1650589 - Using <feColorMatrix> to increase contrast of alpha channel for svgs shows as transparent in <img> tag (regression)

Status: UNCONFIRMED

(Core :: Graphics: WebRender, defect, P3)

Description

[cmbartschat]

Attachment: Comparison of how the svg is rendered between the expected behavior vs the current behavior of Firefox.

User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:79.0) Gecko/20100101 Firefox/79.0

Steps to reproduce:

Create a file called heart.svg with the following contents:

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16">
<defs>
<filter id='contrastAlpha'>
<feColorMatrix in="SourceGraphic"
type="matrix"
values="1 0 0 0 0
0 1 0 0 0
0 0 1 0 0
0 0 0 1000 -500" />
</filter>
</defs>
<g filter="url(#contrastAlpha)">
<path d="M 1 8 l 6.9 6.9 l 0.2 0 l 6.9 -6.9 l 0 -3 l -2 -2 l -3 0 l -2 2 l -2 -2 l -3 0 l -2 2 z" stroke="#000" stroke-width="2" fill="none"></path>
</g>
</svg>

When viewed directly, the svg displays correctly. However, when loaded in an <img> tag like:

<img src="heart.svg" style="outline: 2px solid red">

The image does not show up, only displaying the outline.

I'm on Windows 7, Firefox 79.0b3 (64-bit)

I used the mozregression gui (fantastic) which narrowed it down to:

Bug 1636482 - Allow WebRender on all versions of Windows. r=aosmond

Previously we were blocking older Windows and only allowing on Windows
10. This switches us to relying on the blocking to prevent WebRender
from riding the trains on Win7/8.

Differential Revision: https://phabricator.services.mozilla.com/D74409

Actual results:

Nothing is displayed, as if the image is completely transparent.

Expected results:

There should have been a heart icon with a black stroke and no fill displayed, with only fully black and fully transparent pixels (no antialiasing) as a result of the color matrix.

Comment 1

[cmbartschat]

The filter appears to work correctly with values up to "508 -254" in the place of "1000 -500", with "509 -254.5" being partially broken, and "510 -255" being fully broken.

Comment 2

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

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 3

[cmbartschat]

Attachment: Test html document with svg assets showing the innacuracy of the filter over different stope values

Comment 4

[cmbartschat]

Attachment: Screenshots showing expected and actual behavior of the test page

Comment 5

[Timothy Nikkel (:tnikkel)]

Using the svg from comment 0 either on it's own or inside an img, we used to display both, but in 2013 we stopped displaying both in this range

http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=6ecf0c4dfcbe&tochange=3c44c1f43a67

Bug 924102 and Bug 924103 seem like good candidates for this.

With webrender we used to display blank for both the svg and inside an img tag, but with this fix range we started drawing the svg (but not inside an img tag):

https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=06b6157616fcf3bdbed05d65b6d533ea5423eec5&tochange=9cf306212866ac92184fa5dbfdabd3629e9dc0be

bug 1606742

Comment 6

[cmbartschat]

I'm confused, are you saying that this svg wouldn't have been visible since 2013? It was completely fine for me up until yesterday in Firefox Developer Edition, and still displays correctly in the main version of Firefox.

Comment 7

[Timothy Nikkel (:tnikkel)]

I'm reporting what I saw on my system, it's seems like your system sees different results.

Comment 8

[cmbartschat]

Ok, I understand. Please let me know if I can provide any additional information.

Comment 9

[Jessie [:jbonisteel] pls NI]

Can either of you reproduce this on Win7?

Comment 10

[Jessie [:jbonisteel] pls NI]

Can you please attach the contents of your about:support as a text file?

Comment 11

[cmbartschat]

Attachment: Output taken from about:support

Comment 12

[Sotaro Ikeda [:sotaro]]

(In reply to Jessie [:jbonisteel] pls NI from comment #9)

Can either of you reproduce this on Win7?

I saw the problem on win7 and on win10 with WebRender.

Comment 13

[Sotaro Ikeda [:sotaro]]

I tried mozregression with the following command on my Win10 PC. But it did not work around regression range.

./mach mozregression --good 2018-03-01 --bad 2018-04-01 --pref gfx.webrender.all:true

I got the following range. The range is a bit wide because of the problem.
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=2667f0b010c959940d7a12b4311d54a6abd74ac5&tochange=8cced2a46f73238da13e41bcae8f6f801419bb7a

Comment 14

[Rares Doghi, Desktop QA]

I was also able to reproduce this issue on Windows 7 as well in Beta 79.0b6 and our Nightly build 80.0a1 (2020-07-10) when WebRender is enabled.

Comment 15

[Jessie [:jbonisteel] pls NI]

Hey Nical - any thoughts on what could cause this issue?

Comment 16

[Kris Taeleman (:ktaeleman)]

@Nical: Ping

Comment 17

[Jim Mathies [:jimm]]

Not actively looking at this, removing from our release metas.