Add OpenType example

hello-harfbuzz-opentype uses HarfBuzz's native OpenType implementation
and has no other dependencies (e.g. on FreeType or Cairo). It only
outputs glyph and offset information and does no rendering.

Makefile

@@ -1,9 +1,16 @@
-PKGS = harfbuzz cairo-ft freetype2
+HB_PKGS = harfbuzz
+FT_PKGS = harfbuzz cairo-ft freetype2
 
-CFLAGS = `pkg-config --cflags $(PKGS)`
-LDFLAGS = `pkg-config --libs $(PKGS)` -lm
+HB_CFLAGS = `pkg-config --cflags $(HB_PKGS)`
+HB_LDFLAGS = `pkg-config --libs $(HB_PKGS)` -lm
 
-all: hello-harfbuzz
+FT_CFLAGS = `pkg-config --cflags $(FT_PKGS)`
+FT_LDFLAGS = `pkg-config --libs $(FT_PKGS)` -lm
 
-%: %.c
-	$(CC) -std=c99 -o $@ $^ $(CFLAGS) $(LDFLAGS)
+all: hello-harfbuzz-freetype hello-harfbuzz-opentype
+
+hello-harfbuzz-opentype: hello-harfbuzz-opentype.c
+	$(CC) -std=c99 -o $@ $^ $(HB_CFLAGS) $(HB_LDFLAGS)
+
+hello-harfbuzz-freetype: hello-harfbuzz-freetype.c
+	$(CC) -std=c99 -o $@ $^ $(FT_CFLAGS) $(FT_LDFLAGS)

hello-harfbuzz-opentype.c

@@ -0,0 +1,113 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+#include <hb.h>
+#include <hb-ot.h>
+
+#define FONT_SIZE 36
+#define MARGIN (FONT_SIZE * .5)
+
+/* Use native open type implementation to load font
+  https://github.com/harfbuzz/harfbuzz/issues/255 */
+hb_font_t*
+get_font_ot(const char *filename, int size)
+{
+  FILE* file = fopen(filename, "rb");
+  fseek(file, 0, SEEK_END);
+  unsigned int length = ftell(file);
+  fseek(file, 0, SEEK_SET);
+
+  char* data = malloc(length);
+  fread(data, length, 1, file);
+  fclose(file);
+
+  hb_blob_t* blob = hb_blob_create(data, length, HB_MEMORY_MODE_WRITABLE, (void*)data, NULL);
+  hb_face_t* face = hb_face_create(blob, 0);
+  hb_font_t* font = hb_font_create(face);
+
+  hb_ot_font_set_funcs(font);
+  hb_font_set_scale(font, size, size);
+
+  return font;
+}
+
+int
+main(int argc, char **argv)
+{
+  const char *fontfile;
+  const char *text;
+
+  if (argc < 3)
+  {
+    fprintf (stderr, "usage: hello-harfbuzz font-file.ttf text\n");
+    exit (1);
+  }
+
+  fontfile = argv[1];
+  text = argv[2];
+
+  /* Create hb-ft font. */
+  hb_font_t *hb_font;
+  hb_font = get_font_ot (fontfile, FONT_SIZE*64);
+
+  /* Create hb-buffer and populate. */
+  hb_buffer_t *hb_buffer;
+  hb_buffer = hb_buffer_create ();
+  hb_buffer_add_utf8 (hb_buffer, text, -1, 0, -1);
+  hb_buffer_guess_segment_properties (hb_buffer);
+
+  /* Shape it! */
+  hb_shape (hb_font, hb_buffer, NULL, 0);
+
+  /* Get glyph information and positions out of the buffer. */
+  unsigned int len = hb_buffer_get_length (hb_buffer);
+  hb_glyph_info_t *info = hb_buffer_get_glyph_infos (hb_buffer, NULL);
+  hb_glyph_position_t *pos = hb_buffer_get_glyph_positions (hb_buffer, NULL);
+
+  /* Print them out as is. */
+  printf ("Raw buffer contents:\n");
+  for (unsigned int i = 0; i < len; i++)
+  {
+    hb_codepoint_t gid   = info[i].codepoint;
+    unsigned int cluster = info[i].cluster;
+    double x_advance = pos[i].x_advance / 64.;
+    double y_advance = pos[i].y_advance / 64.;
+    double x_offset  = pos[i].x_offset / 64.;
+    double y_offset  = pos[i].y_offset / 64.;
+
+    char glyphname[32];
+    hb_font_get_glyph_name (hb_font, gid, glyphname, sizeof (glyphname));
+
+    printf ("glyph='%s'	cluster=%d	advance=(%g,%g)	offset=(%g,%g)\n",
+            glyphname, cluster, x_advance, y_advance, x_offset, y_offset);
+  }
+
+  printf ("Converted to absolute positions:\n");
+  /* And converted to absolute positions. */
+  {
+    double current_x = 0;
+    double current_y = 0;
+    for (unsigned int i = 0; i < len; i++)
+    {
+      hb_codepoint_t gid   = info[i].codepoint;
+      unsigned int cluster = info[i].cluster;
+      double x_position = current_x + pos[i].x_offset / 64.;
+      double y_position = current_y + pos[i].y_offset / 64.;
+
+
+      char glyphname[32];
+      hb_font_get_glyph_name (hb_font, gid, glyphname, sizeof (glyphname));
+
+      printf ("glyph='%s'	cluster=%d	position=(%g,%g)\n",
+	      glyphname, cluster, x_position, y_position);
+
+      current_x += pos[i].x_advance / 64.;
+      current_y += pos[i].y_advance / 64.;
+    }
+  }
+
+  hb_buffer_destroy (hb_buffer);
+  hb_font_destroy (hb_font);
+
+  return 0;
+}