1287829 - Come up with a better alternative to event regions

Status: RESOLVED WONTFIX

(Core :: Layout, defect)

Description

[Kartikaya Gupta (email:[e-mail])]

I'd like to come up with a better way to transfer hit-testing information from layout the compositor. The current event regions approach sort of works, but as I chase down more bugs with touch-action it seems like the event regions architecture gets increasingly complex and brittle. It's also been a long-standing perf issue. The Level 2 Pointer Events spec [1] adds even more touch-action properties and that means we'd have to expand the number of regions being passed around, so things are only going to get worse.

I don't have any concrete suggestions/thoughts on this, but I feel like we can probably come up with a better scheme. Filing this as a placeholder so people can start thinking about it - any suggestions welcome!

[1] https://w3c.github.io/pointerevents/#the-touch-action-css-property

Comment 1

[Kartikaya Gupta (email:[e-mail])]

This problem will be addressed with WebRender/APZ integration. We discussed it today, there are some notes at the bottom of https://public.etherpad-mozilla.org/p/wr-plan. I basically don't feel it's worth rewriting event regions in Gecko at this point, when we'll have to do it over in WebRender anyway.