main.c: Modern text rendering with Linux: Part 1

main.c

#include <stdio.h>

#include <freetype2/ft2build.h>
#include FT_FREETYPE_H

int main() {
  FT_Library ft;
  FT_Error err = FT_Init_FreeType(&ft);
  if (err != 0) {
    printf("Failed to initialize FreeType\n");
    exit(EXIT_FAILURE);
  }

  FT_Int major, minor, patch;
  FT_Library_Version(ft, &major, &minor, &patch);
  printf("FreeType's version is %d.%d.%d\n", major, minor, patch);

  FT_Face face;
  err = FT_New_Face(ft, "./UbuntuMono.ttf", 0, &face);
  if (err != 0) {
    printf("Failed to load face\n");
    exit(EXIT_FAILURE);
  }

  err = FT_Set_Pixel_Sizes(face, 0, 32);
  if (err != 0) {
    printf("Failed to set pixel size\n");
    exit(EXIT_FAILURE);
  }

  FT_UInt glyph_index = FT_Get_Char_Index(face, 'a');

  FT_Int32 load_flags = FT_LOAD_DEFAULT;
  err = FT_Load_Glyph(face, glyph_index, load_flags);
  if (err != 0) {
    printf("Failed to load glyph\n");
    exit(EXIT_FAILURE);
  }

  FT_Int32 render_flags = FT_RENDER_MODE_NORMAL;
  err = FT_Render_Glyph(face->glyph, render_flags);
  if (err != 0) {
    printf("Failed to render the glyph\n");
    exit(EXIT_FAILURE);
  }

  FT_Bitmap bitmap = face->glyph->bitmap;

  for (size_t i = 0; i < bitmap.rows; i++) {
      for (size_t j = 0; j < bitmap.width; j++) {
          unsigned char pixel_brightness =
              bitmap.buffer[i * bitmap.pitch + j];

          if (pixel_brightness > 169) {
              printf("*");
          } else if (pixel_brightness > 84) {
              printf(".");
          } else {
              printf(" ");
          }
      }
      printf("\n");
  }

  return 0;
}

Thanks for the tutorial. I enjoy going through it.

I have a suggestion. The chain of face->glyph->bitmap is hard to read, so why not putting it into a variable, like this?

FT_Bitmap bitmap = face->glyph->bitmap;

for (size_t i = 0; i < bitmap.rows; i++) {
    for (size_t j = 0; j < bitmap.width; j++) {
        unsigned char pixel_brightness =
            bitmap.buffer[i * bitmap.pitch + j];

        if (pixel_brightness > 169) {
            printf("*");
        } else if (pixel_brightness > 84) {
            printf(".");
        } else {
            printf(" ");
        }
    }
    printf("\n");
}

You forget about memory management. Where is memory free?
FT_Done_Glyph()
FT_Done_Face()
FT_Done_Library()