src/hb-ft.cc - third_party/harfbuzz - Git at Google

 /*
  * Copyright © 2009  Red Hat, Inc.
  * Copyright © 2009  Keith Stribley
  *
  *  This is part of HarfBuzz, a text shaping library.
  *
  * Permission is hereby granted, without written agreement and without
  * license or royalty fees, to use, copy, modify, and distribute this
  * software and its documentation for any purpose, provided that the
  * above copyright notice and the following two paragraphs appear in
  * all copies of this software.
  *
  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  * DAMAGE.
  *
  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  *
  * Red Hat Author(s): Behdad Esfahbod
  */

 #include "hb-private.hh"

 #include "hb-ft.h"

 #include "hb-font-private.hh"

 #include FT_ADVANCES_H
 #include FT_TRUETYPE_TABLES_H


 #ifndef HB_DEBUG_FT
 #define HB_DEBUG_FT (HB_DEBUG+0)
 #endif


 /* TODO:
  *
  * In general, this file does a fine job of what it's supposed to do.
  * There are, however, things that need more work:
  *
  *   - We don't handle any load_flags.  That definitely has API implications. :(
  *     I believe hb_ft_font_create() should take load_flags input.
  *     In particular, FT_Get_Advance() without the NO_HINTING flag seems to be
  *     buggy.
  *
  *   - We don't handle / allow for emboldening / obliqueing.
  *
  *   - In the future, we should add constructors to create fonts in font space?
  *
  *   - FT_Load_Glyph() is exteremely costly.  Do something about it?
  */


 static hb_bool_t
 hb_ft_get_glyph (hb_font_t *font HB_UNUSED,
 		 void *font_data,
 		 hb_codepoint_t unicode,
 		 hb_codepoint_t variation_selector,
 		 hb_codepoint_t *glyph,
 		 void *user_data HB_UNUSED)

 {
   FT_Face ft_face = (FT_Face) font_data;

 #ifdef HAVE_FT_FACE_GETCHARVARIANTINDEX
   if (unlikely (variation_selector)) {
     *glyph = FT_Face_GetCharVariantIndex (ft_face, unicode, variation_selector);
     if (*glyph)
       return true;
   }
 #endif

   *glyph = FT_Get_Char_Index (ft_face, unicode);
   return *glyph != 0;
 }

 static hb_position_t
 hb_ft_get_glyph_h_advance (hb_font_t *font HB_UNUSED,
 			   void *font_data,
 			   hb_codepoint_t glyph,
 			   void *user_data HB_UNUSED)
 {
   FT_Face ft_face = (FT_Face) font_data;
   int load_flags = FT_LOAD_DEFAULT | FT_LOAD_NO_HINTING;
   FT_Fixed v;

   if (unlikely (FT_Get_Advance (ft_face, glyph, load_flags, &v)))
     return 0;

   return v >> 10;
 }

 static hb_position_t
 hb_ft_get_glyph_v_advance (hb_font_t *font HB_UNUSED,
 			   void *font_data,
 			   hb_codepoint_t glyph,
 			   void *user_data HB_UNUSED)
 {
   FT_Face ft_face = (FT_Face) font_data;
   int load_flags = FT_LOAD_DEFAULT | FT_LOAD_NO_HINTING | FT_LOAD_VERTICAL_LAYOUT;
   FT_Fixed v;

   if (unlikely (FT_Get_Advance (ft_face, glyph, load_flags, &v)))
     return 0;

