[ft] API: Add hb_font_[sg]et_load_flags() API

This changes the default load_flags of fonts created using
hb_ft_font_create() from NO_HINTING to DEFAULT.  Hope that doesn't
break too much client code.

Code calling hb_ft_font_set_funcs() is unaffected.

src/hb-ft.cc

 /*
  * Copyright © 2009  Red Hat, Inc.
  * Copyright © 2009  Keith Stribley
+ * Copyright © 2015  Google, Inc.
  *
  *  This is part of HarfBuzz, a text shaping library.
  *
@@ -23,6 +24,7 @@
  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  *
  * Red Hat Author(s): Behdad Esfahbod
+ * Google Author(s): Behdad Esfahbod
  */
 
 #include "hb-private.hh"
@@ -46,17 +48,15 @@
  * 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.
+ *   - I remember seeing FT_Get_Advance() without the NO_HINTING flag to be buggy.
+ *     Have not investigated.
  *
- *     FreeType works in 26.6 mode.  Clients can decide to use that mode, and everything
+ *   - FreeType works in 26.6 mode.  Clients can decide to use that mode, and everything
  *     would work fine.  However, we also abuse this API for performing in font-space,
  *     but don't pass the correct flags to FreeType.  We just abuse the no-hinting mode
  *     for that, such that no rounding etc happens.  As such, we don't set ppem, and
- *     pass NO_HINTING around.  This seems to work best, until we go ahead and add a full
- *     load_flags API.
+ *     pass NO_HINTING as load_flags.  Would be much better to use NO_SCALE, and scale
+ *     ourselves, like we do in uniscribe, etc.
  *
  *   - We don't handle / allow for emboldening / obliqueing.
  *
@@ -66,6 +66,76 @@
  */
 
 
+struct hb_ft_font_t
+{
+  FT_Face ft_face;
+  int load_flags;
+  bool unref; /* Whether to destroy ft_face when done. */
+};
+
+static hb_ft_font_t *
+_hb_ft_font_create (FT_Face ft_face, bool unref)
+{
+  hb_ft_font_t *ft_font = (hb_ft_font_t *) calloc (1, sizeof (hb_ft_font_t));
+
+  if (unlikely (!ft_font))
+    return NULL;
+
+  ft_font->ft_face = ft_face;
+  ft_font->unref = unref;
+
+  ft_font->load_flags = FT_LOAD_DEFAULT;
+
+  return ft_font;
+}
+
+static void
+_hb_ft_font_destroy (hb_ft_font_t *ft_font)
+{
+  if (ft_font->unref)
+    FT_Done_Face (ft_font->ft_face);
+
+  free (ft_font);
+}
+
+void
+hb_ft_font_set_load_flags (hb_font_t *font, int load_flags)
+{
+  if (font->immutable)
+    return;
+
+  if (font->destroy != (hb_destroy_func_t) _hb_ft_font_destroy)
+    return;
+
+  hb_ft_font_t *ft_font = (hb_ft_font_t *) font->user_data;
+
+  ft_font->load_flags = load_flags;
+}
+
+int
+hb_ft_font_get_load_flags (hb_font_t *font)
+{
+  if (font->destroy != (hb_destroy_func_t) _hb_ft_font_destroy)
+    return 0;
+
+  const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font->user_data;
+
+  return ft_font->load_flags;
+}
+
+FT_Face
+hb_ft_font_get_face (hb_font_t *font)
+{
+  if (font->destroy != (hb_destroy_func_t) _hb_ft_font_destroy)
+    return NULL;
+
+  const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font->user_data;
+
+  return ft_font->ft_face;
+}
+
+
+
 static hb_bool_t
 hb_ft_get_glyph (hb_font_t *font HB_UNUSED,
 		 void *font_data,
@@ -75,13 +145,13 @@ hb_ft_get_glyph (hb_font_t *font HB_UNUSED,
 		 void *user_data HB_UNUSED)
 
