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Commit 9937f81a authored by Phil Weaver's avatar Phil Weaver
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Reduce extra a11y events when alpha changes. 

Changes in alpha only matter if they affect visibility,
so only 0 <-> nonzero changes are worth reporting. Report
them as subtree changes, as visibility affects subviews.

Not reporting every change greatly reduces the number of
event reported when alpha is animated.

Bug: 30183085
Change-Id: I905d53aa81ca8248b3aed86a91842ef499f303a8
parent d7a59636

core/java/android/view/View.java

+4 −2
Original line number Diff line number Diff line
@@ -12303,6 +12303,10 @@ public class View implements Drawable.Callback, KeyEvent.Callback, 
    public void setAlpha(@FloatRange(from=0.0, to=1.0) float alpha) {

        ensureTransformationInfo();

        if (mTransformationInfo.mAlpha != alpha) {

            // Report visibility changes, which can affect children, to accessibility

            if ((alpha == 0) ^ (mTransformationInfo.mAlpha == 0)) {

                notifySubtreeAccessibilityStateChangedIfNeeded();

            }

            mTransformationInfo.mAlpha = alpha;

            if (onSetAlpha((int) (alpha * 255))) {

                mPrivateFlags |= PFLAG_ALPHA_SET;
@@ -12313,8 +12317,6 @@ public class View implements Drawable.Callback, KeyEvent.Callback, 
                mPrivateFlags &= ~PFLAG_ALPHA_SET;

                invalidateViewProperty(true, false);

                mRenderNode.setAlpha(getFinalAlpha());

                notifyViewAccessibilityStateChangedIfNeeded(

                        AccessibilityEvent.CONTENT_CHANGE_TYPE_UNDEFINED);

            }

        }

    }