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3.8. User Interface Compatibility
3.8.1. Launcher (Home Screen)
Android includes a launcher application (home screen) and support for third-party applications to replace the device launcher (home screen).
If device implementations allow third-party applications to replace the device home screen, they:
- [C-1-1] MUST declare the platform feature
android.software.home_screen
. - [C-1-2] MUST return the
AdaptiveIconDrawable
object when the third party application use<adaptive-icon>
tag to provide their icon, and thePackageManager
methods to retrieve icons are called.
If device implementations include a default launcher that supports in-app pinning of shortcuts and widgets, they:
- [C-2-1] MUST report
true
forShortcutManager.isRequestPinShortcutSupported()
andAppWidgetManager.html.isRequestPinAppWidgetSupported()
. - [C-2-2] MUST have user affordance asking the user before adding a shortcut requested
by apps via the [
ShortcutManager.requestPinShortcut()
]( https://developer.android.com/reference/android/content/pm/ShortcutManager.html#requestPinShortcut%28android.content.pm.ShortcutInfo, android.content.IntentSender%29) and the [AppWidgetManager.requestPinAddWidget()
]( https://developer.android.com/reference/android/appwidget/AppWidgetManager.html#requestPinAppWidget%28android.content.ComponentName,android.os.Bundle, android.app.PendingIntent%29) API method.
Conversely, if device implementations do not support in-app pinning, they:
- [C-3-1] MUST report
false
forShortcutManager.isRequestPinShortcutSupported()
andAppWidgetManager.html#isRequestPinAppWidgetSupported()
.
If device implementations implement a default launcher that provides quick access to the additional shortcuts provided by third-party apps through the ShortcutManager API, they:
- [C-4-1] MUST support all documented shortcut features (e.g. static and
dynamic shortcuts, pinning shortcuts) and fully implement the APIs of the
ShortcutManager
API class.
If device implementations include a default launcher app that shows badges for the app icons, they:
- [C-5-1] MUST respect the
NotificationChannel.setShowBadge()
API method. In other words, show a visual affordance associated with the app icon if the value is set astrue
, and do not show any app icon badging scheme when all of the app's notification channels have set the value asfalse
. - MAY override the app icon badges with their proprietary badging scheme when
third-party applications indicate support of the proprietary badging scheme
through the use of proprietary APIs, but SHOULD use the resources and values
provided through the notification badges APIs described in the SDK
, such as the
Notification.Builder.setNumber()
and theNotification.Builder.setBadgeIconType()
API.
3.8.2. Widgets
Android supports third-party app widgets by defining a component type and corresponding API and lifecycle that allows applications to expose an “AppWidget” to the end user.
If device implementations support third-party app widgets, they:
- [C-1-1] MUST declare support for platform feature android.software.app_widgets.
- [C-1-2] MUST include built-in support for AppWidgets and expose user interface affordances to add, configure, view, and remove AppWidgets directly within the Launcher.
- [C-1-3] MUST be capable of rendering widgets that are 4 x 4 in the standard grid size. See the App Widget Design Guidelines in the Android SDK documentation for details.
- MAY support application widgets on the lock screen.
3.8.3. Notifications
Android includes Notification
and
NotificationManager
APIs that allow third-party app developers to notify users of notable events and
attract users' attention using the hardware components (e.g. sound, vibration
and light) and software features (e.g. notification shade, system bar) of the
device.
3.8.3.1. Presentation of Notifications
If device implementations allow third party apps to notify users of notable events, they:
- [C-1-1] MUST support notifications that use hardware features, as described in the SDK documentation, and to the extent possible with the device implementation hardware. For instance, if a device implementation includes a vibrator, it MUST correctly implement the vibration APIs. If a device implementation lacks hardware, the corresponding APIs MUST be implemented as no-ops. This behavior is further detailed in section 7.
- [C-1-2] MUST correctly render all resources (icons, animation files etc.) provided for in the APIs, or in the Status/System Bar icon style guide, although they MAY provide an alternative user experience for notifications than that provided by the reference Android Open Source implementation.
- [C-1-3] MUST honor and implement properly the behaviors described for the APIs to update, remove and group notifications.
- [C-1-4] MUST provide the full behavior of the NotificationChannel API documented in the SDK.
- [C-1-5] MUST provide a user affordance to block and modify a certain third-party app's notification per each channel and app package level.
- [C-1-6] MUST also provide a user affordance to display deleted notification channels.
- SHOULD support rich notifications.
- SHOULD present some higher priority notifications as heads-up notifications.
