Issue 4880: Add ly:get-font-format to get the font format

Most of the OpenType/CFF Collection (OTC) fonts
have the extension `*.ttc'.
TrueType Collection (TTC) fonts
also have the same extension `*.ttc'.

However, it is necessary that different embed method,
between OTC and TTC.
So we need to distinguish them.

This commit adds ly:get-font-format
that can get font format for distinguishing them.

diff --git a/lily/open-type-font-scheme.cc b/lily/open-type-font-scheme.cc
index 79370fa698dffa4b3eeea8d997c53163ee7ffe4f..365ccb1a630f83756980b2d9fc9f2a40eba96008 100644 (file)
--- a/lily/open-type-font-scheme.cc
+++ b/lily/open-type-font-scheme.cc
@@ -17,8 +17,19 @@
   along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include "international.hh"
 #include "modified-font-metric.hh"
 #include "open-type-font.hh"
+#include "freetype.hh"
+
+#ifdef FT_FONT_FORMATS_H
+/* FreeType 2.6+ */
+#include FT_FONT_FORMATS_H
+#else
+/* FreeType 2.5.5 and earlier */
+#include FT_XFREE86_H
+#define FT_Get_Font_Format FT_Get_X11_Font_Format
+#endif
 
 LY_DEFINE (ly_font_sub_fonts, "ly:font-sub-fonts", 1, 0, 0,
            (SCM font),
@@ -115,3 +126,49 @@ LY_DEFINE (ly_otf_glyph_list, "ly:otf-glyph-list", 1, 0, 0,
 
   return otf->glyph_list ();
 }
+
+LY_DEFINE (ly_get_font_format, "ly:get-font-format",
+           1, 1, 0, (SCM font_file_name, SCM idx),
+           "Get the font format for @var{font_file_name},"
+           " returning it as a symbol.  The optional"
+           " @var{idx} argument is useful for TrueType Collections (TTC) and"
+           " OpenType/CFF collections (OTC) only;"
+           " it specifies the font index within the TTC/OTC."
+           " The default value of @var{idx} is@tie{}0.")
+{
+  LY_ASSERT_TYPE (scm_is_string, font_file_name, 1);
+
+  int i = 0;
+  if (!SCM_UNBNDP (idx))
+    {
+      LY_ASSERT_TYPE (scm_is_integer, idx, 2);
+      i = scm_to_int (idx);
+      if (i < 0)
+        {
+          warning (_ ("font index must be non-negative, using index 0"));
+          i = 0;
+        }
+    }
+
+  string file_name = ly_scm2string (font_file_name);
+
+  FT_Face face;
+  /* check whether font index is valid */
+  if (i > 0)
+    {
+      face = open_ft_face (file_name, -1);
+      if (i >= face->num_faces)
+        {
+          warning (_f ("font index %d too large for font `%s', using index 0",
+                       i, file_name.c_str ()));
+          i = 0;
+        }
+      FT_Done_Face (face);
+    }
+
+  face = open_ft_face (file_name, i);
+  SCM asscm = scm_from_ascii_symbol (FT_Get_Font_Format (face));
+  FT_Done_Face (face);
+
+  return asscm;
+}