Interrogation of the view hierarchy from an AccessibilityService.
1. Views are represented as AccessibilityNodeInfos to AccessibilityServices.
2. An accessibility service receives AccessibilityEvents and can ask
for its source and gets an AccessibilityNodeInfo which can be used
to get its parent and children infos and so on.
3. AccessibilityNodeInfo contains some attributes and actions that
can be performed on the source.
4. AccessibilityService can request the system to preform an action
on the source of an AccessibilityNodeInfo.
5. ViewAncestor provides an interaction connection to the
AccessibiltyManagerService and an accessibility service uses
its connection to the latter to interact with screen content.
6. AccessibilityService can interact ONLY with the focused window
and all calls are routed through the AccessibilityManagerService
which imposes security.
7. Hidden APIs on AccessibilityService can find AccessibilityNodeInfos
based on some criteria. These API go through the AccessibilityManagerServcie
for security check.
8. Some actions are hidden and are exposes only to eng builds for UI testing.
Change-Id: Ie34fa4219f350eb3f4f6f9f45b24f709bd98783c
31 files changed