1850815 - Incorrectly rendered pie chart on Wikipedia

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Justin Peter]

(Not sure if this is the right component or not; apologies and please move it if it isn't)

Reported on Wikpedia here; some (rather janky, from the sounds of it) HTML pie charts are not displaying properly.

This appears to happen with Firefox for Android on some devices but not others. The one person who has confirmed this occurring is on a device with a Mali-G77.

Comment 1

[Timothy Nikkel (:tnikkel)]

I can reproduce artifacts on desktop since at least 2020.

Comment 2

[Justin Peter]

Two quick comments:

• This appears to be somehow device/driver specific; I can't reproduce it on Windows or Android.
• This is not conic gradient - there's talk of replacing this current system with a conic gradent-based one, but this is not rendered that way.

Comment 3

[Jamie Nicol [:jnicol]]

Can reproduce on Pixel 7 (Mali G710)

https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=3919fbd972a62e6b9876b71738bf1b98a5019f8c&tochange=78da6a675a0afca12749e2965837253a38299014

Bug 1823411 makes sense

Comment 4

[Jamie Nicol [:jnicol]]

This was caused by reducing the precision of vColorLine in cs_border_solid to mediump. It's unclear why this only occurs on a specific range of Mali GPUs. Also it does not occur with shader optimisation disabled, and we know that doesn't always handle precision correctly. So there could perhaps be more to investigate there.

But there's a strong argument that this should never have been made mediump in the first place, as calculations regarding positions etc require the extra precision. So I think the best solution is simply to revert it to highp.

Comment 5

[Jamie Nicol [:jnicol]]

Attachment: Bug 1850815 - Make cs_border_solid's vColorLine highp. r?#gfx-reviewers

This varying's precision being reduced to mediump in bug bug 1823411
is causing rendering glitches on certain Mali devices. It should never
have been reduced in the first place, as calculations regarding
positions may require the extra precision. This patch therefore
reverts it to highp.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/aee77156969b
Make cs_border_solid's vColorLine highp. r=gfx-reviewers,bradwerth

Comment 7

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/aee77156969b

Comment 8

[Pascal Chevrel:pascalc]

Jamie, is this a good candidate for uplifting in beta and/or our planned dot release? Thanks

Comment 9

[Jamie Nicol [:jnicol]]

I think this landed before 119 branched to beta so no point uplifting there? but I think it's a good candidate for the planned dot release

Comment 10

[Jamie Nicol [:jnicol]]

Comment on attachment 9354595 [details]
Bug 1850815 - Make cs_border_solid's vColorLine highp. r?#gfx-reviewers

Beta/Release Uplift Approval Request

• User impact if declined: Incorrect rendering of certain elements on some devices with Mali GPUs (including Pixel 6 and 7)
• 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): Reverts shader back to its previous code before the bug was introduced
• String changes made/needed:
• Is Android affected?: Yes

Comment 11

[Pascal Chevrel:pascalc]

Comment on attachment 9354595 [details]
Bug 1850815 - Make cs_border_solid's vColorLine highp. r?#gfx-reviewers

Approved for our next 118 dot release, thanks.

Comment 12

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-release/rev/6a10dcee7423

Comment 13

[Pascal Chevrel:pascalc]

https://hg.mozilla.org/releases/mozilla-release/rev/6a10dcee7423

Comment 14

[Donal Meehan [:dmeehan]]

Comment on attachment 9354595 [details]
Bug 1850815 - Make cs_border_solid's vColorLine highp. r?#gfx-reviewers

Approved for 115.4esr

Comment 15

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-esr115/rev/c6a32b928430