Using non-scalable fonts with the cache API

[Thomas Pedersen]

Hi All

I’m sorry if this has been asked before and answered, but I’ve scoured the web 
for a solution without success. I’m currently building a simple left-to-right 
string shaper based on freetype and using the cache API. This works very well 
for scalable fonts, but trying to add support for emoji bitmap fonts such as 
“Apple Color Emoji” has left me slightly non-plussed. I can use 
FTC_Manager_LookupFace() without a problem, and by using the right values from 
fave->available_sizes I can also successfully perform FTC_Manager_LookupSize().

However, when I try to call FT_Load_Glyph() on the face I get a freetype error 
36 (bad size handle). Solutions on the web has pointed to requiring a call to 
FT_Set_Char_Size() before FT_Load_Glyph(), using this or any other size related 
functions are discouraged in the docs ("Don't use this function if you are 
using the FreeType cache API.”).

So, can anyone point me towards best practices for using the cache API along 
with non-scalable fonts? Any help would be greatly appreciated!

With best wishes
Thomas