1538399 - Transparent grey background has lines in it with firefox

Status: UNCONFIRMED

(Core :: Graphics, defect, P3)

Description

[Thomas Andre]

Attachment: Capture.PNG

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Firefox/68.0

Steps to reproduce:

1:Go to https://www.head-fi.org/threads/dsavitsk-beezar-torpedo-build-thread.570317/page-32#post-10131551

2:Click the picture to expand it

Actual results:

The grey semi-transparent background on the sides of the picture has lines in it.

Expected results:

The grey semi-transparent background on the sides of the picture should not have lines in it

Comment 1

[Thomas Andre]

Seems like the lines are happening on that background to due scaling in windows when using webrender,scaling other than 100% triggers it.

Comment 2

[Jeff Muizelaar [:jrmuizel]]

Can you post screenshots with and without webrender disabled?

Comment 3

[Thomas Andre]

Attachment: webremder disabled.PNG

Comment 4

[Thomas Andre]

Attachment: Webremder Enabled.PNG

Comment 5

[Thomas Andre]

(In reply to Thomas Andre from comment #4)

Created attachment 9054643 [details]
Webremder Enabled.PNG(In reply to Jeff Muizelaar [:jrmuizel] from comment #2)

Can you post screenshots with and without webrender disabled?

I've uploaded screenshots with webrender enabled & disabled, seems like it happens with webrender disabled too,seems like it's a firefox specific bug as it doesn't happen on chrome, or edge.

Comment 6

[Nicolas Silva [:nical]]

Not 100% certain but I think that this is caused by a difference between how Gecko repeats background images when the size of the repeated pattern is not an integer. Firefox actually tries to be more correct than its competitors by doing pixel on snapping each individual repetition of the pattern to avoid accumulating the rounding error while Chrome and the others do the simple thing of first rounding the bounds of the pattern and then repeat it.

We've talked about changing our behavior to match the others, even if ours is theoretically more correct, because websites end up designed around Chrome's behavior and it is simpler to implement.