Bug 215214 – REGRESSION(r254506): [Freetype] Spektra variable font does not work properly

• Component: Text
• Status: RESOLVED FIXED

[Adrian Perez]

The following font changes it slant (backwards to forwards) depending
on a variable parameter: https://v-fonts.com/fonts/spektra

With a current WebKitGTK build from “trunk” the slant is always backwards.

[Adrian Perez]

Created attachment 406082 [details]
Side by side comparison of Epiphany (WebKitGTK) and Firefox

Screenshot showing Epiphany (left, with a WebKitGTK build from trunk)
and Firefox (right) with the test URL loaded and the “Italic” parameter
set to +20 in both cases.

[Adrian Perez]

WebKitGTK 2.28.4 (the most recent stable release at the moment) also
shows this issue, so it does not seem to be a recent regression.

[Radar WebKit Bug Importer]

<rdar://problem/66984524>

[Carlos Garcia Campos]

It turns out the problem is not the spektra font, not even the font variation implementation, it's the webkit-font-smoothing cairo implementation that breaks font variations. So, what's different in https://v-fonts.com/fonts/spektra is that webkit-font-smoothing is used. This regressed in r254506, when a font smoothing mode is passed to drawGlyphsToContext() a new cairo font options is set, using the default font options and changing the antialiasing. This means the font options from the font (the ones containing the variation settings), set in the context by cairo_set_scaled_font() are lost. We should copy the scaled font options instead, then set the antialiasing and apply them. I'll prepare a patch and try to add a test.

[Carlos Garcia Campos]

Created attachment 406518 [details]
Patch

[Adrian Perez]

Tested patch locally as well, worked like a charm!

[Carlos Garcia Campos]

Committed r265648: <https://trac.webkit.org/changeset/265648>