Are color glyphs only supported by the FreeType2 backend?

[pangocoder]

I’m using PangoCairo to draw text but I can’t get color glyphs to work with the Windows and macOS font backends, i.e. CAIRO_FONT_TYPE_WIN32 and CAIRO_FONT_TYPE_QUARTZ.

On macOS when using fonts such as “Apple Color Emoji” color emojis aren’t drawn at all when using CAIRO_FONT_TYPE_QUARTZ. When using CAIRO_FONT_TYPE_FT instead, color emojis work.

On Windows when using fonts such as “Segoe UI Emoji” emojis are drawn as black & white outlines instead of as colored emojis. Once again, when using CAIRO_FONT_TYPE_FT color emojis are drawn correctly.

So are colored glyphs like emojis generally unsupported for CAIRO_FONT_TYPE_WIN32 and CAIRO_FONT_TYPE_QUARTZ or am I doing something wrong here?

[lb90]

Good question! Yes, colored emojis are actually supported on Windows, but only when rendering via Cairo-DirectWrite. That’s an inherent limitation of the underlying technology: GDI cannot handle colored glyphs.

However, right now Pango in MSYS2 is built without support for Cairo-DirectWrite. That’s because the latest Cairo snapshot (1.17.8) is missing important fixes that have already landed in git main. So we’re waiting for a new Cairo release, which should happen for the GNOME 45 release in October.

[pangocoder]

Thanks for the information! What about macOS?

[lb90]

I don’t know much about macOS, unfortunately. There’s an open issue in Pango GitLab for that: Emojis don't render on macOS (#753) · Issues · GNOME / pango · GitLab. However I suspect that the issue is in Cairo, as it’s in charge of drawing glyphs.