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v811_spc009/compatibility/cdd/7_hardware-compatibility/7_1_display-and-graphics.md

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7.1. Display and Graphics

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. On the Android-compatible display(s) where all third-party Android-compatible applications can run, device implementations 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.
  • aspect ratio. 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. Screen Configuration

7.1.1.1. Screen Size and Shape

The Android UI framework supports a variety of different logical screen layout sizes, and allows applications to query the current configuration's screen layout size via Configuration.screenLayout with the SCREENLAYOUT_SIZE_MASK and Configuration.smallestScreenWidthDp.

Device implementations:

  • [C-0-1] MUST report the correct layout size for the Configuration.screenLayout as defined in the Android SDK documentation. Specifically, device implementations MUST report the correct logical density-independent pixel (dp) screen dimensions as below:

    • Devices with the Configuration.uiMode set as any value other than UI_MODE_TYPE_WATCH, and reporting a small size for the Configuration.screenLayout, MUST have at least 426 dp x 320 dp.
    • Devices reporting a normal size for the Configuration.screenLayout, MUST have at least 480 dp x 320 dp.
    • Devices reporting a large size for the Configuration.screenLayout, MUST have at least 640 dp x 480 dp.
    • Devices reporting a xlarge size for the Configuration.screenLayout, MUST have at least 960 dp x 720 dp.

  • [C-0-2] MUST correctly honor applications' stated support for screen sizes through the <supports-screens> attribute in the AndroidManifest.xml, as described in the Android SDK documentation.

  • MAY have the Android-compatible display(s) with rounded corners.

If device implementations support UI_MODE_TYPE_NORMAL and include Android-compatible display(s) with rounded corners, they:

  • [C-1-1] MUST ensure that at least one of the following requirements is met:

  • The radius of the rounded corners is less than or equal to 38 dp.

  • When a 15 dp by 15 dp box is anchored at each corner of the logical display, at least one pixel of each box is visible on the screen.

  • SHOULD include user affordance to switch to the display mode with the rectangular corners.

If device implementations include an Android-compatible display(s) that is foldable, or includes a folding hinge between multiple display panels and makes such display(s) available to render third-party apps, they:

If device implementations include an Android-compatible display(s) that is foldable, or includes a folding hinge between multiple display panels and if the hinge or fold crosses a fullscreen application window, they:

  • [C-3-1] MUST report the position, bounds and state of hinge or fold through extensions or sidecar APIs to the application.

For details on correctly implementing the sidecar or extension APIs refer to the public documentation of Window Manager Jetpack.

7.1.1.2. Screen Aspect Ratio

While there is no restriction to the aspect ratio of the physical display for the Android-compatible display(s), the aspect ratio of the logical display where third-party apps are rendered, which can be derived from the height and width values reported through the view.Display APIs and Configuration APIs, MUST meet the following requirements:

  • [C-0-1] Device implementations with Configuration.uiMode set to UI_MODE_TYPE_NORMAL MUST have an aspect ratio value less than or equal to 1.86 (roughly 16:9), unless the app meets one of the following conditions:

  • [C-0-2] Device implementations with Configuration.uiMode set to UI_MODE_TYPE_NORMAL MUST have an aspect ratio value equal to or greater than 1.3333 (4:3), unless the app can be stretched wider by meeting one of the following conditions:

  • [C-0-3] Device implementations with the Configuration.uiMode set as UI_MODE_TYPE_WATCH MUST have an aspect ratio value set as 1.0 (1:1).

7.1.1.3. Screen Density

The Android UI framework defines a set of standard logical densities to help application developers target application resources.

  • [C-0-1] 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)
*   140 dpi (140dpi)
*   160 dpi (mdpi)
*   180 dpi (180dpi)
*   200 dpi (200dpi)
*   213 dpi (tvdpi)
*   220 dpi (220dpi)
*   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.

If there is an affordance to change the display size of the device:

  • [C-1-1] 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.
  • [C-1-2] 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. Display Metrics

If device implementations include the Android-compatible display(s) or video output to the Android-compatible display screen(s), they:

If device implementations does not include an embedded screen or video output, they:

  • [C-2-1] MUST report correct values of the Android-compatible display as defined in the android.util.DisplayMetrics API for the emulated default view.Display.

