diff --git a/src/hb-blob.cc b/src/hb-blob.cc
index 44379301d36ebe529ebeff3947499ac98e250e00..d8b295e60753cb95c2b617daf7622746a158f594 100644
--- a/src/hb-blob.cc
+++ b/src/hb-blob.cc
@@ -79,11 +79,11 @@ _hb_blob_destroy_user_data (hb_blob_t *blob)
 
 /**
  * hb_blob_create: (Xconstructor)
- * @data: (array length=length) (closure user_data) (destroy destroy) (scope notified) (transfer none): Pointer to blob data.
+ * @data: (array length=length) (element-type uint8_t) (closure user_data) (destroy destroy) (scope notified) (transfer none): Pointer to blob data.
  * @length: Length of @data in bytes.
  * @mode: Memory mode for @data.
- * @user_data: Data parameter to pass to @destroy.
- * @destroy: Callback to call when @data is not needed anymore.
+ * @user_data: (allow-none): Data parameter to pass to @destroy.
+ * @destroy: (allow-none): Callback to call when @data is not needed anymore.
  *
  * Creates a new "blob" object wrapping @data.  The @mode parameter is used
  * to negotiate ownership and lifecycle of @data.
diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index 74ae273eeca79803487bf5d580eea92ea12986cb..7bf232d760395e72b1d5d719bb9b78abba2794d8 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -1400,7 +1400,7 @@ hb_buffer_add_utf (hb_buffer_t  *buffer,
 /**
  * hb_buffer_add_utf8:
  * @buffer: a buffer.
- * @text: (array length=text_length):
+ * @text: (array length=text_length) (element-type uint8_t):
  * @text_length: 
  * @item_offset: 
  * @item_length: 
diff --git a/src/sample.py b/src/sample.py
index 317a47e0f4d90fc3694215cc9836ef2edf68979b..e2daba81a4318a545492f07ba6eee59ff1aeeede 100755
--- a/src/sample.py
+++ b/src/sample.py
@@ -1,13 +1,35 @@
 #!/usr/bin/python
+# -*- coding: utf-8 -*-
 
+from __future__ import print_function
 import sys
 from gi.repository import HarfBuzz as hb
 
-def nothing():
-	pass
+def nothing(data):
+	print(data)
 
-fontdata = file (sys.argv[1]).read ()
-blob = hb.blob_create (fontdata, hb.memory_mode_t.WRITABLE, None, nothing)
-print blob
-buffer = hb.buffer_create ()
+fontdata = open (sys.argv[1], 'rb').read ()
 
+blob = hb.blob_create (fontdata, hb.memory_mode_t.DUPLICATE, 1234, None)
+buf = hb.buffer_create ()
+hb.buffer_add_utf8 (buf, "Hello بهداد", 0, -1)
+hb.buffer_guess_segment_properties (buf)
+
+face = hb.face_create (blob, 0)
+font = hb.font_create (face)
+upem = hb.face_get_upem (face)
+hb.font_set_scale (font, upem, upem)
+#hb.ft_font_set_funcs (font)
+hb.ot_font_set_funcs (font)
+
+hb.shape (font, buf, [])
+
+infos = hb.buffer_get_glyph_infos (buf)
+positions = hb.buffer_get_glyph_positions (buf)
+
+for info,pos in zip(infos, positions):
+	gid = info.codepoint
+	cluster = info.cluster
+	advance = pos.x_advance
+
+	print(gid, cluster, advance)