 45.

5.2.2. H-264

Android device implementations with H.264 codec support:

• MUST support Baseline Profile Level 3.
  However, support for ASO (Arbitrary Slice Ordering), FMO (Flexible Macroblock Ordering) and RS (Redundant Slices) is OPTIONAL. Moreover, to maintain compatibility with other Android devices, it is RECOMMENDED that ASO, FMO and RS are not used for Baseline Profile by encoders.
• MUST support the SD (Standard Definition) video encoding profiles in the following table.
• SHOULD support Main Profile Level 4.
• SHOULD support the HD (High Definition) video encoding profiles as indicated in the following table.
• In addition, Android Television devices are STRONGLY RECOMMENDED to encode HD 1080p video at 30 fps.

1 When supported by hardware, but STRONGLY RECOMMENDED for Android Television devices.

5.2.3. VP8

Android device implementations with VP8 codec support MUST support the SD video encoding profiles and SHOULD support the following HD (High Definition) video encoding profiles.

1 When supported by hardware.

5.3. Decodifica video

Device implementations—

• MUST support dynamic video resolution and frame rate switching through the standard Android APIs within the same stream for all VP8, VP9, H.264, and H.265 codecs in real time and up to the maximum resolution supported by each codec on the device.

• Implementations that support the Dolby Vision decoder—

• MUST provide a Dolby Vision-capable extractor.

• MUST properly display Dolby Vision content on the device screen or on a standard video output port (eg, HDMI).

• Implementations that provide a Dolby Vision-capable extractor MUST set the track index of backward-compatible base-layer(s) (if present) to be the same as the combined Dolby Vision layer's track index.

5.3.1. MPEG-2

Android device implementations with MPEG-2 decoders must support the Main Profile High Level.

5.3.2. H.263

Android device implementations with H.263 decoders MUST support Baseline Profile Level 30 and Level 45.

5.3.3. MPEG-4

Android device implementations with MPEG-4 decoders MUST support Simple Profile Level 3.

5.3.4. H.264

Android device implementations with H.264 decoders:

• MUST support Main Profile Level 3.1 and Baseline Profile.
  Support for ASO (Arbitrary Slice Ordering), FMO (Flexible Macroblock Ordering) and RS (Redundant Slices) is OPTIONAL.
• MUST be capable of decoding videos with the SD (Standard Definition) profiles listed in the following table and encoded with the Baseline Profile and Main Profile Level 3.1 (including 720p30).
• SHOULD be capable of decoding videos with the HD (High Definition) profiles as indicated in the following table.
• In addition, Android Television devices—
  • MUST support High Profile Level 4.2 and the HD 1080p60 decoding profile.
  • MUST be capable of decoding videos with both HD profiles as indicated in the following table and encoded with either the Baseline Profile, Main Profile, or the High Profile Level 4.2

1 REQUIRED for when the height as reported by the Display.getSupportedModes() method is equal or greater than the video resolution.

2 REQUIRED for Android Television device implementations.

5.3.5. H.265 (HEVC)

Android device implementations, when supporting H.265 codec as described in section 5.1.3 :

• MUST support the Main Profile Level 3 Main tier and the SD video decoding profiles as indicated in the following table.
• SHOULD support the HD decoding profiles as indicated in the following table.
• MUST support the HD decoding profiles as indicated in the following table if there is a hardware decoder.
• In addition, Android Television devices:
• MUST support the HD 720p decoding profile.
• STRONGLY RECOMMENDED to support the HD 1080p decoding profile. If the HD 1080p decoding profile is supported, it MUST support the Main Profile Level 4.1 Main tier.
• SHOULD support the UHD decoding profile. If the UHD decoding profile is supported the codec MUST support Main10 Level 5 Main Tier profile.

1 REQUIRED for Android Television device implementations with H.265 hardware decoding.

5.3.6. VP8

Android device implementations, when supporting VP8 codec as described in section 5.1.3 :

• MUST support the SD decoding profiles in the following table.
• SHOULD support the HD decoding profiles in the following table.
• Android Television devices MUST support the HD 1080p60 decoding profile.

1 REQUIRED for when the height as reported by the Display.getSupportedModes() method is equal or greater than the video resolution.

2 REQUIRED for Android Television device implementations.

5.3.7. VP9

Android device implementations, when supporting VP9 codec as described in section 5.1.3 :

• MUST support the SD video decoding profiles as indicated in the following table.
• SHOULD support the HD decoding profiles as indicated in the following table.
• MUST support the HD decoding profiles as indicated in the following table, if there is a hardware decoder.

• In addition, Android Television devices:

  • MUST support the HD 720p decoding profile.
  • STRONGLY RECOMMENDED to support the HD 1080p decoding profile.
  • SHOULD support the UHD decoding profile. If the UHD video decoding profile is supported, it MUST support 8-bit color depth and SHOULD support VP9 Profile 2 (10-bit).

1 REQUIRED for Android Television device implementations with VP9 hardware decoding.

5.4. Registrazione audio

While some of the requirements outlined in this section are stated as SHOULD since Android 4.3, the Compatibility Definition for a future version is planned to change these to MUST. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements that are stated as SHOULD, or they will not be able to attain Android compatibility when upgraded to the future version.

5.4.1. Raw Audio Capture

Device implementations that declare android.hardware.microphone MUST allow capture of raw audio content with the following characteristics:

• Format : Linear PCM, 16-bit
• Sampling rates : 8000, 11025, 16000, 44100
• Channels : Mono

The capture for the above sample rates MUST be done without up-sampling, and any down-sampling MUST include an appropriate anti-aliasing filter.

Device implementations that declare android.hardware.microphone SHOULD allow capture of raw audio content with the following characteristics:

• Format : Linear PCM, 16-bit
• Sampling rates : 22050, 48000
• Channels : Stereo

If capture for the above sample rates is supported, then the capture MUST be done without up-sampling at any ratio higher than 16000:22050 or 44100:48000. Any up-sampling or down-sampling MUST include an appropriate anti-aliasing filter.

5.4.2. Capture for Voice Recognition

The android.media.MediaRecorder.AudioSource.VOICE_RECOGNITION audio source MUST support capture at one of the sampling rates, 44100 and 48000.

In addition to the above recording specifications, when an application has started recording an audio stream using the android.media.MediaRecorder.AudioSource.VOICE_RECOGNITION audio source:

• The device SHOULD exhibit approximately flat amplitude versus frequency characteristics: specifically, ±3 dB, from 100 Hz to 4000 Hz.
• Audio input sensitivity SHOULD be set such that a 90 dB sound power level (SPL) source at 1000 Hz yields RMS of 2500 for 16-bit samples.
• PCM amplitude levels SHOULD linearly track input SPL changes over at least a 30 dB range from -18 dB to +12 dB re 90 dB SPL at the microphone.
• Total harmonic distortion SHOULD be less than 1% for 1 kHz at 90 dB SPL input level at the microphone.
• Noise reduction processing, if present, MUST be disabled.
• Automatic gain control, if present, MUST be disabled.

If the platform supports noise suppression technologies tuned for speech recognition, the effect MUST be controllable from the android.media.audiofx.NoiseSuppressor API. Moreover, the UUID field for the noise suppressor's effect descriptor MUST uniquely identify each implementation of the noise suppression technology.

5.4.3. Capture for Rerouting of Playback

The android.media.MediaRecorder.AudioSource class includes the REMOTE_SUBMIX audio source. Devices that declare android.hardware.audio.output MUST properly implement the REMOTE_SUBMIX audio source so that when an application uses the android.media.AudioRecord API to record from this audio source, it can capture a mix of all audio streams except for the following :

• STREAM_RING
• STREAM_ALARM
• STREAM_NOTIFICATION

5.5. Riproduzione audio

Device implementations that declare android.hardware.audio.output MUST conform to the requirements in this section.

5.5.1. Raw Audio Playback

The device MUST allow playback of raw audio content with the following characteristics:

• Format : Linear PCM, 16-bit
• Sampling rates : 8000, 11025, 16000, 22050, 32000, 44100
• Channels : Mono, Stereo

The device SHOULD allow playback of raw audio content with the following characteristics:

• Sampling rates : 24000, 48000

5.5.2. Effetti audio

Android provides an API for audio effects for device implementations. Device implementations that declare the feature android.hardware.audio.output:

• MUST support the EFFECT_TYPE_EQUALIZER and EFFECT_TYPE_LOUDNESS_ENHANCER implementations controllable through the AudioEffect subclasses Equalizer, LoudnessEnhancer.
• MUST support the visualizer API implementation, controllable through the Visualizer class.
• SHOULD support the EFFECT_TYPE_BASS_BOOST, EFFECT_TYPE_ENV_REVERB, EFFECT_TYPE_PRESET_REVERB, and EFFECT_TYPE_VIRTUALIZER implementations controllable through the AudioEffect sub-classes BassBoost, EnvironmentalReverb, PresetReverb, and Virtualizer.

5.5.3. Audio Output Volume

Android Television device implementations MUST include support for system Master Volume and digital audio output volume attenuation on supported outputs, except for compressed audio passthrough output (where no audio decoding is done on the device).

Android Automotive device implementations SHOULD allow adjusting audio volume separately per each audio stream using the content type or usage as defined by AudioAttributes and car audio usage as publicly defined in android.car.CarAudioManager .

5.6. Audio Latency

Audio latency is the time delay as an audio signal passes through a system. Many classes of applications rely on short latencies, to achieve real-time sound effects.

For the purposes of this section, use the following definitions:

• output latency . The interval between when an application writes a frame of PCM-coded data and when the corresponding sound is presented to environment at an on-device transducer or signal leaves the device via a port and can be observed externally.
• cold output latency . The output latency for the first frame, when the audio output system has been idle and powered down prior to the request.
• continuous output latency . The output latency for subsequent frames, after the device is playing audio.
• input latency . The interval between when a sound is presented by environment to device at an on-device transducer or signal enters the device via a port and when an application reads the corresponding frame of PCM-coded data.
• lost input . The initial portion of an input signal that is unusable or unavailable.
• cold input latency . The sum of lost input time and the input latency for the first frame, when the audio input system has been idle and powered down prior to the request.
• continuous input latency . The input latency for subsequent frames, while the device is capturing audio.
• cold output jitter . The variability among separate measurements of cold output latency values.
• cold input jitter . The variability among separate measurements of cold input latency values.
• continuous round-trip latency . The sum of continuous input latency plus continuous output latency plus one buffer period. The buffer period allows time for the app to process the signal and time for the app to mitigate phase difference between input and output streams.
• OpenSL ES PCM buffer queue API . The set of PCM-related OpenSL ES APIs within Android NDK .

Device implementations that declare android.hardware.audio.output are STRONGLY RECOMMENDED to meet or exceed these audio output requirements:

• cold output latency of 100 milliseconds or less
• continuous output latency of 45 milliseconds or less
• minimize the cold output jitter

If a device implementation meets the requirements of this section after any initial calibration when using the OpenSL ES PCM buffer queue API, for continuous output latency and cold output latency over at least one supported audio output device, it is STRONGLY RECOMMENDED to report support for low-latency audio, by reporting the feature android.hardware.audio.low_latency via the android.content.pm.PackageManager class. Conversely, if the device implementation does not meet these requirements it MUST NOT report support for low-latency audio.

Device implementations that include android.hardware.microphone are STRONGLY RECOMMENDED to meet these input audio requirements:

• cold input latency of 100 milliseconds or less
• continuous input latency of 30 milliseconds or less
• continuous round-trip latency of 50 milliseconds or less
• minimize the cold input jitter

5.7. Protocolli di rete

Devices MUST support the media network protocols for audio and video playback as specified in the Android SDK documentation. Specifically, devices MUST support the following media network protocols:

• HTTP(S) progressive streaming
  All required codecs and container formats in section 5.1 MUST be supported over HTTP(S)

• HTTP Live Streaming draft protocol, Version 7
  The following media segment formats MUST be supported:

• RTSP (RTP, SDP)

  The following RTP audio video profile and related codecs MUST be supported. For exceptions please see the table footnotes in section 5.1 .

5.8. Supporti sicuri

Device implementations that support secure video output and are capable of supporting secure surfaces MUST declare support for Display.FLAG_SECURE. Device implementations that declare support for Display.FLAG_SECURE, if they support a wireless display protocol, MUST secure the link with a cryptographically strong mechanism such as HDCP 2.x or higher for Miracast wireless displays. Similarly if they support a wired external display, the device implementations MUST support HDCP 1.2 or higher. Android Television device implementations MUST support HDCP 2.2 for devices supporting 4K resolution and HDCP 1.4 or above for lower resolutions. The upstream Android open source implementation includes support for wireless (Miracast) and wired (HDMI) displays that satisfies this requirement.

5.9. Interfaccia digitale per strumenti musicali (MIDI)

If a device implementation supports the inter-app MIDI software transport (virtual MIDI devices), and it supports MIDI over all of the following MIDI-capable hardware transports for which it provides generic non-MIDI connectivity, it is STRONGLY RECOMMENDED to report support for feature android.software.midi via the android.content.pm.PackageManager class.

The MIDI-capable hardware transports are:

• USB host mode (section 7.7 USB)
• USB peripheral mode (section 7.7 USB)
• MIDI over Bluetooth LE acting in central role (section 7.4.3 Bluetooth)

Conversely, if the device implementation provides generic non-MIDI connectivity over a particular MIDI-capable hardware transport listed above, but does not support MIDI over that hardware transport, it MUST NOT report support for feature android.software.midi.

5.10. Audio professionale

If a device implementation meets all of the following requirements, it is STRONGLY RECOMMENDED to report support for feature android.hardware.audio.pro via the android.content.pm.PackageManager class.

• The device implementation MUST report support for feature android.hardware.audio.low_latency.
• The continuous round-trip audio latency, as defined in section 5.6 Audio Latency, MUST be 20 milliseconds or less and SHOULD be 10 milliseconds or less over at least one supported path.
• If the device includes a 4 conductor 3.5mm audio jack, the continuous round-trip audio latency MUST be 20 milliseconds or less over the audio jack path, and SHOULD be 10 milliseconds or less over at the audio jack path.
• The device implementation MUST include a USB port(s) supporting USB host mode and USB peripheral mode.
• The USB host mode MUST implement the USB audio class.
• If the device includes an HDMI port, the device implementation MUST support output in stereo and eight channels at 20-bit or 24-bit depth and 192 kHz without bit-depth loss or resampling.
• The device implementation MUST report support for feature android.software.midi.
• If the device includes a 4 conductor 3.5mm audio jack, the device implementation is STRONGLY RECOMMENDED to comply with section Mobile device (jack) specifications of the Wired Audio Headset Specification (v1.1) .

Latencies and USB audio requirements MUST be met using the OpenSL ES PCM buffer queue API.

In addition, a device implementation that reports support for this feature SHOULD:

• Provide a sustainable level of CPU performance while audio is active.
• Minimize audio clock inaccuracy and drift relative to standard time.
• Minimize audio clock drift relative to the CPU CLOCK_MONOTONIC when both are active.
• Minimize audio latency over on-device transducers.
• Minimize audio latency over USB digital audio.
• Document audio latency measurements over all paths.
• Minimize jitter in audio buffer completion callback entry times, as this affects usable percentage of full CPU bandwidth by the callback.
• Provide zero audio underruns (output) or overruns (input) under normal use at reported latency.
• Provide zero inter-channel latency difference.
• Minimize MIDI mean latency over all transports.
• Minimize MIDI latency variability under load (jitter) over all transports.
• Provide accurate MIDI timestamps over all transports.
• Minimize audio signal noise over on-device transducers, including the period immediately after cold start.
• Provide zero audio clock difference between the input and output sides of corresponding end-points, when both are active. Examples of corresponding end-points include the on-device microphone and speaker, or the audio jack input and output.
• Handle audio buffer completion callbacks for the input and output sides of corresponding end-points on the same thread when both are active, and enter the output callback immediately after the return from the input callback. Or if it is not feasible to handle the callbacks on the same thread, then enter the output callback shortly after entering the input callback to permit the application to have a consistent timing of the input and output sides.
• Minimize the phase difference between HAL audio buffering for the input and output sides of corresponding end-points.
• Minimize touch latency.
• Minimize touch latency variability under load (jitter).

