1 files changed, 303 insertions, 0 deletions

diff --git a/fontbaker/fontbaker.c b/fontbaker/fontbaker.c
new file mode 100644
index 0000000..a11aa88
--- /dev/null
+++ b/fontbaker/fontbaker.c
@@ -0,0 +1,303 @@
+#include <font.h>
+
+#include <ft2build.h>
+#include FT_FREETYPE_H
+
+#include <assert.h>
+#include <math.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static const FT_Int32 LoadFlags = FT_LOAD_DEFAULT;
+
+static void RenderGlyph(
+    unsigned char c, const unsigned char* pixels, int width, int height) {
+  assert(pixels);
+
+  printf("Glyph (%c), %dx%d\n", c, width, height);
+
+  const unsigned char* pixel = pixels;
+  for (int y = 0; y < height; ++y) {
+    printf("%02d  ", y);
+    for (int x = 0; x < width; ++x, ++pixel) {
+      unsigned char p = ' ';
+      if (*pixel >= 128) {
+        p = '#';
+      } else if (*pixel >= 32) {
+        p = '*';
+      } else if (*pixel > 0) {
+        p = '.';
+      }
+      printf("%c", p);
+    }
+    printf("\n");
+  }
+  printf("\n");
+}
+
+static void RenderText(const FontAtlas* atlas, const char* text) {
+  assert(text);
+
+  const int glyph_width  = atlas->header.glyph_width;
+  const int glyph_height = atlas->header.glyph_height;
+  const int glyph_size   = glyph_width * glyph_height;
+
+  for (int y = 0; y < glyph_height; ++y) {
+    printf("%02d  ", y);
+
+    for (size_t i = 0; i < strlen(text); ++i) {
+      const char c            = text[i];
+      const int  glyph_offset = (c - FontGlyphStart) * glyph_size;
+      const int  row_offset   = (y * glyph_width);
+
+      const unsigned char* pixel = atlas->pixels + glyph_offset + row_offset;
+
+      for (int x = 0; x < glyph_width; ++x, ++pixel) {
+        unsigned char p = ' ';
+        if (*pixel >= 128) {
+          p = '#';
+        } else if (*pixel >= 32) {
+          p = '*';
+        } else if (*pixel > 0) {
+          p = '.';
+        }
+        printf("%c", p);
+      }
+    }
+    printf("\n");
+  }
+}
+
+static bool WriteAtlas(const FontAtlas* atlas, const char* output_path) {
+  assert(atlas);
+  assert(output_path);
+
+  bool success = true;
+
+  FILE* out = NULL;
+
+  const int num_pixels = atlas->header.num_glyphs * atlas->header.glyph_width *
+                         atlas->header.glyph_height;
+
+  out = fopen(output_path, "wb");
+  if (out == NULL) {
+    fprintf(stderr, "Failed opening output file: %s\n", output_path);
+    success = false;
+    goto cleanup;
+  }
+  if (fwrite(&atlas->header, sizeof(atlas->header), 1, out) != 1) {
+    fprintf(stderr, "Failed writing atlas header\n");
+    success = false;
+    goto cleanup;
+  }
+  if (fwrite(atlas->pixels, num_pixels, 1, out) != 1) {
+    fprintf(stderr, "Failed writing atlas\n");
+    success = false;
+    goto cleanup;
+  }
+
+cleanup:
+  if (out != NULL) {
+    fclose(out);
+  }
+  return success;
+}
+
+static int GetYOffset(FT_Face face, int font_size) {
+  const int y_offset = font_size - face->glyph->bitmap_top;
+  assert(y_offset >= 0);
+  return y_offset;
+}
+
+static bool GetMaxGlyphDimensions(
+    FT_Library ft, FT_Face face, int font_size, int* width, int* height) {
+  assert(ft);
+  assert(face);
+  assert(width);
+  assert(height);
+
+  FT_Error error = 0;
+
+  int max_width  = 0;
+  int max_height = 0;
+
+  for (unsigned char c = FontGlyphStart; c < FontGlyphEnd; ++c) {
+    const FT_UInt glyph_index = FT_Get_Char_Index(face, c);
+    assert(glyph_index > 0);
+
+    error = FT_Load_Glyph(face, glyph_index, LoadFlags);
+    assert(error == 0);
+
+    error = FT_Render_Glyph(face->glyph, FT_RENDER_MODE_NORMAL);
+    assert(error == 0);
+
+    const int y_offset = GetYOffset(face, font_size);
+
+    const int xmax = (int)face->glyph->bitmap.width;
+    const int ymax = (int)face->glyph->bitmap.rows + y_offset;
+
+    if (xmax > max_width) {
+      max_width = xmax;
+    }
+
+    if (ymax > max_height) {
+      max_height = ymax;
+    }
+  }
+
+  *width  = max_width;
+  *height = max_height;
+
+  return true;
+}
+
+static void GammaCorrect(unsigned char* pixels, int num_pixels) {
+  assert(pixels);
+
+  for (int i = 0; i < num_pixels; ++i) {
+    pixels[i] =
+        (unsigned char)(pow((double)pixels[i] / 255.0, 1.0 / 2.2) * 255.0);
+  }
+}
+
+int main(int argc, const char** argv) {
+  const int font_size = 26;
+
+  bool success = true;
+
+  if (argc < 3) {
+    fprintf(stderr, "Usage: %s <font file> <output file>\n", argv[0]);
+    return 0;
+  }
+
+  const char* font_path   = argv[1];
+  const char* output_path = argv[2];
+
+  FT_Library ft    = {0};
+  FT_Face    face  = {0};
+  FT_Error   error = 0;
+  FontAtlas* atlas = 0;
+
+  if (FT_Init_FreeType(&ft) != 0) {
+    fprintf(stderr, "FT_Init_FreeType() failed\n");
+    success = false;
+    goto cleanup;
+  }
+
+  if (FT_New_Face(ft, font_path, 0, &face) != 0) {
+    fprintf(stderr, "Failed loading font file: %s\n", font_path);
+    success = false;
+    goto cleanup;
+  }
+
+  if (FT_Set_Pixel_Sizes(face, 0, font_size) != 0) {
+    fprintf(stderr, "Failed to set character size\n");
+    success = false;
+    goto cleanup;
+  }
+
+  // Find the largest glyph dimensions.
