Separate nil font-funcs from parent-peeking font-funcs

API change: all fonts created with hb_font_create() now inherit from
(ie have parent) hb_font_get_empty().

src/hb-font.cc

@@ -45,130 +45,176 @@
  */
 
 static hb_bool_t
-hb_font_get_glyph_nil (hb_font_t *font,
+hb_font_get_glyph_nil (hb_font_t *font HB_UNUSED,
 		       void *font_data HB_UNUSED,
 		       hb_codepoint_t unicode,
 		       hb_codepoint_t variation_selector,
 		       hb_codepoint_t *glyph,
 		       void *user_data HB_UNUSED)
 {
-  if (font->parent)
-    return font->parent->get_glyph (unicode, variation_selector, glyph);
-
   *glyph = 0;
   return false;
 }
+static hb_bool_t
+hb_font_get_glyph_parent (hb_font_t *font,
+			  void *font_data HB_UNUSED,
+			  hb_codepoint_t unicode,
+			  hb_codepoint_t variation_selector,
+			  hb_codepoint_t *glyph,
+			  void *user_data HB_UNUSED)
+{
+  return font->parent->get_glyph (unicode, variation_selector, glyph);
+}
 
 static hb_position_t
-hb_font_get_glyph_h_advance_nil (hb_font_t *font,
+hb_font_get_glyph_h_advance_nil (hb_font_t *font HB_UNUSED,
 				 void *font_data HB_UNUSED,
 				 hb_codepoint_t glyph,
 				 void *user_data HB_UNUSED)
 {
-  if (font->parent)
-    return font->parent_scale_x_distance (font->parent->get_glyph_h_advance (glyph));
-
   return font->x_scale;
 }
+static hb_position_t
+hb_font_get_glyph_h_advance_parent (hb_font_t *font,
+				    void *font_data HB_UNUSED,
+				    hb_codepoint_t glyph,
+				    void *user_data HB_UNUSED)
+{
+  return font->parent_scale_x_distance (font->parent->get_glyph_h_advance (glyph));
+}
 
 static hb_position_t
-hb_font_get_glyph_v_advance_nil (hb_font_t *font,
+hb_font_get_glyph_v_advance_nil (hb_font_t *font HB_UNUSED,
 				 void *font_data HB_UNUSED,
 				 hb_codepoint_t glyph,
 				 void *user_data HB_UNUSED)
 {
-  if (font->parent)
-    return font->parent_scale_y_distance (font->parent->get_glyph_v_advance (glyph));
-
   return font->y_scale;
 }
-
+static hb_position_t
-static hb_bool_t
+hb_font_get_glyph_v_advance_parent (hb_font_t *font,
-hb_font_get_glyph_h_origin_nil (hb_font_t *font,
+				    void *font_data HB_UNUSED,
-				void *font_data HB_UNUSED,
+				    hb_codepoint_t glyph,
-				hb_codepoint_t glyph,
+				    void *user_data HB_UNUSED)
-				hb_position_t *x,
-				hb_position_t *y,
-				void *user_data HB_UNUSED)
 {
-  if (font->parent) {
+  return font->parent_scale_y_distance (font->parent->get_glyph_v_advance (glyph));
-    hb_bool_t ret = font->parent->get_glyph_h_origin (glyph, x, y);
-    if (ret)
-      font->parent_scale_position (x, y);
-    return ret;
-  }
-
-  *x = *y = 0;
-  return false;
 }
 
 static hb_bool_t
-hb_font_get_glyph_v_origin_nil (hb_font_t *font,
+hb_font_get_glyph_h_origin_nil (hb_font_t *font HB_UNUSED,
 				void *font_data HB_UNUSED,
 				hb_codepoint_t glyph,
 				hb_position_t *x,
 				hb_position_t *y,
 				void *user_data HB_UNUSED)
 {
-  if (font->parent) {
-    hb_bool_t ret = font->parent->get_glyph_v_origin (glyph, x, y);
-    if (ret)
-      font->parent_scale_position (x, y);
-    return ret;
-  }
-
   *x = *y = 0;
   return false;
 }
+static hb_bool_t
+hb_font_get_glyph_h_origin_parent (hb_font_t *font,
+				   void *font_data HB_UNUSED,
+				   hb_codepoint_t glyph,
+				   hb_position_t *x,
+				   hb_position_t *y,
+				   void *user_data HB_UNUSED)
+{
+  hb_bool_t ret = font->parent->get_glyph_h_origin (glyph, x, y);
+  if (ret)
+    font->parent_scale_position (x, y);
+  return ret;
+}
+
+static hb_bool_t
+hb_font_get_glyph_v_origin_nil (hb_font_t *font HB_UNUSED,
+				void *font_data HB_UNUSED,
+				hb_codepoint_t glyph,
+				hb_position_t *x,
+				hb_position_t *y,
+				void *user_data HB_UNUSED)
+{
+  *x = *y = 0;
+  return false;
+}
+static hb_bool_t
+hb_font_get_glyph_v_origin_parent (hb_font_t *font,
+				   void *font_data HB_UNUSED,
+				   hb_codepoint_t glyph,
+				   hb_position_t *x,
+				   hb_position_t *y,
+				   void *user_data HB_UNUSED)
+{
+  hb_bool_t ret = font->parent->get_glyph_v_origin (glyph, x, y);
+  if (ret)
+    font->parent_scale_position (x, y);
+  return ret;
+}
 
