Update the docs

Mention that the color index will always be 0xFFFF
when using hb_paint API with fonts that don't have
color palettes.

And add an outline about which kinds of glyphs
require which callbacks.
This commit is contained in:
Matthias Clasen 2022-12-16 23:58:37 -05:00 committed by Behdad Esfahbod
parent 9461ab7088
commit 56b02b6599
1 changed files with 7 additions and 1 deletions

View File

@ -48,7 +48,13 @@ HB_BEGIN_DECLS
*
* The callbacks also assume that the caller uses
* hb_ot_color_palette_get_colors() to obtain colors
* from one of the fonts color palettes.
* from one of the fonts color palettes. If the font does
* not have color palettes, the color index will always
* be 0xFFFF, indicating the use of the foreground color.
*
* Not all callbacks are required for all kinds of glyphs.
* For rendering COLRv0 or non-color outline glyphs, the
* gradient and composite callbacks are not needed.
*
* Since: REPLACEME
**/