- SHOULD have user affordance to snooze notifications.
- MAY only manage the visibility and timing of when third-party apps can notify users of notable events to mitigate safety issues such as driver distraction.
If device implementations support rich notifications, they:
- [C-2-1] MUST use the exact resources as
provided through the
Notification.Style
API class and its subclasses for the presented resource elements. - SHOULD present each and every resource element (e.g.
icon, title and summary text) defined in the
Notification.Style
API class and its subclasses.
If device impelementations support heads-up notifications: they:
- [C-3-1] MUST use the heads-up notification view and resources
as described in the
Notification.Builder
API class when heads-up notifications are presented.
3.8.3.2. Notification Listener Service
Android includes the NotificationListenerService
APIs that allow apps (once explicitly enabled by the user) to receive a copy of
all notifications as they are posted or updated.
Device implementations:
- [C-0-1] MUST correctly and promptly update notifications in their entirety to all such installed and user-enabled listener services, including any and all metadata attached to the Notification object.
- [C-0-2] MUST respect the [
snoozeNotification()
]( https://developer.android.com/reference/android/service/notification/NotificationListenerService.html#snoozeNotification%28java.lang.String, long%29) API call, and dismiss the notification and make a callback after the snooze duration that is set in the API call.
If device implementations have a user affordance to snooze notifications, they:
- [C-1-1] MUST reflect the snoozed notification status properly
through the standard APIs such as
NotificationListenerService.getSnoozedNotifications()
. - [C-1-2] MUST make this user affordance available to snooze notifications from each installed third-party app's, unless they are from persistent/foreground services.
3.8.3.3. DND (Do not Disturb)
If device implementations support the DND feature, they:
- [C-1-1] MUST implement an activity that would respond to the intent ACTION_NOTIFICATION_POLICY_ACCESS_SETTINGS, which for implementations with UI_MODE_TYPE_NORMAL it MUST be an activity where the user can grant or deny the app access to DND policy configurations.
- [C-1-2] MUST, for when the device implementation has provided a means for the user to grant or deny third-party apps to access the DND policy configuration, display Automatic DND rules created by applications alongside the user-created and pre-defined rules.
- [C-1-3] MUST honor the
suppressedVisualEffects
values passed along the [NotificationManager.Policy
](https://developer.android.com/reference/android/app/NotificationManager.Policy.html#NotificationManager.Policy%28int, int, int, int%29) and if an app has set any of the SUPPRESSED_EFFECT_SCREEN_OFF or SUPPRESSED_EFFECT_SCREEN_ON flags, it SHOULD indicate to the user that the visual effects are suppressed in the DND settings menu.
3.8.4. Search
Android includes APIs that allow developers to incorporate search into their applications and expose their application’s data into the global system search. Generally speaking, this functionality consists of a single, system-wide user interface that allows users to enter queries, displays suggestions as users type, and displays results. The Android APIs allow developers to reuse this interface to provide search within their own apps and allow developers to supply results to the common global search user interface.
- Android device implementations SHOULD include global search, a single, shared, system-wide search user interface capable of real-time suggestions in response to user input.
If device implementations implement the global search interface, they:
- [C-1-1] MUST implement the APIs that allow third-party applications to add suggestions to the search box when it is run in global search mode.
If no third-party applications are installed that make use of the global search:
- The default behavior SHOULD be to display web search engine results and suggestions.
Android also includes the Assist APIs to allow applications to elect how much information of the current context is shared with the assistant on the device.
If device implementations support the Assist action, they:
- [C-2-1] MUST indicate clearly to the end user when the context is shared, by
either:
- Each time the assist app accesses the context, displaying a white light around the edges of the screen that meet or exceed the duration and brightness of the Android Open Source Project implementation.
- For the preinstalled assist app, providing a user affordance less than two navigations away from the default voice input and assistant app settings menu, and only sharing the context when the assist app is explicitly invoked by the user through a hotword or assist navigation key input.
- [C-2-2] The designated interaction to launch the assist app as described
in section 7.2.3 MUST launch the user-selected
assist app, in other words the app that implements
VoiceInteractionService
, or an activity handling theACTION_ASSIST
intent. - [SR] STRONGLY RECOMMENDED to use long press on
HOME
key as this designated interaction.
3.8.5. Alerts and Toasts
Applications can use the Toast
API to display short non-modal strings to the end user that disappear after a
brief period of time, and use the TYPE_APPLICATION_OVERLAY
window type API to display alert windows as an overlay over other apps.
