HarfBuzz->stb_truetype

hb_stb_truetype.c

// ---- loading a font

static void load_font(void)
{
   hb_blob_t *blob;
   hb_face_t *face;
   size_t filelen = 0;
   void *filedata = stb_file("c:/windows/fonts/arial.ttf", &filelen);

   if (filedata == 0)                                                               stbpg_fatal("Couldn't load font");
   if (!stbtt_InitFont(&font, filedata, stbtt_GetFontOffsetForIndex(filedata,0)))   stbpg_fatal("Couldn't parse font");

   font_scale = stbtt_ScaleForPixelHeight(&font, 32);

   blob = hb_blob_create((const char *)filedata, (unsigned int)filelen, HB_MEMORY_MODE_READONLY, NULL, NULL);
   if (!blob) stbpg_fatal("Font blob create failed");
   face = hb_face_create(blob, 0);
   if (!face) stbpg_fatal("Font face create failed");
   hb_blob_destroy(blob); // face keeps its ref.

   hb_font = hb_font_create(face);
   if (!hb_font) stbpg_fatal("Font create failed");
   hb_face_destroy(face); // font keeps ref

   // stb_truetype only does TrueType/OpenType which HB supports natively
   hb_ot_font_set_funcs(hb_font);
}

static void cleanup_font(void)
{
   hb_font_destroy(hb_font);
}

// ---- shaping and rendering

static void print_message_shaped(int x, int y, const char *msg)
{
   hb_buffer_t *buf;
   hb_glyph_info_t *ginf;
   hb_glyph_position_t *gpos;
   unsigned int len = 0;
   unsigned int i;
   int j;

   buf = hb_buffer_create();
   if (!buf) stbpg_fatal("no buf");

   // set up the buffer
   hb_buffer_set_flags(buf, HB_BUFFER_FLAG_BOT | HB_BUFFER_FLAG_EOT); // beginning and end of text both
   hb_buffer_add_utf8(buf, msg, -1, 0, -1);

   hb_buffer_guess_segment_properties(buf);

   // shape it
   hb_shape(hb_font, buf, NULL, 0);

   ginf = hb_buffer_get_glyph_infos(buf, &len);
   gpos = hb_buffer_get_glyph_positions(buf, &len);
   if ((!ginf || !gpos) && len) stbpg_fatal("no glyph info");

   // make sure we have the glyphs
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
   for (i = 0; i < len; ++i) {
      int glyph = ginf[i].codepoint;
      if (!glyphs[glyph].init)
         bake_glyph(&font, font_scale, glyph);
   }

   // render the text
   glBegin(GL_QUADS);
   for (i = 0; i < len; ++i) {
      hb_glyph_info_t *gi = &ginf[i];
      hb_glyph_position_t *gp = &gpos[i];
      glyph_quad *gq = &glyphs[gi->codepoint];
      float xb, yb;

      xb = x + gp->x_offset*font_scale;
      yb = y - gp->y_offset*font_scale; // our +y goes down, glyph +y goes up

      for (j = 0; j < 4; ++j) {
         int k = j ^ (j >> 1);
         int xd = ((k&1) ? gq->w : 0);
         int yd = ((k&2) ? gq->h : 0);
         glTexCoord2f(1.0f * (gq->x0 + xd) / FONT_W, 1.0f * (gq->y0 + yd) / FONT_H);
         glVertex2f(xb + (gq->xo + xd)/((float) OVERSAMPLE), yb + (gq->yo + yd)/((float)OVERSAMPLE));
      }

      x += gp->x_advance*font_scale;
   }
   glEnd();
   
   hb_buffer_destroy(buf);
}