Android: Enabled services

Description

Similar to issue #30864 and heavily intertwined with #30863, it is sometimes useful to query what accessibility services a user has currently enabled. This would allow your to tailor your app's UI to the specific service. For example, if a user has the "Talkback" screen reader service enabled, you probably don't want videos to auto-play, as the audio would be interruptive to the screen readers announcements, and if auto-played without audio the videos would be playing and taking bandwidth without the user likely realizing this was happening.

Right now, there is a method in the AccessibilityInfo API to detect talkback specifically (isScreenReaderEnabled), but there is not a general purpose method to get a list of all enabled services.

React Native version:

v0.63

Expected Behavior

The AccessibilityInfo API should have some general purpose method to get a list of all enabled services.

Android Details

This functionality is available in the AccessibilityManager class via the getEnabledAccessibilityServiceList method.
https://developer.android.com/reference/android/view/accessibility/AccessibilityManager#getEnabledAccessibilityServiceList(int)

从 issue 中链接的 React Native AccessibilityInfo API 和 Android 的 AccessibilityManager.getEnabledAccessibilityServiceList 方法入手。确定应如何通过 API 暴露已启用的服务，然后验证调用方能够获取完整列表，并且行为与相关的无障碍 issue 一致。