1559389 - Document splitting fails to render Customizable UI after Bug 1558995

Status: RESOLVED FIXED

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

Description

[Brian Grinstead [:bgrins]]

See this discussion: https://phabricator.services.mozilla.com/D34792#inline-208116.

Previously the markup looked like:

<window>
  <deck id="content-deck" renderoot="content">
    <hbox id="browser" />
    <box id="customization-container" />
  </deck>
</window>

And then after Bug 1558995 it will look like:

<window>
  <hbox id="browser" renderoot="content" />
  <box id="customization-container" renderoot="content" />
</window>

If I ./mach run --temp-profile --setpref gfx.webrender.all=true --setpref gfx.webrender.split-render-roots=true with the change, then the content area continues to render properly, but the Customizable UI doesn't get painted.

One observation I've made is that if I remove renderroot="content" from the #browser element then the web content stops rendering (as expected) but the Customizable UI starts working (both with and without the attribute set on #customization-container).

Comment 2

[Jeff Muizelaar [:jrmuizel]]

Doug: "we just need to add something somewhere in Gecko display list building to appropriately create an nsDisplayRenderRoot for this. It doesn't go through nsBoxFrame. I think it goes through nsFlexContainerFrame? This side of things is a bit outside my knowledge anyway, and I would just be poking around and trying to cargo cult something together."

Comment 3

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

Indeed, modifying nsFlexContainerFrame::BuildDisplayList wrap stuff in a nsDisplayRenderRoot seems to fix things locally. Will clean my patch a bit and do a try push.

Comment 4

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

https://treeherder.mozilla.org/#/jobs?repo=try&group_state=expanded&revision=5d94ea95abad92f08ecca8b72f14a32e014fbb5b

Comment 5

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

Attachment: Bug 1559389 - Clean up renderroot-finding methods. r?Gankro

Only the parent process ever respects the renderroot attribute, so we can
add some extra early-exit checks for this. This also adds a bit of safety
for the next patch, to avoid inadvertently exposing renderroot stuff to
web content.

Also, the GetRenderRootForElement function is only ever called by the
GetRenderRootForFrame function, so let's scope it down to avoid doing
unnecessary work.

Comment 6

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

Attachment: Bug 1559389 - Support renderroot attributes on XUL elements that generate nsFlexContainer frames. r?mattwoodrow

Depends on D37504

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/33dc819da62f
Clean up renderroot-finding methods. r=Gankro
https://hg.mozilla.org/integration/autoland/rev/9e4404e0c267
Support renderroot attributes on XUL elements that generate nsFlexContainer frames. r=mattwoodrow

Comment 8

[Oana Pop-Rus]

https://hg.mozilla.org/mozilla-central/rev/33dc819da62f
https://hg.mozilla.org/mozilla-central/rev/9e4404e0c267