1668905 - Get rid of dummy event listener in nsRangeFrame

Status: RESOLVED FIXED

(Core :: Layout: Form Controls, enhancement)

Description

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

There's a dummy event listener registered in nsRangeFrame whose sole purpose is to mark the frame apz-aware, so that APZ knows it handles touch events. However we have a better mechanism to do this (vs when the code was originally written). Instead of the event listener, we can just set the eApzAwareListeners flag on the CompositorHitTestInfo item directly.

I verified that if we remove the dummy event listener, then touch-dragging the slider on an <input type=range> does NOT prevent the page from scrolling simultaneously. However setting the flag on the CompositorHitTestInfo does prevent the page scrolling, as I would expect. I don't know if there's an automated test for this but it seems kinda hard to write one.

Comment 1

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

https://treeherder.mozilla.org/#/jobs?repo=try&group_state=expanded&revision=31c54b960a7da0ff450f681c126f19119e5b0ff2

Comment 2

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

Attachment: Bug 1668905 - Replace the nsRangeFrame dummy listener with setting a flag on CompositorHitTestInfo directly. r?miko

The purpose of the dummy listener was to make APZ aware of the fact that
the range frame handles touch events without having any other explicit touch
listener. But we can do that more simply/cheaply by setting the eApzAwareListener
flag directly without the dummy listener.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/2e3686ee35ae
Replace the nsRangeFrame dummy listener with setting a flag on CompositorHitTestInfo directly. r=miko

Comment 4

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/2e3686ee35ae