5.11. Capture for Unprocessed

Starting from Android 7.0, a new recording source has been added. It can be accessed using the android.media.MediaRecorder.AudioSource.UNPROCESSED audio source. In OpenSL ES, it can be accessed with the record preset SL_ANDROID_RECORDING_PRESET_UNPROCESSED .

A device MUST satisfy all of the following requirements to report support of the unprocessed audio source via the android.media.AudioManager property PROPERTY_SUPPORT_AUDIO_SOURCE_UNPROCESSED :

• The device MUST exhibit approximately flat amplitude-versus-frequency characteristics in the mid-frequency range: specifically ±10dB from 100 Hz to 7000 Hz.

• The device MUST exhibit amplitude levels in the low frequency range: specifically from ±20 dB from 5 Hz to 100 Hz compared to the mid-frequency range.

• The device MUST exhibit amplitude levels in the high frequency range: specifically from ±30 dB from 7000 Hz to 22 KHz compared to the mid-frequency range.

• Audio input sensitivity MUST be set such that a 1000 Hz sinusoidal tone source played at 94 dB Sound Pressure Level (SPL) yields a response with RMS of 520 for 16 bit-samples (or -36 dB Full Scale for floating point/double precision samples ).

• SNR > 60 dB (difference between 94 dB SPL and equivalent SPL of self noise, A-weighted).

• Total harmonic distortion MUST be less than 1% for 1 kHZ at 90 dB SPL input level at the microphone.

• The only signal processing allowed in the path is a level multiplier to bring the level to desired range. This level multiplier MUST NOT introduce delay or latency to the signal path.

• No other signal processing is allowed in the path, such as Automatic Gain Control, High Pass Filter, or Echo Cancellation. If any signal processing is present in the architecture for any reason, it MUST be disabled and effectively introduce zero delay or extra latency to the signal path.

All SPL measurements are made directly next to the microphone under test.

For multiple microphone configurations, these requirements apply to each microphone.

It is STRONGLY RECOMMENDED that a device satisfy as many of the requirements for the signal path for the unprocessed recording source; however, a device must satisfy all of these requirements, listed above, if it claims to support the unprocessed audio source.

6. Developer Tools and Options Compatibility

6.1. Strumenti di sviluppo

Device implementations MUST support the Android Developer Tools provided in the Android SDK. Android compatible devices MUST be compatible with:

• Android Debug Bridge (adb)
  • Device implementations MUST support all adb functions as documented in the Android SDK including dumpsys .
  • The device-side adb daemon MUST be inactive by default and there MUST be a user-accessible mechanism to turn on the Android Debug Bridge. If a device implementation omits USB peripheral mode, it MUST implement the Android Debug Bridge via local-area network (such as Ethernet or 802.11).
  • Android includes support for secure adb. Secure adb enables adb on known authenticated hosts. Device implementations MUST support secure adb.
• Dalvik Debug Monitor Service (ddms)
  • Device implementations MUST support all ddms features as documented in the Android SDK.
  • As ddms uses adb, support for ddms SHOULD be inactive by default, but MUST be supported whenever the user has activated the Android Debug Bridge, as above.
• Monkey Device implementations MUST include the Monkey framework, and make it available for applications to use.
• SysTrace
  • Device implementations MUST support systrace tool as documented in the Android SDK. Systrace must be inactive by default, and there MUST be a user-accessible mechanism to turn on Systrace.
  • Most Linux-based systems and Apple Macintosh systems recognize Android devices using the standard Android SDK tools, without additional support; however Microsoft Windows systems typically require a driver for new Android devices. (For instance, new vendor IDs and sometimes new device IDs require custom USB drivers for Windows systems.)
  • If a device implementation is unrecognized by the adb tool as provided in the standard Android SDK, device implementers MUST provide Windows drivers allowing developers to connect to the device using the adb protocol. These drivers MUST be provided for Windows XP, Windows Vista, Windows 7, Windows 8, and Windows 10 in both 32-bit and 64-bit versions.

6.2. Opzioni sviluppatore

Android includes support for developers to configure application development-related settings. Device implementations MUST honor the android.settings.APPLICATION_DEVELOPMENT_SETTINGS intent to show application development-related settings The upstream Android implementation hides the Developer Options menu by default and enables users to launch Developer Options after pressing seven (7) times on the Settings > About Device > Build Number menu item. Device implementations MUST provide a consistent experience for Developer Options. Specifically, device implementations MUST hide Developer Options by default and MUST provide a mechanism to enable Developer Options that is consistent with the upstream Android implementation.

7. Hardware Compatibility

If a device includes a particular hardware component that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation. If an API in the SDK interacts with a hardware component that is stated to be optional and the device implementation does not possess that component:

• Complete class definitions (as documented by the SDK) for the component APIs MUST still be presented.
• The API's behaviors MUST be implemented as no-ops in some reasonable fashion.
• API methods MUST return null values where permitted by the SDK documentation.
• API methods MUST return no-op implementations of classes where null values are not permitted by the SDK documentation.
• API methods MUST NOT throw exceptions not documented by the SDK documentation.

A typical example of a scenario where these requirements apply is the telephony API: Even on non-phone devices, these APIs must be implemented as reasonable no-ops.

Device implementations MUST consistently report accurate hardware configuration information via the getSystemAvailableFeatures() and hasSystemFeature(String) methods on the android.content.pm.PackageManager class for the same build fingerprint.

7.1. Visualizzazione e grafica

Android includes facilities that automatically adjust application assets and UI layouts appropriately for the device to ensure that third-party applications run well on a variety of hardware configurations . Devices MUST properly implement these APIs and behaviors, as detailed in this section.

The units referenced by the requirements in this section are defined as follows:

• physical diagonal size . The distance in inches between two opposing corners of the illuminated portion of the display.
• dots per inch (dpi) . The number of pixels encompassed by a linear horizontal or vertical span of 1”. Where dpi values are listed, both horizontal and vertical dpi must fall within the range.
• proporzioni . The ratio of the pixels of the longer dimension to the shorter dimension of the screen. For example, a display of 480x854 pixels would be 854/480 = 1.779, or roughly “16:9”.
• density-independent pixel (dp) . The virtual pixel unit normalized to a 160 dpi screen, calculated as: pixels = dps * (density/160).

7.1.1. Configurazione dello schermo

7.1.1.1. Dimensione dello schermo

The Android UI framework supports a variety of different screen sizes, and allows applications to query the device screen size (aka “screen layout") via android.content.res.Configuration.screenLayout with the SCREENLAYOUT_SIZE_MASK. Device implementations MUST report the correct screen size as defined in the Android SDK documentation and determined by the upstream Android platform. Specifically, device implementations MUST report the correct screen size according to the following logical density-independent pixel (dp) screen dimensions.

• Devices MUST have screen sizes of at least 426 dp x 320 dp ('small'), unless it is an Android Watch device.
• Devices that report screen size 'normal' MUST have screen sizes of at least 480 dp x 320 dp.
• Devices that report screen size 'large' MUST have screen sizes of at least 640 dp x 480 dp.
• Devices that report screen size 'xlarge' MUST have screen sizes of at least 960 dp x 720 dp.

Inoltre:

• Android Watch devices MUST have a screen with the physical diagonal size in the range from 1.1 to 2.5 inches.
• Android Automotive devices MUST have a screen with the physical diagonal size greater than or equal to 6 inches.
• Android Automotive devices MUST have a screen size of at least 750 dp x 480 dp.
• Other types of Android device implementations, with a physically integrated screen, MUST have a screen at least 2.5 inches in physical diagonal size.

Devices MUST NOT change their reported screen size at any time.

Applications optionally indicate which screen sizes they support via the <supports-screens> attribute in the AndroidManifest.xml file. Device implementations MUST correctly honor applications' stated support for small, normal, large, and xlarge screens, as described in the Android SDK documentation.

7.1.1.2. Proporzioni dello schermo

While there is no restriction to the screen aspect ratio value of the physical screen display, the screen aspect ratio of the surface that third-party apps are rendered on and which can be derived from the values reported via the DisplayMetrics MUST meet the following requirements:

• If the uiMode is configured as UI_MODE_TYPE_WATCH, the aspect ratio value MAY be set as 1.0 (1:1).
• If the third-party app indicates that it is resizeable via the android:resizeableActivity attribute, there are no restrictions to the aspect ratio value.
• For all other cases, the aspect ratio MUST be a value between 1.3333 (4:3) and 1.86 (roughly 16:9) unless the app has indicated explicitly that it supports a higher screen aspect ratio through the maxAspectRatio metadata value.

7.1.1.3. Densità dello schermo

The Android UI framework defines a set of standard logical densities to help application developers target application resources. By default, device implementations MUST report only one of the following logical Android framework densities through the DENSITY_DEVICE_STABLE API and this value MUST NOT change at any time; however, the device MAY report a different arbitrary density according to the display configuration changes made by the user (for example, display size) set after initial boot.

• 120 dpi (ldpi)
• 160 dpi (mdpi)
• 213 dpi (tvdpi)
• 240 dpi (hdpi)
• 260 dpi (260dpi)
• 280 dpi (280dpi)
• 300 dpi (300dpi)
• 320 dpi (xhdpi)
• 340 dpi (340dpi)
• 360 dpi (360dpi)
• 400 dpi (400dpi)
• 420 dpi (420dpi)
• 480 dpi (xxhdpi)
• 560 dpi (560dpi)
• 640 dpi (xxxhdpi)

Device implementations SHOULD define the standard Android framework density that is numerically closest to the physical density of the screen, unless that logical density pushes the reported screen size below the minimum supported. If the standard Android framework density that is numerically closest to the physical density results in a screen size that is smaller than the smallest supported compatible screen size (320 dp width), device implementations SHOULD report the next lowest standard Android framework density.

Device implementations are STRONGLY RECOMMENDED to provide users a setting to change the display size. If there is an implementation to change the display size of the device, it MUST align with the AOSP implementation as indicated below:

• The display size MUST NOT be scaled any larger than 1.5 times the native density or produce an effective minimum screen dimension smaller than 320dp (equivalent to resource qualifier sw320dp), whichever comes first.
• Display size MUST NOT be scaled any smaller than 0.85 times the native density.
• To ensure good usability and consistent font sizes, it is RECOMMENDED that the following scaling of Native Display options be provided (while complying with the limits specified above)
• Small: 0.85x
• Default: 1x (Native display scale)
• Large: 1.15x
• Larger: 1.3x
• Largest 1.45x

7.1.2. Visualizza metriche

Device implementations MUST report correct values for all display metrics defined in android.util.DisplayMetrics and MUST report the same values regardless of whether the embedded or external screen is used as the default display.

7.1.3. Orientamento schermo

Devices MUST report which screen orientations they support (android.hardware.screen.portrait and/or android.hardware.screen.landscape) and MUST report at least one supported orientation. For example, a device with a fixed orientation landscape screen, such as a television or laptop, SHOULD only report android.hardware.screen.landscape.

Devices that report both screen orientations MUST support dynamic orientation by applications to either portrait or landscape screen orientation. That is, the device must respect the application's request for a specific screen orientation. Device implementations MAY select either portrait or landscape orientation as the default.

Devices MUST report the correct value for the device's current orientation, whenever queried via the android.content.res.Configuration.orientation, android.view.Display.getOrientation(), or other APIs.

Devices MUST NOT change the reported screen size or density when changing orientation.

7.1.4. 2D and 3D Graphics Acceleration

Device implementations MUST support both OpenGL ES 1.0 and 2.0, as embodied and detailed in the Android SDK documentations. Device implementations SHOULD support OpenGL ES 3.0, 3.1, or 3.2 on devices capable of supporting it. Device implementations MUST also support Android RenderScript , as detailed in the Android SDK documentation.

Device implementations MUST also correctly identify themselves as supporting OpenGL ES 1.0, OpenGL ES 2.0, OpenGL ES 3.0, OpenGL 3.1, or OpenGL 3.2. Questo è:

• The managed APIs (such as via the GLES10.getString() method) MUST report support for OpenGL ES 1.0 and OpenGL ES 2.0.
• The native C/C++ OpenGL APIs (APIs available to apps via libGLES_v1CM.so, libGLES_v2.so, or libEGL.so) MUST report support for OpenGL ES 1.0 and OpenGL ES 2.0.
• Device implementations that declare support for OpenGL ES 3.0, 3.1, or 3.2 MUST support the corresponding managed APIs and include support for native C/C++ APIs. On device implementations that declare support for OpenGL ES 3.0, 3.1, or 3.2 libGLESv2.so MUST export the corresponding function symbols in addition to the OpenGL ES 2.0 function symbols.

Android provides an OpenGL ES extension pack with Java interfaces and native support for advanced graphics functionality such as tessellation and the ASTC texture compression format. Android device implementations MUST support the extension pack if the device supports OpenGL ES 3.2 and MAY support it otherwise. If the extension pack is supported in its entirety, the device MUST identify the support through the android.hardware.opengles.aep feature flag.

Also, device implementations MAY implement any desired OpenGL ES extensions. However, device implementations MUST report via the OpenGL ES managed and native APIs all extension strings that they do support, and conversely MUST NOT report extension strings that they do not support.

Note that Android includes support for applications to optionally specify that they require specific OpenGL texture compression formats. These formats are typically vendor-specific. Device implementations are not required by Android to implement any specific texture compression format. However, they SHOULD accurately report any texture compression formats that they do support, via the getString() method in the OpenGL API.

Android includes a mechanism for applications to declare that they want to enable hardware acceleration for 2D graphics at the Application, Activity, Window, or View level through the use of a manifest tag android:hardwareAccelerated or direct API calls.

Device implementations MUST enable hardware acceleration by default, and MUST disable hardware acceleration if the developer so requests by setting android:hardwareAccelerated="false” or disabling hardware acceleration directly through the Android View APIs.

In addition, device implementations MUST exhibit behavior consistent with the Android SDK documentation on hardware acceleration .

Android includes a TextureView object that lets developers directly integrate hardware-accelerated OpenGL ES textures as rendering targets in a UI hierarchy. Device implementations MUST support the TextureView API, and MUST exhibit consistent behavior with the upstream Android implementation.

Android includes support for EGL_ANDROID_RECORDABLE, an EGLConfig attribute that indicates whether the EGLConfig supports rendering to an ANativeWindow that records images to a video. Device implementations MUST support EGL_ANDROID_RECORDABLE extension.

7.1.5. Legacy Application Compatibility Mode

Android specifies a “compatibility mode” in which the framework operates in a 'normal' screen size equivalent (320dp width) mode for the benefit of legacy applications not developed for old versions of Android that pre-date screen-size independence.

• Android Automotive does not support legacy compatibility mode.
• All other device implementations MUST include support for legacy application compatibility mode as implemented by the upstream Android open source code. That is, device implementations MUST NOT alter the triggers or thresholds at which compatibility mode is activated, and MUST NOT alter the behavior of the compatibility mode itself.

7.1.6. Tecnologia dello schermo

The Android platform includes APIs that allow applications to render rich graphics to the display. Devices MUST support all of these APIs as defined by the Android SDK unless specifically allowed in this document.

• Devices MUST support displays capable of rendering 16-bit color graphics and SHOULD support displays capable of 24-bit color graphics.
• Devices MUST support displays capable of rendering animations.
• The display technology used MUST have a pixel aspect ratio (PAR) between 0.9 and 1.15. That is, the pixel aspect ratio MUST be near square (1.0) with a 10 ~ 15% tolerance.

