[colr] Add hb_ot_color_layer_t

We never return parallel arrays from functions.  That's inconvenient
and hard to bind.

src/hb-ot-color.cc

@@ -244,25 +244,23 @@ hb_ot_color_has_layers (hb_face_t *face)
 }
 
 /**
- * hb_ot_color_get_color_layers:
+ * hb_ot_color_glyph_get_layers:
  * @face: a font face.
  * @glyph:
  * @start_offset:
  * @count:  (inout) (optional):
- * @glyphs: (array length=count) (out) (optional):
- * @color_indices: (array length=count) (out) (optional):
+ * @layers: (array length=count) (out) (optional):
  *
  * Returns:
  *
  * Since: REPLACEME
  */
 unsigned int
-hb_ot_color_get_color_layers (hb_face_t        *face,
-			      hb_codepoint_t    glyph,
-			      unsigned int      start_offset,
-			      unsigned int     *count         /* IN/OUT.  May be NULL. */,
-			      hb_codepoint_t   *glyphs        /* OUT.     May be NULL. */,
-			      unsigned int     *color_indices /* OUT.     May be NULL. */)
+hb_ot_color_glyph_get_layers (hb_face_t           *face,
+			      hb_codepoint_t       glyph,
+			      unsigned int         start_offset,
+			      unsigned int        *count, /* IN/OUT.  May be NULL. */
+			      hb_ot_color_layer_t *layers /* OUT.     May be NULL. */)
 {
   const OT::COLR& colr = _get_colr (face);
   unsigned int num_results = 0;
@@ -275,7 +273,7 @@ hb_ot_color_get_color_layers (hb_face_t        *face,
       for (unsigned int i = 0; i < layer_count; i++)
       {
 	if (colr.get_layer_record (start_layer_index + start_offset + i,
-				   &glyphs[num_results], &color_indices[num_results]))
+				   &layers[num_results].glyph, &layers[num_results].color_index))
 	  ++num_results;
       }
     }

src/hb-ot-color.h

@@ -91,13 +91,23 @@ hb_ot_color_get_palette_flags (hb_face_t *face, unsigned int palette);
 HB_EXTERN hb_bool_t
 hb_ot_color_has_layers (hb_face_t *face);
 
+/**
+ * hb_ot_color_layer_t:
+ *
+ * Since: REPLACEME
+ **/
+typedef struct hb_ot_color_layer_t
+{
+  hb_codepoint_t glyph;
+  unsigned int   color_index;
+} hb_ot_color_layer_t;
+
 HB_EXTERN unsigned int
-hb_ot_color_get_color_layers (hb_face_t       *face,
-			      hb_codepoint_t   glyph,
-			      unsigned int     start_offset,
-			      unsigned int    *count,        /* IN/OUT.  May be NULL. */
-			      hb_codepoint_t  *glyphs,       /* OUT.     May be NULL. */
-			      unsigned int    *color_indices /* OUT.     May be NULL. */);
+hb_ot_color_glyph_get_layers (hb_face_t           *face,
+			      hb_codepoint_t       glyph,
+			      unsigned int         start_offset,
+			      unsigned int        *count, /* IN/OUT.  May be NULL. */
+			      hb_ot_color_layer_t *layers /* OUT.     May be NULL. */);
 
 
 HB_END_DECLS

test/api/test-ot-color.c

@@ -317,36 +317,33 @@ test_hb_ot_color_get_palette_entry_name_id (void)
 
 
 static void
-test_hb_ot_color_get_color_layers (void)
+test_hb_ot_color_glyph_get_layers (void)
 {
-  hb_codepoint_t layer_gids[1];
-  unsigned int color_indices[1];
+  hb_ot_color_layer_t layers[1];
   unsigned int count = 1;
 
-  g_assert_cmpuint (hb_ot_color_get_color_layers (cpal_v1, 0, 0,
-						  NULL, NULL, NULL), ==, 0);
-  g_assert_cmpuint (hb_ot_color_get_color_layers (cpal_v1, 1, 0,
-						  NULL, NULL, NULL), ==, 0);
-  g_assert_cmpuint (hb_ot_color_get_color_layers (cpal_v1, 2, 0,
-						  NULL, NULL, NULL), ==, 2);
+  g_assert_cmpuint (hb_ot_color_glyph_get_layers (cpal_v1, 0, 0,
+						  NULL, NULL), ==, 0);
+  g_assert_cmpuint (hb_ot_color_glyph_get_layers (cpal_v1, 1, 0,
+						  NULL, NULL), ==, 0);
+  g_assert_cmpuint (hb_ot_color_glyph_get_layers (cpal_v1, 2, 0,
+						  NULL, NULL), ==, 2);
 
   unsigned int num_layers;
-  num_layers = hb_ot_color_get_color_layers (cpal_v1, 2, 0, &count, layer_gids,
-					     color_indices);
+  num_layers = hb_ot_color_glyph_get_layers (cpal_v1, 2, 0, &count, layers);
 
   g_assert_cmpuint (num_layers, ==, 2);
   g_assert_cmpuint (count, ==, 1);
-  g_assert_cmpuint (layer_gids[0], ==, 3);
-  g_assert_cmpuint (color_indices[0], ==, 1);
+  g_assert_cmpuint (layers[0].glyph, ==, 3);
+  g_assert_cmpuint (layers[0].color_index, ==, 1);
 
   count = 1;
-  hb_ot_color_get_color_layers (cpal_v1, 2, 1, &count, layer_gids,
-				color_indices);
+  hb_ot_color_glyph_get_layers (cpal_v1, 2, 1, &count, layers);
 
   g_assert_cmpuint (num_layers, ==, 2);
   g_assert_cmpuint (count, ==, 1);
-  g_assert_cmpuint (layer_gids[0], ==, 4);
-  g_assert_cmpuint (color_indices[0], ==, 0);
+  g_assert_cmpuint (layers[0].glyph, ==, 4);
+  g_assert_cmpuint (layers[0].color_index, ==, 0);
 }
 
 static void
@@ -394,7 +391,7 @@ main (int argc, char **argv)
   hb_test_add (test_hb_ot_color_get_palette_colors_v0);
   hb_test_add (test_hb_ot_color_get_palette_colors_v1);
   hb_test_add (test_hb_ot_color_get_palette_entry_name_id);
-  hb_test_add (test_hb_ot_color_get_color_layers);
+  hb_test_add (test_hb_ot_color_glyph_get_layers);
   hb_test_add (test_hb_ot_color_has_data);
   status = hb_test_run();
   hb_face_destroy (cpal_v0);