   /* Note: FreeType's vertical metrics grows downward while other FreeType coordinates
    * have a Y growing upward.  Hence the extra negation. */
   return -v >> 10;
 }

 static hb_bool_t
 hb_ft_get_glyph_h_origin (hb_font_t *font HB_UNUSED,
 			  void *font_data HB_UNUSED,
 			  hb_codepoint_t glyph HB_UNUSED,
 			  hb_position_t *x HB_UNUSED,
 			  hb_position_t *y HB_UNUSED,
 			  void *user_data HB_UNUSED)
 {
   /* We always work in the horizontal coordinates. */
   return true;
 }

 static hb_bool_t
 hb_ft_get_glyph_v_origin (hb_font_t *font HB_UNUSED,
 			  void *font_data,
 			  hb_codepoint_t glyph,
 			  hb_position_t *x,
 			  hb_position_t *y,
 			  void *user_data HB_UNUSED)
 {
   FT_Face ft_face = (FT_Face) font_data;
   int load_flags = FT_LOAD_DEFAULT;

   if (unlikely (FT_Load_Glyph (ft_face, glyph, load_flags)))
     return false;

   /* Note: FreeType's vertical metrics grows downward while other FreeType coordinates
    * have a Y growing upward.  Hence the extra negation. */
   *x = ft_face->glyph->metrics.horiBearingX -   ft_face->glyph->metrics.vertBearingX;
   *y = ft_face->glyph->metrics.horiBearingY - (-ft_face->glyph->metrics.vertBearingY);

   return true;
 }

 static hb_position_t
 hb_ft_get_glyph_h_kerning (hb_font_t *font,
 			   void *font_data,
 			   hb_codepoint_t left_glyph,
 			   hb_codepoint_t right_glyph,
 			   void *user_data HB_UNUSED)
 {
   FT_Face ft_face = (FT_Face) font_data;
   FT_Vector kerningv;

   FT_Kerning_Mode mode = font->x_ppem ? FT_KERNING_DEFAULT : FT_KERNING_UNFITTED;
   if (FT_Get_Kerning (ft_face, left_glyph, right_glyph, mode, &kerningv))
     return 0;

   return kerningv.x;
 }

 static hb_position_t
 hb_ft_get_glyph_v_kerning (hb_font_t *font HB_UNUSED,
 			   void *font_data HB_UNUSED,
 			   hb_codepoint_t top_glyph HB_UNUSED,
 			   hb_codepoint_t bottom_glyph HB_UNUSED,
 			   void *user_data HB_UNUSED)
 {
   /* FreeType API doesn't support vertical kerning */
   return 0;
 }

 static hb_bool_t
 hb_ft_get_glyph_extents (hb_font_t *font HB_UNUSED,
 			 void *font_data,
 			 hb_codepoint_t glyph,
 			 hb_glyph_extents_t *extents,
 			 void *user_data HB_UNUSED)
 {
   FT_Face ft_face = (FT_Face) font_data;
   int load_flags = FT_LOAD_DEFAULT;

   if (unlikely (FT_Load_Glyph (ft_face, glyph, load_flags)))
     return false;

   extents->x_bearing = ft_face->glyph->metrics.horiBearingX;
   extents->y_bearing = ft_face->glyph->metrics.horiBearingY;
   extents->width = ft_face->glyph->metrics.width;
   extents->height = -ft_face->glyph->metrics.height;
   return true;
 }

 static hb_bool_t
 hb_ft_get_glyph_contour_point (hb_font_t *font HB_UNUSED,
 			       void *font_data,
 			       hb_codepoint_t glyph,
 			       unsigned int point_index,
 			       hb_position_t *x,
 			       hb_position_t *y,
 			       void *user_data HB_UNUSED)
 {
   FT_Face ft_face = (FT_Face) font_data;
   int load_flags = FT_LOAD_DEFAULT;

   if (unlikely (FT_Load_Glyph (ft_face, glyph, load_flags)))
       return false;

   if (unlikely (ft_face->glyph->format != FT_GLYPH_FORMAT_OUTLINE))
       return false;

   if (unlikely (point_index >= (unsigned int) ft_face->glyph->outline.n_points))
       return false;