7.1.7. Secondary Displays

Android includes support for secondary display to enable media sharing capabilities and developer APIs for accessing external displays. If a device supports an external display either via a wired, wireless, or an embedded additional display connection then the device implementation MUST implement the display manager API as described in the Android SDK documentation.

7.2. Dispositivi di input

Devices MUST support a touchscreen or meet the requirements listed in 7.2.2 for non-touch navigation.

7.2.1. Tastiera

Device implementations:

• MUST include support for the Input Management Framework (which allows third-party developers to create Input Method Editors—ie soft keyboard) as detailed at http://developer.android.com .
• MUST provide at least one soft keyboard implementation (regardless of whether a hard keyboard is present) except for Android Watch devices where the screen size makes it less reasonable to have a soft keyboard.
• MAY include additional soft keyboard implementations.
• MAY include a hardware keyboard.
• MUST NOT include a hardware keyboard that does not match one of the formats specified in android.content.res.Configuration.keyboard (QWERTY or 12-key).

7.2.2. Non-touch Navigation

Device implementations:

• MAY omit a non-touch navigation option (trackball, d-pad, or wheel) if the device implementation is not an Android Television device.
• MUST report the correct value for android.content.res.Configuration.navigation .
• MUST provide a reasonable alternative user interface mechanism for the selection and editing of text, compatible with Input Management Engines. The upstream Android open source implementation includes a selection mechanism suitable for use with devices that lack non-touch navigation inputs.

7.2.3. Tasti di navigazione

The Home, Recents, and Back functions (mapped to the key events KEYCODE_HOME, KEYCODE_APP_SWITCH, KEYCODE_BACK, respectively) are essential to the Android navigation paradigm and therefore:

• Android Handheld device implementations MUST provide the Home, Recents, and Back functions.
• Android Television device implementations MUST provide the Home and Back functions.
• Android Watch device implementations MUST have the Home function available to the user, and the Back function except for when it is in UI_MODE_TYPE_WATCH .
• Android Watch device implementations, and no other Android device types, MAY consume the long press event on the key event KEYCODE_BACK and omit it from being sent to the foreground application.
• Android Automotive implementations MUST provide the Home function and MAY provide Back and Recent functions.
• All other types of device implementations MUST provide the Home and Back functions.

These functions MAY be implemented via dedicated physical buttons (such as mechanical or capacitive touch buttons), or MAY be implemented using dedicated software keys on a distinct portion of the screen, gestures, touch panel, etc. Android supports both implementations. All of these functions MUST be accessible with a single action (eg tap, double-click or gesture) when visible.

Recents function, if provided, MUST have a visible button or icon unless hidden together with other navigation functions in full-screen mode. This does not apply to devices upgrading from earlier Android versions that have physical buttons for navigation and no recents key.

The Home and Back functions, if provided, MUST each have a visible button or icon unless hidden together with other navigation functions in full-screen mode or when the uiMode UI_MODE_TYPE_MASK is set to UI_MODE_TYPE_WATCH.

The Menu function is deprecated in favor of action bar since Android 4.0. Therefore the new device implementations shipping with Android 7.1 and later MUST NOT implement a dedicated physical button for the Menu function. Older device implementations SHOULD NOT implement a dedicated physical button for the Menu function, but if the physical Menu button is implemented and the device is running applications with targetSdkVersion > 10, the device implementation:

• MUST display the action overflow button on the action bar when it is visible and the resulting action overflow menu popup is not empty. For a device implementation launched before Android 4.4 but upgrading to Android 7.1, this is RECOMMENDED.
• MUST NOT modify the position of the action overflow popup displayed by selecting the overflow button in the action bar.
• MAY render the action overflow popup at a modified position on the screen when it is displayed by selecting the physical menu button.

For backwards compatibility, device implementations MUST make the Menu function available to applications when targetSdkVersion is less than 10, either by a physical button, a software key, or gestures. This Menu function should be presented unless hidden together with other navigation functions.

Android device implementations supporting the Assist action and/or VoiceInteractionService MUST be able to launch an assist app with a single interaction (eg tap, double-click, or gesture) when other navigation keys are visible. It is STRONGLY RECOMMENDED to use long press on home as this interaction. The designated interaction MUST launch the user-selected assist app, in other words the app that implements a VoiceInteractionService, or an activity handling the ACTION_ASSIST intent.

Device implementations MAY use a distinct portion of the screen to display the navigation keys, but if so, MUST meet these requirements:

• Device implementation navigation keys MUST use a distinct portion of the screen, not available to applications, and MUST NOT obscure or otherwise interfere with the portion of the screen available to applications.
• Device implementations MUST make available a portion of the display to applications that meets the requirements defined in section 7.1.1 .
• Device implementations MUST display the navigation keys when applications do not specify a system UI mode, or specify SYSTEM_UI_FLAG_VISIBLE.
• Device implementations MUST present the navigation keys in an unobtrusive “low profile” (eg. dimmed) mode when applications specify SYSTEM_UI_FLAG_LOW_PROFILE.
• Device implementations MUST hide the navigation keys when applications specify SYSTEM_UI_FLAG_HIDE_NAVIGATION.

7.2.4. Touchscreen Input

Device implementations SHOULD have a pointer input system of some kind (either mouse-like or touch). However, if a device implementation does not support a pointer input system, it MUST NOT report the android.hardware.touchscreen or android.hardware.faketouch feature constant. Device implementations that do include a pointer input system:

• SHOULD support fully independently tracked pointers, if the device input system supports multiple pointers.
• MUST report the value of android.content.res.Configuration.touchscreen corresponding to the type of the specific touchscreen on the device.

Android includes support for a variety of touchscreens, touch pads, and fake touch input devices. Touchscreen-based device implementations are associated with a display such that the user has the impression of directly manipulating items on screen. Since the user is directly touching the screen, the system does not require any additional affordances to indicate the objects being manipulated. In contrast, a fake touch interface provides a user input system that approximates a subset of touchscreen capabilities. For example, a mouse or remote control that drives an on-screen cursor approximates touch, but requires the user to first point or focus then click. Numerous input devices like the mouse, trackpad, gyro-based air mouse, gyro-pointer, joystick, and multi-touch trackpad can support fake touch interactions. Android includes the feature constant android.hardware.faketouch, which corresponds to a high-fidelity non-touch (pointer-based) input device such as a mouse or trackpad that can adequately emulate touch-based input (including basic gesture support), and indicates that the device supports an emulated subset of touchscreen functionality. Device implementations that declare the fake touch feature MUST meet the fake touch requirements in section 7.2.5 .

Device implementations MUST report the correct feature corresponding to the type of input used. Device implementations that include a touchscreen (single-touch or better) MUST report the platform feature constant android.hardware.touchscreen. Device implementations that report the platform feature constant android.hardware.touchscreen MUST also report the platform feature constant android.hardware.faketouch. Device implementations that do not include a touchscreen (and rely on a pointer device only) MUST NOT report any touchscreen feature, and MUST report only android.hardware.faketouch if they meet the fake touch requirements in section 7.2.5 .

7.2.5. Fake Touch Input

Device implementations that declare support for android.hardware.faketouch:

• MUST report the absolute X and Y screen positions of the pointer location and display a visual pointer on the screen.
• MUST report touch event with the action code that specifies the state change that occurs on the pointer going down or up on the screen .
• MUST support pointer down and up on an object on the screen, which allows users to emulate tap on an object on the screen.
• MUST support pointer down, pointer up, pointer down then pointer up in the same place on an object on the screen within a time threshold, which allows users to emulate double tap on an object on the screen.
• MUST support pointer down on an arbitrary point on the screen, pointer move to any other arbitrary point on the screen, followed by a pointer up, which allows users to emulate a touch drag.
• MUST support pointer down then allow users to quickly move the object to a different position on the screen and then pointer up on the screen, which allows users to fling an object on the screen.

Devices that declare support for android.hardware.faketouch.multitouch.distinct MUST meet the requirements for faketouch above, and MUST also support distinct tracking of two or more independent pointer inputs.

7.2.6. Supporto per controller di gioco

Android Television device implementations MUST support button mappings for game controllers as listed below. The upstream Android implementation includes implementation for game controllers that satisfies this requirement.

7.2.6.1. Mappature dei pulsanti

Android Television device implementations MUST support the following key mappings:

1 KeyEvent

2 The above HID usages must be declared within a Game pad CA (0x01 0x0005).

3 This usage must have a Logical Minimum of 0, a Logical Maximum of 7, a Physical Minimum of 0, a Physical Maximum of 315, Units in Degrees, and a Report Size of 4. The logical value is defined to be the clockwise rotation away from the vertical axis; for example, a logical value of 0 represents no rotation and the up button being pressed, while a logical value of 1 represents a rotation of 45 degrees and both the up and left keys being pressed.

4 MotionEvent

1 MotionEvent

7.2.7. Telecomando

Android Television device implementations SHOULD provide a remote control to allow users to access the TV interface. The remote control MAY be a physical remote or can be a software-based remote that is accessible from a mobile phone or tablet. The remote control MUST meet the requirements defined below.

• Search affordance . Device implementations MUST fire KEYCODE_SEARCH (or KEYCODE_ASSIST if the device supports an assistant) when the user invokes voice search on either the physical or software-based remote.
• Navigazione . All Android Television remotes MUST include Back, Home, and Select buttons and support for D-pad events .

7.3. Sensori

Android includes APIs for accessing a variety of sensor types. Devices implementations generally MAY omit these sensors, as provided for in the following subsections. If a device includes a particular sensor type that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation and the Android Open Source documentation on sensors . For example, device implementations:

• MUST accurately report the presence or absence of sensors per the android.content.pm.PackageManager class.
• MUST return an accurate list of supported sensors via the SensorManager.getSensorList() and similar methods.
• MUST behave reasonably for all other sensor APIs (for example, by returning true or false as appropriate when applications attempt to register listeners, not calling sensor listeners when the corresponding sensors are not present; etc.).
• MUST report all sensor measurements using the relevant International System of Units (metric) values for each sensor type as defined in the Android SDK documentation.
• SHOULD report the event time in nanoseconds as defined in the Android SDK documentation, representing the time the event happened and synchronized with the SystemClock.elapsedRealtimeNano() clock. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements so they will be able to upgrade to the future platform releases where this might become a REQUIRED component. The synchronization error SHOULD be below 100 milliseconds.
• MUST report sensor data with a maximum latency of 100 milliseconds + 2 * sample_time for the case of a sensor streamed with a minimum required latency of 5 ms + 2 * sample_time when the application processor is active. This delay does not include any filtering delays.
• MUST report the first sensor sample within 400 milliseconds + 2 * sample_time of the sensor being activated. It is acceptable for this sample to have an accuracy of 0.

The list above is not comprehensive; the documented behavior of the Android SDK and the Android Open Source Documentations on sensors is to be considered authoritative.

Some sensor types are composite, meaning they can be derived from data provided by one or more other sensors. (Examples include the orientation sensor and the linear acceleration sensor.) Device implementations SHOULD implement these sensor types, when they include the prerequisite physical sensors as described in sensor types . If a device implementation includes a composite sensor it MUST implement the sensor as described in the Android Open Source documentation on composite sensors .

Some Android sensors support a “continuous” trigger mode , which returns data continuously. For any API indicated by the Android SDK documentation to be a continuous sensor, device implementations MUST continuously provide periodic data samples that SHOULD have a jitter below 3%, where jitter is defined as the standard deviation of the difference of the reported timestamp values between consecutive eventi.

Note that the device implementations MUST ensure that the sensor event stream MUST NOT prevent the device CPU from entering a suspend state or waking up from a suspend state.

Finally, when several sensors are activated, the power consumption SHOULD NOT exceed the sum of the individual sensor's reported power consumption.

7.3.1. Accelerometro

Device implementations SHOULD include a 3-axis accelerometer. Android Handheld devices, Android Automotive implementations, and Android Watch devices are STRONGLY RECOMMENDED to include this sensor. If a device implementation does include a 3-axis accelerometer, it:

• MUST implement and report TYPE_ACCELEROMETER sensor .
• MUST be able to report events up to a frequency of at least 50 Hz for Android Watch devices as such devices have a stricter power constraint and 100 Hz for all other device types.
• SHOULD report events up to at least 200 Hz.
• MUST comply with the Android sensor coordinate system as detailed in the Android APIs. Android Automotive implementations MUST comply with the Android car sensor coordinate system .
• MUST be capable of measuring from freefall up to four times the gravity (4g) or more on any axis.
• MUST have a resolution of at least 12-bits and SHOULD have a resolution of at least 16-bits.
• SHOULD be calibrated while in use if the characteristics changes over the life cycle and compensated, and preserve the compensation parameters between device reboots.
• SHOULD be temperature compensated.
• MUST have a standard deviation no greater than 0.05 m/s^, where the standard deviation should be calculated on a per axis basis on samples collected over a period of at least 3 seconds at the fastest sampling rate.
• SHOULD implement the TYPE_SIGNIFICANT_MOTION, TYPE_TILT_DETECTOR, TYPE_STEP_DETECTOR, TYPE_STEP_COUNTER composite sensors as described in the Android SDK document. Existing and new Android devices are STRONGLY RECOMMENDED to implement the TYPE_SIGNIFICANT_MOTION composite sensor. If any of these sensors are implemented, the sum of their power consumption MUST always be less than 4 mW and SHOULD each be below 2 mW and 0.5 mW for when the device is in a dynamic or static condition.
• If a gyroscope sensor is included, MUST implement the TYPE_GRAVITY and TYPE_LINEAR_ACCELERATION composite sensors and SHOULD implement the TYPE_GAME_ROTATION_VECTOR composite sensor. Existing and new Android devices are STRONGLY RECOMMENDED to implement the TYPE_GAME_ROTATION_VECTOR sensor.
• MUST implement a TYPE_ROTATION_VECTOR composite sensor, if a gyroscope sensor and a magnetometer sensor is also included.

7.3.2. Magnetometro

Device implementations SHOULD include a 3-axis magnetometer (compass). If a device does include a 3-axis magnetometer, it:

• MUST implement the TYPE_MAGNETIC_FIELD sensor and SHOULD also implement TYPE_MAGNETIC_FIELD_UNCALIBRATED sensor. Existing and new Android devices are STRONGLY RECOMMENDED to implement the TYPE_MAGNETIC_FIELD_UNCALIBRATED sensor.
• MUST be able to report events up to a frequency of at least 10 Hz and SHOULD report events up to at least 50 Hz.
• MUST comply with the Android sensor coordinate system as detailed in the Android APIs.
• MUST be capable of measuring between -900 µT and +900 µT on each axis before saturating.
• MUST have a hard iron offset value less than 700 µT and SHOULD have a value below 200 µT, by placing the magnetometer far from dynamic (current-induced) and static (magnet-induced) magnetic fields.
• MUST have a resolution equal or denser than 0.6 µT and SHOULD have a resolution equal or denser than 0.2 µT.
• SHOULD be temperature compensated.
• MUST support online calibration and compensation of the hard iron bias, and preserve the compensation parameters between device reboots.
• MUST have the soft iron compensation applied—the calibration can be done either while in use or during the production of the device.
• SHOULD have a standard deviation, calculated on a per axis basis on samples collected over a period of at least 3 seconds at the fastest sampling rate, no greater than 0.5 µT.
• MUST implement a TYPE_ROTATION_VECTOR composite sensor, if an accelerometer sensor and a gyroscope sensor is also included.
• MAY implement the TYPE_GEOMAGNETIC_ROTATION_VECTOR sensor if an accelerometer sensor is also implemented. However if implemented, it MUST consume less than 10 mW and SHOULD consume less than 3 mW when the sensor is registered for batch mode at 10 Hz.

