1785223 - backdrop-filter not working with z-index and mix-blend-mode

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect)

Description

[adrian.drechsel]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:103.0) Gecko/20100101 Firefox/103.0

Steps to reproduce:

1. Make a background container with position and z-index that contains an element with mix-blend-mode other than normal.
2. Make a separate overlay element with backdrop-filter (e.g. blur).

example: https://jsfiddle.net/Dollhopf/tpdeabr1/67/

Actual results:

The complete background is not effected by any backdrop-filter.

Expected results:

The complete background should be affected by a backdrop-filter (e.g. blur).

Comment 1

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

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

Comment 2

[Bob Hood [:bhood]]

Adrian, could you please attach your about:support output to this report when you get a chance? Thanks!

Comment 3

[Mayank Bansal]

Attachment: about:support

Comment 4

[Mayank Bansal]

Attachment: Standalone testcase.html

Comment 5

[Mayank Bansal]

Attachment: Bug.png

Firefox Vs Chrome

Comment 6

[Glenn Watson [:gw]]

The problem is at [1] - what happens is that we create a picture cache slice for the mix-blend container, assuming that no other content will rely on it. However, it is part of a valid backdrop-root in this case.

[1] https://searchfox.org/mozilla-central/source/gfx/wr/webrender/src/scene_building.rs#2222

Comment 7

[Mayank Bansal]

This is fixed by bug 1787089