1773823 - devPixelsPerPx scales system fonts too much on HiDPI

Status: RESOLVED FIXED

(Core :: Widget: Gtk, defect)

Description

[krzysztof.krason]

Attachment: 2022-06-11-142557_3840x2400_scrot.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.5005.63 Safari/537.36

Steps to reproduce:

HiDPI screen, xrandr set to --scale 1.5x1.5, layout.css.devPixelsPerPx to 1.5. Everything looks like it should. Firefox Nightly somewhere before Jun 9.

Update to latest Firefox Nightly (both two last versions have this issue, but with different proportions), currently 103.0a1 (2022-06-11).

Actual results:

Have text, icons, tabs of gigantic proportions.

Expected results:

Size of text, icons, tabs should remain as it was before.

Using layout.css.devPixelsPerPx I can get the page to display correctly, but tabs are ridiculusly large compared to icons that are in them. Also context menu has text that is still gigantic.

Comment 1

[krzysztof.krason]

Also the menu, autocomplete and URL bar have fonts that are way to big (I mean 2-3x times bigger than normal)

Comment 2

[krzysztof.krason]

Attachment: 2022-06-11-142957_3840x2400_scrot.png

Comment 3

[Emilio Cobos Álvarez (:emilio)]

Is it better on the very latest nightly? What is the behavior if you don't change devPixelsPerPx?

Comment 4

[Emilio Cobos Álvarez (:emilio)]

Also, what desktop environment and so?

Comment 5

[krzysztof.krason]

Window Manager: xmonad.

1. I tried with latest nightly (todays) and it was the same.
2. Reverted devPixelsPerPx to default, and everything was even bigger (literally 90% of screen was for context menu).
3. Restarted: everything works perfectly, no more big icons/text/context menu.

Thank you very much, it works like before :)

I'll close it as duplicate of https://bugzilla.mozilla.org/show_bug.cgi?id=1773633.

Comment 6

[Emilio Cobos Álvarez (:emilio)]

Ok, I'll double check the behavior with devPixelsPerPx just in case there's something to fix there, since some people will maybe use it, but glad to hear that with default settings stuff works as expected, thanks!

Comment 7

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1773823 - Remove devPixelsPerPx special cases in LookAndFeel. r=stransky

LookAndFeel::GetFont should always return CSS font sizes.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7305249ed4b6
Remove devPixelsPerPx special cases in LookAndFeel. r=stransky

Comment 9

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/7305249ed4b6

Comment 10

[Karl Tomlinson (:karlt)]

As of https://hg.mozilla.org/mozilla-central/rev/6e1cbabce0af, the meaning of devPixelsPerPx changed to something like dpi-scaled device pixels per CSS pixel. The old behavior could be somewhat restored by dividing the old devPixelsPerPx value by dpi/96.0, but text that should have been system font size was as if the system dpi scale factor was applied twice if devPixelsPerPx was any +ve value.

A workaround was to create a "ui.textScaleFactor" pref set to the number 100, with which devPixelsPerPx meaning was restored to device pixels per CSS pixel and system font text was rendered at system font sizes.

Comment 11

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

Set release status flags based on info from the regressing bug 1773342