7.3.3. GPS

Device implementations SHOULD include a GPS/GNSS receiver. If a device implementation does include a GPS/GNSS receiver and reports the capability to applications through the android.hardware.location.gps feature flag:

• It is STRONGLY RECOMMENDED that the device continue to deliver normal GPS/GNSS outputs to applications during an emergency phone call and that location output not be blocked during an emergency phone call.
• It MUST support location outputs at a rate of at least 1 Hz when requested via LocationManager#requestLocationUpdate .
• It MUST be able to determine the location in open-sky conditions (strong signals, negligible multipath, HDOP < 2) within 10 seconds (fast time to first fix), when connected to a 0.5 Mbps or faster data speed internet connection. This requirement is typically met by the use of some form of Assisted or Predicted GPS/GNSS technique to minimize GPS/GNSS lock-on time (Assistance data includes Reference Time, Reference Location and Satellite Ephemeris/Clock).
  • After making such a location calculation, it is STRONGLY RECOMMENDED for the device to be able to determine its location, in open sky, within 10 seconds, when location requests are restarted, up to an hour after the initial location calculation, even when the subsequent request is made without a data connection, and/or after a power cycle.
• In open sky conditions after determining the location, while stationary or moving with less than 1 meter per second squared of acceleration:
  • It MUST be able to determine location within 20 meters, and speed within 0.5 meters per second, at least 95% of the time.
  • It MUST simultaneously track and report via GnssStatus.Callback at least 8 satellites from one constellation.
  • It SHOULD be able to simultaneously track at least 24 satellites, from multiple constellations (eg GPS + at least one of Glonass, Beidou, Galileo).
• It MUST report the GNSS technology generation through the test API 'getGnssYearOfHardware'.
• It is STRONGLY RECOMMENDED to meet and MUST meet all requirements below if the GNSS technology generation is reported as the year "2016" or newer.
  • It MUST report GPS measurements, as soon as they are found, even if a location calculated from GPS/GNSS is not yet reported.
  • It MUST report GPS pseudoranges and pseudorange rates, that, in open-sky conditions after determining the location, while stationary or moving with less than 0.2 meter per second squared of acceleration, are sufficient to calculate position within 20 meters, and speed within 0.2 meters per second, at least 95% of the time.

Note that while some of the GPS requirements above are stated as STRONGLY RECOMMENDED, the Compatibility Definition for the next major version is expected to change these to a MUST.

7.3.4. Giroscopio

Device implementations SHOULD include a gyroscope (angular change sensor). Devices SHOULD NOT include a gyroscope sensor unless a 3-axis accelerometer is also included. If a device implementation includes a gyroscope, it:

• MUST implement the TYPE_GYROSCOPE sensor and SHOULD also implement TYPE_GYROSCOPE_UNCALIBRATED sensor. Existing and new Android devices are STRONGLY RECOMMENDED to implement the SENSOR_TYPE_GYROSCOPE_UNCALIBRATED sensor.
• MUST be capable of measuring orientation changes up to 1,000 degrees per second.
• MUST be able to report events up to a frequency of at least 50 Hz for Android Watch devices as such devices have a stricter power constraint and 100 Hz for all other device types.
• SHOULD report events up to at least 200 Hz.
• MUST have a resolution of 12-bits or more and SHOULD have a resolution of 16-bits or more.
• MUST be temperature compensated.
• MUST be calibrated and compensated while in use, and preserve the compensation parameters between device reboots.
• MUST have a variance no greater than 1e-7 rad^2 / s^2 per Hz (variance per Hz, or rad^2 / s). The variance is allowed to vary with the sampling rate, but must be constrained by this value. In other words, if you measure the variance of the gyro at 1 Hz sampling rate it should be no greater than 1e-7 rad^2/s^2.
• MUST implement a TYPE_ROTATION_VECTOR composite sensor, if an accelerometer sensor and a magnetometer sensor is also included.
• If an accelerometer sensor is included, MUST implement the TYPE_GRAVITY and TYPE_LINEAR_ACCELERATION composite sensors and SHOULD implement the TYPE_GAME_ROTATION_VECTOR composite sensor. Existing and new Android devices are STRONGLY RECOMMENDED to implement the TYPE_GAME_ROTATION_VECTOR sensor.

7.3.5. Barometro

Device implementations SHOULD include a barometer (ambient air pressure sensor). If a device implementation includes a barometer, it:

• MUST implement and report TYPE_PRESSURE sensor.
• MUST be able to deliver events at 5 Hz or greater.
• MUST have adequate precision to enable estimating altitude.
• MUST be temperature compensated.

7.3.6. Termometro

Device implementations MAY include an ambient thermometer (temperature sensor). If present, it MUST be defined as SENSOR_TYPE_AMBIENT_TEMPERATURE and it MUST measure the ambient (room) temperature in degrees Celsius.

Device implementations MAY but SHOULD NOT include a CPU temperature sensor. If present, it MUST be defined as SENSOR_TYPE_TEMPERATURE, it MUST measure the temperature of the device CPU, and it MUST NOT measure any other temperature. Note the SENSOR_TYPE_TEMPERATURE sensor type was deprecated in Android 4.0.

7.3.7. Fotometro

Device implementations MAY include a photometer (ambient light sensor).

7.3.8. Sensore di prossimità

Device implementations MAY include a proximity sensor. Devices that can make a voice call and indicate any value other than PHONE_TYPE_NONE in getPhoneType SHOULD include a proximity sensor. If a device implementation does include a proximity sensor, it:

• MUST measure the proximity of an object in the same direction as the screen. That is, the proximity sensor MUST be oriented to detect objects close to the screen, as the primary intent of this sensor type is to detect a phone in use by the user. If a device implementation includes a proximity sensor with any other orientation, it MUST NOT be accessible through this API.
• MUST have 1-bit of accuracy or more.

7.3.9. High Fidelity Sensors

Device implementations supporting a set of higher quality sensors that can meet all the requirements listed in this section MUST identify the support through the android.hardware.sensor.hifi_sensors feature flag.

A device declaring android.hardware.sensor.hifi_sensors MUST support all of the following sensor types meeting the quality requirements as below:

• SENSOR_TYPE_ACCELEROMETER
  • MUST have a measurement range between at least -8g and +8g.
  • MUST have a measurement resolution of at least 1024 LSB/G.
  • MUST have a minimum measurement frequency of 12.5 Hz or lower.
  • MUST have a maximum measurement frequency of 400 Hz or higher.
  • MUST have a measurement noise not above 400 uG/√Hz.
  • MUST implement a non-wake-up form of this sensor with a buffering capability of at least 3000 sensor events.
  • MUST have a batching power consumption not worse than 3 mW.
  • SHOULD have a stationary noise bias stability of \<15 μg √Hz from 24hr static dataset.
  • SHOULD have a bias change vs. temperature of ≤ +/- 1mg / °C.
  • SHOULD have a best-fit line non-linearity of ≤ 0.5%, and sensitivity change vs. temperature of ≤ 0.03%/C°.

• SENSOR_TYPE_GYROSCOPE

  • MUST have a measurement range between at least -1000 and +1000 dps.
  • MUST have a measurement resolution of at least 16 LSB/dps.
  • MUST have a minimum measurement frequency of 12.5 Hz or lower.
  • MUST have a maximum measurement frequency of 400 Hz or higher.
  • MUST have a measurement noise not above 0.014°/s/√Hz.
  • SHOULD have a stationary bias stability of < 0.0002 °/s √Hz from 24-hour static dataset.
  • SHOULD have a bias change vs. temperature of ≤ +/- 0.05 °/ s / °C.
  • SHOULD have a sensitivity change vs. temperature of ≤ 0.02% / °C.
  • SHOULD have a best-fit line non-linearity of ≤ 0.2%.
  • SHOULD have a noise density of ≤ 0.007 °/s/√Hz.

• SENSOR_TYPE_GYROSCOPE_UNCALIBRATED with the same quality requirements as SENSOR_TYPE_GYROSCOPE.

• SENSOR_TYPE_GEOMAGNETIC_FIELD
  • MUST have a measurement range between at least -900 and +900 uT.
  • MUST have a measurement resolution of at least 5 LSB/uT.
  • MUST have a minimum measurement frequency of 5 Hz or lower.
  • MUST have a maximum measurement frequency of 50 Hz or higher.
  • MUST have a measurement noise not above 0.5 uT.
• SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED with the same quality requirements as SENSOR_TYPE_GEOMAGNETIC_FIELD and in addition:
  • MUST implement a non-wake-up form of this sensor with a buffering capability of at least 600 sensor events.
• SENSOR_TYPE_PRESSURE
  • MUST have a measurement range between at least 300 and 1100 hPa.
  • MUST have a measurement resolution of at least 80 LSB/hPa.
  • MUST have a minimum measurement frequency of 1 Hz or lower.
  • MUST have a maximum measurement frequency of 10 Hz or higher.
  • MUST have a measurement noise not above 2 Pa/√Hz.
  • MUST implement a non-wake-up form of this sensor with a buffering capability of at least 300 sensor events.
  • MUST have a batching power consumption not worse than 2 mW.
• SENSOR_TYPE_GAME_ROTATION_VECTOR
  • MUST implement a non-wake-up form of this sensor with a buffering capability of at least 300 sensor events.
  • MUST have a batching power consumption not worse than 4 mW.
• SENSOR_TYPE_SIGNIFICANT_MOTION
  • MUST have a power consumption not worse than 0.5 mW when device is static and 1.5 mW when device is moving.
• SENSOR_TYPE_STEP_DETECTOR
  • MUST implement a non-wake-up form of this sensor with a buffering capability of at least 100 sensor events.
  • MUST have a power consumption not worse than 0.5 mW when device is static and 1.5 mW when device is moving.
  • MUST have a batching power consumption not worse than 4 mW.
• SENSOR_TYPE_STEP_COUNTER
  • MUST have a power consumption not worse than 0.5 mW when device is static and 1.5 mW when device is moving.
• SENSOR_TILT_DETECTOR
  • MUST have a power consumption not worse than 0.5 mW when device is static and 1.5 mW when device is moving.

Also such a device MUST meet the following sensor subsystem requirements:

• The event timestamp of the same physical event reported by the Accelerometer, Gyroscope sensor and Magnetometer MUST be within 2.5 milliseconds of each other.
• The Gyroscope sensor event timestamps MUST be on the same time base as the camera subsystem and within 1 milliseconds of error.
• High Fidelity sensors MUST deliver samples to applications within 5 milliseconds from the time when the data is available on the physical sensor to the application.
• The power consumption MUST not be higher than 0.5 mW when device is static and 2.0 mW when device is moving when any combination of the following sensors are enabled:
  • SENSOR_TYPE_SIGNIFICANT_MOTION
  • SENSOR_TYPE_STEP_DETECTOR
  • SENSOR_TYPE_STEP_COUNTER
  • SENSOR_TILT_DETECTORS

Note that all power consumption requirements in this section do not include the power consumption of the Application Processor. It is inclusive of the power drawn by the entire sensor chain—the sensor, any supporting circuitry, any dedicated sensor processing system, etc.

The following sensor types MAY also be supported on a device implementation declaring android.hardware.sensor.hifi_sensors, but if these sensor types are present they MUST meet the following minimum buffering capability requirement:

• SENSOR_TYPE_PROXIMITY: 100 sensor events

7.3.10. Sensore di impronte digitali

Device implementations with a secure lock screen SHOULD include a fingerprint sensor. If a device implementation includes a fingerprint sensor and has a corresponding API for third-party developers, it:

• MUST declare support for the android.hardware.fingerprint feature.
• MUST fully implement the corresponding API as described in the Android SDK documentation.
• MUST have a false acceptance rate not higher than 0.002%.
• Is STRONGLY RECOMMENDED to have a false rejection rate of less than 10%, as measured on the device
• Is STRONGLY RECOMMENDED to have a latency below 1 second, measured from when the fingerprint sensor is touched until the screen is unlocked, for one enrolled finger.
• MUST rate limit attempts for at least 30 seconds after five false trials for fingerprint verification.
• MUST have a hardware-backed keystore implementation, and perform the fingerprint matching in a Trusted Execution Environment (TEE) or on a chip with a secure channel to the TEE.
• MUST have all identifiable fingerprint data encrypted and cryptographically authenticated such that they cannot be acquired, read or altered outside of the Trusted Execution Environment (TEE) as documented in the implementation guidelines on the Android Open Source Project site.
• MUST prevent adding a fingerprint without first establishing a chain of trust by having the user confirm existing or add a new device credential (PIN/pattern/password) that's secured by TEE; the Android Open Source Project implementation provides the mechanism in the framework to do so.
• MUST NOT enable 3rd-party applications to distinguish between individual fingerprints.
• MUST honor the DevicePolicyManager.KEYGUARD_DISABLE_FINGERPRINT flag.
• MUST, when upgraded from a version earlier than Android 6.0, have the fingerprint data securely migrated to meet the above requirements or removed.
• SHOULD use the Android Fingerprint icon provided in the Android Open Source Project.

7.3.11. Android Automotive-only sensors

Automotive-specific sensors are defined in the android.car.CarSensorManager API .

7.3.11.1. Marcia attuale

Android Automotive implementations SHOULD provide current gear as SENSOR_TYPE_GEAR.

7.3.11.2. Day Night Mode

Android Automotive implementations MUST support day/night mode defined as SENSOR_TYPE_NIGHT. The value of this flag MUST be consistent with dashboard day/night mode and SHOULD be based on ambient light sensor input. The underlying ambient light sensor MAY be the same as Photometer .

7.3.11.3. Stato di guida

Android Automotive implementations MUST support driving status defined as SENSOR_TYPE_DRIVING_STATUS, with a default value of DRIVE_STATUS_UNRESTRICTED when the vehicle is fully stopped and parked. It is the responsibility of device manufacturers to configure SENSOR_TYPE_DRIVING_STATUS in compliance with all laws and regulations that apply to markets where the product is shipping.

7.3.11.4. Velocità della ruota

Android Automotive implementations MUST provide vehicle speed defined as SENSOR_TYPE_CAR_SPEED.

7.3.12. Pose Sensor

Device implementations MAY support pose sensor with 6 degrees of freedom. Android Handheld devices are RECOMMENDED to support this sensor. If a device implementation does support pose sensor with 6 degrees of freedom, it:

• MUST implement and report TYPE_POSE_6DOF sensor.
• MUST be more accurate than the rotation vector alone.

7.4. Connettività dati

7.4.1. Telefonia

“Telephony” as used by the Android APIs and this document refers specifically to hardware related to placing voice calls and sending SMS messages via a GSM or CDMA network. While these voice calls may or may not be packet-switched, they are for the purposes of Android considered independent of any data connectivity that may be implemented using the same network. In other words, the Android “telephony” functionality and APIs refer specifically to voice calls and SMS. For instance, device implementations that cannot place calls or send/receive SMS messages MUST NOT report the android.hardware.telephony feature or any subfeatures, regardless of whether they use a cellular network for data connectivity.

Android MAY be used on devices that do not include telephony hardware. That is, Android is compatible with devices that are not phones. However, if a device implementation does include GSM or CDMA telephony, it MUST implement full support for the API for that technology. Device implementations that do not include telephony hardware MUST implement the full APIs as no-ops.

7.4.1.1. Number Blocking Compatibility

Android Telephony device implementations MUST include number blocking support and:

• MUST fully implement BlockedNumberContract and the corresponding API as described in the SDK documentation.
• MUST block all calls and messages from a phone number in 'BlockedNumberProvider' without any interaction with apps. The only exception is when number blocking is temporarily lifted as described in the SDK documentation.
• MUST NOT write to the platform call log provider for a blocked call.
• MUST NOT write to the Telephony provider for a blocked message.
• MUST implement a blocked numbers management UI, which is opened with the intent returned by TelecomManager.createManageBlockedNumbersIntent() method.
• MUST NOT allow secondary users to view or edit the blocked numbers on the device as the Android platform assumes the primary user to have full control of the telephony services, a single instance, on the device. All blocking related UI MUST be hidden for secondary users and the blocked list MUST still be respected.
• SHOULD migrate the blocked numbers into the provider when a device updates to Android 7.0.

