support rendering of wider range of combinging characters by ftfont backend
* lisp/language/hebrew.el (hebrew-shape-gstring): If the font backend supports rendering of combining characters, call font-shape-gstring. * src/font.c (Ffont_get): Handle `combining-capability' property. (syms_of_font): New symbol ":combining-capability'. * src/font.h (struct font_driver): New member combining_capability. * src/ftfont.c: Include "category.h". (ftfont_driver): Initialize combining_capability to ftfont_combining_capability. (ftfont_shape_by_flt): If OTF is null, try to find a suitable FLT in advance. (ftfont_combining_capability): New function.
Showing with 72 additions and 29 deletions