Create a font from an SDL_RWops, using a specified face index.
int freesrc, int ptsize, long index);TTF_Font * TTF_OpenFontIndexRW(SDL_RWops *src,
|src||an SDL_RWops to provide a font file's data.|
|freesrc||non-zero to close the RWops before returning, zero to leave it open.|
|ptsize||point size to use for the newly-opened font.|
|index||index of the face in the font file.|
Returns a valid TTF_Font, or NULL on error.
Some .fon fonts will have several sizes embedded in the file, so the point size becomes the index of choosing which size. If the value is too high, the last indexed size will be the default.
freesrc is non-zero, the RWops will be closed before returning, whether this function succeeds or not. SDL_ttf reads everything it needs from the RWops during this call in any case.
Some fonts have multiple "faces" included. The index specifies which face to use from the font file. Font files with only one face should specify zero for the index.
When done with the returned TTF_Font, use TTF_CloseFont() to dispose of it.
This function is available since SDL_ttf 2.0.12.