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Commit 13801aec authored by Shai Barack's avatar Shai Barack
Browse files

Improve View scrollbar fade scheduling efficiency 

When rescheduling a scrollbar fade animation, we only ever postpone the animation.
Take advantage of this by not bothering to remove and re-post scheduled animation.
Rather, let an already-scheduled animation happen at the elapsed time, and re-post itself
to a future time if the scheduled animation start time had since been updated.

This fixes an issue where many View invalidations would cause the same animation to be
cancelled and re-issued.
See the referenced bug for evidence and impact analysis.

Fixes: 419083356
Bug: 415954362
Flag: EXEMPT bugfix
Change-Id: If4bf8664adcc0641209ec5bb849bf7db75ceb347
parent 3da4a3ba

core/java/android/view/View.java

+24 −10
Original line number Diff line number Diff line
@@ -21120,7 +21120,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback, 
     *        should start; when the delay is 0, the animation starts

     *        immediately

     *

     * @param invalidate Whether this method should call invalidate

     * @param invalidate Whether this method should call invalidate if an animation

     *        is scheduled

     *

     * @return true if the animation is played, false otherwise

     *
@@ -21146,11 +21147,6 @@ public class View implements Drawable.Callback, KeyEvent.Callback, 














        if (isHorizontalScrollBarEnabled() || isVerticalScrollBarEnabled()) {



























            if (invalidate) {













                // Invalidate to show the scrollbars













                postInvalidateOnAnimation();













            }



























            if (scrollCache.state == ScrollabilityCache.OFF) {















                // FIXME: this is copied from WindowManagerService.















                // We should get this value from the system when it









@@ -21165,10 +21161,18 @@ public class View implements Drawable.Callback, KeyEvent.Callback,













            scrollCache.fadeStartTime = fadeStartTime;















            scrollCache.state = ScrollabilityCache.ON;



























            // Schedule our fader to run, unscheduling any old ones first













            // Schedule our fader to run if it's not already scheduled













            if (!scrollCache.fadeScrollBarsScheduled) {













                if (invalidate) {













                    // Invalidate to show the scrollbars













                    postInvalidateOnAnimation();













                }















                if (mAttachInfo != null) {













                mAttachInfo.mHandler.removeCallbacks(scrollCache);













                mAttachInfo.mHandler.postAtTime(scrollCache, fadeStartTime);













                    final Handler handler = mAttachInfo.mHandler;













                    scrollCache.handler = handler;













                    scrollCache.fadeScrollBarsScheduled = true;













                    handler.postAtTime(scrollCache, fadeStartTime);













                }















            }





























            return true;










@@ -32849,6 +32853,7 @@ public class View implements Drawable.Callback, KeyEvent.Callback,













        public static final int FADING = 2;





























        public boolean fadeScrollBars;













        public boolean fadeScrollBarsScheduled;





























        public int fadingEdgeLength;















        public int scrollBarDefaultDelayBeforeFade;










@@ -32877,6 +32882,10 @@ public class View implements Drawable.Callback, KeyEvent.Callback,













         */















        public long fadeStartTime;



























        /**













         * Handler used for scheduling fade animations.













         */













        Handler handler;





























        /**















         * The current state of the scrollbars: ON, OFF, or FADING










@@ -32935,6 +32944,8 @@ public class View implements Drawable.Callback, KeyEvent.Callback,













        public void run() {















            long now = AnimationUtils.currentAnimationTimeMillis();















            if (now >= fadeStartTime) {













                fadeScrollBarsScheduled = false;













                handler = null;





























                // the animation fades the scrollbars out by changing















                // the opacity (alpha) from fully opaque to fully









@@ -32955,6 +32966,9 @@ public class View implements Drawable.Callback, KeyEvent.Callback,



























                // Kick off the fade animation















                host.invalidate(true);













            } else if (handler != null) {













                // Reschedule the fade animation













                handler.postAtTime(this, fadeStartTime);















            }















        }















    }