Android 简单实现Activity界面变暗效果

效果图：

代码实现如下：

private void dimBackground(final float from, final float to) {        final Window window = getWindow();        ValueAnimator valueAnimator = ValueAnimator.ofFloat(from, to);        valueAnimator.setDuration(500);        valueAnimator.addUpdateListener(new AnimatorUpdateListener() {            @Override            public void onAnimationUpdate(ValueAnimator animation) {                WindowManager.LayoutParams params = window.getAttributes();                params.alpha = (Float) animation.getAnimatedValue();                window.setAttributes(params);            }        });        valueAnimator.start();    }

　变亮

dimBackground(0.5f,1.0f);

　变暗

  dimBackground(1.0f,0.5f);