7.4.2. IEEE 802.11 (Wi-Fi)

All Android device implementations SHOULD include support for one or more forms of 802.11. If a device implementation does include support for 802.11 and exposes the functionality to a third-party application, it MUST implement the corresponding Android API and:

• MUST report the hardware feature flag android.hardware.wifi.
• MUST implement the multicast API as described in the SDK documentation.
• MUST support multicast DNS (mDNS) and MUST NOT filter mDNS packets (224.0.0.251) at any time of operation including:
  • Even when the screen is not in an active state.
  • For Android Television device implementations, even when in standby power states.

7.4.2.1. Wi-Fi diretto

Device implementations SHOULD include support for Wi-Fi Direct (Wi-Fi peer-to-peer). If a device implementation does include support for Wi-Fi Direct, it MUST implement the corresponding Android API as described in the SDK documentation. If a device implementation includes support for Wi-Fi Direct, then it:

• MUST report the hardware feature android.hardware.wifi.direct.
• MUST support regular Wi-Fi operation.
• SHOULD support concurrent Wi-Fi and Wi-Fi Direct operation.

7.4.2.2. Wi-Fi Tunneled Direct Link Setup

Device implementations SHOULD include support for Wi-Fi Tunneled Direct Link Setup (TDLS) as described in the Android SDK Documentation. If a device implementation does include support for TDLS and TDLS is enabled by the WiFiManager API, the device:

• SHOULD use TDLS only when it is possible AND beneficial.
• SHOULD have some heuristic and NOT use TDLS when its performance might be worse than going through the Wi-Fi access point.

7.4.3. Bluetooth

Device implementations that support android.hardware.vr.high_performance feature MUST support Bluetooth 4.2 and Bluetooth LE Data Length Extension.

Android includes support for Bluetooth and Bluetooth Low Energy . Device implementations that include support for Bluetooth and Bluetooth Low Energy MUST declare the relevant platform features (android.hardware.bluetooth and android.hardware.bluetooth_le respectively) and implement the platform APIs. Device implementations SHOULD implement relevant Bluetooth profiles such as A2DP, AVCP, OBEX, etc. as appropriate for the device.

Android Automotive implementations SHOULD support Message Access Profile (MAP). Android Automotive implementations MUST support the following Bluetooth profiles:

• Phone calling over Hands-Free Profile (HFP).
• Media playback over Audio Distribution Profile (A2DP).
• Media playback control over Remote Control Profile (AVRCP).
• Contact sharing using the Phone Book Access Profile (PBAP).

Device implementations including support for Bluetooth Low Energy:

• MUST declare the hardware feature android.hardware.bluetooth_le.
• MUST enable the GATT (generic attribute profile) based Bluetooth APIs as described in the SDK documentation and android.bluetooth .
• are STRONGLY RECOMMENDED to implement a Resolvable Private Address (RPA) timeout no longer than 15 minutes and rotate the address at timeout to protect user privacy.
• SHOULD support offloading of the filtering logic to the bluetooth chipset when implementing the ScanFilter API , and MUST report the correct value of where the filtering logic is implemented whenever queried via the android.bluetooth.BluetoothAdapter.isOffloadedFilteringSupported() method.
• SHOULD support offloading of the batched scanning to the bluetooth chipset, but if not supported, MUST report 'false' whenever queried via the android.bluetooth.BluetoothAdapter.isOffloadedScanBatchingSupported() method.
• SHOULD support multi advertisement with at least 4 slots, but if not supported, MUST report 'false' whenever queried via the android.bluetooth.BluetoothAdapter.isMultipleAdvertisementSupported() method.

7.4.4. Near-Field Communications

Device implementations SHOULD include a transceiver and related hardware for Near-Field Communications (NFC). If a device implementation does include NFC hardware and plans to make it available to third-party apps, then it:

• MUST report the android.hardware.nfc feature from the android.content.pm.PackageManager.hasSystemFeature() method .
• MUST be capable of reading and writing NDEF messages via the following NFC standards:
  • MUST be capable of acting as an NFC Forum reader/writer (as defined by the NFC Forum technical specification NFCForum-TS-DigitalProtocol-1.0) via the following NFC standards:
    • NfcA (ISO14443-3A)
    • NfcB (ISO14443-3B)
    • NfcF (JIS X 6319-4)
    • IsoDep (ISO 14443-4)
    • NFC Forum Tag Types 1, 2, 3, 4 (defined by the NFC Forum)
  • STRONGLY RECOMMENDED to be capable of reading and writing NDEF messages as well as raw data via the following NFC standards. Note that while the NFC standards below are stated as STRONGLY RECOMMENDED, the Compatibility Definition for a future version is planned to change these to MUST. These standards are optional in this version but will be required in future versions. Existing and new devices that run this version of Android are very strongly encouraged to meet these requirements now so they will be able to upgrade to the future platform releases.
    • NfcV (ISO 15693)
  • SHOULD be capable of reading the barcode and URL (if encoded) of Thinfilm NFC Barcode products.
  • MUST be capable of transmitting and receiving data via the following peer-to-peer standards and protocols:
    • ISO 18092
    • LLCP 1.2 (defined by the NFC Forum)
    • SDP 1.0 (defined by the NFC Forum)
    • NDEF Push Protocol
    • SNEP 1.0 (defined by the NFC Forum)
  • MUST include support for Android Beam .
  • MUST implement the SNEP default server. Valid NDEF messages received by the default SNEP server MUST be dispatched to applications using the android.nfc.ACTION_NDEF_DISCOVERED intent. Disabling Android Beam in settings MUST NOT disable dispatch of incoming NDEF message.
  • MUST honor the android.settings.NFCSHARING_SETTINGS intent to show NFC sharing settings .
  • MUST implement the NPP server. Messages received by the NPP server MUST be processed the same way as the SNEP default server.
  • MUST implement a SNEP client and attempt to send outbound P2P NDEF to the default SNEP server when Android Beam is enabled. If no default SNEP server is found then the client MUST attempt to send to an NPP server.
  • MUST allow foreground activities to set the outbound P2P NDEF message using android.nfc.NfcAdapter.setNdefPushMessage, and android.nfc.NfcAdapter.setNdefPushMessageCallback, and android.nfc.NfcAdapter.enableForegroundNdefPush.
  • SHOULD use a gesture or on-screen confirmation, such as 'Touch to Beam', before sending outbound P2P NDEF messages.
  • SHOULD enable Android Beam by default and MUST be able to send and receive using Android Beam, even when another proprietary NFC P2p mode is turned on.
  • MUST support NFC Connection handover to Bluetooth when the device supports Bluetooth Object Push Profile. Device implementations MUST support connection handover to Bluetooth when using android.nfc.NfcAdapter.setBeamPushUris, by implementing the “ Connection Handover version 1.2 ” and “ Bluetooth Secure Simple Pairing Using NFC version 1.0 ” specs from the NFC Forum. Such an implementation MUST implement the handover LLCP service with service name “urn:nfc:sn:handover” for exchanging the handover request/select records over NFC, and it MUST use the Bluetooth Object Push Profile for the actual Bluetooth data transfer. For legacy reasons (to remain compatible with Android 4.1 devices), the implementation SHOULD still accept SNEP GET requests for exchanging the handover request/select records over NFC. However an implementation itself SHOULD NOT send SNEP GET requests for performing connection handover.
  • MUST poll for all supported technologies while in NFC discovery mode.
  • SHOULD be in NFC discovery mode while the device is awake with the screen active and the lock-screen unlocked.

(Note that publicly available links are not available for the JIS, ISO, and NFC Forum specifications cited above.)

Android includes support for NFC Host Card Emulation (HCE) mode. If a device implementation does include an NFC controller chipset capable of HCE (for NfcA and/or NfcB) and it supports Application ID (AID) routing, then it:

• MUST report the android.hardware.nfc.hce feature constant.
• MUST support NFC HCE APIs as defined in the Android SDK.

If a device implementation does include an NFC controller chipset capable of HCE for NfcF, and it implements the feature for third-party applications, then it:

• MUST report the android.hardware.nfc.hcef feature constant.
• MUST implement the NfcF Card Emulation APIs as defined in the Android SDK.

Additionally, device implementations MAY include reader/writer support for the following MIFARE technologies.

• MIFARE Classico
• MIFARE Ultraleggero
• NDEF on MIFARE Classic

Note that Android includes APIs for these MIFARE types. If a device implementation supports MIFARE in the reader/writer role, it:

• MUST implement the corresponding Android APIs as documented by the Android SDK.
• MUST report the feature com.nxp.mifare from the android.content.pm.PackageManager.hasSystemFeature() method. Note that this is not a standard Android feature and as such does not appear as a constant in the android.content.pm.PackageManager class.
• MUST NOT implement the corresponding Android APIs nor report the com.nxp.mifare feature unless it also implements general NFC support as described in this section.

If a device implementation does not include NFC hardware, it MUST NOT declare the android.hardware.nfc feature from the android.content.pm.PackageManager.hasSystemFeature() method, and MUST implement the Android NFC API as a no-op.

As the classes android.nfc.NdefMessage and android.nfc.NdefRecord represent a protocol-independent data representation format, device implementations MUST implement these APIs even if they do not include support for NFC or declare the android.hardware.nfc feature.

7.4.5. Minimum Network Capability

Device implementations MUST include support for one or more forms of data networking. Specifically, device implementations MUST include support for at least one data standard capable of 200Kbit/sec or greater. Examples of technologies that satisfy this requirement include EDGE, HSPA, EV-DO, 802.11g, Ethernet, Bluetooth PAN, etc.

Device implementations where a physical networking standard (such as Ethernet) is the primary data connection SHOULD also include support for at least one common wireless data standard, such as 802.11 (Wi-Fi).

Devices MAY implement more than one form of data connectivity.

Devices MUST include an IPv6 networking stack and support IPv6 communication using the managed APIs, such as java.net.Socket and java.net.URLConnection , as well as the native APIs, such as AF_INET6 sockets. The required level of IPv6 support depends on the network type, as follows:

• Devices that support Wi-Fi networks MUST support dual-stack and IPv6-only operation on Wi-Fi.
• Devices that support Ethernet networks MUST support dual-stack operation on Ethernet.
• Devices that support cellular data SHOULD support IPv6 operation (IPv6-only and possibly dual-stack) on cellular data.
• When a device is simultaneously connected to more than one network (eg, Wi-Fi and cellular data), it MUST simultaneously meet these requirements on each network to which it is connected.

IPv6 MUST be enabled by default.

In order to ensure that IPv6 communication is as reliable as IPv4, unicast IPv6 packets sent to the device MUST NOT be dropped, even when the screen is not in an active state. Redundant multicast IPv6 packets, such as repeated identical Router Advertisements, MAY be rate-limited in hardware or firmware if doing so is necessary to save power. In such cases, rate-limiting MUST NOT cause the device to lose IPv6 connectivity on any IPv6-compliant network that uses RA lifetimes of at least 180 seconds.

IPv6 connectivity MUST be maintained in doze mode.

7.4.6. Sincronizza impostazioni

Device implementations MUST have the master auto-sync setting on by default so that the method getMasterSyncAutomatically() returns “true”.

7.4.7. Risparmio dati

Device implementations with a metered connection are STRONGLY RECOMMENDED to provide the data saver mode.

If a device implementation provides the data saver mode, it:

• MUST support all the APIs in the ConnectivityManager class as described in the SDK documentation

• MUST provide a user interface in the settings, allowing users to add applications to or remove applications from the allowlist.

Conversely if a device implementation does not provide the data saver mode, it:

• MUST return the value RESTRICT_BACKGROUND_STATUS_DISABLED for ConnectivityManager.getRestrictBackgroundStatus()

• MUST not broadcast ConnectivityManager.ACTION_RESTRICT_BACKGROUND_CHANGED

• MUST have an activity that handles the Settings.ACTION_IGNORE_BACKGROUND_DATA_RESTRICTIONS_SETTINGS intent but MAY implement it as a no-op.

7.5. Macchine fotografiche

Device implementations SHOULD include a rear-facing camera and MAY include a front-facing camera. A rear-facing camera is a camera located on the side of the device opposite the display; that is, it images scenes on the far side of the device, like a traditional camera. A front-facing camera is a camera located on the same side of the device as the display; that is, a camera typically used to image the user, such as for video conferencing and similar applications.

If a device implementation includes at least one camera, it MUST be possible for an application to simultaneously allocate 3 RGBA_8888 bitmaps equal to the size of the images produced by the largest-resolution camera sensor on the device, while camera is open for the purpose of basic preview and still capture.

7.5.1. Fotocamera posteriore

Device implementations SHOULD include a rear-facing camera. If a device implementation includes at least one rear-facing camera, it:

• MUST report the feature flag android.hardware.camera and android.hardware.camera.any.
• MUST have a resolution of at least 2 megapixels.
• SHOULD have either hardware auto-focus or software auto-focus implemented in the camera driver (transparent to application software).
• MAY have fixed-focus or EDOF (extended depth of field) hardware.
• MAY include a flash. If the Camera includes a flash, the flash lamp MUST NOT be lit while an android.hardware.Camera.PreviewCallback instance has been registered on a Camera preview surface, unless the application has explicitly enabled the flash by enabling the FLASH_MODE_AUTO or FLASH_MODE_ON attributes of a Camera.Parameters object. Note that this constraint does not apply to the device's built-in system camera application, but only to third-party applications using Camera.PreviewCallback.

7.5.2. Fotocamera frontale

Device implementations MAY include a front-facing camera. If a device implementation includes at least one front-facing camera, it:

• MUST report the feature flag android.hardware.camera.any and android.hardware.camera.front.
• MUST have a resolution of at least VGA (640x480 pixels).
• MUST NOT use a front-facing camera as the default for the Camera API. The camera API in Android has specific support for front-facing cameras and device implementations MUST NOT configure the API to to treat a front-facing camera as the default rear-facing camera, even if it is the only camera on the device.
• MAY include features (such as auto-focus, flash, etc.) available to rear-facing cameras as described in section 7.5.1 .
• MUST horizontally reflect (ie mirror) the stream displayed by an app in a CameraPreview, as follows:
  • If the device implementation is capable of being rotated by user (such as automatically via an accelerometer or manually via user input), the camera preview MUST be mirrored horizontally relative to the device's current orientation.
  • If the current application has explicitly requested that the Camera display be rotated via a call to the android.hardware.Camera.setDisplayOrientation() method, the camera preview MUST be mirrored horizontally relative to the orientation specified by the application.
  • Otherwise, the preview MUST be mirrored along the device's default horizontal axis.
• MUST mirror the image displayed by the postview in the same manner as the camera preview image stream. If the device implementation does not support postview, this requirement obviously does not apply.
• MUST NOT mirror the final captured still image or video streams returned to application callbacks or committed to media storage.

7.5.3. Fotocamera esterna

Device implementations MAY include support for an external camera that is not necessarily always connected. If a device includes support for an external camera, it:

• MUST declare the platform feature flag android.hardware.camera.external and android.hardware camera.any .
• MAY support multiple cameras.
• MUST support USB Video Class (UVC 1.0 or higher) if the external camera connects through the USB port.
• SHOULD support video compressions such as MJPEG to enable transfer of high-quality unencoded streams (ie raw or independently compressed picture streams).
• MAY support camera-based video encoding. If supported, a simultaneous unencoded / MJPEG stream (QVGA or greater resolution) MUST be accessible to the device implementation.

7.5.4. Camera API Behavior

Android includes two API packages to access the camera, the newer android.hardware.camera2 API expose lower-level camera control to the app, including efficient zero-copy burst/streaming flows and per-frame controls of exposure, gain, white balance gains, color conversion, denoising, sharpening, and more.

The older API package, android.hardware.Camera, is marked as deprecated in Android 5.0 but as it should still be available for apps to use Android device implementations MUST ensure the continued support of the API as described in this section and in the Android SDK .