   *x = ft_face->glyph->outline.points[point_index].x;
   *y = ft_face->glyph->outline.points[point_index].y;

   return true;
 }

 static hb_bool_t
 hb_ft_get_glyph_name (hb_font_t *font HB_UNUSED,
 		      void *font_data,
 		      hb_codepoint_t glyph,
 		      char *name, unsigned int size,
 		      void *user_data HB_UNUSED)
 {
   FT_Face ft_face = (FT_Face) font_data;

   hb_bool_t ret = !FT_Get_Glyph_Name (ft_face, glyph, name, size);
   if (ret && (size && !*name))
     ret = false;

   return ret;
 }

 static hb_bool_t
 hb_ft_get_glyph_from_name (hb_font_t *font HB_UNUSED,
 			   void *font_data,
 			   const char *name, int len, /* -1 means nul-terminated */
 			   hb_codepoint_t *glyph,
 			   void *user_data HB_UNUSED)
 {
   FT_Face ft_face = (FT_Face) font_data;

   if (len < 0)
     *glyph = FT_Get_Name_Index (ft_face, (FT_String *) name);
   else {
     /* Make a nul-terminated version. */
     char buf[128];
     len = MIN (len, (int) sizeof (buf) - 1);
     strncpy (buf, name, len);
     buf[len] = '\0';
     *glyph = FT_Get_Name_Index (ft_face, buf);
   }

   return *glyph != 0;
 }


 static hb_font_funcs_t *
 _hb_ft_get_font_funcs (void)
 {
   static const hb_font_funcs_t ft_ffuncs = {
     HB_OBJECT_HEADER_STATIC,

     true, /* immutable */

     {
 #define HB_FONT_FUNC_IMPLEMENT(name) hb_ft_get_##name,
       HB_FONT_FUNCS_IMPLEMENT_CALLBACKS
 #undef HB_FONT_FUNC_IMPLEMENT
     }
   };

   return const_cast<hb_font_funcs_t *> (&ft_ffuncs);
 }


 static hb_blob_t *
 reference_table  (hb_face_t *face HB_UNUSED, hb_tag_t tag, void *user_data)
 {
   FT_Face ft_face = (FT_Face) user_data;
   FT_Byte *buffer;
   FT_ULong  length = 0;
   FT_Error error;

   /* Note: FreeType like HarfBuzz uses the NONE tag for fetching the entire blob */

   error = FT_Load_Sfnt_Table (ft_face, tag, 0, NULL, &length);
   if (error)
     return NULL;

   buffer = (FT_Byte *) malloc (length);
   if (buffer == NULL)
     return NULL;

   error = FT_Load_Sfnt_Table (ft_face, tag, 0, buffer, &length);
   if (error)
     return NULL;

   return hb_blob_create ((const char *) buffer, length,
 			 HB_MEMORY_MODE_WRITABLE,
 			 buffer, free);
 }


 hb_face_t *
 hb_ft_face_create (FT_Face           ft_face,
 		   hb_destroy_func_t destroy)
 {
   hb_face_t *face;

   if (ft_face->stream->read == NULL) {
     hb_blob_t *blob;

     blob = hb_blob_create ((const char *) ft_face->stream->base,
 			   (unsigned int) ft_face->stream->size,
 			   /* TODO: We assume that it's mmap()'ed, but FreeType code
 			    * suggests that there are cases we reach here but font is
 			    * not mmapped.  For example, when mmap() fails.  No idea
 			    * how to deal with it better here. */
 			   HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITABLE,
 			   ft_face, destroy);
     face = hb_face_create (blob, ft_face->face_index);
     hb_blob_destroy (blob);
   } else {
     face = hb_face_create_for_tables (reference_table, ft_face, destroy);
   }

   hb_face_set_index (face, ft_face->face_index);
   hb_face_set_upem (face, ft_face->units_per_EM);

   return face;
 }

 static void
 hb_ft_face_finalize (FT_Face ft_face)
 {
   hb_face_destroy ((hb_face_t *) ft_face->generic.data);
 }

 hb_face_t *
 hb_ft_face_create_cached (FT_Face ft_face)
 {
   if (unlikely (!ft_face->generic.data || ft_face->generic.finalizer != (FT_Generic_Finalizer) hb_ft_face_finalize))
   {
     if (ft_face->generic.finalizer)
       ft_face->generic.finalizer (ft_face);

