1474968 - Font rendering is sometimes different on Windows with WebRender turned on

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, enhancement, P1)

Description

[Jeff Muizelaar [:jrmuizel]]

We don't know when or why.
See also: https://github.com/servo/webrender/issues/2407 and https://github.com/servo/webrender/issues/2867

Comment 1

[Lee Salzman [:lsalzman]]

The when and why is actually known.

Currently in Moz2D we track whether ClearType is enabled and limit the FontRenderMode that is passed into WR accordingly. However, any other parameters that govern how ClearType is interpreted (like gamma/contrast/etc.) are not transmitted at all.

Glenn and I had roughly sketched out some ideas about how to send this info. Option 1 would be to just send over some global state to the font backend which controls how fonts created afterwards get interpreted, or option 2 is to bloat up FontInstancePlatformOptions substantially with all the necessary parameters. Still to-be-determined which option is least evil and/or ugly.

Comment 2

[Jeff Muizelaar [:jrmuizel]]

I'd prefer the global state option. These parameters aren't going to be changing much and if they do it's ok for us to get them sort of wrong.

Comment 3

[Lee Salzman [:lsalzman]]

This will be resolved in part by WR PR https://github.com/servo/webrender/pull/2896

Comment 4

[Lee Salzman [:lsalzman]]

Attachment: pass DWrite font gamma and contrast to WebRender

Comment 5

[Lee Salzman [:lsalzman]]

Turned out the path of least resistance was just to stuff the parameters in FontInstancePlatformOptions. There didn't end up being too many, and it more closely follows what we do in Skia.

Comment 6

[Lee Salzman [:lsalzman]]

Attachment: pass DWrite font gamma and contrast to WebRender. r=jrmuizel

Small fix to prevent an assertion from getting triggered when contrast is bigger than 1.0.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/99f53302e68d
pass DWrite font gamma and contrast to WebRender. r=jrmuizel

Comment 8

[Raul Gurzau (:RaulG)]

https://hg.mozilla.org/mozilla-central/rev/99f53302e68d