Handle GSUB Lookup type 8, and ReverseChainContextualSubst table. (bug

2006-01-30  Behdad Esfahbod  <behdad@gnome.org>

        * pango/opentype/ftxgsub.c: Handle GSUB Lookup type 8,
        and ReverseChainContextualSubst table.  (bug #149696,
        patch from Aamir Wali)

src/ftxgsub.h

@@ -32,14 +32,14 @@ extern "C" {
 
 /* Lookup types for glyph substitution */
 
-#define GSUB_LOOKUP_SINGLE     1
-#define GSUB_LOOKUP_MULTIPLE   2
-#define GSUB_LOOKUP_ALTERNATE  3
-#define GSUB_LOOKUP_LIGATURE   4
-#define GSUB_LOOKUP_CONTEXT    5
-#define GSUB_LOOKUP_CHAIN      6
-#define GSUB_LOOKUP_EXTENSION  7
-
+#define GSUB_LOOKUP_SINGLE        1
+#define GSUB_LOOKUP_MULTIPLE      2
+#define GSUB_LOOKUP_ALTERNATE     3
+#define GSUB_LOOKUP_LIGATURE      4
+#define GSUB_LOOKUP_CONTEXT       5
+#define GSUB_LOOKUP_CHAIN         6
+#define GSUB_LOOKUP_EXTENSION     7
+#define GSUB_LOOKUP_REVERSE_CHAIN 8
 
 /* Use this if a feature applies to all glyphs */
 
@@ -467,14 +467,33 @@ extern "C" {
   typedef struct TTO_ChainContextSubst_  TTO_ChainContextSubst;
 
 
+  /* LookupType 8 */
+  struct TTO_ReverseChainContextSubst_
+  {
+    FT_UShort      SubstFormat;         /* always 1 */
+    TTO_Coverage   Coverage;	        /* coverage table for input glyphs */
+    FT_UShort      BacktrackGlyphCount; /* number of backtrack glyphs      */
+    TTO_Coverage*  BacktrackCoverage;   /* array of backtrack Coverage
+                                           tables                          */
+    FT_UShort      LookaheadGlyphCount; /* number of lookahead glyphs      */
+    TTO_Coverage*  LookaheadCoverage;   /* array of lookahead Coverage
+                                           tables                          */
+    FT_UShort      GlyphCount;          /* number of Glyph IDs             */
+    FT_UShort*     Substitute;          /* array of substitute Glyph ID    */
+  };
+
+  typedef struct TTO_ReverseChainContextSubst_  TTO_ReverseChainContextSubst;
+
+
   union  TTO_GSUB_SubTable_
   {
-    TTO_SingleSubst        single;
-    TTO_MultipleSubst      multiple;
-    TTO_AlternateSubst     alternate;
-    TTO_LigatureSubst      ligature;
-    TTO_ContextSubst       context;
-    TTO_ChainContextSubst  chain;
+    TTO_SingleSubst              single;
+    TTO_MultipleSubst            multiple;
+    TTO_AlternateSubst           alternate;
+    TTO_LigatureSubst            ligature;
+    TTO_ContextSubst             context;
+    TTO_ChainContextSubst        chain;
+    TTO_ReverseChainContextSubst reverse;
   };
 
   typedef union TTO_GSUB_SubTable_  TTO_GSUB_SubTable;

src/ftxopen.c

@@ -469,6 +469,9 @@
 
       case GSUB_LOOKUP_CHAIN:
         return Load_ChainContextSubst( &st->st.gsub.chain, stream );
+	
+      case GSUB_LOOKUP_REVERSE_CHAIN:
+        return Load_ReverseChainContextSubst( &st->st.gsub.reverse, stream );
 
       default:
         return TTO_Err_Invalid_GSUB_SubTable_Format;
@@ -536,6 +539,10 @@
         Free_ContextSubst( &st->st.gsub.context, memory );
         break;
 
+      case GSUB_LOOKUP_REVERSE_CHAIN:
+        Free_ReverseChainContextSubst( &st->st.gsub.reverse, memory );
+        break;
+
       case GSUB_LOOKUP_CHAIN:
         Free_ChainContextSubst( &st->st.gsub.chain, memory );
         break;

src/ftxopenf.h

@@ -74,6 +74,8 @@ extern "C" {
                                FT_Stream          input );
   FT_Error  Load_ChainContextSubst( TTO_ChainContextSubst*  ccs,
                                     FT_Stream               input );
+  FT_Error  Load_ReverseChainContextSubst( TTO_ReverseChainContextSubst*  rccs,
+					   FT_Stream                      input );
 
   void  Free_SingleSubst( TTO_SingleSubst*  ss,
 			  FT_Memory         memory );
@@ -87,7 +89,8 @@ extern "C" {
 			   FT_Memory         memory );
   void  Free_ChainContextSubst( TTO_ChainContextSubst*  ccs,
 				FT_Memory               memory );
-
+  void  Free_ReverseChainContextSubst( TTO_ReverseChainContextSubst*  rccs,
+				       FT_Memory                      memory );
 
   /* functions from ftxgpos.c */