1973380 - Content area shadow shows white shade behind the toolbar due to content shadow, if you use mica wih HDR on (Windows Explorer also affected)

Status: NEW

(Core :: Graphics, defect, P3)

Comment 1

[Emilio Cobos Álvarez [:emilio]]

So at first I thought this was a styling issue, but if that was the case then a lot of themes with transparent toolbar colors would be affected. Looking further into it, this only reproduces on one of my machines (which uses an NVidia GPU), and the white probably comes from https://searchfox.org/mozilla-central/rev/10ecded0ef6e96a933b08d1cd946ab3bbcfe7a15/gfx/webrender_bindings/RenderCompositorANGLE.cpp#250 or so...

Comment 2

[Emilio Cobos Álvarez [:emilio]]

Ironically I can't even take an screenshot with the builtin tool because doing so "fixes" the rendering...

Comment 3

[Emilio Cobos Álvarez [:emilio]]

Attachment: image.png

Ok the Game bar let me take a screenshot that shows the issue...

Comment 4

[Emilio Cobos Álvarez [:emilio]]

So I tracked it down to the HDR settings. If I turn HDR off then the rendering is the expected one. I also tried to change those backgrounds and I don't see any improvement...

Furthermore, I also see something very similar if not the same in some menus outside of Firefox, like "Open Start menu, search for "game bar", right-click on the result"...

Ashley, Sotaro, does this ring a bell? It feels like we're blending against white or something to me, but could be anything really...

Comment 5

[Sotaro Ikeda [:sotaro]]

:emilio, the problem also happens with the following STR?

• Set pref gfx.webrender.compositor = false
• Restart Firefox.

OR

• Set pref gfx.webrender.layer-compositor = true
• Restart Firefox.

Comment 6

[Emilio Cobos Álvarez [:emilio]]

Attachment: about:support info

Yeah both those tweaks still show the issue. It feels like if the blending Windows is doing with the native backdrop is wrong (thinking our content is hdr instead of sdr or vice versa...)

Comment 7

[Emilio Cobos Álvarez [:emilio]]

Attachment: HDR on

Comment 8

[Emilio Cobos Álvarez [:emilio]]

Attachment: HDR off (how it's supposed to look)

Comment 9

[Emilio Cobos Álvarez [:emilio]]

It seems Windows Explorer is also affected... So maybe not our bug? But the white shade looks very bad, maybe we can disable it when HDR mode is on at least...

Comment 10

[Emilio Cobos Álvarez [:emilio]]

Attachment: Windows explorer HDR on

Comment 11

[Emilio Cobos Álvarez [:emilio]]

Attachment: Windows explorer HDR off

Comment 12

[Emilio Cobos Álvarez [:emilio]]

I sent a feedback hub (here) since at the very least, if this is an app problem, this also affects Explorer :)

Comment 13

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1973001

Comment 14

[Emilio Cobos Álvarez [:emilio]]

I think this is probable either:

• A windows bug (blending our SDR content with an HDR backdrop).
• A graphics bug (not tagging our swapchain as SDR somehow?).

Comment 15

[Ashley Hale [:ahale]]

My hunch from a first look is that I think this is probably related to linear blending of compositor swapchains in DWM, when HDR or ACM mode is on in Windows the entire desktop is rendered in scRGB which is a linear color space, so blending results between stacked transparent windows differ, but I'm not familiar enough to know why it affects this part of the window that way, perhaps Glenn has an idea?

Comment 16

[Glenn Watson [:gw]]

I don't think we explicitly tag our swapchains as SDR, but I assume that would be the default when creating a RGBA8 surface. I'm not very familiar with the HDR functionality in DC.