@Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        mBallTop = RADIUS;
        mBallLeft = RADIUS;
        mBallRight = getWidth() - RADIUS;
        mBallBottom = getHeight() - RADIUS;
        mBallWidth = mBallRight - mBallLeft;
        mBallHeight = mBallBottom - mBallTop;
    }
This view displays two objects sliding right and down while the animation runs.
The setFraction() method is called by the animation, which causes the view to
invalidate and draw the objects in their new positions.
AnimationsInterpolatorPlayground/app/src/main/java/com/example/android/interpolatorplayground/TimingVisualizer.java