public void setFraction(float fraction) {
        mFraction = fraction;
        invalidate();
    }
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