MatRipple.launch() coordinates are relative to viewport and not host element, contradicting the documentation.

[simon-mathewson]

Documentation Feedback

The description for MatRipple.launch() is as follows:

Launches a manual ripple at the specified coordinates within the element.

However, the coordinates passed are interpreted as relative to the viewport, as demonstrated here. It took me a long time to figure this out, but of course this behavior is intuitive, since in most cases you just pass coordinates from a mouse click event.

Suggested replacement:

Launches a manual ripple at the specified coordinates relative to the viewport.

Affected documentation page: https://material.angular.io/components/ripple/api

[devversion]

We should clarify this behavior. The coordinates are not relative to the viewport either. Coordinates are absolute based on the closest parent that has a relative position (based on the stacking context)

[devversion]

@simon-mathewson Created a PR to clarify this. I was wrong with my comment above as I assumed (without looking at the code) that we do not offset the ripple container position (which has position: relative).

[simon-mathewson]

👍