1582528 - SVG's clip doesn't seem to restrict the visual/building rect.

Status: RESOLVED FIXED

(Core :: Web Painting, enhancement)

Description

[Jeff Muizelaar [:jrmuizel]]

Scroll frames reduce the visual/building rect:
https://searchfox.org/mozilla-central/source/layout/generic/nsGfxScrollFrame.cpp#3405

SVG doesn't use a scroll frame to implement it's overflow behaviour.
https://searchfox.org/mozilla-central/rev/7531325c8660cfa61bf71725f83501028178cbb9/layout/svg/nsSVGOuterSVGFrame.cpp#770

It doesn't seem to restrict the visual/building rect, but perhaps should?

Comment 1

[Matt Woodrow (:mattwoodrow)]

Yes, I think it should clip the visible/dirty rect (and Markus agrees).

Comment 2

[Markus Stange [:mstange]]

I've audited the other users of DisplayListClipState::AutoSaveRestore and only found one other location which re-enters BuildDisplayList and does not modify the building rect: https://searchfox.org/mozilla-central/rev/7531325c8660cfa61bf71725f83501028178cbb9/layout/forms/nsHTMLButtonControlFrame.cpp#102
All the other users only build a single display item while the DisplayListClipState::AutoSaveRestore is on the stack, or they already use nsDisplayListBuilder::AutoBuildingDisplayList to modify the building rect.

Comment 3

[Timothy Nikkel (:tnikkel)]

I wrote the obvious patch without thinking about it at all and pushed that to try to see and it's green on reftests.

https://treeherder.mozilla.org/#/jobs?repo=try&revision=c4716e4f1db138b01c209bb24630c696af8b2893

Comment 4

[Markus Stange [:mstange]]

Looks good! Instead of adding another if, I'd move the intersecting into the existing if that sets the clip.

Comment 5

[Timothy Nikkel (:tnikkel)]

Attachment: Bug 1582528. Restrict visual and dirty rect when building the display list for svg contents that cannot overflow. r?mstange

Comment 6

[Timothy Nikkel (:tnikkel)]

Perhaps you could verify that this fixes your issue?

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/840f7be6f7e3
Restrict visual and dirty rect when building the display list for svg contents that cannot overflow. r=mstange

Comment 8

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/840f7be6f7e3

Comment 9

[Jeff Muizelaar [:jrmuizel]]

This fixes the problem that I was seeing. Thanks everyone.