[[["容易理解","easyToUnderstand","thumb-up"],["確實解決了我的問題","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["缺少我需要的資訊","missingTheInformationINeed","thumb-down"],["過於複雜/步驟過多","tooComplicatedTooManySteps","thumb-down"],["過時","outOfDate","thumb-down"],["翻譯問題","translationIssue","thumb-down"],["示例/程式碼問題","samplesCodeIssue","thumb-down"],["其他","otherDown","thumb-down"]],["上次更新時間：2025-07-27 (世界標準時間)。"],[],[],null,["# Surface and SurfaceHolder\n\nSurface objects enable apps to render images to be presented on screens.\nSurfaceHolder interfaces enable apps to edit and control surfaces.\n\nSurface\n-------\n\nA [surface](https://developer.android.com/reference/android/view/Surface.html) is an interface for a producer to exchange buffers\nwith a consumer.\n\nThe BufferQueue for a display surface is typically configured for\ntriple-buffering. Buffers are allocated on demand, so if the producer\ngenerates buffers slowly enough, such as at 30 fps on a 60 fps\ndisplay, there might only be two allocated buffers in the queue.\nAllocating buffers on demand helps\nminimize memory consumption. You can see a summary of the buffers associated\nwith every layer in the `dumpsys SurfaceFlinger` output.\n\nMost clients render onto surfaces using [OpenGL ES](/docs/core/graphics/arch-egl-opengl) or [Vulkan](/docs/core/graphics/arch-vulkan). However, some clients render\nonto surfaces using a canvas.\n\n\n### Canvas rendering\n\nThe canvas implementation is provided by the\n[Skia Graphics Library](https://skia.org/).\nIf you want to draw a rectangle, you call the Canvas API, which sets bytes in a\nbuffer appropriately. To ensure that a buffer isn't updated by two clients at\nonce, or written to while being displayed, lock the buffer to access\nit. Use the following commands to work with canvas locks:\n\n- [`lockCanvas()`](https://developer.android.com/reference/android/view/Surface.html#lockCanvas(android.graphics.Rect)) locks the buffer for rendering on the CPU and returns a Canvas to use for drawing.\n- [`unlockCanvasAndPost()`](https://developer.android.com/reference/android/view/Surface.html#unlockCanvasAndPost(android.graphics.Canvas)) unlocks the buffer and sends it to the compositor.\n- [`lockHardwareCanvas()`](https://developer.android.com/reference/android/view/Surface.html#lockHardwareCanvas()) locks the buffer for rendering on the GPU and returns a canvas to use for drawing.\n\n| **Note:** The canvas obtained when an app locks a surface with `lockCanvas()` is never hardware accelerated.\n| **Caution:** You can't draw on a surface with GLES or send it frames from a video decoder if you've ever called `lockCanvas()`. `lockCanvas()` connects the CPU renderer to the producer side of the BufferQueue and doesn't disconnect until the surface is destroyed. The canvas-based CPU renderer can't be disconnected and reconnected to a surface, unlike most producers (like GLES or Vulkan).\n\nThe first time the producer requests a buffer from a BufferQueue, the\nbuffer is\nallocated and initialized to zero. Initialization is necessary to avoid\ninadvertently sharing data between processes. However, if you reuse a buffer,\nthe previous contents are still present. If you repeatedly call\n`lockCanvas()` and `unlockCanvasAndPost()` without\ndrawing anything, the producer cycles between previously rendered frames.\n\nThe surface lock/unlock code keeps a reference to the previously rendered\nbuffer. If you specify a dirty region when locking the surface, it copies\nthe nondirty pixels from the previous buffer. SurfaceFlinger or HWC typically\nhandle the buffer; but because we only need to read from\nthe buffer, there's no need to wait for exclusive access.\n\nSurfaceHolder\n-------------\n\nA [SurfaceHolder](https://developer.android.com/reference/android/view/SurfaceHolder.html) is an interface the system uses to share ownership of\nsurfaces with apps. Some clients that work with surfaces want a SurfaceHolder,\nbecause APIs to get and set surface parameters are implemented through a\nSurfaceHolder. A [SurfaceView](/docs/core/graphics/arch-sv-glsv) contains\na SurfaceHolder.\n\nMost components that interact with a view involve a SurfaceHolder.\nSome other APIs, such as MediaCodec, operate on the surface itself."]]
