Android provides an accessibility layer that helps users with disabilities to navigate their devices more easily. In addition, Android provides platform APIs that enable accessibility service implementations to receive callbacks for user and system events and generate alternate feedback mechanisms, such as text-to-speech, haptic feedback, and trackball/d-pad navigation.
Device implementations include the following requirements:
Android Automotive implementations SHOULD provide an implementation of the Android accessibility framework consistent with the default Android implementation.
Device implementations (Android Automotive excluded) MUST provide an implementation of the Android accessibility framework consistent with the default Android implementation.
Device implementations (Android Automotive excluded) MUST support third-party accessibility service implementations through the android.accessibilityservice APIs.
Device implementations (Android Automotive excluded) MUST generate AccessibilityEvents and deliver these events to all registered AccessibilityService implementations in a manner consistent with the default Android implementation
Device implementations (Android Automotive and Android Watch devices with no audio output excluded), MUST provide a user-accessible mechanism to enable and disable accessibility services, and MUST display this interface in response to the android.provider.Settings.ACTION_ACCESSIBILITY_SETTINGS intent.
Android device implementations with audio output are STRONGLY RECOMMENDED to provide implementations of accessibility services on the device comparable in or exceeding functionality of the TalkBack** and Switch Access accessibility services (https://github.com/google/talkback).
Android Watch devices with audio output SHOULD provide implementations of an accessibility service on the device comparable in or exceeding functionality of the TalkBack accessibility service (https://github.com/google/talkback).
Device implementations SHOULD provide a mechanism in the out-of-box setup flow for users to enable relevant accessibility services, as well as options to adjust the font size, display size and magnification gestures.
** For languages supported by Text-to-speech.
Also, note that if there is a preloaded accessibility service, it MUST be a Direct Boot aware {directBootAware} app if the device has encrypted storage using File Based Encryption (FBE).