If device implementations include a screen or video output, they:
-
[C-1-1] MUST provide a user affordance to block an app from displaying alert windows that use the
TYPE_APPLICATION_OVERLAY
. The AOSP implementation meets this requirement by having controls in the notification shade. -
[C-1-2] MUST honor the Toast API and display Toasts from applications to end users in some highly visible manner.
3.8.6. Themes
Android provides “themes” as a mechanism for applications to apply styles across an entire Activity or application.
Android includes a “Holo” and "Material" theme family as a set of defined styles for application developers to use if they want to match the Holo theme look and feel as defined by the Android SDK.
If device implementations include a screen or video output, they:
- [C-1-1] MUST NOT alter any of the Holo theme attributes exposed to applications.
- [C-1-2] MUST support the “Material” theme family and MUST NOT alter any of the Material theme attributes or their assets exposed to applications.
Android also includes a “Device Default” theme family as a set of defined styles for application developers to use if they want to match the look and feel of the device theme as defined by the device implementer.
- Device implementations MAY modify the Device Default theme attributes exposed to applications.
Android supports a variant theme with translucent system bars, which allows application developers to fill the area behind the status and navigation bar with their app content. To enable a consistent developer experience in this configuration, it is important the status bar icon style is maintained across different device implementations.
If device implementations include a system status bar, they:
- [C-2-1] MUST use white for system status icons (such as signal strength and battery level) and notifications issued by the system, unless the icon is indicating a problematic status or an app requests a light status bar using the SYSTEM_UI_FLAG_LIGHT_STATUS_BAR flag.
- [C-2-2] Android device implementations MUST change the color of the system status icons to black (for details, refer to R.style) when an app requests a light status bar.
3.8.7. Live Wallpapers
Android defines a component type and corresponding API and lifecycle that allows applications to expose one or more “Live Wallpapers” to the end user. Live wallpapers are animations, patterns, or similar images with limited input capabilities that display as a wallpaper, behind other applications.
Hardware is considered capable of reliably running live wallpapers if it can run all live wallpapers, with no limitations on functionality, at a reasonable frame rate with no adverse effects on other applications. If limitations in the hardware cause wallpapers and/or applications to crash, malfunction, consume excessive CPU or battery power, or run at unacceptably low frame rates, the hardware is considered incapable of running live wallpaper. As an example, some live wallpapers may use an OpenGL 2.0 or 3.x context to render their content. Live wallpaper will not run reliably on hardware that does not support multiple OpenGL contexts because the live wallpaper use of an OpenGL context may conflict with other applications that also use an OpenGL context.
- Device implementations capable of running live wallpapers reliably as described above SHOULD implement live wallpapers.
If device implementations implement live wallpapers, they:
- [C-1-1] MUST report the platform feature flag android.software.live_wallpaper.
3.8.8. Activity Switching
The upstream Android source code includes the overview screen, a system-level user interface for task switching and displaying recently accessed activities and tasks using a thumbnail image of the application’s graphical state at the moment the user last left the application.
Device implementations including the recents function navigation key as detailed in section 7.2.3 MAY alter the interface.
If device implementations including the recents function navigation key as detailed in section 7.2.3 alter the interface, they:
-
[C-1-1] MUST support at least up to 20 displayed activities.
-
SHOULD at least display the title of 4 activities at a time.
-
[C-1-2] MUST implement the screen pinning behavior and provide the user with a settings menu to toggle the feature.
-
SHOULD display highlight color, icon, screen title in recents.
-
SHOULD display a closing affordance ("x") but MAY delay this until user interacts with screens.
-
SHOULD implement a shortcut to switch easily to the previous activity
-
SHOULD trigger the fast-switch action between the two most recently used apps, when the recents function key is tapped twice.
-
SHOULD trigger the split-screen multiwindow-mode, if supported, when the recents functions key is long pressed.
-
MAY display affiliated recents as a group that moves together.
-
[SR] Device implementations are STRONGLY RECOMMENDED to use the upstream Android user interface (or a similar thumbnail-based interface) for the overview screen.
3.8.9. Input Management
Android includes support for Input Management and support for third-party input method editors.
If device implementations allow users to use third-party input methods on the device, they:
- [C-1-1] MUST declare the platform feature android.software.input_methods and support IME APIs as defined in the Android SDK documentation.
- [C-1-2] MUST provide a user-accessible mechanism to add and configure third-party input methods in response to the android.settings.INPUT_METHOD_SETTINGS intent.
