[sfnt] Preliminary support of coloured layer outlines.

This commit enables OpenType's COLR/CPAL table handling; a typical
application are color emojis that can be scaled to any size.

If the color palette does not exist or is invalid, the rendering
step rasterizes the outline instead.  The current implementation
assumes that the foreground is black.

Enable this by defining option TT_CONFIG_OPTION_COLOR_LAYERS.

There are still some issues with metrics; additionally, an API to
fetch color layers is missing.

* devel/ftoption.h, include/freetype/config/ftoption.h
(TT_CONFIG_OPTION_COLOR_LAYERS): New macro.

* include/freetype/internal/ftobjs.h (FT_Glyph_LayerRec,
FT_Colr_InternalRec): New structures.
(FT_Slot_InternalRec): Add `color_layers' field.

* include/freetype/internal/sfnt.h (TT_Load_Colr_Layer_Func,
TT_Blend_Colr_Func): New function types.
(SFNT_Interface): Add `load_colr', `free_colr', `load_colr_layer',
and `colr_blend' fields.

* include/freetype/internal/tttypes.h (TT_FaceRec): Add
`colr_and_cpal' field.

* include/freetype/internal/tttags. (TTAG_COLR, TTAG_CPAL): New
macros.

* src/sfnt/ttcolr.c, src/sfnt/ttcolr.h: New files.

* src/base/ftobjs.c (ft_glyphslot_done, FT_Render_Glyph_Internal):
Handle glyph color layers.

* src/sfnt/Jamfile (_sources), src/sfnt/rules.mk (SFNT_DRV_SRC): Add
`ttcolr.c'.

* src/sfnt/sfdriver.c: Include `ttcolr.h'.
(PUT_COLOR_LAYERS): New macro.
Update call to `FT_DEFINE_SFNT_INTERFACE'.

* src/sfnt/sfnt.c: Include `ttcolr.c'.

* src/sfnt/sfobjs.c (sfnt_load_face): Load `COLR' and `CPAL' tables.
(sfnt_done_face): Updated.

* src/truetype/ttgload.c (TT_Load_Glyph): Handle color layers.
This commit is contained in:
Shao Yu Zhang
2018-05-13 03:25:09 +02:00
committed by Werner Lemberg
parent 84eebf4802
commit f04d81751a
17 changed files with 912 additions and 4 deletions

View File

@@ -485,6 +485,15 @@ FT_BEGIN_HEADER
#define TT_CONFIG_OPTION_EMBEDDED_BITMAPS
/*************************************************************************/
/* */
/* Define TT_CONFIG_OPTION_COLOR_LAYERS if you want to support coloured */
/* outlines (from the COLR/CPAL tables) in all formats using the SFNT */
/* module (namely TrueType & OpenType). */
/* */
#define TT_CONFIG_OPTION_COLOR_LAYERS
/*************************************************************************/
/* */
/* Define TT_CONFIG_OPTION_POSTSCRIPT_NAMES if you want to be able to */