https://source.android.com/ 
/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.
 */

package android.view;

import android.animation.Animator;
import android.animation.Animator.AnimatorListener;
import android.animation.RevealAnimator;


Defines common utilities for working with View's animations.

/**
 * Defines common utilities for working with View's animations.
 *
 */
public final class ViewAnimationUtils {
    private ViewAnimationUtils() {}
    
Returns an Animator which can animate a clipping circle.


Any shadow cast by the View will respect the circular clip from this animator.

 Only a single non-rectangular clip can be applied on a View at any time. Views clipped by a circular reveal animation take priority over View Outline clipping. 
 Note that the animation returned here is a one-shot animation. It cannot be re-used, and once started it cannot be paused or resumed. It is also an asynchronous animation that automatically runs off of the UI thread. As a result AnimatorListener.onAnimationEnd(Animator) will occur after the animation has ended, but it may be delayed depending on thread responsiveness. 

Note that if any start delay is set on the reveal animator, the start radius
will not be applied to the reveal circle until the start delay has passed.
If it's desired to set a start radius on the reveal circle during the start
delay, one workaround could be adding an animator with the same start and
end radius. For example:


public static Animator createRevealWithDelay(View view, int centerX, int centerY, float startRadius, float endRadius) {
    Animator delayAnimator = ViewAnimationUtils.createCircularReveal(view, centerX, centerY, startRadius, startRadius);
    delayAnimator.setDuration(delayTimeMS);
    Animator revealAnimator = ViewAnimationUtils.createCircularReveal(view, centerX, centerY, startRadius, endRadius);
    AnimatorSet set = new AnimatorSet();
    set.playSequentially(delayAnimator, revealAnimator);
    return set;
}



Params:
  • view – The View will be clipped to the animating circle.
  • centerX – The x coordinate of the center of the animating circle, relative to
               view.
  • centerY – The y coordinate of the center of the animating circle, relative to
               view.
  • startRadius – The starting radius of the animating circle.
  • endRadius – The ending radius of the animating circle.
/**
     * Returns an Animator which can animate a clipping circle.
     * <p>
     * Any shadow cast by the View will respect the circular clip from this animator.
     * <p>
     * Only a single non-rectangular clip can be applied on a View at any time.
     * Views clipped by a circular reveal animation take priority over
     * {@link View#setClipToOutline(boolean) View Outline clipping}.
     * <p>
     * Note that the animation returned here is a one-shot animation. It cannot
     * be re-used, and once started it cannot be paused or resumed. It is also
     * an asynchronous animation that automatically runs off of the UI thread.
     * As a result {@link AnimatorListener#onAnimationEnd(Animator)}
     * will occur after the animation has ended, but it may be delayed depending
     * on thread responsiveness.
     * <p>
     * Note that if any start delay is set on the reveal animator, the start radius
     * will not be applied to the reveal circle until the start delay has passed.
     * If it's desired to set a start radius on the reveal circle during the start
     * delay, one workaround could be adding an animator with the same start and
     * end radius. For example:
     * <pre><code>
     * public static Animator createRevealWithDelay(View view, int centerX, int centerY, float startRadius, float endRadius) {
     *     Animator delayAnimator = ViewAnimationUtils.createCircularReveal(view, centerX, centerY, startRadius, startRadius);
     *     delayAnimator.setDuration(delayTimeMS);
     *     Animator revealAnimator = ViewAnimationUtils.createCircularReveal(view, centerX, centerY, startRadius, endRadius);
     *     AnimatorSet set = new AnimatorSet();
     *     set.playSequentially(delayAnimator, revealAnimator);
     *     return set;
     * }
     * </code></pre>
     *
     * @param view The View will be clipped to the animating circle.
     * @param centerX The x coordinate of the center of the animating circle, relative to
     *                <code>view</code>.
     * @param centerY The y coordinate of the center of the animating circle, relative to
     *                <code>view</code>.
     * @param startRadius The starting radius of the animating circle.
     * @param endRadius The ending radius of the animating circle.
     */
    public static Animator createCircularReveal(View view,
            int centerX,  int centerY, float startRadius, float endRadius) {
        return new RevealAnimator(view, centerX, centerY, startRadius, endRadius);
    }
}