If device implementations declare the android.software.autofill
feature flag, they:
- [C-2-1] MUST fully implement the
AutofillService
andAutofillManager
APIs and honor theandroid.settings.REQUEST_SET_AUTOFILL_SERVICE
intent to show a default app settings menu to enable and disable autofill and change the default autofill service for the user.
3.8.10. Lock Screen Media Control
The Remote Control Client API is deprecated from Android 5.0 in favor of the Media Notification Template that allows media applications to integrate with playback controls that are displayed on the lock screen.
3.8.11. Screen savers (previously Dreams)
Android includes support for interactivescreensavers,
previously referred to as Dreams. Screen savers allow users to interact with
applications when a device connected to a power source is idle or docked in a
desk dock. Android Watch devices MAY implement screen savers, but other types
of device implementations SHOULD include support for screen savers and provide
a settings option for users toconfigure screen savers in response to the
android.settings.DREAM_SETTINGS
intent.
3.8.12. Location
If device implementations include a hardware sensor (e.g. GPS) that is capable of providing the location coordinates:
- [C-1-1] location modes MUST be displayed in the Location menu within Settings.
3.8.13. Unicode and Font
Android includes support for the emoji characters defined in Unicode 10.0.
If device implementations include a screen or video output, they:
- [C-1-1] MUST be capable of rendering these emoji characters in color glyph.
- [C-1-2] MUST include support for:
- Roboto 2 font with different weights—sans-serif-thin, sans-serif-light, sans-serif-medium, sans-serif-black, sans-serif-condensed, sans-serif-condensed-light for the languages available on the device.
- Full Unicode 7.0 coverage of Latin, Greek, and Cyrillic, including the Latin Extended A, B, C, and D ranges, and all glyphs in the currency symbols block of Unicode 7.0.
- SHOULD support the skin tone and diverse family emojis as specified in the Unicode Technical Report #51.
If device implementations include an IME, they:
- SHOULD provide an input method to the user for these emoji characters.
3.8.14. Multi-windows
If device implementations have the capability to display multiple activities at the same time, they:
- [C-1-1] MUST implement such multi-window mode(s) in accordance with the application behaviors and APIs described in the Android SDK multi-window mode support documentation and meet the following requirements:
- [C-1-2] Applications can indicate whether they are capable of operating in
multi-window mode in the
AndroidManifest.xml
file, either explicitly via setting theandroid:resizeableActivity
attribute totrue
or implicitly by having the targetSdkVersion > 24. Apps that explicitly set this attribute tofalse
in their manifest MUST NOT be launched in multi-window mode. Older apps with targetSdkVersion < 24 that did not set thisandroid:resizeableActivity
attribute MAY be launched in multi-window mode, but the system MUST provide warning that the app may not work as expected in multi-window mode. - [C-1-3] MUST NOT offer split-screen or freeform mode if the screen height < 440 dp and the the screen width < 440 dp.
- Device implementations with screen size
xlarge
SHOULD support freeform mode.
If device implementations support multi-window mode(s), and the split screen mode, they:
- [C-2-1] MUST preload a resizeable launcher as the default.
- [C-2-2] MUST crop the docked activity of a split-screen multi-window but SHOULD show some content of it, if the Launcher app is the focused window.
- [C-2-3] MUST honor the declared
AndroidManifestLayout_minWidth
andAndroidManifestLayout_minHeight
values of the third-party launcher application and not override these values in the course of showing some content of the docked activity.
If device implementations support multi-window mode(s) and Picture-in-Picture multi-window mode, they:
- [C-3-1] MUST launch activities in picture-in-picture multi-window mode
when the app is:
* Targeting API level 26 or higher and declares
android:supportsPictureInPicture
* Targeting API level 25 or lower and declares bothandroid:resizeableActivity
andandroid:supportsPictureInPicture
. - [C-3-2] MUST expose the actions in their SystemUI as
specified by the current PIP activity through the
setActions()
API. - [C-3-3] MUST support aspect ratios greater than or equal to
1:2.39 and less than or equal to 2.39:1, as specified by the PIP activity through
the
setAspectRatio()
API. - [C-3-4] MUST use
KeyEvent.KEYCODE_WINDOW
to control the PIP window; if PIP mode is not implemented, the key MUST be available to the foreground activity. - [C-3-5] MUST provide a user affordance to block an app from displaying in PIP mode; the AOSP implementation meets this requirement by having controls in the notification shade.
- [C-3-6] MUST allocate minimum width and height of 108 dp for the PIP window
and minimum width of 240 dp and height of 135 dp for the PIP window when the
Configuration.uiMode
is configured asUI_MODE_TYPE_TELEVISION