code: @TargetApi(Build.VERSION_CODES.LOLLIPOP)
      public static SupportAnimator createCircularReveal(View view,
                                                  int centerX,  int centerY,
                                                  float startRadius, float endRadius) {
  
          if(!(view.getParent() instanceof RevealAnimator)){
              throw new IllegalArgumentException("View must be inside RevealFrameLayout or RevealLinearLayout.");
          }
  
          RevealAnimator revealLayout = (RevealAnimator) view.getParent();
          revealLayout.attachRevealInfo(new RevealInfo(centerX, centerY, startRadius, endRadius,
                  new WeakReference<>(view)));
  
          if(LOLLIPOP_PLUS){
              return new SupportAnimatorLollipop(android.view.ViewAnimationUtils
                      .createCircularReveal(view, centerX, centerY, startRadius, endRadius), revealLayout);
          }
  
          ObjectAnimator reveal = ObjectAnimator.ofFloat(revealLayout, CLIP_RADIUS,
                  startRadius, endRadius);
          reveal.addListener(getRevealFinishListener(revealLayout));
  
          return new SupportAnimatorPreL(reveal, revealLayout);
      }
docs: 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 android.view.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.
  
  @param view The View will be clipped to the animating circle.
  @param centerX The x coordinate of the center of the animating circle.
  @param centerY The y coordinate of the center of the animating circle.
  @param startRadius The starting radius of the animating circle.
  @param endRadius The ending radius of the animating circle.