[HarfBuzz] Inheriting/copying font functions

[Tom Hacohen]

On Wed, 2011-05-11 at 10:09 -0400, Behdad Esfahbod wrote:
> You start by subclassing the font:
> 
>   font = hb_font_create_sub_font (parent);
> 
> And set your own font-funcs on it:
> 
>   hb_font_set_funcs (font, ffuncs, your_user_data, your_destroy);
> 
> Now you only have to override any functions you need, and in your function if
> you need to chain up, you do, eg.
> 
> {
>   if (not in cache...) {
>     hb_font_get_contour_point (hb_font_get_parent (font),
>                                glyph, point_index, x, y);
>     add to cache...
>   } else {
>     lookup from cache...
>   }
> }

My code now looks like:

   hb_ft_font = hb_ft_font_create(ft_face, NULL);
   hb_font = hb_font_create_sub_font(hb_ft_font);

   hb_font_set_funcs(hb_font, my_font_funcs_get(), my_data,NULL);

   hb_shape(hb_font, buffer, NULL, 0);

   hb_font_destroy(hb_font);
   hb_font_destroy(hb_ft_font);

my_font_funcs_get() return my font functions that have either nil or my
implementation alternatives.

Thanks,
Tom.