1694982 - Large backgrounds with blend-mode, image and gradient loose colour

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect)

Description

[ric]

Attachment: Screenshot 2021-02-25 161345.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:88.0) Gecko/20100101 Firefox/88.0

Steps to reproduce:

Create large background with mix-blendmode containing a gradient and image.

Examples on these pages:

https://thecuriosityofachild.com/

https://thecuriosityofachild.com/episodes/old-toys-and-christmas-elves

Actual results:

Only the initially visible part of the gradient is applied. Scrolling down shows the gradient ends. This is new in the latest build. Opening dev tools forced a redraw which fixed the issue.

Expected results:

Gradient should continue.

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 revert this change in case you think the bot is wrong.

Comment 2

[Timothy Nikkel (:tnikkel)]

Regression range
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=cf0951d3d50c5d6bf0b631ae776ca12b87de4f33&tochange=23bd3cec784397ac9ce2d1d69fda2aa334ed9515

Bug 1684781

Comment 3

[Glenn Watson [:gw]]

Attachment: Bug 1694982 - Fix mix-blend backdrop sampling from scrolled + clipped picture caches.

The calculation of the available backdrop rect was incorrect in the
case of a picture cache slice that is both scrolled and also clipped
by long content which is affected by the mix-blend-mode.

Comment 4

[Lee Salzman [:lsalzman]]

Does this affect the advanced blend equation support? If so, we'll need to remember to ask for uplift on it.

Comment 5

[Glenn Watson [:gw]]

It does, we will also need to make sure this gets uplifted if/when we uplift my mix-blend optimization patch.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/89739cb6b392
Fix mix-blend backdrop sampling from scrolled + clipped picture caches. r=nical

Comment 7

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/89739cb6b392

Comment 8

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

Set release status flags based on info from the regressing bug 1684781