1632738 - Blurry fonts on perfherder with gfx.e10s.font-list.shared set to true

Status: RESOLVED FIXED

(Core :: Layout: Text and Fonts, defect, P3)

Description

[Mayank Bansal]

Attachment: bug.png

1. Start new profile
2. Set gfx.e10s.font-list.shared to true.
3. Restart browser
4. Go to https://treeherder.mozilla.org/perf.html#/graphs?highlightAlerts=1&series=mozilla-central,1646973,1,1&timerange=1209600&zoom=1586686988940,1586878926245,73.15294371056893,74.398502462258

AR: The axis labels are blurred
ER: Not so

Comment 1

[Mayank Bansal]

Attachment: about:support

Comment 2

[Jonathan Kew [:jfkthame]]

Oh, it's using Gill Sans. I seem to recall there's something weird about that font family on Windows, and we need to special-case the handling of its styles (ugh).

Comment 3

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1632738 - Hide the Gill Sans family on Windows if it contains only Ultra Bold faces. r=jwatt

Comment 4

[Jonathan Kew [:jfkthame]]

Note that this isn't an issue with just default Windows fonts installed, as they don't include Gill Sans. But it's provided by MS Office products, so it's likely that a lot of users do have it.

So the background to this can be found in bug 551313. The Gill Sans fonts provided by Office on Windows are organized weirdly, such that the "usual" faces (regular/bold, italic and non-italic) have the family name "Gill Sans MT", but then there are also UltraBold faces with the family name "Gill Sans". This causes a problem when a site (like perfherder) says font-family: Gill Sans, Gill Sans MT, ..., aiming to support both macOS (where the family name is just "Gill Sans") and Windows, but ends up getting an UltraBold-only family on Windows unless we hack around it.

The above patch is only a partial fix, hiding the UltraBold-only family, sufficient to avoid the bad rendering reported here. For a complete "fix", we should really merge the UltraBold faces into the Gill Sans MT family, but that's going to be more complex and may not really be worth the hack.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/66ac56cc2c7c
Hide the Gill Sans family on Windows if it contains only Ultra Bold faces. r=jwatt

Comment 6

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/66ac56cc2c7c