 {
+  const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
   unsigned int g;
-  FT_Face ft_face = (FT_Face) font_data;
 
   if (likely (!variation_selector))
-    g = FT_Get_Char_Index (ft_face, unicode);
+    g = FT_Get_Char_Index (ft_font->ft_face, unicode);
   else
-    g = FT_Face_GetCharVariantIndex (ft_face, unicode, variation_selector);
+    g = FT_Face_GetCharVariantIndex (ft_font->ft_face, unicode, variation_selector);
 
   if (unlikely (!g))
     return false;
@@ -96,11 +166,10 @@ hb_ft_get_glyph_h_advance (hb_font_t *font HB_UNUSED,
 			   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;
+  const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
   FT_Fixed v;
 
-  if (unlikely (FT_Get_Advance (ft_face, glyph, load_flags, &v)))
+  if (unlikely (FT_Get_Advance (ft_font->ft_face, glyph, ft_font->load_flags, &v)))
     return 0;
 
   if (font->x_scale < 0)
@@ -115,11 +184,10 @@ hb_ft_get_glyph_v_advance (hb_font_t *font HB_UNUSED,
 			   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;
+  const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
   FT_Fixed v;
 
-  if (unlikely (FT_Get_Advance (ft_face, glyph, load_flags, &v)))
+  if (unlikely (FT_Get_Advance (ft_font->ft_face, glyph, ft_font->load_flags | FT_LOAD_VERTICAL_LAYOUT, &v)))
     return 0;
 
   if (font->y_scale < 0)
@@ -150,10 +218,10 @@ hb_ft_get_glyph_v_origin (hb_font_t *font HB_UNUSED,
 			  hb_position_t *y,
 			  void *user_data HB_UNUSED)
 {
-  FT_Face ft_face = (FT_Face) font_data;
-  int load_flags = FT_LOAD_DEFAULT | FT_LOAD_NO_HINTING;
+  const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
+  FT_Face ft_face = ft_font->ft_face;
 
-  if (unlikely (FT_Load_Glyph (ft_face, glyph, load_flags)))
+  if (unlikely (FT_Load_Glyph (ft_face, glyph, ft_font->load_flags)))
     return false;
 
   /* Note: FreeType's vertical metrics grows downward while other FreeType coordinates
@@ -176,11 +244,11 @@ hb_ft_get_glyph_h_kerning (hb_font_t *font,
 			   hb_codepoint_t right_glyph,
 			   void *user_data HB_UNUSED)
 {
-  FT_Face ft_face = (FT_Face) font_data;
+  const hb_ft_font_t *ft_font = (const hb_ft_font_t *) 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))
+  if (FT_Get_Kerning (ft_font->ft_face, left_glyph, right_glyph, mode, &kerningv))
     return 0;
 
   return kerningv.x;
@@ -204,10 +272,10 @@ hb_ft_get_glyph_extents (hb_font_t *font HB_UNUSED,
 			 hb_glyph_extents_t *extents,
 			 void *user_data HB_UNUSED)
 {
-  FT_Face ft_face = (FT_Face) font_data;
-  int load_flags = FT_LOAD_DEFAULT | FT_LOAD_NO_HINTING;
+  const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
+  FT_Face ft_face = ft_font->ft_face;
 
-  if (unlikely (FT_Load_Glyph (ft_face, glyph, load_flags)))
+  if (unlikely (FT_Load_Glyph (ft_face, glyph, ft_font->load_flags)))
     return false;
 
   extents->x_bearing = ft_face->glyph->metrics.horiBearingX;
@@ -226,10 +294,10 @@ hb_ft_get_glyph_contour_point (hb_font_t *font HB_UNUSED,
 			       hb_position_t *y,
 			       void *user_data HB_UNUSED)
 {
-  FT_Face ft_face = (FT_Face) font_data;
-  int load_flags = FT_LOAD_DEFAULT;
+  const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
+  FT_Face ft_face = ft_font->ft_face;
 
-  if (unlikely (FT_Load_Glyph (ft_face, glyph, load_flags)))
+  if (unlikely (FT_Load_Glyph (ft_face, glyph, ft_font->load_flags)))
       return false;
 
   if (unlikely (ft_face->glyph->format != FT_GLYPH_FORMAT_OUTLINE))
@@ -251,9 +319,9 @@ hb_ft_get_glyph_name (hb_font_t *font HB_UNUSED,
 		      char *name, unsigned int size,
 		      void *user_data HB_UNUSED)
 {
-  FT_Face ft_face = (FT_Face) font_data;
+  const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
 