7.1.3. Screen Orientation

Device implementations:

  • [C-0-1] 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.
  • [C-0-2] 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.

If device implementations support both screen orientations, they:

  • [C-1-1] 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.
  • [C-1-2] MUST NOT change the reported screen size or density when changing orientation.
  • MAY select either portrait or landscape orientation as the default.

7.1.4. 2D and 3D Graphics Acceleration

7.1.4.1 OpenGL ES

Device implementations:

  • [C-0-1] MUST correctly identify the supported OpenGL ES versions (1.1, 2.0, 3.0, 3.1, 3.2) through the managed APIs (such as via the GLES10.getString() method) and the native APIs.
  • [C-0-2] MUST include the support for all the corresponding managed APIs and native APIs for every OpenGL ES versions they identified to support.

If device implementations include a screen or video output, they:

  • [C-1-1] MUST support both OpenGL ES 1.1 and 2.0, as embodied and detailed in the Android SDK documentation.
  • [C-SR] Are STRONGLY RECOMMENDED to support OpenGL ES 3.1.
  • SHOULD support OpenGL ES 3.2.

If device implementations support any of the OpenGL ES versions, they:

  • [C-2-1] MUST report via the OpenGL ES managed APIs and native APIs any other OpenGL ES extensions they have implemented, and conversely MUST NOT report extension strings that they do not support.
  • [C-2-2] MUST support the EGL_KHR_image, EGL_KHR_image_base, EGL_ANDROID_image_native_buffer, EGL_ANDROID_get_native_client_buffer, EGL_KHR_wait_sync, EGL_KHR_get_all_proc_addresses, EGL_ANDROID_presentation_time, EGL_KHR_swap_buffers_with_damage, EGL_ANDROID_recordable, and EGL_ANDROID_GLES_layers extensions.
  • [C-SR] Are STRONGLY RECOMMENDED to support the EGL_KHR_partial_update and OES_EGL_image_external extensions.
  • SHOULD accurately report via the getString() method, any texture compression format that they support, which is typically vendor-specific.

If device implementations declare support for OpenGL ES 3.0, 3.1, or 3.2, they:

  • [C-3-1] MUST export the corresponding function symbols for these version in addition to the OpenGL ES 2.0 function symbols in the libGLESv2.so library.
  • [SR] Are STRONGLY RECOMMENDED to support the OES_EGL_image_external_essl3 extension.

If device implementations support OpenGL ES 3.2, they:

  • [C-4-1] MUST support the OpenGL ES Android Extension Pack in its entirety.

If device implementations support the OpenGL ES Android Extension Pack in its entirety, they:

  • [C-5-1] MUST identify the support through the android.hardware.opengles.aep feature flag.

If device implementations expose support for the EGL_KHR_mutable_render_buffer extension, they:

  • [C-6-1] MUST also support the EGL_ANDROID_front_buffer_auto_refresh extension.

7.1.4.2 Vulkan

Android includes support for Vulkan , a low-overhead, cross-platform API for high-performance 3D graphics.

If device implementations support OpenGL ES 3.1, they:

  • [SR] Are STRONGLY RECOMMENDED to include support for Vulkan 1.1.

If device implementations include a screen or video output, they:

  • SHOULD include support for Vulkan 1.1.

The Vulkan dEQP tests are partitioned into a number of test lists, each with an associated date/version. These are in the Android source tree at external/deqp/android/cts/master/vk-master-YYYY-MM-DD.txt. A device that supports Vulkan at a self-reported level indicates that it can pass the dEQP tests in all test lists from this level and earlier.

