1654736 - text is blurry when rotated

Status: RESOLVED WORKSFORME

(Core :: Graphics: Text, defect)

Description

[maggus.staab]

Attachment: blurry-text.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:80.0) Gecko/20100101 Firefox/80.0

Steps to reproduce:

see https://codepen.io/anon/embed/vYLVZNK?height=450&theme-id=1&slug-hash=vYLVZNK&default-tab=result#result-box

which is the 2nd code-example from this article https://css-tricks.com/position-vertical-scrollbars-on-opposite-side-with-css/

Actual results:

the text is blurry rendered, see attached screenshot

Expected results:

text should stay sharp, like if the elements were not rotated

Comment 1

[Alice0775 White]

I can reproduce the issue on Nightly80.0a1 with/without WebRender when certain zoom level and scroll position.

Comment 2

[Alice0775 White]

Attachment: Bug 1654736 - text is blurry when rotated.html

FWIW，there are 2 regressions at least.

#1 It becomes blurry when certain zoom level and scroll. However it becomes clear after few second
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=f2a500997116&tochange=dec6aa71da64
Suspect: Bug 663776

#2 It becomes blurry when certain zoom level. And it persists.
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=d74a9133f9a5c0a7374bef2a0be15e3ed7b37113&tochange=41d7a4864f3325cd9abcc5c5a17788334c8ca863
Suspect: Bug 1310788

Comment 3

[Kelsey Gilbert [:jgilbert]]

This sounds a lot like hitting-vs-missing subpixel-aa blending?
Neither of those bugs are recent, and the more recent one is 'enable a11y'.
With or without WR is surprising, and points to this (probably) not being a compositor issue at least. Maybe the subpixel choice is made during layout?
Who's best for subpixel aa these days?

Comment 4

[Glenn Watson [:gw]]

It might be subpixel related, but I suspect it might be that WR is choosing an incorrect scale / transform value?

Comment 1 suggests this occurs without WR as well - is the bug exactly the same with/without WR, or just similar?

Lee, any ideas on what might cause this?

Comment 5

[Alice0775 White]

Attachment: screenshot comparison

When bug appears, sub-pixel colors seem to be drawn in opposite side.

Comment 6

[Wayne Mery (:wsmwk)]

Does this still reproduce for you?

Comment 7

[Alice0775 White]

I can no longer reproduce this in Nightly 99.0a1.

Comment 8

[maggus.staab]

agree, it seems fixed

Comment 9

[Wayne Mery (:wsmwk)]

Thanks for the update