     ft_face->generic.data = hb_ft_face_create (ft_face, NULL);
     ft_face->generic.finalizer = (FT_Generic_Finalizer) hb_ft_face_finalize;
   }

   return hb_face_reference ((hb_face_t *) ft_face->generic.data);
 }

 static void
 _do_nothing (void)
 {
 }


 hb_font_t *
 hb_ft_font_create (FT_Face           ft_face,
 		   hb_destroy_func_t destroy)
 {
   hb_font_t *font;
   hb_face_t *face;

   face = hb_ft_face_create (ft_face, destroy);
   font = hb_font_create (face);
   hb_face_destroy (face);
   hb_font_set_funcs (font,
 		     _hb_ft_get_font_funcs (),
 		     ft_face, (hb_destroy_func_t) _do_nothing);
   hb_font_set_scale (font,
 		     ((uint64_t) ft_face->size->metrics.x_scale * (uint64_t) ft_face->units_per_EM) >> 16,
 		     ((uint64_t) ft_face->size->metrics.y_scale * (uint64_t) ft_face->units_per_EM) >> 16);
   hb_font_set_ppem (font,
 		    ft_face->size->metrics.x_ppem,
 		    ft_face->size->metrics.y_ppem);

   return font;
 }


 /* Thread-safe, lock-free, FT_Library */

 static FT_Library ft_library;

 static inline
 void free_ft_library (void)
 {
   FT_Done_FreeType (ft_library);
 }

 static FT_Library
 get_ft_library (void)
 {
 retry:
   FT_Library library = (FT_Library) hb_atomic_ptr_get (&ft_library);

   if (unlikely (!library))
   {
     /* Not found; allocate one. */
     if (FT_Init_FreeType (&library))
       return NULL;

     if (!hb_atomic_ptr_cmpexch (&ft_library, NULL, library)) {
       FT_Done_FreeType (library);
       goto retry;
     }

 #ifdef HAVE_ATEXIT
     atexit (free_ft_library); /* First person registers atexit() callback. */
 #endif
   }

   return library;
 }

 static void
 _release_blob (FT_Face ft_face)
 {
   hb_blob_destroy ((hb_blob_t *) ft_face->generic.data);
 }

 void
 hb_ft_font_set_funcs (hb_font_t *font)
 {
   hb_blob_t *blob = hb_face_reference_blob (font->face);
   unsigned int blob_length;
   const char *blob_data = hb_blob_get_data (blob, &blob_length);
   if (unlikely (!blob_length))
     DEBUG_MSG (FT, font, "Font face has empty blob");

   FT_Face ft_face = NULL;
   FT_Error err = FT_New_Memory_Face (get_ft_library (),
 				     (const FT_Byte *) blob_data,
 				     blob_length,
 				     hb_face_get_index (font->face),
 				     &ft_face);

   if (unlikely (err)) {
     hb_blob_destroy (blob);
     DEBUG_MSG (FT, font, "Font face FT_New_Memory_Face() failed");
     return;
   }

   FT_Select_Charmap (ft_face, FT_ENCODING_UNICODE);

   assert (font->y_scale >= 0);
   FT_Set_Char_Size (ft_face,
 		    font->x_scale, font->y_scale,
 		    0, 0);
 #if 0
 		    font->x_ppem * 72 * 64 / font->x_scale,
 		    font->y_ppem * 72 * 64 / font->y_scale);
 #endif

   ft_face->generic.data = blob;
   ft_face->generic.finalizer = (FT_Generic_Finalizer) _release_blob;

   hb_font_set_funcs (font,
 		     _hb_ft_get_font_funcs (),
 		     ft_face,
 		     (hb_destroy_func_t) FT_Done_Face);
 }

