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I'm using Facebook's Rebound library to replicate the bouncy animations seen in their chat heads implementation. The problem is, most of the time the animation stutters. A few pictures will explain this better. Here's the buttery-smooth chat heads animation:

Facebook Messenger

And here's my attempt (notice how the animation for the white View skips nearly all frames):

Stuttering animation

Once in a while it works smoothly:

Smooth animation

Below is the code I'm using currently (the entire project is up on Github if you want to set it up quickly). I'm guessing this has something to do with hardware acceleration not being enabled correctly on my View. There are 2 Springs in my SpringSystem, one for the "bubble" (the Android icon) and another for the content (the white View that is displayed on tapping the bubble). Any help on how to solve this issue would be greatly appreciated. Thanks.

AndroidManifest.xml:

    <application android:hardwareAccelerated="true" ...>
        ...
    </application>

AppService.java:

    // the following code is in AppService#onCreate()
    // AppService extends android.app.Service
    // full code at https://github.com/vickychijwani/BubbleNote

    mContent.setLayerType(View.LAYER_TYPE_HARDWARE, null);

    final Spring bubbleSpring = system.createSpring();
    bubbleSpring.setCurrentValue(1.0);
    bubbleSpring.addListener(new SpringListener() {
        @Override
        public void onSpringUpdate(Spring spring) {
            float value = (float) spring.getCurrentValue();
            params.x = (int) (mPos[0] * value);
            params.y = (int) (mPos[1] * value);
            mWindowManager.updateViewLayout(mBubble, params);
            // fire the second animation when this one is about to end
            if (spring.isOvershooting() && contentSpring.isAtRest()) {
                contentSpring.setEndValue(1.0);
            }
        }

        // ...
    });

    final Spring contentSpring = system.createSpring();
    contentSpring.setCurrentValue(0.0);
    contentSpring.addListener(new SpringListener() {
        @Override
        public void onSpringUpdate(Spring spring) {
            // always prints false?!
            Log.d(TAG, "hardware acc = " + mContent.isHardwareAccelerated());
            float value = (float) spring.getCurrentValue();
            // clamping is required to prevent flicker
            float clampedValue = Math.min(Math.max(value, 0.0f), 1.0f);
            mContent.setScaleX(value);
            mContent.setScaleY(value);
            mContent.setAlpha(clampedValue);
        }

        // ...
    });
Vicky Chijwani
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1 Answers1

10

I've figured it out by going through the framework source code.

TL;DR: add WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED to the layout flags when you manually attach a View to a Window / WindowManager; setting android:hardwareAccelerated=true in the manifest won't work.


I'm manually attaching my View to the WindowManager (because I need to create my UI in a Service to emulate chat heads) like so:

    // code at https://github.com/vickychijwani/BubbleNote/blob/eb708e3910a7279c5490f614a7150009b59bad0b/app/src/main/java/io/github/vickychijwani/bubblenote/BubbleNoteService.java#L54
    mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
    LayoutInflater inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
    mBubble = (LinearLayout) inflater.inflate(R.layout.bubble, null, false);
    // ...
    final WindowManager.LayoutParams params = new WindowManager.LayoutParams(
            WindowManager.LayoutParams.WRAP_CONTENT,
            WindowManager.LayoutParams.WRAP_CONTENT,
            WindowManager.LayoutParams.TYPE_PHONE,
            WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
            PixelFormat.TRANSLUCENT);
    // ...
    mWindowManager.addView(mBubble, params);

Let's go digging...

