lavu/parseutils: add av_get_known_color_name()

libavutil/parseutils.c

@@ -420,6 +420,20 @@ int av_parse_color(uint8_t *rgba_color, const char *color_string, int slen,
     return 0;
 }
 
+const char *av_get_known_color_name(int color_idx, const uint8_t **rgbp)
+{
+    const ColorEntry *color;
+
+    if ((unsigned)color_idx >= FF_ARRAY_ELEMS(color_table))
+        return NULL;
+
+    color = &color_table[color_idx];
+    if (rgbp)
+        *rgbp = color->rgb_color;
+
+    return color->name;
+}
+
 /* get a positive number between n_min and n_max, for a maximum length
    of len_max. Return -1 if error. */
 static int date_get_num(const char **pp,