Starting March 27, 2025, we recommend using android-latest-release instead of aosp-main to build and contribute to AOSP. For more information, see Changes to AOSP.
Testing and development environment
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The fastest and easiest way to test secondary displays is to use a simulated
display, which is owned by the system. Because it shares the system_server
UID, it's trusted and allowed to host all decor windows and activities.
If you have a device that supports a hardware connection (for example, HDMI
or DisplayPort over USB-C), you can use external hardware displays to test.
By default, virtual displays that aren't owned by the system UID are considered
to be not trusted and a number of restrictions are applied to prevent the
leaking of user data.
Use desktop mode to test new windowing features and capabilities added to
the platform in Android 10. It's a developer option
targeted for app developers and enables developers to test apps in
multi-display and freeform windowing mode environments.
Figure 1. Desktop mode on two displays, simulated (top) and
external (bottom)
When device manufacturers want to provide a desktop-like experience, use this
feature to showcase the recommended way to implement some of the windowing features.
- Enable the Force desktop mode developer option.
- Reboot the phone.
- Connect the mouse (via USB or Bluetooth).
- Create a simulated display from the developer options or use a hardware
display.
- Launch activities from the launcher on that display and use the mouse to interact.
MD Launcher (platform/development/samples/MultiDisplay) is useful
for testing a targeted activity launch and to request a new instance.
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Last updated 2025-06-12 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-06-12 UTC."],[],[],null,["# Testing and development environment\n\nThe fastest and easiest way to test secondary displays is to use a simulated\ndisplay, which is owned by the system. Because it shares the `system_server`\nUID, it's trusted and allowed to host all decor windows and activities.\n\nIf you have a device that supports a hardware connection (for example, HDMI\nor DisplayPort over USB-C), you can use external hardware displays to test.\n\nBy default, virtual displays that aren't owned by the system UID are considered\nto be *not trusted* and a number of restrictions are applied to prevent the\nleaking of user data.\n\nUse desktop mode to test new windowing features and capabilities added to\nthe platform in Android 10. It's a developer option\ntargeted for app developers and enables developers to test apps in\nmulti-display and freeform windowing mode environments.\n\n**Figure 1.** Desktop mode on two displays, simulated (top) and\nexternal (bottom)\n\nWhen device manufacturers want to provide a desktop-like experience, use this\nfeature to showcase the recommended way to implement some of the windowing features.\n\n1. Enable the **Force desktop mode** developer option.\n2. Reboot the phone.\n3. Connect the mouse (via USB or Bluetooth).\n4. Create a simulated display from the developer options or use a hardware display.\n5. Launch activities from the launcher on that display and use the mouse to interact.\n\nMD Launcher (`platform/development/samples/MultiDisplay`) is useful\nfor testing a targeted activity launch and to request a new instance."]]
