1850727 - Canvas2D lines rasterization bug when using clip

Status: VERIFIED FIXED

(Core :: Graphics: Canvas2D, defect)

Description

[George]

Attachment: this archive contains HTML file with JavaScript needed to reproduce the problem, as well as output from Firefox 117 (buggy) and Chrome (reference).

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/115.0.0.0 Safari/537.36

Steps to reproduce:

When I try to render lines using Canvas2D APIs the output contains several artefacts. The code for rendering needs to be very exact, so I've attached HTML with JS code that is needed to reproduce the problem. The bug may be flaky, so it's better to restart Firefox and open this HTML while app is in clean state.
I can reproduce this issue on 117 version (Stable), as well as 118.0b2 (Dev).

Actual results:

Artefacts are present in rendering of lines in Firefox 117 and 118.0b2 (Dev). See "firefox_output.png" in attached archive.

Expected results:

Correct rendering of lines (as in Chrome output in attached files).

Comment 1

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

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

Comment 2

[Mayank Bansal]

Thanks for the report!

Regressed by:
Bug 1837068 - Support alpha strokes by rendering with AAStroke to a mask render target. r=aosmond

Comment 3

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

Set release status flags based on info from the regressing bug 1837068

Comment 4

[Lee Salzman [:lsalzman]]

Attachment: Bug 1850727 - Ignore the clip mask when drawing a stroke mask. r?aosmond

The clip mask state was leaking into the drawing of the stroke mask texture.
This caused the stroke mask to be erroneously clipped out.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/843e65079be1
Ignore the clip mask when drawing a stroke mask. r=aosmond

Comment 6

[Cristian Tuns]

Backed out for causing build bustages in DrawTargetWebgl.cpp

• Backout link
• Push with failures
• Failure Log
• Failure line: /builds/worker/checkouts/gecko/dom/canvas/DrawTargetWebgl.cpp:3122:24: error: no viable conversion from 'RefPtr<WebGLTextureJS>' to 'RefPtr<WebGLTexture>'

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0d100cd406fa
Ignore the clip mask when drawing a stroke mask. r=aosmond

Comment 8

[Atila Butkovits]

Backed out for causing reftest failures at 1850727-1.html.

Backout link: https://hg.mozilla.org/integration/autoland/rev/569ff0f1d1bd225e2e5b48647521d102fb540669

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&selectedTaskRun=U4rqkesJRAegkPIR-CqeeQ.0&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=0d100cd406fac31edd725aaa2ca36c72593b7207

Failure log:
https://treeherder.mozilla.org/logviewer?job_id=427788215&repo=autoland&lineNumber=8850

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e18fb59cd6ce
Ignore the clip mask when drawing a stroke mask. r=aosmond

Comment 10

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/e18fb59cd6ce

Comment 11

[Mayank Bansal]

Attachment: gpu-canvas Vs skia-canvas Vs Chrome.png

The lines have started drawing, but they look different.

See the attached picture : gpu-canvas Vs Skia-Canvas Vs Chrome

Comment 12

[Lee Salzman [:lsalzman]]

Attachment: Bug 1850727 - Only clear last clip mask when destroying clip mask. r?aosmond

Comment 13

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/8fe83891664d
Only clear last clip mask when destroying clip mask. r=aosmond

Comment 14

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/8fe83891664d

Comment 15

[Lee Salzman [:lsalzman]]

Comment on attachment 9351417 [details]
Bug 1850727 - Only clear last clip mask when destroying clip mask. r?aosmond

Beta/Release Uplift Approval Request

• User impact if declined: Canvas2D will fail to draw certain types of stroked geometry.
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Verified by repro'd testcase.
• String changes made/needed:
• Is Android affected?: Yes

Comment 16

[Pascal Chevrel:pascalc]

Comment on attachment 9351417 [details]
Bug 1850727 - Only clear last clip mask when destroying clip mask. r?aosmond

Approved for 118.0b6, thanks.

Comment 17

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-beta/rev/ce8a0b058af8
https://hg.mozilla.org/releases/mozilla-beta/rev/09f20f258694

Comment 18

[Pascal Chevrel:pascalc]

https://hg.mozilla.org/releases/mozilla-beta/rev/ce8a0b058af8
https://hg.mozilla.org/releases/mozilla-beta/rev/09f20f258694

Comment 19

[Monica Chiorean]

I was able to reproduce the issue on Mac 12.6 using FF build 117.0 (the square was not completely displayed on old builds).
Verified as fixed on Mac 12.6 / Win10x64 using FF build 119.0a1 and 118.0b7.