Render Persian RTL Text in SDL2 with SDL_ttf

render_text.c

SDL_Texture *renderText(const char *text, bool isUTF8, const char *fontPath, SDL_Color color, int fontSize, SDL_Renderer *renderer)
{
	TTF_Font *font = TTF_OpenFont(fontPath, fontSize);
	if (font == NULL)
	{
		//logErrorSDL("Failed to Open Font!");
		return NULL;
	}

	SDL_Surface *surface;
	
	if (isUTF8)
	{
		TTF_SetDirection(5);    // HB_DIRECTION_RTL
		TTF_SetScript(1098015074);  // HB_SCRIPT_ARABIC
		surface = TTF_RenderUTF8_Blended(font, text, color);
	}
	else
	{
		surface = TTF_RenderText_Blended(font, text, *color);
	}

	if (surface == NULL)
	{
		TTF_CloseFont(font);
		//logErrorSDL("Failed to Render Text!");
		return NULL;
	}

	TTF_CloseFont(font);

	SDL_Texture *texture = SDL_CreateTextureFromSurface(renderer, surface);
	if (texture == NULL)
	{
		//logErrorSDL("Failed to Create Text Texture!");
	}

	SDL_FreeSurface(surface);

	return texture;
}

sdl_render_rtl_text.md

TTF_SetDirection(5);  // [1]
TTF_SetScript(1098015074);  // [2]
surface = TTF_RenderUTF8_Blended(font, text, color);

Where I found the numbers:

[1]

HB_DIRECTION_RTL = 5;

direction: https://github.com/harfbuzz/harfbuzz/blob/8a69e0063936764cbd149985e0b57e1dc35935c2/src/hb-common.h#L222

typedef enum {
 HB_DIRECTION_INVALID = 0,
 HB_DIRECTION_LTR = 4,
 HB_DIRECTION_RTL,
 HB_DIRECTION_TTB,
 HB_DIRECTION_BTT
} hb_direction_t;

[2]

uint32_t script_code = ((uint32_t)((((uint32_t)('A')&0xFF)<<24)|(((uint32_t)('r')&0xFF)<<16)|(((uint32_t)('a')&0xFF)<<8)|((uint32_t)('b')&0xFF)));
printf("%d\n", script_code);

script tag: https://github.com/harfbuzz/harfbuzz/blob/8a69e0063936764cbd149985e0b57e1dc35935c2/src/hb-common.h#L500

HB_SCRIPT_ARABIC			= HB_TAG ('A','r','a','b'), /*1.1*/

calculate value of script tag: https://github.com/harfbuzz/harfbuzz/blob/8a69e0063936764cbd149985e0b57e1dc35935c2/src/hb-common.h#L159

#define HB_TAG(c1,c2,c3,c4) ((hb_tag_t)((((uint32_t)(c1)&0xFF)<<24)|(((uint32_t)(c2)&0xFF)<<16)|(((uint32_t)(c3)&0xFF)<<8)|((uint32_t)(c4)&0xFF)))