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Commit b378059f authored by Ahan Wu's avatar Ahan Wu
Browse files

Fix wallpaper flicker issue while transiting from home to aod. 

There is a race condition between window visibility and wallpaper
transition, so wallpaper window might become visible before background
thread has done its rendering work and a flicker happens.

This solution just lets main thread wait for background thread to
synchronize window visibility and wallpaper transition.

Bug: 136643341
Test: atest SystemUITests
Test: Screen off  Launcher/APP -> AOD : No extra transition by design,
      The duration between press Power Key and AOD show should be same.
Test: Screen on AOD -> Launcher : Face unlock work without flickr
Test: Screen off Keyguard -> AOD : Either Panel or background transition without flickr
Test: Screen on AOD -> Keyguard : Either Panel or background transition without flickr
Test: Reach in AOD -> Keyguard : Either Panel or background transition without flickr
Test: Reach out Keyguard -> AOD : Either Panel or background transition without flickr
Test: Manually operate and observe log.
Change-Id: Iebfdac18972569864c047bc2c4a33d7791940896
parent 6f672a38

packages/SystemUI/src/com/android/systemui/ImageWallpaper.java

+45 −3
Original line number Diff line number Diff line
@@ -46,6 +46,8 @@ public class ImageWallpaper extends WallpaperService { 
    // We delayed destroy render context that subsequent render requests have chance to cancel it.

    // This is to avoid destroying then recreating render context in a very short time.

    private static final int DELAY_FINISH_RENDERING = 1000;

    private static final int INTERVAL_WAIT_FOR_RENDERING = 100;

    private static final int PATIENCE_WAIT_FOR_RENDERING = 5;

    private HandlerThread mWorker;



    @Override
@@ -80,7 +82,10 @@ public class ImageWallpaper extends WallpaperService { 
        private StatusBarStateController mController;

        private final Runnable mFinishRenderingTask = this::finishRendering;

        private final boolean mNeedTransition;

        private final Object mMonitor = new Object();

        private boolean mNeedRedraw;

        // This variable can only be accessed in synchronized block.

        private boolean mWaitingForRendering;



        GLEngine(Context context) {

            mNeedTransition = ActivityManager.isHighEndGfx()
@@ -122,6 +127,27 @@ public class ImageWallpaper extends WallpaperService { 
            long duration = mNeedTransition || animationDuration != 0 ? animationDuration : 0;

            mWorker.getThreadHandler().post(

                    () -> mRenderer.updateAmbientMode(inAmbientMode, duration));

            if (inAmbientMode && duration == 0) {

                // This means that we are transiting from home to aod, to avoid

                // race condition between window visibility and transition,

                // we don't return until the transition is finished. See b/136643341.

                waitForBackgroundRendering();

            }

        }



        private void waitForBackgroundRendering() {

            synchronized (mMonitor) {

                try {

                    mWaitingForRendering = true;

                    for (int patience = 1; mWaitingForRendering; patience++) {

                        mMonitor.wait(INTERVAL_WAIT_FOR_RENDERING);

                        mWaitingForRendering &= patience < PATIENCE_WAIT_FOR_RENDERING;

                    }

                } catch (InterruptedException ex) {

                } finally {

                    mWaitingForRendering = false;

                }

            }

        }



        @Override
@@ -178,7 +204,8 @@ public class ImageWallpaper extends WallpaperService { 


        @Override

        public void preRender() {

            mWorker.getThreadHandler().post(this::preRenderInternal);

            // This method should only be invoked from worker thread.

            preRenderInternal();

        }



        private void preRenderInternal() {
@@ -212,7 +239,8 @@ public class ImageWallpaper extends WallpaperService { 


        @Override

        public void requestRender() {

            mWorker.getThreadHandler().post(this::requestRenderInternal);

            // This method should only be invoked from worker thread.

            requestRenderInternal();

        }



        private void requestRenderInternal() {
@@ -234,7 +262,21 @@ public class ImageWallpaper extends WallpaperService { 


        @Override

        public void postRender() {

            mWorker.getThreadHandler().post(this::scheduleFinishRendering);

            // This method should only be invoked from worker thread.

            notifyWaitingThread();

            scheduleFinishRendering();

        }



        private void notifyWaitingThread() {

            synchronized (mMonitor) {

                if (mWaitingForRendering) {

                    try {

                        mWaitingForRendering = false;

                        mMonitor.notify();

                    } catch (IllegalMonitorStateException ex) {

                    }

                }

            }

        }



        private void cancelFinishRenderingTask() {

packages/SystemUI/src/com/android/systemui/glwallpaper/ImageRevealHelper.java

+11 −1
Original line number Diff line number Diff line
@@ -84,8 +84,18 @@ class ImageRevealHelper { 
    void updateAwake(boolean awake, long duration) {

        mAwake = awake;

        mAnimator.setDuration(duration);

        if (!mAwake && duration == 0) {

            // We are transiting from home to aod,

            // since main thread is waiting for rendering finished, we only need draw

            // the last state directly, which is a black screen.

            mReveal = MIN_REVEAL;

            mRevealListener.onRevealStart();

            mRevealListener.onRevealStateChanged();

            mRevealListener.onRevealEnd();

        } else {

            animate();

        }

    }



    /**

     * A listener to trace value changes of reveal.