Draw high res animations with high frame rate on Android

Question

I've got 30+ single bitmaps (320x240 pixels) that I would like to display one after another in full screen on Android devices resulting in an animation. Currently I implemented the animation using an ImageView and a Timer that sets the next frame and then sends a message that will apply the next frame. The resulting frame rate is very low: < 2 fps.

The timer:

animationTimer.scheduleAtFixedRate(new TimerTask() {
    @Override
    public void run() {
        Drawable frame = getNextFrame();
            if (frame != null) {
                Message message = animationFrameHandler.obtainMessage(1, frame);
                animationFrameHandler.sendMessage(message);
            }
        }
    }, 0, (int) (1000.0d / fps));

The handler:

final Handler animationFrameHandler = new Handler() {
    @Override
    public void handleMessage(Message message) {
        setImageDrawable((Drawable) message.obj);
    }
};

Since I want to achieve frame rates up to 30 fps I have to make use of another mechanism and heard of Canvas.drawBitmapMesh() and OpenGL.

If possible I would like to avoid using OpenGL.

Thank you very sharing your experiences!

Answer 1

My now working approach is the following:

Before starting the animation, load every frame into a List<Bitmap>. Important: Call System.gc() if you're getting OutOfMemoryErrors – that really helps loading more bitmaps into the memory. Then have a thread running that posts the next frame to a View instance that then update it's canvas.

Loading the frames and starting the animation

// Loading the frames before starting the animation
List<Bitmap> frames = new ArrayList<Bitmap>();
for (int i = 0; i < 30; i++) {
    // Load next frame (e. g. from drawable or assets folder)
    frames.add(...);
    // Do garbage collection every 3rd frame; really helps loading all frames into memory
    if (i %% 3 == 0) {
        System.gc();
    }
}

// Start animation
frameIndex = 0;
animationThread.start();

Thread that applies the next frame

private final class AnimationThread extends Thread {
    @Override
    public void run() {
        while (!isInterrupted()) {
            // Post next frame to be displayed
            animationView.postFrame(frames.get(frameIndex));

            // Apply next frame (restart if last frame has reached)
            frameIndex++;
            if (frameIndex >= frames.size()) {
                frameIndex = 0;
            }

            try {
                sleep(33); // delay between frames in msec (33 msec mean 30 fps)
            } catch (InterruptedException e) {
                break;
            }
        }
    }
}

The animation view

class AnimationView extends View {
    Bitmap frame = null;

    public void postFrame(Bitmap frame) {
        Message message = frameHandler.obtainMessage(0, frame);
        frameHandler.sendMessage(message);
    }

    protected final Handler frameHandler = new Handler() {
        @Override
        public void handleMessage(Message message) {
            if (message.obj != null) {
                frame = (Bitmap) message.obj;
            } else {
                frame = null;
            }
            invalidate();
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (frame == null) return;
        canvas.drawARGB(0, 0, 0, 0);
        canvas.drawBitmap(frame, null, null, null);
    }
}

Answer 2

You should look at the FrameAnimation class; http://developer.android.com/guide/topics/graphics/2d-graphics.html#frame-animation to do frame animation with Androids animation.

Though that might still be too slow.

The other alternative if you don't want to use OpenGL ES is to draw to the Canvas as you've mentioned. But just use .drawBitmap, not the drawBitmapMesh. Create a SurfaceView, which has a thread, that thread should draw on your Canvas at whatever interval you want.

It's pretty straightforward, just read the Android docs, the information is all there.