Export TT_New_GDEF_Table to create an empty GDEF table.

Fri Jan 10 18:56:36 2003  Owen Taylor  <otaylor@redhat.com>

        * pango/opentype/ftxgdef.c: Export TT_New_GDEF_Table
        to create an empty GDEF table.

        * pango/opentype/pango-ot-info.c: If the font doesn't
        have a class definition table, synthesize one using
        the charmap and the unicode properties of characters
        in the charmap. (Needed to make things work with various
        old Arabic fonts, such as the KACST fonts)

src/ftxgdef.c

@@ -132,6 +132,37 @@
   }
 #endif
 
+  EXPORT_FUNC
+  FT_Error  TT_New_GDEF_Table( FT_Face          face,
+			       TTO_GDEFHeader** retptr )
+  {
+    FT_Error         error;
+    FT_Memory        memory = face->memory;
+
+    TTO_GDEFHeader*  gdef;
+
+    if ( !retptr )
+      return TT_Err_Invalid_Argument;
+
+    if ( ALLOC( gdef, sizeof( *gdef ) ) )
+      return error;
+
+    gdef->memory = face->memory;
+
+    gdef->GlyphClassDef.loaded = FALSE;
+    gdef->AttachList.loaded = FALSE;
+    gdef->LigCaretList.loaded = FALSE;
+    gdef->MarkAttachClassDef_offset = 0;
+    gdef->MarkAttachClassDef.loaded = FALSE;
+
+    gdef->LastGlyph = 0;
+    gdef->NewGlyphClasses = NULL;
+
+    *retptr = gdef;
+
+    return TT_Err_Ok;
+  }
+
   EXPORT_FUNC
   FT_Error  TT_Load_GDEF_Table( FT_Face          face,
                                 TTO_GDEFHeader** retptr )
@@ -151,11 +182,9 @@
     if (( error = tt_face->goto_table( tt_face, TTAG_GDEF, stream, 0 ) ))
       return error;
 
-    if ( ALLOC( gdef, sizeof( *gdef ) ) )
+    if (( error = TT_New_GDEF_Table ( face, &gdef ) ))
       return error;
 
-    gdef->memory = face->memory;
-
     base_offset = FILE_Pos();
 
     /* skip version */
@@ -183,8 +212,6 @@
         goto Fail0;
       (void)FILE_Seek( cur_offset );
     }
-    else
-      gdef->GlyphClassDef.loaded = FALSE;
 
     if ( ACCESS_Frame( 2L ) )
       goto Fail1;
@@ -204,8 +231,6 @@
         goto Fail1;
       (void)FILE_Seek( cur_offset );
     }
-    else
-      gdef->AttachList.loaded = FALSE;
 
     if ( ACCESS_Frame( 2L ) )
       goto Fail2;
@@ -225,8 +250,6 @@
         goto Fail2;
       (void)FILE_Seek( cur_offset );
     }
-    else
-      gdef->LigCaretList.loaded = FALSE;
 
     /* OpenType 1.2 has introduced the `MarkAttachClassDef' field.  We
        first have to scan the LookupFlag values to find out whether we
@@ -244,11 +267,6 @@
     else
       gdef->MarkAttachClassDef_offset = 0;
 
-    gdef->MarkAttachClassDef.loaded = FALSE;
-
-    gdef->LastGlyph       = 0;
-    gdef->NewGlyphClasses = NULL;
-
     *retptr = gdef;
 
     return TT_Err_Ok;

src/ftxgdef.h

@@ -191,6 +191,10 @@ extern "C" {
   /*  EXPORT_DEF
       FT_Error  TT_Init_GDEF_Extension( TT_Engine  engine ); */
 
+  EXPORT_FUNC
+  FT_Error  TT_New_GDEF_Table( FT_Face          face,
+			       TTO_GDEFHeader** retptr );
+	
   EXPORT_DEF
   FT_Error  TT_Load_GDEF_Table( FT_Face          face,
                                 TTO_GDEFHeader** gdef );

src/pango-ot-info.c

@@ -140,6 +140,108 @@ is_truetype (FT_Face face)
   return strcmp (FT_MODULE_CLASS (face->driver)->module_name, "truetype") == 0;
 }
 