+  int glyph_width, glyph_height;
+  GetMaxGlyphDimensions(ft, face, font_size, &glyph_width, &glyph_height);
+
+  const int glyph_size = glyph_width * glyph_height;
+  const int atlas_size = glyph_size * FontAtlasNumGlyphs;
+
+  printf("Glyph: %dx%d (%d bytes)\n", glyph_width, glyph_height, glyph_size);
+  printf(
+      "Atlas: %dx%d (%d bytes)\n", FontAtlasNumGlyphs * glyph_width,
+      glyph_height, atlas_size);
+
+  // -1 because Atlas already includes 1 pixel.
+  atlas = calloc(1, sizeof(FontAtlas) + atlas_size - 1);
+  if (!atlas) {
+    success = false;
+    goto cleanup;
+  }
+  atlas->header = (FontHeader){
+      .glyph_width  = glyph_width,
+      .glyph_height = glyph_height,
+      .num_glyphs   = FontAtlasNumGlyphs,
+  };
+
+  // Render into atlas in glyph-major order so that glyphs can later be rendered
+  // by scanning memory linearly.
+  for (unsigned char c = FontGlyphStart; c < FontGlyphEnd; ++c) {
+    const FT_UInt glyph_index = FT_Get_Char_Index(face, c);
+    assert(glyph_index > 0);
+
+    error = FT_Load_Glyph(face, glyph_index, LoadFlags);
+    assert(error == 0);
+
+    error = FT_Render_Glyph(face->glyph, FT_RENDER_MODE_NORMAL);
+    assert(error == 0);
+
+    const int this_width  = (int)face->glyph->bitmap.width;
+    const int this_height = (int)face->glyph->bitmap.rows;
+
+    // For debugging.
+    if ((c == 'A') || (c == 'B') || (c == 'C') || (c == 'e') || (c == '!')) {
+      RenderGlyph(c, face->glyph->bitmap.buffer, this_width, this_height);
+    }
+
+    // Space gets no bitmap allocated, skip rendering.
+    if (c == ' ') {
+      continue;
+    }
+
+    // Render into atlas.
+    const int glyph_offset = (c - FontGlyphStart) * glyph_size;
+    assert(glyph_offset + glyph_size <= atlas_size);
+
+    assert(this_width <= glyph_width);
+    assert(this_height <= glyph_height);
+
+    const int x_offset = (glyph_width - this_width) / 2;
+    const int y_offset = GetYOffset(face, font_size);
+
+    assert(y_offset >= 0);
+    assert(x_offset >= 0);
+    assert(y_offset + this_height <= glyph_height);
+    assert(x_offset + this_width <= glyph_width);
+
+    unsigned char* pAtlas =
+        atlas->pixels + glyph_offset + (y_offset * glyph_width) + x_offset;
+    const unsigned char* pixel = face->glyph->bitmap.buffer;
+
+    for (int y = 0; y < this_height; ++y) {
+      for (int x = 0; x < this_width; ++x, ++pixel, ++pAtlas) {
+        *pAtlas = *pixel;
+      }
+      // Glyph may be narrower than the maximum width.
+      if (glyph_width > this_width) {
+        pAtlas += (glyph_width - this_width);
+      }
+    }
+  }
+
+  // FreeType renders glyphs in linear space. Gamma-correct the atlas so that
+  // applications can directly render to screen.
+  GammaCorrect(atlas->pixels, atlas_size);
+
+  // Quick test.
+  const char* test = "Good Stuff! \"g_g\", Baking Complete.";
+  RenderText(atlas, test);
+
+  if (!WriteAtlas(atlas, output_path)) {
+    goto cleanup;
+  }
+
+cleanup:
+  if (atlas) {
+    free(atlas);
+  }
+  if (face) {
+    FT_Done_Face(face);
+  }
+  if (ft) {
+    FT_Done_FreeType(ft);
+  }
+  return success ? 0 : 1;
+}