 FT_Face
 hb_ft_font_get_face (hb_font_t *font)
 {
   if (font->destroy == (hb_destroy_func_t) FT_Done_Face ||
       font->destroy == (hb_destroy_func_t) _do_nothing)
     return (FT_Face) font->user_data;

   return NULL;
 }
	/*
	* Copyright © 2009 Red Hat, Inc.
	* Copyright © 2009 Keith Stribley
	*
	* This is part of HarfBuzz, a text shaping library.
	*
	* Permission is hereby granted, without written agreement and without
	* license or royalty fees, to use, copy, modify, and distribute this
	* software and its documentation for any purpose, provided that the
	* above copyright notice and the following two paragraphs appear in
	* all copies of this software.
	*
	* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
	* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
	* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
	* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
	* DAMAGE.
	*
	* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
	* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
	* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
	* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
	* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
	*
	* Red Hat Author(s): Behdad Esfahbod
	*/

	#include "hb-private.hh"

	#include "hb-ft.h"

	#include "hb-font-private.hh"

	#include FT_ADVANCES_H
	#include FT_TRUETYPE_TABLES_H



	#ifndef HB_DEBUG_FT
	#define HB_DEBUG_FT (HB_DEBUG+0)
	#endif


	/* TODO:
	*
	* In general, this file does a fine job of what it's supposed to do.
	* There are, however, things that need more work:
	*
	* - We don't handle any load_flags. That definitely has API implications. :(
	* I believe hb_ft_font_create() should take load_flags input.
	* In particular, FT_Get_Advance() without the NO_HINTING flag seems to be
	* buggy.
	*
	* - We don't handle / allow for emboldening / obliqueing.
	*
	* - In the future, we should add constructors to create fonts in font space?
	*
	* - FT_Load_Glyph() is exteremely costly. Do something about it?
	*/


	static hb_bool_t
	hb_ft_get_glyph (hb_font_t *font HB_UNUSED,
	void *font_data,
	hb_codepoint_t unicode,
	hb_codepoint_t variation_selector,
	hb_codepoint_t *glyph,
	void *user_data HB_UNUSED)

	{
	FT_Face ft_face = (FT_Face) font_data;

	#ifdef HAVE_FT_FACE_GETCHARVARIANTINDEX
	if (unlikely (variation_selector)) {
	*glyph = FT_Face_GetCharVariantIndex (ft_face, unicode, variation_selector);
	if (*glyph)
	return true;
	}
	#endif

	*glyph = FT_Get_Char_Index (ft_face, unicode);
	return *glyph != 0;
	}

	static hb_position_t
	hb_ft_get_glyph_h_advance (hb_font_t *font HB_UNUSED,
	void *font_data,
	hb_codepoint_t glyph,
	void *user_data HB_UNUSED)
	{
	FT_Face ft_face = (FT_Face) font_data;
	int load_flags = FT_LOAD_DEFAULT \| FT_LOAD_NO_HINTING;
	FT_Fixed v;

	if (unlikely (FT_Get_Advance (ft_face, glyph, load_flags, &v)))
	return 0;

	return v >> 10;
	}

	static hb_position_t
	hb_ft_get_glyph_v_advance (hb_font_t *font HB_UNUSED,
	void *font_data,
	hb_codepoint_t glyph,
	void *user_data HB_UNUSED)
	{
	FT_Face ft_face = (FT_Face) font_data;
	int load_flags = FT_LOAD_DEFAULT \| FT_LOAD_NO_HINTING \| FT_LOAD_VERTICAL_LAYOUT;
	FT_Fixed v;

	if (unlikely (FT_Get_Advance (ft_face, glyph, load_flags, &v)))
	return 0;

