custom_font.c

#include <ft2build.h>
#include FT_FREETYPE_H

static FT_Library library;
static FT_Face face;

int load_custom_font(void)
{
    int error;
    error = FT_Init_FreeType(&library);
    if (error) {
        printf("error init freetype\n");
        return EXIT_FAILURE;
    }

    error = FT_New_Face(library, "./freudian.ttf", 0, &face);
    if (error == FT_Err_Unknown_File_Format) {
        printf("unkown file format\n");
        return EXIT_FAILURE;
    } else if (error) {
        printf("error loading font\n");
        return EXIT_FAILURE;
    }

    error = FT_Set_Char_Size(face, 0, 16*64, 300, 300);
    // error = FT_Set_Pixel_Sizes(face, 0, 16);
    if (error) {
        printf("coudlnt get char size\n");
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}

const uint8_t * get_ttf_bitmap(const lv_font_t * font, uint32_t unicode_letter)
{
    printf("get bitmap\n");
    int error;

    error = FT_Load_Char ( face, unicode_letter, FT_LOAD_RENDER);
    if (error) {
        printf("could not load char in bitmap\n");
        return NULL;
    }

    printf("buffer : %s\n", face->glyph->bitmap.buffer);

    return face->glyph->bitmap.buffer;
}

int16_t get_ttf_width(const lv_font_t * font, uint32_t unicode_letter)
{
    int error;

    error = FT_Load_Char(face, unicode_letter, FT_LOAD_RENDER);
    if (error) {
        printf("could not load char in width\n");
        return -1;
    }

    printf("width : %i\n", face->glyph->bitmap.width);

    return face->glyph->bitmap.width;
}

lv_font_t custom_font = 
{
  .unicode_first = 32,
  .unicode_last = 126,
  .h_px = 0,
  .glyph_bitmap = NULL,
  .glyph_dsc = NULL,
  .unicode_list = NULL,
  .get_bitmap = get_ttf_bitmap,
  .get_width = get_ttf_width,
  .bpp = 8,
  .next_page = NULL
};