Animating and rotating an image in a Surface View

Question

I would like to animate movement on a SurfaceView . Ideally I would like to also be notified once the animation had finished.

For example: I might have a car facing

Answer 1

Do you want multiple independent animated object? If so, then you should use a game loop. (One master while loop that incrementally updates all game objects.) Here's a good discussion on various loop implementations. (I'm currently using "FPS dependent on Constant Game Speed" for my Android game project.)

So then your Car will look something like this (lots of code missing):

class Car {
    final Matrix transform = new Matrix();
    final Bitmap image;

    Car(Bitmap sprite) {
        image = sprite;  // Created by BitmapFactory.decodeResource in SurfaceView
    }
    void update() {
        this.transform.preRotate(turnDegrees, width, height);
    }
    void display(Canvas canvas) {
        canvas.drawBitmap(this.image, this.transform, null);
    }
}

You only need to load your bitmap once. So if you have multiple Cars, you may want to give them each the same Bitmap object (cache the Bitmap in your SurfaceView).

I haven't got into walk animations yet, but the simplest solution is to have multiple Bitmaps and just draw a different bitmap each time display is called.

Have a look at lunarlander.LunarView in the Android docs if you haven't already.

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If you want to be notified when the animation is complete, you should make a callback.

interface CompletedTurnCallback {
    void turnCompleted(Car turningCar);
}

Have your logic class implement the callback and have your Car call it when the turn's complete (in update()). Note that you'll get a ConcurrentModificationException if you are iterating over a list of Cars in update_game() and you try to remove a Car from that list in your callback. (You can solve this with a command queue.)