	/* Note: FreeType's vertical metrics grows downward while other FreeType coordinates
	* have a Y growing upward. Hence the extra negation. */
	return -v >> 10;
	}

	static hb_bool_t
	hb_ft_get_glyph_h_origin (hb_font_t *font HB_UNUSED,
	void *font_data HB_UNUSED,
	hb_codepoint_t glyph HB_UNUSED,
	hb_position_t *x HB_UNUSED,
	hb_position_t *y HB_UNUSED,
	void *user_data HB_UNUSED)
	{
	/* We always work in the horizontal coordinates. */
	return true;
	}

	static hb_bool_t
	hb_ft_get_glyph_v_origin (hb_font_t *font HB_UNUSED,
	void *font_data,
	hb_codepoint_t glyph,
	hb_position_t *x,
	hb_position_t *y,
	void *user_data HB_UNUSED)
	{
	FT_Face ft_face = (FT_Face) font_data;
	int load_flags = FT_LOAD_DEFAULT;

	if (unlikely (FT_Load_Glyph (ft_face, glyph, load_flags)))
	return false;

	/* Note: FreeType's vertical metrics grows downward while other FreeType coordinates
	* have a Y growing upward. Hence the extra negation. */
	*x = ft_face->glyph->metrics.horiBearingX - ft_face->glyph->metrics.vertBearingX;
	*y = ft_face->glyph->metrics.horiBearingY - (-ft_face->glyph->metrics.vertBearingY);

	return true;
	}

	static hb_position_t
	hb_ft_get_glyph_h_kerning (hb_font_t *font,
	void *font_data,
	hb_codepoint_t left_glyph,
	hb_codepoint_t right_glyph,
	void *user_data HB_UNUSED)
	{
	FT_Face ft_face = (FT_Face) font_data;
	FT_Vector kerningv;

	FT_Kerning_Mode mode = font->x_ppem ? FT_KERNING_DEFAULT : FT_KERNING_UNFITTED;
	if (FT_Get_Kerning (ft_face, left_glyph, right_glyph, mode, &kerningv))
	return 0;

	return kerningv.x;
	}

	static hb_position_t
	hb_ft_get_glyph_v_kerning (hb_font_t *font HB_UNUSED,
	void *font_data HB_UNUSED,
	hb_codepoint_t top_glyph HB_UNUSED,
	hb_codepoint_t bottom_glyph HB_UNUSED,
	void *user_data HB_UNUSED)
	{
	/* FreeType API doesn't support vertical kerning */
	return 0;
	}

	static hb_bool_t
	hb_ft_get_glyph_extents (hb_font_t *font HB_UNUSED,
	void *font_data,
	hb_codepoint_t glyph,
	hb_glyph_extents_t *extents,
	void *user_data HB_UNUSED)
	{
	FT_Face ft_face = (FT_Face) font_data;
	int load_flags = FT_LOAD_DEFAULT;

	if (unlikely (FT_Load_Glyph (ft_face, glyph, load_flags)))
	return false;

	extents->x_bearing = ft_face->glyph->metrics.horiBearingX;
	extents->y_bearing = ft_face->glyph->metrics.horiBearingY;
	extents->width = ft_face->glyph->metrics.width;
	extents->height = -ft_face->glyph->metrics.height;
	return true;
	}

	static hb_bool_t
	hb_ft_get_glyph_contour_point (hb_font_t *font HB_UNUSED,
	void *font_data,
	hb_codepoint_t glyph,
	unsigned int point_index,
	hb_position_t *x,
	hb_position_t *y,
	void *user_data HB_UNUSED)
	{
	FT_Face ft_face = (FT_Face) font_data;
	int load_flags = FT_LOAD_DEFAULT;

	if (unlikely (FT_Load_Glyph (ft_face, glyph, load_flags)))
	return false;

	if (unlikely (ft_face->glyph->format != FT_GLYPH_FORMAT_OUTLINE))
	return false;

	if (unlikely (point_index >= (unsigned int) ft_face->glyph->outline.n_points))
	return false;

