Java tutorial
//package com.java2s; /** * Copyright 2016 JustWayward Team * <p> * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * <p> * http://www.apache.org/licenses/LICENSE-2.0 * <p> * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import android.animation.ValueAnimator; import android.app.Activity; import android.view.Window; import android.view.WindowManager; public class Main { public static void dimBackground(final float from, final float to, Activity context) { final Window window = context.getWindow(); ValueAnimator valueAnimator = ValueAnimator.ofFloat(from, to); valueAnimator.setDuration(500); valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { WindowManager.LayoutParams params = window.getAttributes(); params.alpha = (Float) animation.getAnimatedValue(); window.setAttributes(params); } }); valueAnimator.start(); } }