I don't see any real improvement by changing the animation, which we would also need to change in iOS. It isn't clear that this would be demonstrably better or that it would somehow help the user.

Re-activating with some additional details for re-evaluation.

I'm not sure it is a requirement that Android and iOS have 100% parity (they don't today) but this would be an improvement there as well.  I don't think iOS implementation is a reason not to do this.

Here is the scenario that is worth considering:

Say there is a button on the screen, a user taps near the edge of the button but the button is not invoked.

With the current animation, we begin the animation at the center point of the touch event and it grows outward over some amount of time.  By the time the user has lifted their finger the radius has already grown large enough that the exact center of the touch point is not apparent.

With a reversed animation, the touch point shrinks down to the center of the touch.  the center point of the animation is clearly visible as the finger is lifted so it is more apparent why the touch was not registered.

I also think using a reversed animation would make longpress events seem faster as well because the user will see the animation feedback sooner (since it would start out at the max radius and shrink).

This can help fixing  bug 638317 .

Fixed the empty status.

Yuwei, is this still useful in light of the fix for  bug 638317 ?

I don't think it needs to be fixed any more. We've switched to use a decelerating radius-time function, which have made the animation more visible.