Make default font-funcs chain-up to the parent

src/hb-font.cc

@@ -49,7 +49,16 @@ hb_font_get_contour_point_nil (hb_font_t *font HB_UNUSED,
 			       hb_position_t *x HB_UNUSED,
 			       hb_position_t *y HB_UNUSED,
 			       const void *user_data HB_UNUSED)
-{ return false; }
+{
+  if (font->parent)
+    return hb_font_get_contour_point (font->parent,
+				      point_index, glyph,
+				      x, y);
+
+  *x = *y = 0;
+
+  return false;
+}
 
 static void
 hb_font_get_glyph_advance_nil (hb_font_t *font HB_UNUSED,
@@ -58,7 +67,14 @@ hb_font_get_glyph_advance_nil (hb_font_t *font HB_UNUSED,
 			       hb_position_t *x_advance HB_UNUSED,
 			       hb_position_t *y_advance HB_UNUSED,
 			       const void *user_data HB_UNUSED)
-{ }
+{
+  if (font->parent) {
+    hb_font_get_glyph_advance (font->parent, glyph, x_advance, y_advance);
+    return;
+  }
+
+  *x_advance = *y_advance = 0;
+}
 
 static void
 hb_font_get_glyph_extents_nil (hb_font_t *font HB_UNUSED,
@@ -66,7 +82,15 @@ hb_font_get_glyph_extents_nil (hb_font_t *font HB_UNUSED,
 			       hb_codepoint_t glyph HB_UNUSED,
 			       hb_glyph_extents_t *extents HB_UNUSED,
 			       const void *user_data HB_UNUSED)
-{ }
+{
+  if (font->parent) {
+    hb_font_get_glyph_extents (font->parent, glyph, extents);
+    return;
+  }
+
+  extents->x_bearing = extents->y_bearing = 0;
+  extents->width = extents->height = 0;
+}
 
 static hb_codepoint_t
 hb_font_get_glyph_nil (hb_font_t *font HB_UNUSED,
@@ -74,7 +98,12 @@ hb_font_get_glyph_nil (hb_font_t *font HB_UNUSED,
 		       hb_codepoint_t unicode HB_UNUSED,
 		       hb_codepoint_t variation_selector HB_UNUSED,
 		       const void *user_data HB_UNUSED)
-{ return 0; }
+{
+  if (font->parent)
+    return hb_font_get_glyph (font->parent, unicode, variation_selector);
+
+  return 0;
+}
 
 static hb_position_t
 hb_font_get_kerning_nil (hb_font_t *font HB_UNUSED,
@@ -82,7 +111,12 @@ hb_font_get_kerning_nil (hb_font_t *font HB_UNUSED,
 			 hb_codepoint_t first_glyph HB_UNUSED,
 			 hb_codepoint_t second_glyph HB_UNUSED,
 			 const void *user_data HB_UNUSED)
-{ return 0; }
+{
+  if (font->parent)
+    return hb_font_get_kerning (font->parent, first_glyph, second_glyph);
+
+  return 0;
+}
 
 
 static hb_font_funcs_t _hb_font_funcs_nil = {

src/hb-font.h

@@ -121,9 +121,11 @@ typedef struct _hb_glyph_extents_t
     hb_position_t height;
 } hb_glyph_extents_t;
 
-typedef hb_codepoint_t (*hb_font_get_glyph_func_t) (hb_font_t *font, const void *font_data,
-						    hb_codepoint_t unicode, hb_codepoint_t variation_selector,
-						    const void *user_data);
+
+typedef hb_bool_t (*hb_font_get_contour_point_func_t) (hb_font_t *font, const void *font_data,
+						       unsigned int point_index, hb_codepoint_t glyph,
+						       hb_position_t *x, hb_position_t *y,
+						       const void *user_data);
 typedef void (*hb_font_get_glyph_advance_func_t) (hb_font_t *font, const void *font_data,
 						  hb_codepoint_t glyph,
 						  hb_position_t *x_advance, hb_position_t *y_advance,
@@ -132,19 +134,18 @@ typedef void (*hb_font_get_glyph_extents_func_t) (hb_font_t *font, const void *f
 						  hb_codepoint_t glyph,
 						  hb_glyph_extents_t *extents,
 						  const void *user_data);
-typedef hb_bool_t (*hb_font_get_contour_point_func_t) (hb_font_t *font, const void *font_data,
-						       unsigned int point_index, hb_codepoint_t glyph,
-						       hb_position_t *x, hb_position_t *y,
-						       const void *user_data);
+typedef hb_codepoint_t (*hb_font_get_glyph_func_t) (hb_font_t *font, const void *font_data,
+						    hb_codepoint_t unicode, hb_codepoint_t variation_selector,
+						    const void *user_data);
 typedef hb_position_t (*hb_font_get_kerning_func_t) (hb_font_t *font, const void *font_data,
 						     hb_codepoint_t first_glyph, hb_codepoint_t second_glyph,
 						     const void *user_data);
 
 
 void
-hb_font_funcs_set_glyph_func (hb_font_funcs_t *ffuncs,
-			      hb_font_get_glyph_func_t glyph_func,
-			      void *user_data, hb_destroy_func_t destroy);
+hb_font_funcs_set_contour_point_func (hb_font_funcs_t *ffuncs,
+				      hb_font_get_contour_point_func_t contour_point_func,
+				      void *user_data, hb_destroy_func_t destroy);
 
 void
 hb_font_funcs_set_glyph_advance_func (hb_font_funcs_t *ffuncs,
@@ -157,9 +158,9 @@ hb_font_funcs_set_glyph_extents_func (hb_font_funcs_t *ffuncs,
 				      void *user_data, hb_destroy_func_t destroy);
 
 void
-hb_font_funcs_set_contour_point_func (hb_font_funcs_t *ffuncs,
-				      hb_font_get_contour_point_func_t contour_point_func,
-				      void *user_data, hb_destroy_func_t destroy);
+hb_font_funcs_set_glyph_func (hb_font_funcs_t *ffuncs,
+			      hb_font_get_glyph_func_t glyph_func,
+			      void *user_data, hb_destroy_func_t destroy);
 
 void
 hb_font_funcs_set_kerning_func (hb_font_funcs_t *ffuncs,
@@ -167,9 +168,10 @@ hb_font_funcs_set_kerning_func (hb_font_funcs_t *ffuncs,
 				void *user_data, hb_destroy_func_t destroy);
 
 
-hb_codepoint_t
-hb_font_get_glyph (hb_font_t *font,
-		   hb_codepoint_t unicode, hb_codepoint_t variation_selector);
+hb_bool_t
+hb_font_get_contour_point (hb_font_t *font,
+			   unsigned int point_index, hb_codepoint_t glyph,
+			   hb_position_t *x, hb_position_t *y);
 
 void
 hb_font_get_glyph_advance (hb_font_t *font,
@@ -181,10 +183,9 @@ hb_font_get_glyph_extents (hb_font_t *font,
 			   hb_codepoint_t glyph,
 			   hb_glyph_extents_t *extents);
 
-hb_bool_t
-hb_font_get_contour_point (hb_font_t *font,
-			   unsigned int point_index, hb_codepoint_t glyph,
-			   hb_position_t *x, hb_position_t *y);
+hb_codepoint_t
+hb_font_get_glyph (hb_font_t *font,
+		   hb_codepoint_t unicode, hb_codepoint_t variation_selector);
 
 hb_position_t
 hb_font_get_kerning (hb_font_t *font,