Bug 104403 - Support multi-colored fonts using COLR/CPAL tables
Summary: Support multi-colored fonts using COLR/CPAL tables
Status: NEW
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: graphics stack (show other bugs)
(earliest affected)
Hardware: All All
: medium enhancement
Assignee: Not Assigned
Depends on: HarfBuzz
Blocks: Font-Rendering
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Reported: 2016-12-05 06:09 UTC by Khaled Hosny
Modified: 2018-01-14 00:56 UTC (History)
7 users (show)

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Crash report or crash signature:


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Description Khaled Hosny 2016-12-05 06:09:43 UTC
The latest version of the OpenType specification introduced few tables that allow for having multi-colored glyphs.

The simplest of them is COLR/CPAL (https://www.microsoft.com/typography/otspec/colr.htm, https://www.microsoft.com/typography/otspec/cpal.htm) which uses layers of normal glyphs and color palettes to assign colors to each.

It shouldn’s be hard to parse the tables in SalGraphics::DrawTextLayout() and draw each layer glyph with its assigned color. We might want to wait until HarfBuzz supports these fonts to avoid parsing the tables on our own.

This would allow supporting fonts like Amiri Quran Colored or several of the new Emoji fonts cross-platform (Windows 8.1+ already supports this format, though I don’t think we make use of that support).

Steps to Reproduce:
Try using Amiri Quran Colored font with Arabic text.

Actual Results:  
Text comes out using the foreground color.

Expected Results:
Text should use the colors defined in the font.

Reproducible: Always

User Profile Reset: 

Additional Info:

User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0
Comment 1 Volga 2016-12-05 10:02:49 UTC
We can expect this pull request will be merged to get support for CPAL table.
Comment 2 Volga 2017-01-23 04:07:41 UTC
We can also explore how Firefox implemented.