 static hb_position_t
-hb_font_get_glyph_h_kerning_nil (hb_font_t *font,
+hb_font_get_glyph_h_kerning_nil (hb_font_t *font HB_UNUSED,
 				 void *font_data HB_UNUSED,
 				 hb_codepoint_t left_glyph,
 				 hb_codepoint_t right_glyph,
 				 void *user_data HB_UNUSED)
 {
-  if (font->parent)
-    return font->parent_scale_x_distance (font->parent->get_glyph_h_kerning (left_glyph, right_glyph));
-
   return 0;
 }
+static hb_position_t
+hb_font_get_glyph_h_kerning_parent (hb_font_t *font,
+				    void *font_data HB_UNUSED,
+				    hb_codepoint_t left_glyph,
+				    hb_codepoint_t right_glyph,
+				    void *user_data HB_UNUSED)
+{
+  return font->parent_scale_x_distance (font->parent->get_glyph_h_kerning (left_glyph, right_glyph));
+}
 
 static hb_position_t
-hb_font_get_glyph_v_kerning_nil (hb_font_t *font,
+hb_font_get_glyph_v_kerning_nil (hb_font_t *font HB_UNUSED,
 				 void *font_data HB_UNUSED,
 				 hb_codepoint_t top_glyph,
 				 hb_codepoint_t bottom_glyph,
 				 void *user_data HB_UNUSED)
 {
-  if (font->parent)
-    return font->parent_scale_y_distance (font->parent->get_glyph_v_kerning (top_glyph, bottom_glyph));
-
   return 0;
 }
+static hb_position_t
+hb_font_get_glyph_v_kerning_parent (hb_font_t *font,
+				    void *font_data HB_UNUSED,
+				    hb_codepoint_t top_glyph,
+				    hb_codepoint_t bottom_glyph,
+				    void *user_data HB_UNUSED)
+{
+  return font->parent_scale_y_distance (font->parent->get_glyph_v_kerning (top_glyph, bottom_glyph));
+}
 
 static hb_bool_t
-hb_font_get_glyph_extents_nil (hb_font_t *font,
+hb_font_get_glyph_extents_nil (hb_font_t *font HB_UNUSED,
 			       void *font_data HB_UNUSED,
 			       hb_codepoint_t glyph,
 			       hb_glyph_extents_t *extents,
 			       void *user_data HB_UNUSED)
 {
-  if (font->parent) {
-    hb_bool_t ret = font->parent->get_glyph_extents (glyph, extents);
-    if (ret) {
-      font->parent_scale_position (&extents->x_bearing, &extents->y_bearing);
-      font->parent_scale_distance (&extents->width, &extents->height);
-    }
-    return ret;
-  }
-
   memset (extents, 0, sizeof (*extents));
   return false;
 }
+static hb_bool_t
+hb_font_get_glyph_extents_parent (hb_font_t *font,
+				  void *font_data HB_UNUSED,
+				  hb_codepoint_t glyph,
+				  hb_glyph_extents_t *extents,
+				  void *user_data HB_UNUSED)
+{
+  hb_bool_t ret = font->parent->get_glyph_extents (glyph, extents);
+  if (ret) {
+    font->parent_scale_position (&extents->x_bearing, &extents->y_bearing);
+    font->parent_scale_distance (&extents->width, &extents->height);
+  }
+  return ret;
+}
 
 static hb_bool_t
-hb_font_get_glyph_contour_point_nil (hb_font_t *font,
+hb_font_get_glyph_contour_point_nil (hb_font_t *font HB_UNUSED,
 				     void *font_data HB_UNUSED,
 				     hb_codepoint_t glyph,
 				     unsigned int point_index,
@@ -176,44 +222,63 @@ hb_font_get_glyph_contour_point_nil (hb_font_t *font,
 				     hb_position_t *y,
 				     void *user_data HB_UNUSED)
 {
-  if (font->parent) {
-    hb_bool_t ret = font->parent->get_glyph_contour_point (glyph, point_index, x, y);
-    if (ret)
-      font->parent_scale_position (x, y);
-    return ret;
-  }
-
   *x = *y = 0;
   return false;
 }
+static hb_bool_t
+hb_font_get_glyph_contour_point_parent (hb_font_t *font,
+					void *font_data HB_UNUSED,
+					hb_codepoint_t glyph,
+					unsigned int point_index,
+					hb_position_t *x,
+					hb_position_t *y,
+					void *user_data HB_UNUSED)
+{
+  hb_bool_t ret = font->parent->get_glyph_contour_point (glyph, point_index, x, y);
+  if (ret)
+    font->parent_scale_position (x, y);
+  return ret;
+}
 