-  hb_bool_t ret = !FT_Get_Glyph_Name (ft_face, glyph, name, size);
+  hb_bool_t ret = !FT_Get_Glyph_Name (ft_font->ft_face, glyph, name, size);
   if (ret && (size && !*name))
     ret = false;
 
@@ -267,7 +335,8 @@ hb_ft_get_glyph_from_name (hb_font_t *font HB_UNUSED,
 			   hb_codepoint_t *glyph,
 			   void *user_data HB_UNUSED)
 {
-  FT_Face ft_face = (FT_Face) font_data;
+  const hb_ft_font_t *ft_font = (const hb_ft_font_t *) font_data;
+  FT_Face ft_face = ft_font->ft_face;
 
   if (len < 0)
     *glyph = FT_Get_Name_Index (ft_face, (FT_String *) name);
@@ -293,8 +362,8 @@ hb_ft_get_glyph_from_name (hb_font_t *font HB_UNUSED,
 }
 
 
-static hb_font_funcs_t *
-_hb_ft_get_font_funcs (void)
+static void
+_hb_ft_font_set_funcs (hb_font_t *font, FT_Face ft_face, bool unref)
 {
   static const hb_font_funcs_t ft_ffuncs = {
     HB_OBJECT_HEADER_STATIC,
@@ -308,7 +377,10 @@ _hb_ft_get_font_funcs (void)
     }
   };
 
-  return const_cast<hb_font_funcs_t *> (&ft_ffuncs);
+  hb_font_set_funcs (font,
+		     const_cast<hb_font_funcs_t *> (&ft_ffuncs),
+		     _hb_ft_font_create (ft_face, unref),
+		     (hb_destroy_func_t) _hb_ft_font_destroy);
 }
 
 
@@ -420,11 +492,6 @@ hb_ft_face_create_cached (FT_Face ft_face)
   return hb_face_reference ((hb_face_t *) ft_face->generic.data);
 }
 
-static void
-_do_nothing (void)
-{
-}
-
 
 /**
  * hb_ft_font_create:
@@ -446,9 +513,7 @@ hb_ft_font_create (FT_Face           ft_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_ft_font_set_funcs (font, ft_face, false);
   hb_font_set_scale (font,
 		     (int) (((uint64_t) ft_face->size->metrics.x_scale * (uint64_t) ft_face->units_per_EM + (1<<15)) >> 16),
 		     (int) (((uint64_t) ft_face->size->metrics.y_scale * (uint64_t) ft_face->units_per_EM + (1<<15)) >> 16));
@@ -562,18 +627,6 @@ hb_ft_font_set_funcs (hb_font_t *font)
   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;
+  _hb_ft_font_set_funcs (font, ft_face, true);
+  hb_ft_font_set_load_flags (font, FT_LOAD_DEFAULT | FT_LOAD_NO_HINTING);
 }

src/hb-ft.h

 /*
  * Copyright © 2009  Red Hat, Inc.
+ * Copyright © 2015  Google, Inc.
  *
  *  This is part of HarfBuzz, a text shaping library.
  *
@@ -22,6 +23,7 @@
  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  *
  * Red Hat Author(s): Behdad Esfahbod
+ * Google Author(s): Behdad Esfahbod
  */
 
 #ifndef HB_FT_H
@@ -105,14 +107,19 @@ hb_ft_font_create (FT_Face           ft_face,
 hb_font_t *
 hb_ft_font_create_referenced (FT_Face ft_face);
 
+FT_Face
+hb_ft_font_get_face (hb_font_t *font);
+
+void
+hb_ft_font_set_load_flags (hb_font_t *font, int load_flags);
+
+int
+hb_ft_font_get_load_flags (hb_font_t *font);
 
 /* Makes an hb_font_t use FreeType internally to implement font functions. */
 void
 hb_ft_font_set_funcs (hb_font_t *font);
 
-FT_Face
-hb_ft_font_get_face (hb_font_t *font);
-
 
 HB_END_DECLS