Device implementations MUST implement the following behaviors for the camera-related APIs, for all available cameras:

• If an application has never called android.hardware.Camera.Parameters.setPreviewFormat(int), then the device MUST use android.hardware.PixelFormat.YCbCr_420_SP for preview data provided to application callbacks.
• If an application registers an android.hardware.Camera.PreviewCallback instance and the system calls the onPreviewFrame() method when the preview format is YCbCr_420_SP, the data in the byte[] passed into onPreviewFrame() must further be in the NV21 encoding format. That is, NV21 MUST be the default.
• For android.hardware.Camera, device implementations MUST support the YV12 format (as denoted by the android.graphics.ImageFormat.YV12 constant) for camera previews for both front- and rear-facing cameras. (The hardware video encoder and camera may use any native pixel format, but the device implementation MUST support conversion to YV12.)
• For android.hardware.camera2, device implementations must support the android.hardware.ImageFormat.YUV_420_888 and android.hardware.ImageFormat.JPEG formats as outputs through the android.media.ImageReader API.

Device implementations MUST still implement the full Camera API included in the Android SDK documentation, regardless of whether the device includes hardware autofocus or other capabilities. For instance, cameras that lack autofocus MUST still call any registered android.hardware.Camera.AutoFocusCallback instances (even though this has no relevance to a non-autofocus camera.) Note that this does apply to front-facing cameras; for instance, even though most front-facing cameras do not support autofocus, the API callbacks must still be “faked” as described.

Device implementations MUST recognize and honor each parameter name defined as a constant on the android.hardware.Camera.Parameters class, if the underlying hardware supports the feature. If the device hardware does not support a feature, the API must behave as documented. Conversely, device implementations MUST NOT honor or recognize string constants passed to the android.hardware.Camera.setParameters() method other than those documented as constants on the android.hardware.Camera.Parameters. That is, device implementations MUST support all standard Camera parameters if the hardware allows, and MUST NOT support custom Camera parameter types. For instance, device implementations that support image capture using high dynamic range (HDR) imaging techniques MUST support camera parameter Camera.SCENE_MODE_HDR.

Because not all device implementations can fully support all the features of the android.hardware.camera2 API, device implementations MUST report the proper level of support with the android.info.supportedHardwareLevel property as described in the Android SDK and report the appropriate framework feature flags .

Device implementations MUST also declare its Individual camera capabilities of android.hardware.camera2 via the android.request.availableCapabilities property and declare the appropriate feature flags ; a device must define the feature flag if any of its attached camera devices supports the feature.

Device implementations MUST broadcast the Camera.ACTION_NEW_PICTURE intent whenever a new picture is taken by the camera and the entry of the picture has been added to the media store.

Device implementations MUST broadcast the Camera.ACTION_NEW_VIDEO intent whenever a new video is recorded by the camera and the entry of the picture has been added to the media store.

7.5.5. Orientamento della fotocamera

Both front- and rear-facing cameras, if present, MUST be oriented so that the long dimension of the camera aligns with the screen's long dimension. That is, when the device is held in the landscape orientation, cameras MUST capture images in the landscape orientation. This applies regardless of the device's natural orientation; that is, it applies to landscape-primary devices as well as portrait-primary devices.

7.6. Memoria e archiviazione

7.6.1. Minimum Memory and Storage

The memory available to the kernel and userspace on device implementations MUST be at least equal or larger than the minimum values specified by the following table. (See section 7.1.1 for screen size and density definitions.)

The minimum memory values MUST be in addition to any memory space already dedicated to hardware components such as radio, video, and so on that is not under the kernel's control.

Device implementations with less than 512MB of memory available to the kernel and userspace, unless an Android Watch, MUST return the value "true" for ActivityManager.isLowRamDevice().

Android Television devices MUST have at least 4GB and other device implementations MUST have at least 3GB of non-volatile storage available for application private data. That is, the /data partition MUST be at least 4GB for Android Television devices and at least 3GB for other device implementations. Device implementations that run Android are STRONGLY RECOMMENDED to have at least 4GB of non-volatile storage for application private data so they will be able to upgrade to the future platform releases.

The Android APIs include a Download Manager that applications MAY use to download data files. The device implementation of the Download Manager MUST be capable of downloading individual files of at least 100MB in size to the default “cache” location.

7.6.2. Application Shared Storage

Device implementations MUST offer shared storage for applications also often referred as “shared external storage”.

Device implementations MUST be configured with shared storage mounted by default, “out of the box”. If the shared storage is not mounted on the Linuxpath /sdcard, then the device MUST include a Linux symbolic link from /sdcard to the actual mount point.

Device implementations MAY have hardware for user-accessible removable storage, such as a Secure Digital (SD) card slot. If this slot is used to satisfy the shared storage requirement, the device implementation:

• MUST implement a toast or pop-up user interface warning the user when there is no SD card.
• MUST include a FAT-formatted SD card 1GB in size or larger OR show on the box and other material available at time of purchase that the SD card has to be separately purchased.
• MUST mount the SD card by default.

Alternatively, device implementations MAY allocate internal (non-removable) storage as shared storage for apps as included in the upstream Android Open Source Project; device implementations SHOULD use this configuration and software implementation. If a device implementation uses internal (non-removable) storage to satisfy the shared storage requirement, while that storage MAY share space with the application private data, it MUST be at least 1GB in size and mounted on /sdcard (or /sdcard MUST be a symbolic link to the physical location if it is mounted elsewhere).

Device implementations MUST enforce as documented the android.permission.WRITE_EXTERNAL_STORAGE permission on this shared storage. Shared storage MUST otherwise be writable by any application that obtains that permission.

Device implementations that include multiple shared storage paths (such as both an SD card slot and shared internal storage) MUST allow only pre-installed & privileged Android applications with the WRITE_EXTERNAL_STORAGE permission to write to the secondary external storage, except when writing to their package-specific directories or within the URI returned by firing the ACTION_OPEN_DOCUMENT_TREE intent.

However, device implementations SHOULD expose content from both storage paths transparently through Android's media scanner service and android.provider.MediaStore.

Regardless of the form of shared storage used, if the device implementation has a USB port with USB peripheral mode support, it MUST provide some mechanism to access the contents of shared storage from a host computer. Device implementations MAY use USB mass storage, but SHOULD use Media Transfer Protocol to satisfy this requirement. If the device implementation supports Media Transfer Protocol, it:

• SHOULD be compatible with the reference Android MTP host, Android File Transfer .
• SHOULD report a USB device class of 0x00.
• SHOULD report a USB interface name of 'MTP'.

7.6.3. Adoptable Storage

Device implementations are STRONGLY RECOMMENDED to implement adoptable storage if the removable storage device port is in a long-term stable location, such as within the battery compartment or other protective cover.

Device implementations such as a television, MAY enable adoption through USB ports as the device is expected to be static and not mobile. But for other device implementations that are mobile in nature, it is STRONGLY RECOMMENDED to implement the adoptable storage in a long-term stable location, since accidentally disconnecting them can cause data loss/corruption.

7.7. USB

Device implementations SHOULD support USB peripheral mode and SHOULD support USB host mode.

7.7.1. USB peripheral mode

If a device implementation includes a USB port supporting peripheral mode:

• The port MUST be connectable to a USB host that has a standard type-A or type-C USB port.
• The port SHOULD use micro-B, micro-AB or Type-C USB form factor. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements so they will be able to upgrade to the future platform releases.
• The port SHOULD be located on the bottom of the device (according to natural orientation) or enable software screen rotation for all apps (including home screen), so that the display draws correctly when the device is oriented with the port at bottom. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements so they will be able to upgrade to future platform releases.
• It MUST allow a USB host connected with the Android device to access the contents of the shared storage volume using either USB mass storage or Media Transfer Protocol.
• It SHOULD implement the Android Open Accessory (AOA) API and specification as documented in the Android SDK documentation, and if it is an Android Handheld device it MUST implement the AOA API. Device implementations implementing the AOA specification:
  • MUST declare support for the hardware feature android.hardware.usb.accessory .
  • MUST implement the USB audio class as documented in the Android SDK documentation.
  • The USB mass storage class MUST include the string "android" at the end of the interface description iInterface string of the USB mass storage
• It SHOULD implement support to draw 1.5 A current during HS chirp and traffic as specified in the USB Battery Charging specification, revision 1.2 . Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements so they will be able to upgrade to the future platform releases.
• Type-C devices MUST detect 1.5A and 3.0A chargers per the Type-C resistor standard and it must detect changes in the advertisement.
• Type-C devices also supporting USB host mode are STRONGLY RECOMMENDED to support Power Delivery for data and power role swapping.
• Type-C devices SHOULD support Power Delivery for high-voltage charging and support for Alternate Modes such as display out.
• The value of iSerialNumber in USB standard device descriptor MUST be equal to the value of android.os.Build.SERIAL.
• Type-C devices are STRONGLY RECOMMENDED to not support proprietary charging methods that modify Vbus voltage beyond default levels, or alter sink/source roles as such may result in interoperability issues with the chargers or devices that support the standard USB Power Delivery methods. While this is called out as "STRONGLY RECOMMENDED", in future Android versions we might REQUIRE all type-C devices to support full interoperability with standard type-C chargers.

7.7.2. USB host mode

If a device implementation includes a USB port supporting host mode, it:

• SHOULD use a type-C USB port, if the device implementation supports USB 3.1.
• MAY use a non-standard port form factor, but if so MUST ship with a cable or cables adapting the port to a standard type-A or type-C USB port.
• MAY use a micro-AB USB port, but if so SHOULD ship with a cable or cables adapting the port to a standard type-A or type-C USB port.
• is STRONGLY RECOMMENDED to implement the USB audio class as documented in the Android SDK documentation.
• MUST implement the Android USB host API as documented in the Android SDK, and MUST declare support for the hardware feature android.hardware.usb.host .
• SHOULD support device charging while in host mode; advertising a source current of at least 1.5A as specified in the Termination Parameters section of the [USB Type-C Cable and Connector Specification Revision 1.2] (http://www.usb.org/developers/docs/usb_31_021517.zip) for USB Type-C connectors or using Charging Downstream Port(CDP) output current range as specified in the USB Battery Charging specifications, revision 1.2 for Micro-AB connectors.
• USB Type-C devices are STRONGLY RECOMMENDED to support DisplayPort, SHOULD support USB SuperSpeed Data Rates, and are STRONGLY RECOMMENDED to support Power Delivery for data and power role swapping.
• Devices with any type-A or type-AB ports MUST NOT ship with an adapter converting from this port to a type-C receptacle.
• MUST recognize any remotely connected MTP (Media Transfer Protocol) devices and make their contents accessible through the ACTION_GET_CONTENT , ACTION_OPEN_DOCUMENT , and ACTION_CREATE_DOCUMENT intents, if the Storage Access Framework (SAF) is supported.
• MUST, if using a Type-C USB port and including support for peripheral mode, implement Dual Role Port functionality as defined by the USB Type-C specification (section 4.5.1.3.3).
• SHOULD, if the Dual Role Port functionality is supported, implement the Try.* model that is most appropriate for the device form factor. For example a handheld device SHOULD implement the Try.SNK model.

7.8. Audio

7.8.1. Microfono

Device implementations MAY omit a microphone. However, if a device implementation omits a microphone, it MUST NOT report the android.hardware.microphone feature constant, and MUST implement the audio recording API at least as no-ops, per section 7 . Conversely, device implementations that do possess a microphone:

• MUST report the android.hardware.microphone feature constant.
• MUST meet the audio recording requirements in section 5.4 .
• MUST meet the audio latency requirements in section 5.6 .
• STRONGLY RECOMMENDED to support near-ultrasound recording as described in section 7.8.3 .

7.8.2. Uscita audio

Device implementations including a speaker or with an audio/multimedia output port for an audio output peripheral as a headset or an external speaker:

• MUST report the android.hardware.audio.output feature constant.
• MUST meet the audio playback requirements in section 5.5 .
• MUST meet the audio latency requirements in section 5.6 .
• STRONGLY RECOMMENDED to support near-ultrasound playback as described in section 7.8.3 .

Conversely, if a device implementation does not include a speaker or audio output port, it MUST NOT report the android.hardware.audio output feature, and MUST implement the Audio Output related APIs as no-ops at least.

Android Watch device implementation MAY but SHOULD NOT have audio output, but other types of Android device implementations MUST have an audio output and declare android.hardware.audio.output.

7.8.2.1. Analog Audio Ports

In order to be compatible with the headsets and other audio accessories using the 3.5mm audio plug across the Android ecosystem, if a device implementation includes one or more analog audio ports, at least one of the audio port(s) SHOULD be a 4 conductor Jack audio da 3,5 mm. If a device implementation has a 4 conductor 3.5mm audio jack, it:

• MUST support audio playback to stereo headphones and stereo headsets with a microphone, and SHOULD support audio recording from stereo headsets with a microphone.
• MUST support TRRS audio plugs with the CTIA pin-out order, and SHOULD support audio plugs with the OMTP pin-out order.
• MUST support the detection of microphone on the plugged in audio accessory, if the device implementation supports a microphone, and broadcast the android.intent.action.HEADSET_PLUG with the extra value microphone set as 1.
• MUST support the detection and mapping to the keycodes for the following 3 ranges of equivalent impedance between the microphone and ground conductors on the audio plug:
  • 70 ohm or less : KEYCODE_HEADSETHOOK
  • 210-290 Ohm : KEYCODE_VOLUME_UP
  • 360-680 Ohm : KEYCODE_VOLUME_DOWN
• STRONGLY RECOMMENDED to detect and map to the keycode for the following range of equivalent impedance between the microphone and ground conductors on the audio plug:
  • 110-180 Ohm: KEYCODE_VOICE_ASSIST
• MUST trigger ACTION_HEADSET_PLUG upon a plug insert, but only after all contacts on plug are touching their relevant segments on the jack.
• MUST be capable of driving at least 150mV ± 10% of output voltage on a 32 Ohm speaker impedance.
• MUST have a microphone bias voltage between 1.8V ~ 2.9V.

7.8.3. Near-Ultrasound

Near-Ultrasound audio is the 18.5 kHz to 20 kHz band. Device implementations MUST correctly report the support of near-ultrasound audio capability via the AudioManager.getProperty API as follows:

• If PROPERTY_SUPPORT_MIC_NEAR_ULTRASOUND is "true", then the following requirements must be met by the VOICE_RECOGNITION and UNPROCESSED audio sources:
  • The microphone's mean power response in the 18.5 kHz to 20 kHz band MUST be no more than 15 dB below the response at 2 kHz.
  • The microphone's unweighted signal to noise ratio over 18.5 kHz to 20 kHz for a 19 kHz tone at -26 dBFS MUST be no lower than 50 dB.
• If PROPERTY_SUPPORT_SPEAKER_NEAR_ULTRASOUND is "true", then the speaker's mean response in 18.5 kHz - 20 kHz MUST be no lower than 40 dB below the response at 2 kHz.

7.9. Realta virtuale

Android includes APIs and facilities to build "Virtual Reality" (VR) applications including high quality mobile VR experiences. Device implementations MUST properly implement these APIs and behaviors, as detailed in this section.

7.9.1. Virtual Reality Mode

Android handheld device implementations that support a mode for VR applications that handles stereoscopic rendering of notifications and disable monocular system UI components while a VR application has user focus MUST declare android.software.vr.mode feature. Devices declaring this feature MUST include an application implementing android.service.vr.VrListenerService that can be enabled by VR applications via android.app.Activity#setVrModeEnabled .

7.9.2. Virtual Reality High Performance

Android handheld device implementations MUST identify the support of high performance virtual reality for longer user periods through the android.hardware.vr.high_performance feature flag and meet the following requirements.

