1626116 - Content is stretched when resizing window with gfx.webrender.force-angle=false (does not happen without GPU process)

Status: NEW

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

Description

[Darkspirit]

Attachment: 2020-03-31_00-45-18.mp4

Radeon RX480 (Win 7 + Win10)
Screencast: mozregression --launch 2020-03-30 --pref gfx.webrender.all:true gfx.webrender.force-angle:false

This seems to be the only bug of WGL WebRender (gfx.webrender.force-angle:false).
It's currently needed for gfx.webrender.software:true (bug 1623705) and anyway good to have (bug 1432302).

Window resizing works perfectly if the GPU process is disabled:
The following command runs OpenGL/Win10 as WebRender can't be enabled without GPU process on Windows.
mozregression --launch 2020-03-30 --pref gfx.webrender.force-disabled:true layers.acceleration.force-enabled:true layers.mlgpu.enabled:false layers.prefer-opengl:true gfx.direct3d11.use-double-buffering:false layers.gpu-process.enabled:false -a about:support

(Only OpenGL/Win10 needs gfx.direct3d11.use-double-buffering:false, otherwise the window is blank. WebRender doesn't need this pref change.)

Comment 1

[Darkspirit]

I forgot about bug 1517472 which might be related.

Comment 2

[Darkspirit]

Attachment: Win7.mp4

Comment 3

[Darkspirit]

Bug 1626822 might help to circumvent this problem temporarily.

Comment 4

[Dzmitry Malyshau [:kvark]]

Thanks for filing a very detailed bug, as always!

Comment 5

[Firefox Bug Husbandry Bot]

Because this bug's Severity has not been changed from the default since it was filed, and it's Priority is P3 (Backlog,) indicating it has been triaged, the bug's Severity is being updated to S3 (normal.)

Comment 6

[Markus Stange [:mstange]]

No longer blocking sw-wr because sw-wr works fine with Angle these days.