+typedef struct _GlyphInfo GlyphInfo;
+
+struct _GlyphInfo {
+  FT_UShort glyph;
+  FT_UShort class;
+};
+
+static int
+compare_glyph_info (gconstpointer a,
+		    gconstpointer b)
+{
+  const GlyphInfo *info_a = a;
+  const GlyphInfo *info_b = b;
+
+  return (info_a->glyph < info_b->glyph) ? -1 :
+    (info_a->glyph == info_b->glyph) ? 0 : 1;
+}
+
+/* Make a guess at the appropriate class for a glyph given 
+ * a character code that maps to the glyph
+ */
+static FT_UShort
+get_glyph_class (gunichar charcode)
+{
+  switch (g_unichar_type (charcode))
+    {
+    case G_UNICODE_COMBINING_MARK:
+    case G_UNICODE_ENCLOSING_MARK:
+    case G_UNICODE_NON_SPACING_MARK:
+      return 3;		/* Mark glyph (non-spacing combining glyph) */
+    default:
+      return 1;		/* Base glyph (single character, spacing glyph) */
+    }
+}
+
+/* Synthesize a GDEF table using the font's charmap and the
+ * unicode property database. We'll fill in class definitions
+ * for glyphs not in the charmap as we walk through the tables.
+ */
+static void
+synthesize_class_def (PangoOTInfo *info)
+{
+  GArray *glyph_infos;
+  FT_UShort *glyph_indices;
+  FT_UShort *classes;
+  FT_ULong charcode;
+  FT_UInt glyph;
+  int i, j;
+  
+  if (info->face->charmap->encoding != ft_encoding_unicode)
+    return;
+
+  glyph_infos = g_array_new (FALSE, FALSE, sizeof (GlyphInfo));
+
+  /* Collect all the glyphs in the charmap, and guess
+   * the appropriate classes for them
+   */
+  charcode = FT_Get_First_Char (info->face, &glyph);
+  while (glyph != 0)
+    {
+      GlyphInfo glyph_info;
+
+      if (glyph > 65535)
+	continue;
+
+      glyph_info.glyph = glyph;
+      glyph_info.class = get_glyph_class (charcode);
+
+      g_array_append_val (glyph_infos, glyph_info);
+      
+      charcode = FT_Get_Next_Char (info->face, charcode, &glyph);
+    }
+
+  /* Sort and remove duplicates
+   */
+  g_array_sort (glyph_infos, compare_glyph_info);
+
+  glyph_indices = g_new (FT_UShort, glyph_infos->len);
+  classes = g_new (FT_UShort, glyph_infos->len);
+
+  for (i = 0, j = 0; i < glyph_infos->len; i++)
+    {
+      GlyphInfo *info = &g_array_index (glyph_infos, GlyphInfo, i);
+
+      if (j == 0 || info->glyph != glyph_indices[j - 1])
+	{
+	  glyph_indices[j] = info->glyph;
+	  classes[j] = info->class;
+	  
+	  j++;
+	}
+    }
+
+  g_array_free (glyph_infos, TRUE);
+
+  TT_GDEF_Build_ClassDefinition (info->gdef, info->face->num_glyphs, j,
+				 glyph_indices, classes);
+
+  g_free (glyph_indices);
+  g_free (classes);
+}
+
 TTO_GDEF 
 pango_ot_info_get_gdef (PangoOTInfo *info)
 {
@@ -157,6 +259,12 @@ pango_ot_info_get_gdef (PangoOTInfo *info)
 	  
 	  if (error && error != TT_Err_Table_Missing)
 	    g_warning ("Error loading GDEF table %d", error);
+
+	  if (!info->gdef)
+	    error = TT_New_GDEF_Table (info->face, &info->gdef);
+
+	  if (info->gdef && !info->gdef->GlyphClassDef.loaded)
+	    synthesize_class_def (info);
 	}
     }