 static hb_bool_t
-hb_font_get_glyph_name_nil (hb_font_t *font,
+hb_font_get_glyph_name_nil (hb_font_t *font HB_UNUSED,
 			    void *font_data HB_UNUSED,
 			    hb_codepoint_t glyph,
 			    char *name, unsigned int size,
 			    void *user_data HB_UNUSED)
 {
-  if (font->parent)
-    return font->parent->get_glyph_name (glyph, name, size);
-
   if (size) *name = '\0';
   return false;
 }
+static hb_bool_t
+hb_font_get_glyph_name_parent (hb_font_t *font,
+			       void *font_data HB_UNUSED,
+			       hb_codepoint_t glyph,
+			       char *name, unsigned int size,
+			       void *user_data HB_UNUSED)
+{
+  return font->parent->get_glyph_name (glyph, name, size);
+}
 
 static hb_bool_t
-hb_font_get_glyph_from_name_nil (hb_font_t *font,
+hb_font_get_glyph_from_name_nil (hb_font_t *font HB_UNUSED,
 				 void *font_data HB_UNUSED,
 				 const char *name, int len, /* -1 means nul-terminated */
 				 hb_codepoint_t *glyph,
 				 void *user_data HB_UNUSED)
 {
-  if (font->parent)
-    return font->parent->get_glyph_from_name (name, len, glyph);
-
   *glyph = 0;
   return false;
 }
+static hb_bool_t
+hb_font_get_glyph_from_name_parent (hb_font_t *font,
+				    void *font_data HB_UNUSED,
+				    const char *name, int len, /* -1 means nul-terminated */
+				    hb_codepoint_t *glyph,
+				    void *user_data HB_UNUSED)
+{
+  return font->parent->get_glyph_from_name (name, len, glyph);
+}
 
 
 static const hb_font_funcs_t _hb_font_funcs_nil = {
@@ -227,6 +292,17 @@ static const hb_font_funcs_t _hb_font_funcs_nil = {
 #undef HB_FONT_FUNC_IMPLEMENT
   }
 };
+static const hb_font_funcs_t _hb_font_funcs_parent = {
+  HB_OBJECT_HEADER_STATIC,
+
+  true, /* immutable */
+
+  {
+#define HB_FONT_FUNC_IMPLEMENT(name) hb_font_get_##name##_parent,
+    HB_FONT_FUNCS_IMPLEMENT_CALLBACKS
+#undef HB_FONT_FUNC_IMPLEMENT
+  }
+};
 
 
 /**
@@ -246,7 +322,7 @@ hb_font_funcs_create (void)
   if (!(ffuncs = hb_object_create<hb_font_funcs_t> ()))
     return hb_font_funcs_get_empty ();
 
-  ffuncs->get = _hb_font_funcs_nil.get;
+  ffuncs->get = _hb_font_funcs_parent.get;
 
   return ffuncs;
 }
@@ -263,7 +339,7 @@ hb_font_funcs_create (void)
 hb_font_funcs_t *
 hb_font_funcs_get_empty (void)
 {
-  return const_cast<hb_font_funcs_t *> (&_hb_font_funcs_nil);
+  return const_cast<hb_font_funcs_t *> (&_hb_font_funcs_parent);
 }
 
 /**
@@ -402,7 +478,7 @@ hb_font_funcs_set_##name##_func (hb_font_funcs_t             *ffuncs,    \
     ffuncs->user_data.name = user_data;                                  \
     ffuncs->destroy.name = destroy;                                      \
   } else {                                                               \
-    ffuncs->get.name = hb_font_get_##name##_nil;                         \
+    ffuncs->get.name = hb_font_get_##name##_parent;                      \
     ffuncs->user_data.name = NULL;                                       \
     ffuncs->destroy.name = NULL;                                         \
   }                                                                      \
@@ -858,6 +934,7 @@ hb_font_create (hb_face_t *face)
     return hb_font_get_empty ();
 
   hb_face_make_immutable (face);
+  font->parent = hb_font_get_empty ();
   font->face = hb_face_reference (face);
   font->klass = hb_font_funcs_get_empty ();
 
@@ -917,8 +994,8 @@ hb_font_get_empty (void)
     NULL, /* parent */
     const_cast<hb_face_t *> (&_hb_face_nil),
 
-    0, /* x_scale */
+    1000, /* x_scale */
-    0, /* y_scale */
+    1000, /* y_scale */
 
     0, /* x_ppem */
     0, /* y_ppem */

test/api/test-font.c

@@ -386,7 +386,7 @@ test_font_properties (void)
 
 
   g_assert (hb_font_get_face (font) == face);
-  g_assert (hb_font_get_parent (font) == NULL);
+  g_assert (hb_font_get_parent (font) == hb_font_get_empty ());
   subfont = hb_font_create_sub_font (font);
   g_assert (hb_font_get_parent (subfont) == font);
   hb_font_set_parent(subfont, NULL);