	*x = ft_face->glyph->outline.points[point_index].x;
	*y = ft_face->glyph->outline.points[point_index].y;

	return true;
	}

	static hb_bool_t
	hb_ft_get_glyph_name (hb_font_t *font HB_UNUSED,
	void *font_data,
	hb_codepoint_t glyph,
	char *name, unsigned int size,
	void *user_data HB_UNUSED)
	{
	FT_Face ft_face = (FT_Face) font_data;

	hb_bool_t ret = !FT_Get_Glyph_Name (ft_face, glyph, name, size);
	if (ret && (size && !*name))
	ret = false;

	return ret;
	}

	static hb_bool_t
	hb_ft_get_glyph_from_name (hb_font_t *font HB_UNUSED,
	void *font_data,
	const char name, int len, / -1 means nul-terminated */
	hb_codepoint_t *glyph,
	void *user_data HB_UNUSED)
	{
	FT_Face ft_face = (FT_Face) font_data;

	if (len < 0)
	glyph = FT_Get_Name_Index (ft_face, (FT_String ) name);
	else {
	/* Make a nul-terminated version. */
	char buf[128];
	len = MIN (len, (int) sizeof (buf) - 1);
	strncpy (buf, name, len);
	buf[len] = '\0';
	*glyph = FT_Get_Name_Index (ft_face, buf);
	}

	return *glyph != 0;
	}


	static hb_font_funcs_t *
	_hb_ft_get_font_funcs (void)
	{
	static const hb_font_funcs_t ft_ffuncs = {
	HB_OBJECT_HEADER_STATIC,

	true, /* immutable */

	{
	#define HB_FONT_FUNC_IMPLEMENT(name) hb_ft_get_##name,
	HB_FONT_FUNCS_IMPLEMENT_CALLBACKS
	#undef HB_FONT_FUNC_IMPLEMENT
	}
	};

	return const_cast<hb_font_funcs_t *> (&ft_ffuncs);
	}


	static hb_blob_t *
	reference_table (hb_face_t face HB_UNUSED, hb_tag_t tag, void user_data)
	{
	FT_Face ft_face = (FT_Face) user_data;
	FT_Byte *buffer;
	FT_ULong length = 0;
	FT_Error error;

	/* Note: FreeType like HarfBuzz uses the NONE tag for fetching the entire blob */

	error = FT_Load_Sfnt_Table (ft_face, tag, 0, NULL, &length);
	if (error)
	return NULL;

	buffer = (FT_Byte *) malloc (length);
	if (buffer == NULL)
	return NULL;

	error = FT_Load_Sfnt_Table (ft_face, tag, 0, buffer, &length);
	if (error)
	return NULL;

	return hb_blob_create ((const char *) buffer, length,
	HB_MEMORY_MODE_WRITABLE,
	buffer, free);
	}


	hb_face_t *
	hb_ft_face_create (FT_Face ft_face,
	hb_destroy_func_t destroy)
	{
	hb_face_t *face;

	if (ft_face->stream->read == NULL) {
	hb_blob_t *blob;

	blob = hb_blob_create ((const char *) ft_face->stream->base,
	(unsigned int) ft_face->stream->size,
	/* TODO: We assume that it's mmap()'ed, but FreeType code
	* suggests that there are cases we reach here but font is
	* not mmapped. For example, when mmap() fails. No idea
	* how to deal with it better here. */
	HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITABLE,
	ft_face, destroy);
	face = hb_face_create (blob, ft_face->face_index);
	hb_blob_destroy (blob);
	} else {
	face = hb_face_create_for_tables (reference_table, ft_face, destroy);
	}

	hb_face_set_index (face, ft_face->face_index);
	hb_face_set_upem (face, ft_face->units_per_EM);

	return face;
	}

	static void
	hb_ft_face_finalize (FT_Face ft_face)
	{
	hb_face_destroy ((hb_face_t *) ft_face->generic.data);
	}

	hb_face_t *
	hb_ft_face_create_cached (FT_Face ft_face)
	{
	if (unlikely (!ft_face->generic.data \|\| ft_face->generic.finalizer != (FT_Generic_Finalizer) hb_ft_face_finalize))
	{
	if (ft_face->generic.finalizer)
	ft_face->generic.finalizer (ft_face);

