[meta] hb_ot_metadata_get_entries, tags iteration API

src/hb-ot-meta-table.hh

@@ -42,6 +42,8 @@ struct DataMap
 {
   int cmp (hb_tag_t a) const { return tag.cmp (a); }
 
+  hb_tag_t get_tag () const { return tag; }
+
   hb_blob_t *reference_entry (hb_blob_t *meta_blob) const
   { return hb_blob_create_sub_blob (meta_blob, dataZ, dataLength); }
 
@@ -76,6 +78,21 @@ struct meta
     hb_blob_t *reference_entry (hb_tag_t tag) const
     { return table->dataMaps.lsearch (tag, Null (DataMap)).reference_entry (table.get_blob ()); }
 
+    unsigned int get_entries (unsigned int      start_offset,
+			      unsigned int     *count,
+			      hb_ot_metadata_t *entries) const
+    {
+      unsigned int entries_count = table->dataMaps.len;
+      if (count && *count)
+      {
+	unsigned int len = hb_min (entries_count - start_offset, *count);
+	for (unsigned int i = 0; i < len; i++)
+	  entries[i] = (hb_ot_metadata_t) table->dataMaps[i + start_offset].get_tag ();
+	*count = len;
+      }
+      return table->dataMaps.len;
+    }
+
     private:
     hb_blob_ptr_t<meta> table;
   };

src/hb-ot-metadata.cc

@@ -38,9 +38,29 @@
  **/
 
 /**
- * hb_ot_meta_reference_entry:
+ * hb_ot_metadata_reference_entry:
+ * @face: a face object
+ * @start_offset: iteration's start offset
+ * @entries_count:(inout) (allow-none): buffer size as input, filled size as output
+ * @entries: (out caller-allocates) (array length=entries_count): entries tags buffer
+ *
+ * Return value: Number of all available feature types.
+ *
+ * Since: REPLACEME
+ **/
+unsigned int
+hb_ot_metadata_get_entries (hb_face_t        *face,
+			    unsigned int      start_offset,
+			    unsigned int     *entries_count, /* IN/OUT.  May be NULL. */
+			    hb_ot_metadata_t *entries        /* OUT.     May be NULL. */)
+{
+  return face->table.meta->get_entries (start_offset, entries_count, entries);
+}
+
+/**
+ * hb_ot_metadata_reference_entry:
  * @face: a #hb_face_t object.
- * @meta_tag: tag of metadata you like to have.
+ * @metadata_tag: tag of metadata you like to have.
  *
  * It fetches metadata entry of a given tag from a font.
  *
@@ -49,9 +69,9 @@
  * Since: REPLACEME
  **/
 hb_blob_t *
-hb_ot_metadata_reference_entry (hb_face_t *face, hb_ot_metadata_t meta_tag)
+hb_ot_metadata_reference_entry (hb_face_t *face, hb_ot_metadata_t metadata_tag)
 {
-  return face->table.meta->reference_entry (meta_tag);
+  return face->table.meta->reference_entry (metadata_tag);
 }
 
 #endif

src/hb-ot-metadata.h

@@ -49,8 +49,14 @@ typedef enum {
   HB_OT_METADATA_SUPPORTED_LANGUAGES	= HB_TAG ('s','l','n','g')
 } hb_ot_metadata_t;
 
+HB_EXTERN unsigned int
+hb_ot_metadata_get_entries (hb_face_t        *face,
+			    unsigned int      start_offset,
+			    unsigned int     *entries_count, /* IN/OUT.  May be NULL. */
+			    hb_ot_metadata_t *entries        /* OUT.     May be NULL. */);
+
 HB_EXTERN hb_blob_t *
-hb_ot_metadata_reference_entry (hb_face_t *face, hb_ot_metadata_t tag);
+hb_ot_metadata_reference_entry (hb_face_t *face, hb_ot_metadata_t metadata_tag);
 
 HB_END_DECLS
 

test/api/test-ot-metadata.c

@@ -28,6 +28,31 @@
 
 /* Unit tests for hb-ot-metadata.h */
 
+static void
+test_ot_metadata_get_entries (void)
+{
+  hb_face_t *face = hb_test_open_font_file ("fonts/meta.ttf");
+  hb_ot_metadata_t entries[2];
+
+  unsigned int entries_count = 2;
+  g_assert_cmpint (hb_ot_metadata_get_entries (face, 0, &entries_count, entries), ==, 5);
+  g_assert_cmpint (entries_count, ==, 2);
+  g_assert_cmpint (entries[0], ==, HB_TAG ('a','p','p','l'));
+  g_assert_cmpint (entries[1], ==, HB_TAG ('b','i','l','d'));
+
+  entries_count = 1;
+  g_assert_cmpint (hb_ot_metadata_get_entries (face, 2, &entries_count, entries), ==, 5);
+  g_assert_cmpint (entries_count, ==, 1);
+  g_assert_cmpint (entries[0], ==, HB_TAG ('d','l','n','g'));
+
+  entries_count = 2;
+  g_assert_cmpint (hb_ot_metadata_get_entries (face, 4, &entries_count, entries), ==, 5);
+  g_assert_cmpint (entries_count, ==, 1);
+  g_assert_cmpint (entries[0], ==, HB_TAG ('s','l','n','g'));
+
+  hb_face_destroy (face);
+}
+
 static void
 test_ot_metadata_reference_entry (void)
 {
@@ -53,6 +78,7 @@ int
 main (int argc, char **argv)
 {
   hb_test_init (&argc, &argv);
+  hb_test_add (test_ot_metadata_get_entries);
   hb_test_add (test_ot_metadata_reference_entry);
   return hb_test_run ();
 }