• Device implementations MUST have at least 2 physical cores.
• Device implementations MUST declare android.software.vr.mode feature.
• Device implementations MAY provide an exclusive core to the foreground application and MAY support the Process.getExclusiveCores API to return the numbers of the cpu cores that are exclusive to the top foreground application. If exclusive core is supported then the core MUST not allow any other userspace processes to run on it (except device drivers used by the application), but MAY allow some kernel processes to run as necessary.
• Device implementations MUST support sustained performance mode.
• Device implementations MUST support OpenGL ES 3.2.
• Device implementations MUST support Vulkan Hardware Level 0 and SHOULD support Vulkan Hardware Level 1.
• Device implementations MUST implement EGL_KHR_mutable_render_buffer and EGL_ANDROID_front_buffer_auto_refresh, EGL_ANDROID_create_native_client_buffer, EGL_KHR_fence_sync and EGL_KHR_wait_sync so that they may be used for Shared Buffer Mode, and expose the extensions in the list of available EGL extensions.
• The GPU and display MUST be able to synchronize access to the shared front buffer such that alternating-eye rendering of VR content at 60fps with two render contexts will be displayed with no visible tearing artifacts.
• Device implementations MUST implement EGL_IMG_context_priority, and expose the extension in the list of available EGL extensions.
• Device implementations MUST implement GL_EXT_multisampled_render_to_texture, GL_OVR_multiview, GL_OVR_multiview2 and GL_OVR_multiview_multisampled_render_to_texture, and expose the extensions in the list of available GL extensions.
• Device implementations MUST implement EGL_EXT_protected_content and GL_EXT_protected_textures so that it may be used for Secure Texture Video Playback, and expose the extensions in the list of available EGL and GL extensions.
• Device implementations MUST support H.264 decoding at least 3840x2160@30fps-40Mbps (equivalent to 4 instances of 1920x1080@30fps-10Mbps or 2 instances of 1920x1080@60fps-20Mbps).
• Device implementations MUST support HEVC and VP9, MUST be capable to decode at least 1920x1080@30fps-10Mbps and SHOULD be capable to decode 3840x2160@30fps-20Mbps (equivalent to 4 instances of 1920x1080@30fps-5Mbps).
• The device implementations are STRONGLY RECOMMENDED to support android.hardware.sensor.hifi_sensors feature and MUST meet the gyroscope, accelerometer, and magnetometer related requirements for android.hardware.hifi_sensors.
• Device implementations MUST support HardwarePropertiesManager.getDeviceTemperatures API and return accurate values for skin temperature.
• The device implementation MUST have an embedded screen, and its resolution MUST be at least be FullHD(1080p) and STRONGLY RECOMMENDED TO BE be QuadHD (1440p) or higher.
• The display MUST measure between 4.7" and 6" diagonal.
• The display MUST update at least 60 Hz while in VR Mode.
• The display latency on Gray-to-Gray, White-to-Black, and Black-to-White switching time MUST be ≤ 3 ms.
• The display MUST support a low-persistence mode with ≤5 ms persistence,persistence being defined as the amount of time for which a pixel is emitting light.
• Device implementations MUST support Bluetooth 4.2 and Bluetooth LE Data Length Extension section 7.4.3 .

8. Performance and Power

Some minimum performance and power criteria are critical to the user experience and impact the baseline assumptions developers would have when developing an app. Android Watch devices SHOULD and other type of device implementations MUST meet the following criteria.

8.1. User Experience Consistency

Device implementations MUST provide a smooth user interface by ensuring a consistent frame rate and response times for applications and games. Device implementations MUST meet the following requirements:

• Consistent frame latency . Inconsistent frame latency or a delay to render frames MUST NOT happen more often than 5 frames in a second, and SHOULD be below 1 frames in a second.
• User interface latency . Device implementations MUST ensure low latency user experience by scrolling a list of 10K list entries as defined by the Android Compatibility Test Suite (CTS) in less than 36 secs.
• Task switching . When multiple applications have been launched, re-launching an already-running application after it has been launched MUST take less than 1 second.

8.2. File I/O Access Performance

Device implementations MUST ensure internal storage file access performance consistency for read and write operations.

• Sequential write . Device implementations MUST ensure a sequential write performance of at least 5MB/s for a 256MB file using 10MB write buffer.
• Random write . Device implementations MUST ensure a random write performance of at least 0.5MB/s for a 256MB file using 4KB write buffer.
• Sequential read . Device implementations MUST ensure a sequential read performance of at least 15MB/s for a 256MB file using 10MB write buffer.
• Random read . Device implementations MUST ensure a random read performance of at least 3.5MB/s for a 256MB file using 4KB write buffer.

8.3. Modalità di risparmio energetico

Android 6.0 introduced App Standby and Doze power-saving modes to optimize battery usage. All Apps exempted from these modes MUST be made visible to the end user. Further, the triggering, maintenance, wakeup algorithms and the use of global system settings of these power-saving modes MUST not deviate from the Android Open Source Project.

In addition to the power-saving modes, Android device implementations MAY implement any or all of the 4 sleeping power states as defined by the Advanced Configuration and Power Interface (ACPI), but if it implements S3 and S4 power states, it can only enter these states when closing a lid that is physically part of the device.

8.4. Power Consumption Accounting

A more accurate accounting and reporting of the power consumption provides the app developer both the incentives and the tools to optimize the power usage pattern of the application. Therefore, device implementations:

• MUST be able to track hardware component power usage and attribute that power usage to specific applications. Specifically, implementations:
  • MUST provide a per-component power profile that defines the current consumption value for each hardware component and the approximate battery drain caused by the components over time as documented in the Android Open Source Project site.
  • MUST report all power consumption values in milliampere hours (mAh).
  • SHOULD be attributed to the hardware component itself if unable to attribute hardware component power usage to an application.
  • MUST report CPU power consumption per each process's UID. The Android Open Source Project meets the requirement through the uid_cputime kernel module implementation.
• MUST make this power usage available via the adb shell dumpsys batterystats shell command to the app developer.
• MUST honor the android.intent.action.POWER_USAGE_SUMMARY intent and display a settings menu that shows this power usage.

8.5. Prestazioni costanti

Performance can fluctuate dramatically for high-performance long-running apps, either because of the other apps running in the background or the CPU throttling due to temperature limits. Android includes programmatic interfaces so that when the device is capable, the top foreground application can request that the system optimize the allocation of the resources to address such fluctuations.

Device implementations SHOULD support Sustained Performance Mode which can provide the top foreground application a consistent level of performance for a prolonged amount of time when requested through the Window.setSustainedPerformanceMode() API method. A Device implementation MUST report the support of Sustained Performance Mode accurately through the PowerManager.isSustainedPerformanceModeSupported() API method.

Device implementations with two or more CPU cores SHOULD provide at least one exclusive core that can be reserved by the top foreground application. If provided, implementations MUST meet the following requirements:

• Implementations MUST report through the Process.getExclusiveCores() API method the id numbers of the exclusive cores that can be reserved by the top foreground application.
• Device implementations MUST not allow any user space processes except the device drivers used by the application to run on the exclusive cores, but MAY allow some kernel processes to run as necessary.

If a device implementation does not support an exclusive core, it MUST return an empty list through the Process.getExclusiveCores() API method.

9. Security Model Compatibility

Device implementations MUST implement a security model consistent with the Android platform security model as defined in Security and Permissions reference document in the APIs in the Android developer documentation. Device implementations MUST support installation of self-signed applications without requiring any additional permissions/certificates from any third parties/authorities. Specifically, compatible devices MUST support the security mechanisms described in the follow subsections.

9.1. Autorizzazioni

Device implementations MUST support the Android permissions model as defined in the Android developer documentation. Specifically, implementations MUST enforce each permission defined as described in the SDK documentation; no permissions may be omitted, altered, or ignored. Implementations MAY add additional permissions, provided the new permission ID strings are not in the android.* namespace.

Permissions with a protectionLevel of 'PROTECTION_FLAG_PRIVILEGED' MUST only be granted to apps preloaded in the allowlisted privileged path(s) of the system image, such as the system/priv-app path in the AOSP implementation.

Permissions with a protection level of dangerous are runtime permissions. Applications with targetSdkVersion > 22 request them at runtime. Device implementations:

• MUST show a dedicated interface for the user to decide whether to grant the requested runtime permissions and also provide an interface for the user to manage runtime permissions.
• MUST have one and only one implementation of both user interfaces.
• MUST NOT grant any runtime permissions to preinstalled apps unless:
  • the user's consent can be obtained before the application uses it
  • the runtime permissions are associated with an intent pattern for which the preinstalled application is set as the default handler

9.2. UID and Process Isolation

Device implementations MUST support the Android application sandbox model, in which each application runs as a unique Unixstyle UID and in a separate process. Device implementations MUST support running multiple applications as the same Linux user ID, provided that the applications are properly signed and constructed, as defined in the Security and Permissions reference .

9.3. Filesystem Permissions

Device implementations MUST support the Android file access permissions model as defined in the Security and Permissions reference .

9.4. Alternate Execution Environments

Device implementations MAY include runtime environments that execute applications using some other software or technology than the Dalvik Executable Format or native code. However, such alternate execution environments MUST NOT compromise the Android security model or the security of installed Android applications, as described in this section.

Alternate runtimes MUST themselves be Android applications, and abide by the standard Android security model, as described elsewhere in section 9 .

Alternate runtimes MUST NOT be granted access to resources protected by permissions not requested in the runtime's AndroidManifest.xml file via the <uses-permission> mechanism.

Alternate runtimes MUST NOT permit applications to make use of features protected by Android permissions restricted to system applications.

Alternate runtimes MUST abide by the Android sandbox model. Specifically, alternate runtimes:

• SHOULD install apps via the PackageManager into separate Android sandboxes (Linux user IDs, etc.).
• MAY provide a single Android sandbox shared by all applications using the alternate runtime.
• Installed applications using an alternate runtime MUST NOT reuse the sandbox of any other app installed on the device, except through the standard Android mechanisms of shared user ID and signing certificate.
• MUST NOT launch with, grant, or be granted access to the sandboxes corresponding to other Android applications.
• MUST NOT be launched with, be granted, or grant to other applications any privileges of the superuser (root), or of any other user ID.

The .apk files of alternate runtimes MAY be included in the system image of a device implementation, but MUST be signed with a key distinct from the key used to sign other applications included with the device implementation.

When installing applications, alternate runtimes MUST obtain user consent for the Android permissions used by the application. If an application needs to make use of a device resource for which there is a corresponding Android permission (such as Camera, GPS, etc.), the alternate runtime MUST inform the user that the application will be able to access that resource. If the runtime environment does not record application capabilities in this manner, the runtime environment MUST list all permissions held by the runtime itself when installing any application using that runtime.

9.5. Supporto multiutente

Android includes support for multiple users and provides support for full user isolation. Device implementations MAY enable multiple users, but when enabled MUST meet the following requirements related to multi-user support :

• Android Automotive device implementations with multi-user support enabled MUST include a guest account that allows all functions provided by the vehicle system without requiring a user to log in.
• Device implementations that do not declare the android.hardware.telephony feature flag MUST support restricted profiles, a feature that allows device owners to manage additional users and their capabilities on the device. With restricted profiles, device owners can quickly set up separate environments for additional users to work in, with the ability to manage finer-grained restrictions in the apps that are available in those environments.
• Conversely device implementations that declare the android.hardware.telephony feature flag MUST NOT support restricted profiles but MUST align with the AOSP implementation of controls to enable /disable other users from accessing the voice calls and SMS.
• Device implementations MUST, for each user, implement a security model consistent with the Android platform security model as defined in Security and Permissions reference document in the APIs.
• Each user instance on an Android device MUST have separate and isolated external storage directories. Device implementations MAY store multiple users' data on the same volume or filesystem. However, the device implementation MUST ensure that applications owned by and running on behalf a given user cannot list, read, or write to data owned by any other user. Note that removable media, such as SD card slots, can allow one user to access another's data by means of a host PC. For this reason, device implementations that use removable media for the external storage APIs MUST encrypt the contents of the SD card if multiuser is enabled using a key stored only on non-removable media accessible only to the system. As this will make the media unreadable by a host PC, device implementations will be required to switch to MTP or a similar system to provide host PCs with access to the current user's data. Accordingly, device implementations MAY but SHOULD NOT enable multi-user if they use removable media for primary external storage.

9.6. Premium SMS Warning

Android includes support for warning users of any outgoing premium SMS message . Premium SMS messages are text messages sent to a service registered with a carrier that may incur a charge to the user. Device implementations that declare support for android.hardware.telephony MUST warn users before sending a SMS message to numbers identified by regular expressions defined in /data/misc/sms/codes.xml file in the device. The upstream Android Open Source Project provides an implementation that satisfies this requirement.

9.7. Kernel Security Features

The Android Sandbox includes features that use the Security-Enhanced Linux (SELinux) mandatory access control (MAC) system, seccomp sandboxing, and other security features in the Linux kernel. SELinux or any other security features implemented below the Android framework:

• MUST maintain compatibility with existing applications.
• MUST NOT have a visible user interface when a security violation is detected and successfully blocked, but MAY have a visible user interface when an unblocked security violation occurs resulting in a successful exploit.
• SHOULD NOT be user or developer configurable.

If any API for configuration of policy is exposed to an application that can affect another application (such as a Device Administration API), the API MUST NOT allow configurations that break compatibility.

Devices MUST implement SELinux or, if using a kernel other than Linux, an equivalent mandatory access control system. Devices MUST also meet the following requirements, which are satisfied by the reference implementation in the upstream Android Open Source Project.

Device implementations:

• MUST set SELinux to global enforcing mode.
• MUST configure all domains in enforcing mode. No permissive mode domains are allowed, including domains specific to a device/vendor.
• MUST NOT modify, omit, or replace the neverallow rules present within the system/sepolicy folder provided in the upstream Android Open Source Project (AOSP) and the policy MUST compile with all neverallow rules present, for both AOSP SELinux domains as well as device/vendor specific domains.
• MUST split the media framework into multiple processes so that it is possible to more narrowly grant access for each process as described in the Android Open Source Project site.

Device implementations SHOULD retain the default SELinux policy provided in the system/sepolicy folder of the upstream Android Open Source Project and only further add to this policy for their own device-specific configuration. Device implementations MUST be compatible with the upstream Android Open Source Project.

Devices MUST implement a kernel application sandboxing mechanism which allows filtering of system calls using a configurable policy from multithreaded programs. The upstream Android Open Source Project meets this requirement through enabling the seccomp-BPF with threadgroup synchronization (TSYNC) as described in the Kernel Configuration section of source.android.com .

9.8. Privacy

If the device implements functionality in the system that captures the contents displayed on the screen and/or records the audio stream played on the device, it MUST continuously notify the user whenever this functionality is enabled and actively capturing/recording.

If a device implementation has a mechanism that routes network data traffic through a proxy server or VPN gateway by default (for example, preloading a VPN service with android.permission.CONTROL_VPN granted), the device implementation MUST ask for the user's consent before enabling that mechanism, unless that VPN is enabled by the Device Policy Controller via the DevicePolicyManager.setAlwaysOnVpnPackage() , in which case the user does not need to provide a separate consent, but MUST only be notified.

Device implementations MUST ship with an empty user-added Certificate Authority (CA) store, and MUST preinstall the same root certificates for the system-trusted CA store as provided in the upstream Android Open Source Project.

When devices are routed through a VPN, or a user root CA is installed, the implementation MUST display a warning indicating the network traffic may be monitored to the user.

If a device implementation has a USB port with USB peripheral mode support, it MUST present a user interface asking for the user's consent before allowing access to the contents of the shared storage over the USB port.

9.9. Data Storage Encryption

If the device implementation supports a secure lock screen as described in section 9.11.1, then the device MUST support data storage encryption of the application private data (/data partition), as well as the application shared storage partition (/sdcard partition) if it is a permanent, non-removable part of the device.

