1787127 - White background on transparent iframes

Status: VERIFIED FIXED

(Core :: Graphics, defect)

Description

[Firelight.thelegit]

Attachment: Stream hidden by white iframe.png

Steps to reproduce:

Open a twitch stream which has twitch extensions enabled.

I've bisected to this commit with no addons or additional settings: https://phabricator.services.mozilla.com/D154931

Actual results:

Iframe that should have a transparent background instead has a white background. Video player consists of a white screen.

Expected results:

The iframe should have a transparent background. The stream should be visible.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Graphics' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1782596

:emilio, since you are the author of the regressor, bug 1782596, could you take a look?
For more information, please visit auto_nag documentation.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

The bug has a release status flag that shows some version of Firefox is affected, thus it will be considered confirmed.

Comment 4

[Emilio Cobos Álvarez (:emilio)]

[Tracking Requested - why for this release]: Seems to make twitch unusable in some cases.

Do you have a channel that reproduces this? I don't see this on any of the channels I found (either channels I've seen or in the "recommended channels" section).

Comment 5

[Firelight.thelegit]

I use the nightly channel.

Comment 6

[Emilio Cobos Álvarez (:emilio)]

Sorry, I meant twitch channel, I also use nightly :)

https://www.twitch.tv/ayinmaiden doesn't seem to be streaming, and I don't see channel with this issue locally... Can you attach about:support? Also do you have dark mode enabled but light mode on twitch? Just light mode everywhere?

Comment 7

[Firelight.thelegit]

Attachment: about:support

Comment 8

[Firelight.thelegit]

Happening on this stream: https://www.twitch.tv/gorgc

Dark mode enabled in Windows. Dark theme selected in Firefox. I've just tried both dark and light theme in twitch and it doesn't matter: both have the same issue.

Comment 9

[Alice0775 White]

Reported in http://forums.mozillazine.org/viewtopic.php?p=14937575#p14937575

You should turn on Windows10 OS dark mode with Firefox's default system theme.
The NSFW web site(https://stripchat.com/) seems to be affected this bug.

Comment 10

[Greg ( Hank1 )]

as Alice said above, i get this issue on Firefox nightly , im using Windows11 Dark Theme

Comment 11

[Greg ( Hank1 )]

(In reply to Greg ( Hank1 ) from comment #10)

as Alice said above, i get this issue on Firefox nightly , im using Windows11 Dark Theme

im just wondering if its more or less a Firefox Dark Theme issue rather than a OS Dark theme that causes the issue, i just changed it back to Light Theme in firefox (i didnt change the OS Theme ) an it worked fine

Comment 12

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1787127 - Use used color-scheme (not preferred) to determine canvas background adjustments. r=#style,#layout

As per spec, see https://drafts.csswg.org/css-color-adjust/#color-scheme-effect:

In order to preserve expected color contrasts, in the case of embedded
documents typically rendered over a transparent canvas (such as
provided via an HTML iframe element), if the used color scheme of the
element and the used color scheme of the embedded document’s root
element do not match, then the UA must use an opaque canvas of the
Canvas color appropriate to the embedded document’s used color scheme
instead of a transparent canvas.

After bug 1782596 we were using the preferred rather than used
color-scheme, which is the right thing to do for prefers-color-scheme,
but not for the canvas background.

Comment 16

[Andreea Pavel [:apavel]]

Patch is working on latest beta sim https://treeherder.mozilla.org/jobs?repo=try&resultStatus=testfailed%2Cbusted%2Cexception&revision=32a537c049fd1feeeb44d20ff8109b5dce6dcd94

Comment 19

[Ömer Fadıl USTA]

#1788911 marked as duplicated for this bug entry ,i just wantted to pointout one comment from there to here
(for not to be missed ) from @ Calin Tanase

Performed mozregression

Last good revision: 7c1e795e3c0750d5dcd99dab73be28e871c38979
First bad revision: 495ffb27c683fe2219b559708d3eb415847faa10
Pushlog: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=7c1e795e3c0750d5dcd99dab73be28e871c38979&tochange=495ffb27c683fe2219b559708d3eb415847faa10

Comment 20

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/56e3b846f3f1
Use used color-scheme (not preferred) to determine canvas background adjustments. r=tnikkel

Comment 21

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/35778 for changes under testing/web-platform/tests

Comment 23

[Cristina Cozmuta (:CrissCozmuta)]

https://hg.mozilla.org/mozilla-central/rev/56e3b846f3f1

Comment 24

[Sandor Molnar[:smolnar]]

Verified fixed for both beta sim bugs (bug 1786527 and bug 1786851), in todays beta-sim

Comment 26

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by jgraham