If device implementations include support for Vulkan 1.0 or higher, they:

  • [C-1-1] MUST report the correct integer value with the android.hardware.vulkan.level and android.hardware.vulkan.version feature flags.
  • [C-1-2] MUST enumerate, at least one VkPhysicalDevice for the Vulkan native API vkEnumeratePhysicalDevices() .
  • [C-1-3] MUST fully implement the Vulkan 1.0 APIs for each enumerated VkPhysicalDevice.
  • [C-1-4] MUST enumerate layers, contained in native libraries named as libVkLayer*.so in the application package’s native library directory, through the Vulkan native APIs vkEnumerateInstanceLayerProperties() and vkEnumerateDeviceLayerProperties() .
  • [C-1-5] MUST NOT enumerate layers provided by libraries outside of the application package, or provide other ways of tracing or intercepting the Vulkan API, unless the application has the android:debuggable attribute set as true.
  • [C-1-6] MUST report all extension strings that they do support via the Vulkan native APIs , and conversely MUST NOT report extension strings that they do not correctly support.
  • [C-1-7] MUST support the VK_KHR_surface, VK_KHR_android_surface, VK_KHR_swapchain, and VK_KHR_incremental_present extensions.
  • [C-1-8] MUST report the maximum version of the Vulkan dEQP Tests supported via the android.software.vulkan.deqp.level feature flag.
  • [C-1-9] MUST at least support version 132317953 (from Mar 1st, 2019) as reported in the android.software.vulkan.deqp.level feature flag.
  • [C-1-10] MUST pass all Vulkan dEQP Tests in the test lists between version 132317953 and the version specified in the android.software.vulkan.deqp.level feature flag.
  • [C-SR] Are STRONGLY RECOMMENDED to support the VK_KHR_driver_properties and VK_GOOGLE_display_timing extensions.

If device implementations do not include support for Vulkan 1.0, they:

  • [C-2-1] MUST NOT declare any of the Vulkan feature flags (e.g. android.hardware.vulkan.level, android.hardware.vulkan.version).
  • [C-2-2] MUST NOT enumerate any VkPhysicalDevice for the Vulkan native API vkEnumeratePhysicalDevices().

If device implementations include support for Vulkan 1.1 and declare any of the Vulkan feature flags, they:

  • [C-3-1] MUST expose support for the SYNC_FD external semaphore and handle types and the VK_ANDROID_external_memory_android_hardware_buffer extension.

7.1.4.3 RenderScript

  • [C-0-1] Device implementations MUST support Android RenderScript, as detailed in the Android SDK documentation.

7.1.4.4 2D Graphics Acceleration

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:

  • [C-0-1] 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.
  • [C-0-2] 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:

  • [C-0-3] MUST support the TextureView API, and MUST exhibit consistent behavior with the upstream Android implementation.

7.1.4.5 Wide-gamut Displays

If device implementations claim support for wide-gamut displays through Configuration.isScreenWideColorGamut() , they:

  • [C-1-1] MUST have a color-calibrated display.
  • [C-1-2] MUST have a display whose gamut covers the sRGB color gamut entirely in CIE 1931 xyY space.
  • [C-1-3] MUST have a display whose gamut has an area of at least 90% of DCI-P3 in CIE 1931 xyY space.
  • [C-1-4] MUST support OpenGL ES 3.1 or 3.2 and report it properly.
  • [C-1-5] MUST advertise support for the EGL_KHR_no_config_context, EGL_EXT_pixel_format_float, EGL_KHR_gl_colorspace, EGL_EXT_gl_colorspace_scrgb, EGL_EXT_gl_colorspace_scrgb_linear, EGL_EXT_gl_colorspace_display_p3, EGL_EXT_gl_colorspace_display_p3_linear, and EGL_EXT_gl_colorspace_display_p3_passthrough extensions.
  • [C-SR] Are STRONGLY RECOMMENDED to support GL_EXT_sRGB.

Conversely, if device implementations do not support wide-gamut displays, they:

  • [C-2-1] SHOULD cover 100% or more of sRGB in CIE 1931 xyY space, although the screen color gamut is undefined.

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.

7.1.6. Screen Technology

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

All of a device implementation's Android-compatible displays:

  • [C-0-1] MUST be capable of rendering 16-bit color graphics.
  • SHOULD support displays capable of 24-bit color graphics.
  • [C-0-2] MUST be capable of rendering animations.
  • [C-0-3] 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 Android-compatible displays to enable media sharing capabilities and developer APIs for accessing external displays.

If device implementations support an external display either via a wired, wireless, or an embedded additional display connection, they:

  • [C-1-1] MUST implement the DisplayManager system service and API as described in the Android SDK documentation.