1402004 - Assertion failure: aMaskContext->GetDrawTarget()->GetFormat() == SurfaceFormat::A8

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect, P1)

Description

[Nicolas Silva [:nical]]

I keep running into this assertion.

> #5  in <signal handler called> () at /lib64/libpthread.so.0
> #6  in nsDisplayMask::PaintMask at layout/painting/nsDisplayList.cpp:8882
> #7  in mozilla::layers::PaintItemByDrawTarget at gfx/layers/wr/WebRenderLayerManager.cpp:482
> #8  in mozilla::layers::WebRenderLayerManager::GenerateFallbackData at gfx/layers/wr/WebRenderLayerManager.cpp:595
> #9  in mozilla::layers::WebRenderLayerManager::BuildWrMaskImage at gfx/layers/wr/WebRenderLayerManager.cpp:653
> #10 in nsDisplayMask::CreateWebRenderCommands at layout/painting/nsDisplayList.cpp:9028
> #11 in mozilla::layers::WebRenderLayerManager::CreateWebRenderCommandsFromDisplayList at gfx/layers/wr/WebRenderLayerManager.cpp:344
> #12 in mozilla::layers::WebRenderLayerManager::EndTransactionInternal at gfx/layers/wr/WebRenderLayerManager.cpp:746
> #13 in nsDisplayList::PaintRoot at layout/painting/nsDisplayList.cpp:2169
> #14 in nsLayoutUtils::PaintFrame at layout/base/nsLayoutUtils.cpp:3772
> #15 in mozilla::PresShell::Paint at layout/base/PresShell.cpp:6454

The DrawTarget in the gfxContext is a recording DrawTarget wrapped around a dummy DrawTarget of format B8G8R8A8 created a few stack frames higher in here: https://searchfox.org/mozilla-central/rev/2ef8bd8a46a02c68ddbb1d5f25fa254dd7be1fbd/gfx/layers/wr/WebRenderLayerManager.cpp#586

The recodring DrawTarget returns the format of its wrapping target so we need to make sure we we create an A8 target when we are going to write into a mask, or remove the assertion and hope that nothing else depends on the exposed format.

Comment 1

[Aria Beingessner [:Gankra]]

I get this deterministically on this page:

https://discussions.apple.com/thread/7881468?start=0&tstart=0

Comment 2

[Jeff Muizelaar [:jrmuizel]]

Attachment: Use A8

I don't know what was broken. Let's try to use it.

Comment 3

[Aria Beingessner [:Gankra]]

Comment on attachment 8912395 [details] [diff] [review]
Use A8

Review of attachment 8912395 [details] [diff] [review]:
-----------------------------------------------------------------

Tried locally, fixes all the crashers I know of.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/a28263319f14
Use A8 as the format for the dummy drawtarget. r=Gankro

Comment 5

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/a28263319f14