Optimizing AccessibilityNodeInfo caching.
1. Before we were firing an accessibility event from the common
predecessor of views with accessibility related state changes
every X amount of time. These events designate that the tree
rooted at the source is invalid and should not be cached.
However, some of the state changes do not affect the view tree
structure and we can just refresh the node instead of evicting
and recaching nodes infos for views that did not change. Hence,
we need a way to distinguish between a subtree changed over a
node changed.
Adding a new event type will not work since if say two siblings
have local changes and their predecessor fires a window state
change event, the client will drop the subtree rooted at the
parent including the two views with changes. Subsequent, more
specialized events emitted from the two changed siblings will
be useless since the parent which did not changed is already
evicted from the cache. Conversely, if the specialized events
are fired from the two siblings with local changes and they
are refreshed in the cache the subsequent window state change
event from the common predecessor will force the refreshed
nodes to be evicted.
Hence, to enable distinction between node being changed and
a subtree baing changed while not changing existing behavior,
we will fire only window content change event with an additional
argument specifying what changed - node or a subtree for now.
Also if the changes are local to a view we fire the window
content changed event from the view. So, the two siblings will
fire such an event independently and the client will know that
these are local changes and can just refresh the node. If the
changes are structural, then we fire the window state change
event from the common predecessor.
2. Added the input type of a text view as one of the properties
reported by an AccessibilityNodeInfo. It is nice to prompt the
user what input is expected.
3. Added a bundle for optional information to AccessiiblityNodeInfo.
For example, it will be used for putting web specific properties
that do not map cleanly to Android specific ones in WebView.
4. AccessibilityInteractionController was not taking into account
whether the current accessibility focused node is shown before
returing it. Hence, a disconnected node would be returned and
caching it puts our cahche in an inconsistent state.
Change-Id: I8ed19cfb4a70bdd7597c3f105487f1651cffd9e0
15 files changed