Welcome to the Android framework

I started debugging at View#draw(...), then went up the call stack to ViewRootImpl#draw(boolean). Here I came across this piece of code:

    if (!dirty.isEmpty() || mIsAnimating) {
        if (attachInfo.mHardwareRenderer != null && attachInfo.mHardwareRenderer.isEnabled()) {
            // Draw with hardware renderer.
            mIsAnimating = false;
            mHardwareYOffset = yoff;
            mResizeAlpha = resizeAlpha;

            mCurrentDirty.set(dirty);
            dirty.setEmpty();

            attachInfo.mHardwareRenderer.draw(mView, attachInfo, this,
                    animating ? null : mCurrentDirty);
        } else {
            // If we get here with a disabled & requested hardware renderer, something went
            // wrong (an invalidate posted right before we destroyed the hardware surface
            // for instance) so we should just bail out. Locking the surface with software
            // rendering at this point would lock it forever and prevent hardware renderer
            // from doing its job when it comes back.
            // Before we request a new frame we must however attempt to reinitiliaze the
            // hardware renderer if it's in requested state. This would happen after an
            // eglTerminate() for instance.
            if (attachInfo.mHardwareRenderer != null &&
                    !attachInfo.mHardwareRenderer.isEnabled() &&
                    attachInfo.mHardwareRenderer.isRequested()) {

                try {
                    attachInfo.mHardwareRenderer.initializeIfNeeded(mWidth, mHeight,
                            mHolder.getSurface());
                } catch (OutOfResourcesException e) {
                    handleOutOfResourcesException(e);
                    return;
                }

                mFullRedrawNeeded = true;
                scheduleTraversals();
                return;
            }

            if (!drawSoftware(surface, attachInfo, yoff, scalingRequired, dirty)) {
                return;
            }
        }
    }

In my case ViewRootImpl#drawSoftware() was being called, which uses the software renderer. Hmm... that means the HardwareRenderer is null. So I went searching for the point of construction of the HardwareRenderer, which is in ViewRootImpl#enableHardwareAcceleration(WindowManager.LayoutParams):

    // Try to enable hardware acceleration if requested
    final boolean hardwareAccelerated =
            (attrs.flags & WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED) != 0;
    if (hardwareAccelerated) {
        // ...
        mAttachInfo.mHardwareRenderer = HardwareRenderer.createGlRenderer(2, translucent);
        // ...
    }

Aha! There's our culprit!

Back to the problem at hand

In this case Android does not automatically set FLAG_HARDWARE_ACCELERATED for this Window, even though I've set android:hardwareAccerelated=true in the manifest. So the fix is simply:

    mWindowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
    LayoutInflater inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
    mBubble = (LinearLayout) inflater.inflate(R.layout.bubble, null, false);
    // ...
    final WindowManager.LayoutParams params = new WindowManager.LayoutParams(
            WindowManager.LayoutParams.WRAP_CONTENT,
            WindowManager.LayoutParams.WRAP_CONTENT,
            WindowManager.LayoutParams.TYPE_PHONE,
            // NOTE
            WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED | WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
            PixelFormat.TRANSLUCENT);
    // ...
    mWindowManager.addView(mBubble, params);

Although the animation is still not as smooth as Facebook's. I wonder why... (before anyone asks: no, there are no copious logs during the animation; and yes, I've tried with a release build)

Vicky Chijwani
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  • I don't add FLAG_HARDWARE_ACCELERATED flag to WindowManager.LayoutParams but when I check Layout.isHardwareAccelerated() it still returns true? – Wayne Jan 16 '15 at 16:23
  • Do you have `android:hardwareAccelerated=true` in your manifest? That automatically enables hardware acceleration throughout the app I think. – Vicky Chijwani Jan 16 '15 at 20:23
  • Of course I have. That means we don't need to add FLAG_HARDWARE_ACCELERATED as you mentioned. – Wayne Jan 19 '15 at 02:26
  • Well either you're not attaching the View to your Window manually, or you're using a different version of Android that doesn't require you to add `FLAG_HARDWARE_ACCELERATED` explicitly. I can't say without seeing the relevant code. – Vicky Chijwani Jan 19 '15 at 06:56
  • Exactly the same problem I'm currently having but I'm not sure if I notice anything different. – Denny Feb 01 '19 at 19:34