1511740 - Android: zooming behaves strangely on about:support

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, enhancement, P3)

Description

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

about:support loads in the UI process I think. But I assumed zoomable content is always in the content process.

https://searchfox.org/mozilla-central/rev/2edebf41a2b2e624859bf15ed5a98bdd002f73b4/gfx/layers/wr/WebRenderCommandBuilder.cpp#1437

This results in some strange behaviour when zooming/scrolling on about:support, and probably on other about: pages.

Comment 1

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

Attachment: Bug 1511740 - Use nsDisplayAsyncZoom items to insert zooming animations in WR. r?jrmuizel,botond

The way we control APZ zooming in WebRender is by inserting an animation
property placeholder on a WR stacking context, and then having APZ
update the animation transform value with the proper matrix at composite
time.

Previously, the stacking context being used was the rootmost
stacking context in the content process. However this doesn't work for
zoomable content in the UI process (e.g. about:support), and after
recent changes, also wraps display items that should not be affected by
zoom (e.g. scrollbars or the background color item).

This patch moves the animation property placeholder so that it
corresponds to the newly added nsDisplayAsyncZoom display item, which
corrects both of the above problems and is conceptually in line with the
desired behaviour.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/fa641ad0f4b8
Use nsDisplayAsyncZoom items to insert zooming animations in WR. r=jrmuizel,botond

Comment 3

[Andrei Ciure[:aciure]]

https://hg.mozilla.org/mozilla-central/rev/fa641ad0f4b8