	ft_face->generic.data = hb_ft_face_create (ft_face, NULL);
	ft_face->generic.finalizer = (FT_Generic_Finalizer) hb_ft_face_finalize;
	}

	return hb_face_reference ((hb_face_t *) ft_face->generic.data);
	}

	static void
	_do_nothing (void)
	{
	}


	hb_font_t *
	hb_ft_font_create (FT_Face ft_face,
	hb_destroy_func_t destroy)
	{
	hb_font_t *font;
	hb_face_t *face;

	face = hb_ft_face_create (ft_face, destroy);
	font = hb_font_create (face);
	hb_face_destroy (face);
	hb_font_set_funcs (font,
	_hb_ft_get_font_funcs (),
	ft_face, (hb_destroy_func_t) _do_nothing);
	hb_font_set_scale (font,
	((uint64_t) ft_face->size->metrics.x_scale * (uint64_t) ft_face->units_per_EM) >> 16,
	((uint64_t) ft_face->size->metrics.y_scale * (uint64_t) ft_face->units_per_EM) >> 16);
	hb_font_set_ppem (font,
	ft_face->size->metrics.x_ppem,
	ft_face->size->metrics.y_ppem);

	return font;
	}


	/* Thread-safe, lock-free, FT_Library */

	static FT_Library ft_library;

	static inline
	void free_ft_library (void)
	{
	FT_Done_FreeType (ft_library);
	}

	static FT_Library
	get_ft_library (void)
	{
	retry:
	FT_Library library = (FT_Library) hb_atomic_ptr_get (&ft_library);

	if (unlikely (!library))
	{
	/* Not found; allocate one. */
	if (FT_Init_FreeType (&library))
	return NULL;

	if (!hb_atomic_ptr_cmpexch (&ft_library, NULL, library)) {
	FT_Done_FreeType (library);
	goto retry;
	}

	#ifdef HAVE_ATEXIT
	atexit (free_ft_library); /* First person registers atexit() callback. */
	#endif
	}

	return library;
	}

	static void
	_release_blob (FT_Face ft_face)
	{
	hb_blob_destroy ((hb_blob_t *) ft_face->generic.data);
	}

	void
	hb_ft_font_set_funcs (hb_font_t *font)
	{
	hb_blob_t *blob = hb_face_reference_blob (font->face);
	unsigned int blob_length;
	const char *blob_data = hb_blob_get_data (blob, &blob_length);
	if (unlikely (!blob_length))
	DEBUG_MSG (FT, font, "Font face has empty blob");

	FT_Face ft_face = NULL;
	FT_Error err = FT_New_Memory_Face (get_ft_library (),
	(const FT_Byte *) blob_data,
	blob_length,
	hb_face_get_index (font->face),
	&ft_face);

	if (unlikely (err)) {
	hb_blob_destroy (blob);
	DEBUG_MSG (FT, font, "Font face FT_New_Memory_Face() failed");
	return;
	}

	FT_Select_Charmap (ft_face, FT_ENCODING_UNICODE);

	assert (font->y_scale >= 0);
	FT_Set_Char_Size (ft_face,
	font->x_scale, font->y_scale,
	0, 0);
	#if 0
	font->x_ppem * 72 * 64 / font->x_scale,
	font->y_ppem * 72 * 64 / font->y_scale);
	#endif

	ft_face->generic.data = blob;
	ft_face->generic.finalizer = (FT_Generic_Finalizer) _release_blob;

	hb_font_set_funcs (font,
	_hb_ft_get_font_funcs (),
	ft_face,
	(hb_destroy_func_t) FT_Done_Face);
	}

	FT_Face
	hb_ft_font_get_face (hb_font_t *font)
	{
	if (font->destroy == (hb_destroy_func_t) FT_Done_Face \|\|
	font->destroy == (hb_destroy_func_t) _do_nothing)
	return (FT_Face) font->user_data;

	return NULL;
	}