ParallaxFragment.java 文件源码

private void setUp(final ScrollingBackgroundView view, final int step, final float speed) {
    view.postOnAnimation(new Runnable() {
        @Override
        public void run() {
            final ValueAnimator animator = ValueAnimator.ofFloat(.0F, 1.F);
            animator.setEvaluator(new FloatEvaluator());
            animator.setDuration(400L);
            animator.setRepeatMode(ValueAnimator.RESTART);
            animator.setRepeatCount(ValueAnimator.INFINITE);
            animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    view.scrollBy(
                            (int) (step * speed + .5F),
                            0
                    );
                }
            });
            animator.start();
        }
    });
}