For device implementations supporting data storage encryption and with Advanced Encryption Standard (AES) crypto performance above 50MiB/sec, the data storage encryption MUST be enabled by default at the time the user has completed the out-of-box setup experience. If a device implementation is already launched on an earlier Android version with encryption disabled by default, such a device cannot meet the requirement through a system software update and thus MAY be exempted.

Device implementations SHOULD meet the above data storage encryption requirement via implementing File Based Encryption (FBE).

9.9.1. Avvio diretto

All devices MUST implement the Direct Boot mode APIs even if they do not support Storage Encryption. In particular, the LOCKED_BOOT_COMPLETED and ACTION_USER_UNLOCKED Intents must still be broadcast to signal Direct Boot aware applications that Device Encrypted (DE) and Credential Encrypted (CE) storage locations are available for user.

9.9.2. File Based Encryption

Device implementations supporting FBE:

• MUST boot up without challenging the user for credentials and allow Direct Boot aware apps to access to the Device Encrypted (DE) storage after the LOCKED_BOOT_COMPLETED message is broadcasted.
• MUST only allow access to Credential Encrypted (CE) storage after the user has unlocked the device by supplying their credentials (eg. passcode, pin, pattern or fingerprint) and the ACTION_USER_UNLOCKED message is broadcasted. Device implementations MUST NOT offer any method to unlock the CE protected storage without the user supplied credentials.
• MUST support Verified Boot and ensure that DE keys are cryptographically bound to the device's hardware root of trust.
• MUST support encrypting file contents using AES with a key length of 256-bits in XTS mode.
• MUST support encrypting file name using AES with a key length of 256-bits in CBC-CTS mode.
• MAY support alternative ciphers, key lengths and modes for file content and file name encryption, but MUST use the mandatorily supported ciphers, key lengths and modes by default.
• SHOULD make preloaded essential apps (eg Alarm, Phone, Messenger) Direct Boot aware.

The keys protecting CE and DE storage areas:

• MUST be cryptographically bound to a hardware-backed Keystore. CE keys must be bound to a user's lock screen credentials. If the user has specified no lock screen credentials then the CE keys MUST be bound to a default passcode.
• MUST be unique and distinct, in other words no user's CE or DE key may match any other user's CE or DE keys.

The upstream Android Open Source project provides a preferred implementation of this feature based on the Linux kernel ext4 encryption feature.

9.9.3. Crittografia dell'intero disco

Device implementations supporting full disk encryption (FDE). MUST use AES with a key of 128-bits (or greater) and a mode designed for storage (for example, AES-XTS, AES-CBC-ESSIV). The encryption key MUST NOT be written to storage at any time without being encrypted. The user MUST be provided with the possibility to AES encrypt the encryption key, except when it is in active use, with the lock screen credentials stretched using a slow stretching algorithm (eg PBKDF2 or scrypt). If the user has not specified a lock screen credentials or has disabled use of the passcode for encryption, the system SHOULD use a default passcode to wrap the encryption key. If the device provides a hardware-backed keystore, the password stretching algorithm MUST be cryptographically bound to that keystore. The encryption key MUST NOT be sent off the device (even when wrapped with the user passcode and/or hardware bound key). The upstream Android Open Source project provides a preferred implementation of this feature based on the Linux kernel feature dm-crypt.

9.10. Device Integrity

The following requirements ensures there is transparency to the status of the device integrity.

Device implementations MUST correctly report through the System API method PersistentDataBlockManager.getFlashLockState() whether their bootloader state permits flashing of the system image. The FLASH_LOCK_UNKNOWN state is reserved for device implementations upgrading from an earlier version of Android where this new system API method did not exist.

Verified boot is a feature that guarantees the integrity of the device software. If a device implementation supports the feature, it MUST:

• Declare the platform feature flag android.software.verified_boot.
• Perform verification on every boot sequence.
• Start verification from an immutable hardware key that is the root of trust and go all the way up to the system partition.
• Implement each stage of verification to check the integrity and authenticity of all the bytes in the next stage before executing the code in the next stage.
• Use verification algorithms as strong as current recommendations from NIST for hashing algorithms (SHA-256) and public key sizes (RSA-2048).
• MUST NOT allow boot to complete when system verification fails, unless the user consents to attempt booting anyway, in which case the data from any non-verified storage blocks MUST not be used.
• MUST NOT allow verified partitions on the device to be modified unless the user has explicitly unlocked the boot loader.

The upstream Android Open Source Project provides a preferred implementation of this feature based on the Linux kernel feature dm-verity.

Starting from Android 6.0, device implementations with Advanced Encryption Standard (AES) crypto performance above 50 MiB/seconds MUST support verified boot for device integrity.

If a device implementation is already launched without supporting verified boot on an earlier version of Android, such a device can not add support for this feature with a system software update and thus are exempted from the requirement.

9.11. Keys and Credentials

The Android Keystore System allows app developers to store cryptographic keys in a container and use them in cryptographic operations through the KeyChain API or the Keystore API .

All Android device implementations MUST meet the following requirements:

• SHOULD not limit the number of keys that can be generated, and MUST at least allow more than 8,192 keys to be imported.
• The lock screen authentication MUST rate limit attempts and MUST have an exponential backoff algorithm. Beyond 150 failed attempts, the delay MUST be at least 24 hours per attempt.
• When the device implementation supports a secure lock screen it MUST back up the keystore implementation with secure hardware and meet following requirements:
  • MUST have implementations of RSA, AES, ECDSA and HMAC cryptographic algorithms and MD5, SHA1, and SHA-2 family hash functions to properly support the Android Keystore system's supported algorithms in an area that is securely isolated from the code running on the kernel and above . Secure isolation MUST block all potential mechanisms by which kernel or userspace code might access the internal state of the isolated environment, including DMA. The upstream Android Open Source Project (AOSP) meets this requirement by using the Trusty implementation, but another ARM TrustZone-based solution or a third-party reviewed secure implementation of a proper hypervisor-based isolation are alternative options.
  • MUST perform the lock screen authentication in the isolated execution environment and only when successful, allow the authentication-bound keys to be used. The upstream Android Open Source Project provides the Gatekeeper Hardware Abstraction Layer (HAL) and Trusty, which can be used to satisfy this requirement.

Note that if a device implementation is already launched on an earlier Android version, such a device is exempted from the requirement to have a hardware-backed keystore, unless it declares the android.hardware.fingerprint feature which requires a hardware-backed keystore.

9.11.1. Secure Lock Screen

Device implementations MAY add or modify the authentication methods to unlock the lock screen, but MUST still meet the following requirements:

• The authentication method, if based on a known secret, MUST NOT be treated as a secure lock screen unless it meets all following requirements:
  • The entropy of the shortest allowed length of inputs MUST be greater than 10 bits.
  • The maximum entropy of all possible inputs MUST be greater than 18 bits.
  • MUST not replace any of the existing authentication methods (PIN, pattern, password) implemented and provided in AOSP.
  • MUST be disabled when the Device Policy Controller (DPC) application has set the password quality policy via the DevicePolicyManager.setPasswordQuality() method with a more restrictive quality constant than PASSWORD_QUALITY_SOMETHING .
• The authentication method, if based on a physical token or the location, MUST NOT be treated as a secure lock screen unless it meets all following requirements:
  • It MUST have a fall-back mechanism to use one of the primary authentication methods which is based on a known secret and meets the requirements to be treated as a secure lock screen.
  • It MUST be disabled and only allow the primary authentication to unlock the screen when the Device Policy Controller (DPC) application has set the policy with either the DevicePolicyManager.setKeyguardDisabledFeatures(KEYGUARD_DISABLE_TRUST_AGENTS) method or the DevicePolicyManager.setPasswordQuality() method with a more restrictive quality constant than PASSWORD_QUALITY_UNSPECIFIED .
• The authentication method, if based on biometrics, MUST NOT be treated as a secure lock screen unless it meets all following requirements:
  • It MUST have a fall-back mechanism to use one of the primary authentication methods which is based on a known secret and meets the requirements to be treated as a secure lock screen.
  • It MUST be disabled and only allow the primary authentication to unlock the screen when the Device Policy Controller (DPC) application has set the keguard feature policy by calling the method DevicePolicyManager.setKeyguardDisabledFeatures(KEYGUARD_DISABLE_FINGERPRINT) .
  • It MUST have a false acceptance rate that is equal or stronger than what is required for a fingerprint sensor as described in section 7.3.10, or otherwise MUST be disabled and only allow the primary authentication to unlock the screen when the Device Policy Controller (DPC) application has set the password quality policy via the DevicePolicyManager.setPasswordQuality() method with a more restrictive quality constant than PASSWORD_QUALITY_BIOMETRIC_WEAK .
• If the authentication method can not be treated as a secure lock screen, it:
  • MUST return false for both the KeyguardManager.isKeyguardSecure() and the KeyguardManager.isDeviceSecure() methods.
  • MUST be disabled when the Device Policy Controller (DPC) application has set the password quality policy via the DevicePolicyManager.setPasswordQuality() method with a more restrictive quality constant than PASSWORD_QUALITY_UNSPECIFIED .
  • MUST NOT reset the password expiration timers set by DevicePolicyManager.setPasswordExpirationTimeout() .
  • MUST NOT authenticate access to keystores if the application has called KeyGenParameterSpec.Builder.setUserAuthenticationRequired(true) ).
• If the authentication method is based on a physical token, the location, or biometrics that has higher false acceptance rate than what is required for fingerprint sensors as described in section 7.3.10, then it:
  • MUST NOT reset the password expiration timers set by DevicePolicyManager.setPasswordExpirationTimeout() .
  • MUST NOT authenticate access to keystores if the application has called KeyGenParameterSpec.Builder.setUserAuthenticationRequired(true) .

9.12. Cancellazione dei dati

Devices MUST provide users with a mechanism to perform a "Factory Data Reset" that allows logical and physical deletion of all data except for the following:

• The system image
• Any operating system files required by the system image

All user-generated data MUST be deleted. This MUST satisfy relevant industry standards for data deletion such as NIST SP800-88. This MUST be used for the implementation of the wipeData() API (part of the Android Device Administration API) described in section 3.9 Device Administration .

Devices MAY provide a fast data wipe that conducts a logical data erase.

9.13. Safe Boot Mode

Android provides a mode enabling users to boot up into a mode where only preinstalled system apps are allowed to run and all third-party apps are disabled. This mode, known as "Safe Boot Mode", provides the user the capability to uninstall potentially harmful third-party apps.

Android device implementations are STRONGLY RECOMMENDED to implement Safe Boot Mode and meet following requirements:

• Device implementations SHOULD provide the user an option to enter Safe Boot Mode from the boot menu which is reachable through a workflow that is different from that of normal boot.

• Device implementations MUST provide the user an option to enter Safe Boot Mode in such a way that is uninterruptible from third-party apps installed on the device, except for when the third party app is a Device Policy Controller and has set the UserManager.DISALLOW_SAFE_BOOT flag come vero.

• Device implementations MUST provide the user the capability to uninstall any third-party apps within Safe Mode.

9.14. Automotive Vehicle System Isolation

Android Automotive devices are expected to exchange data with critical vehicle subsystems, eg, by using the vehicle HAL to send and receive messages over vehicle networks such as CAN bus. Android Automotive device implementations MUST implement security features below the Android framework layers to prevent malicious or unintentional interaction between the Android framework or third-party apps and vehicle subsystems. These security features are as follows:

• Gatekeeping messages from Android framework vehicle subsystems, eg, allowlisting permitted message types and message sources.
• Watchdog against denial of service attacks from the Android framework or third-party apps. This guards against malicious software flooding the vehicle network with traffic, which may lead to malfunctioning vehicle subsystems.

10. Software Compatibility Testing

Device implementations MUST pass all tests described in this section.

However, note that no software test package is fully comprehensive. For this reason, device implementers are STRONGLY RECOMMENDED to make the minimum number of changes as possible to the reference and preferred implementation of Android available from the Android Open Source Project. This will minimize the risk of introducing bugs that create incompatibilities requiring rework and potential device updates.

10.1. Suite di test di compatibilità

Device implementations MUST pass the Android Compatibility Test Suite (CTS) available from the Android Open Source Project, using the final shipping software on the device. Additionally, device implementers SHOULD use the reference implementation in the Android Open Source tree as much as possible, and MUST ensure compatibility in cases of ambiguity in CTS and for any reimplementations of parts of the reference source code.

The CTS is designed to be run on an actual device. Like any software, the CTS may itself contain bugs. The CTS will be versioned independently of this Compatibility Definition, and multiple revisions of the CTS may be released for Android 7.1. Device implementations MUST pass the latest CTS version available at the time the device software is completed.

10.2. CTS Verifier

Device implementations MUST correctly execute all applicable cases in the CTS Verifier. The CTS Verifier is included with the Compatibility Test Suite, and is intended to be run by a human operator to test functionality that cannot be tested by an automated system, such as correct functioning of a camera and sensors.

The CTS Verifier has tests for many kinds of hardware, including some hardware that is optional. Device implementations MUST pass all tests for hardware that they possess; for instance, if a device possesses an accelerometer, it MUST correctly execute the Accelerometer test case in the CTS Verifier. Test cases for features noted as optional by this Compatibility Definition Document MAY be skipped or omitted.

Every device and every build MUST correctly run the CTS Verifier, as noted above. However, since many builds are very similar, device implementers are not expected to explicitly run the CTS Verifier on builds that differ only in trivial ways. Specifically, device implementations that differ from an implementation that has passed the CTS Verifier only by the set of included locales, branding, etc. MAY omit the CTS Verifier test.

11. Updatable Software

Device implementations MUST include a mechanism to replace the entirety of the system software. The mechanism need not perform “live” upgrades—that is, a device restart MAY be required.

Any method can be used, provided that it can replace the entirety of the software preinstalled on the device. For instance, any of the following approaches will satisfy this requirement:

• “Over-the-air (OTA)” downloads with offline update via reboot.
• “Tethered” updates over USB from a host PC.
• “Offline” updates via a reboot and update from a file on removable storage.

However, if the device implementation includes support for an unmetered data connection such as 802.11 or Bluetooth PAN (Personal Area Network) profile, it MUST support OTA downloads with offline update via reboot.

The update mechanism used MUST support updates without wiping user data. That is, the update mechanism MUST preserve application private data and application shared data. Note that the upstream Android software includes an update mechanism that satisfies this requirement.

For device implementations that are launching with Android 6.0 and later, the update mechanism SHOULD support verifying that the system image is binary identical to expected result following an OTA. The block-based OTA implementation in the upstream Android Open Source Project, added since Android 5.1, satisfies this requirement.

Also, device implementations SHOULD support A/B system updates . The AOSP implements this feature using the boot control HAL.

If an error is found in a device implementation after it has been released but within its reasonable product lifetime that is determined in consultation with the Android Compatibility Team to affect the compatibility of third-party applications, the device implementer MUST correct the error via a software update available that can be applied per the mechanism just described.

Android includes features that allow the Device Owner app (if present) to control the installation of system updates. To facilitate this, the system update subsystem for devices that report android.software.device_admin MUST implement the behavior described in the SystemUpdatePolicy class.

12. Document Changelog

For a summary of changes to the Compatibility Definition in this release:

• Document changelog

For a summary of changes to individuals sections:

1. introduzione
2. Tipi di dispositivi
3. Software
4. Imballaggio dell'applicazione
5. Multimedia
6. Developer Tools and Options
7. Compatibilità hardware
8. Prestazioni e potenza
9. Security Model
10. Software Compatibility Testing
11. Updatable Software
12. Document Changelog
13. Contattaci

12.1. Changelog Viewing Tips

Changes are marked as follows:

• CDD
  Substantive changes to the compatibility requirements.

• Documenti
  Cosmetic or build related changes.

For best viewing, append the pretty=full and no-merges URL parameters to your changelog URLs.

13. Contattaci

You can join the android-compatibility forum and ask for clarifications or bring up any issues that you think the document does not cover.