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Only dispatch window visibility aggregation for targetSdk >= N

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Some existing apps treat drawable visibility notifications as a signal
to crossfade from a placeholder to the new image for the purposes of
scrolling onscreen via a recycling collection view or similar. Since
dispatchVisibilityAggregated is now called for window visibility
changes and ImageView informs its drawable of the visiblity change,
the extra call triggers a repeat fade-in in some existing apps when
you return them to visibility.

These apps should pay attention to the second parameter of
Drawable#setVisible, which signals that animations should not restart
in response to a visibility change. Updating to targetSdkVersion=24+
will enable the new behavior.

Bug 30216207

Change-Id: I27ce9f09bc7544863f7f7980c273650949db21cc
This commit is contained in:
Adam Powell
2016-08-22 09:09:44 -07:00
parent 051d6b74eb
commit 64e1ba4398
1 changed files with 10 additions and 1 deletions
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11
core/java/android/view/ViewRootImpl.java
View File

@@ -52,6 +52,7 @@ import android.hardware.input.InputManager;
import android.media.AudioManager;
import android.os.Binder;
import android.os.Build;
import android.os.Build.VERSION_CODES;
import android.os.Bundle;
import android.os.Debug;
import android.os.Handler;
@@ -1540,7 +1541,15 @@ public final class ViewRootImpl implements ViewParent,
if (viewVisibilityChanged) {
mAttachInfo.mWindowVisibility = viewVisibility;
host.dispatchWindowVisibilityChanged(viewVisibility);
host.dispatchVisibilityAggregated(viewVisibility == View.VISIBLE);
// Prior to N we didn't have dispatchVisibilityAggregated to give a more accurate
// view into when views are visible to the user or not. ImageView never dealt with
// telling its drawable about window visibility, among other things. Some apps cause
// an additional crossfade animation when windows become visible if they get this
// additional call, so only send it to new apps to avoid new visual jank.
if (host.getContext().getApplicationInfo().targetSdkVersion >= VERSION_CODES.N) {
host.dispatchVisibilityAggregated(viewVisibility == View.VISIBLE);
}
if (viewVisibility != View.VISIBLE || mNewSurfaceNeeded) {
endDragResizing();
destroyHardwareResources();