Set a font's size dynamically.
Defined in <SDL_ttf.h>
int TTF_SetFontSize(TTF_Font *font, int ptsize);| TTF_Font * | font | the font to resize. | 
| int | ptsize | the new point size. | 
(int) Returns 0 if successful, -1 on error.
This clears already-generated glyphs, if any, from the cache.
This function is available since SDL_ttf 2.0.18.