SDL_TTF with cleartype

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I used SDL_TTF to render small texts, however, it was hard to see through monitor because it was too small. So I thought about cleartype which is a method to render text clearly with some colors.
So, I want to use it through SDL_TTF. How can I implement it?
(I tried subpixel rendering from this commit : https://hg.libsdl.org/SDL_ttf/rev/9f46efc0fde2)

Hello,

ClearType is a Microsoft technology. You need to use directly its API to use it, whereas SDL_ttf relies on Freetype. From “News & Update” ( https://www.freetype.org/index.html#news ), it’s reported to be equivalent with subpixel hinting.

Do you see any change using subpixel hinting ? Some times fonts have no information to produce subpixel ?