Open Bug 1306255 Opened 5 years ago Updated 2 years ago

Make it possible to enable linear blending of fonts on Linux

Categories

(Core :: Graphics: Text, task, P3)

52 Branch
task

Tracking

()

UNCONFIRMED

People

(Reporter: octoploid, Unassigned)

Details

(Keywords: feature, Whiteboard: [gfx-noted])

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0
Build ID: 20160929100416

Steps to reproduce:

It would be great if there was a way to enable linear blending of fonts on Linux.
I've tried to set "SK_GAMMA_EXPONENT" to 1.8 in gfx/skia/moz.build,
but unfortunately it doesn't have any effect.

(In Chromium, setting SK_GAMMA_EXPONENT to 1.8 enables linear font blending.)

See  https://www.freetype.org/freetype2/docs/text-rendering-general.html
for further info.

Thanks.
Component: Untriaged → Graphics: Text
Product: Firefox → Core
Keywords: feature
Priority: -- → P3
Whiteboard: [gfx-noted]
Presently we match cairo-ft's handling of gamma, which is rather that it ignores gamma when blending. In the future we might consider doing otherwise, but for now the primary concern is compatibility and interoperability with cairo.
The corresponding bug report for cairo is at https://bugs.freedesktop.org/show_bug.cgi?id=28549. It's sadly been sitting there for years. An experimental patch enables a hacky blending in software rendering (have a look at the demo pages by Lankila), but more work is apparently needed to enable it for accelerated rendering. No idea how much work that is. Support for stem darkening to prevent stems for thinning out when blending correctly is forthcoming in FreeType.
Does the switch to Skia change anything about the situation?
Type: defect → task
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