date: 2002/09/26 08:40:00;  author: werner;  state: Exp;  lines: +17 -7

Updating GSUB and GPOS support to the forthcoming OpenType 1.4
specification: Backtracking is *not* done in logical order.

Index: ftxgpos.c
===================================================================
RCS file: /cvs/freetype/freetype/lib/extend/ftxgpos.c,v
retrieving revision 1.16
retrieving revision 1.17
diff -u -p -r1.16 -r1.17
--- ftxgpos.c	2002/01/19 00:23:23	1.16
+++ ftxgpos.c	2002/09/26 08:40:00	1.17
@@ -4737,7 +4737,8 @@
     /* backtrack and lookahead data can be optional */
 
     cur_offset = FILE_Pos();
-    if ( backtrack_offset != base_offset ) {
+    if ( backtrack_offset != base_offset )
+    {
       if ( FILE_Seek( backtrack_offset ) ||
            ( error = Load_ClassDefinition( &ccpf2->BacktrackClassDef, count,
                                            input ) ) != TT_Err_Ok )
@@ -4747,7 +4748,8 @@
          ( error = Load_ClassDefinition( &ccpf2->InputClassDef, count,
                                          input ) ) != TT_Err_Ok )
       goto Fail4;
-    if ( lookahead_offset != base_offset ) {
+    if ( lookahead_offset != base_offset )
+    {
       if ( FILE_Seek( lookahead_offset ) ||
            ( error = Load_ClassDefinition( &ccpf2->LookaheadClassDef, count,
                                            input ) ) != TT_Err_Ok )
@@ -5164,7 +5166,7 @@
         curr_pos = 0;
         s_in     = &in->string[curr_pos];
 
-        for ( i = bgc, j = in->pos - 1; i > 0; i--, j-- )
+        for ( i = 0, j = in->pos - 1; i < bgc; i++, j-- )
         {
           while ( CHECK_Property( gdef, s_in[j], flags, &property ) )
           {
@@ -5177,11 +5179,21 @@
               break;
           }
 
-          if ( s_in[j] != curr_cpr.Backtrack[i - 1] )
+          /* In OpenType 1.3, it is undefined whether the offsets of
+             backtrack glyphs is in logical order or not.  Version 1.4
+             will clarify this:
+
+               Logical order -      a  b  c  d  e  f  g  h  i  j
+                                                i
+               Input offsets -                  0  1
+               Backtrack offsets -  3  2  1  0
+               Lookahead offsets -                    0  1  2  3           */
+
+          if ( s_in[j] != curr_cpr.Backtrack[i] )
             break;
         }
 
-        if ( i != 0 )
+        if ( i != bgc )
           continue;
       }
 
@@ -5364,7 +5376,7 @@
             known_backtrack_classes = i;
           }
 
-          if ( bc[bgc - 1 - i] != backtrack_classes[i] )
+          if ( bc[i] != backtrack_classes[i] )
             break;
         }
 
@@ -5512,7 +5524,7 @@
       s_in     = &in->string[curr_pos];
       bc       = ccpf3->BacktrackCoverage;
 
-      for ( i = bgc, j = in->pos - 1; i > 0; i--, j-- )
+      for ( i = 0, j = in->pos - 1; i < bgc; i++, j-- )
       {
         while ( CHECK_Property( gdef, s_in[j], flags, &property ) )
         {
@@ -5525,7 +5537,7 @@
             return TTO_Err_Not_Covered;
         }
 
-        error = Coverage_Index( &bc[i - 1], s_in[j], &index );
+        error = Coverage_Index( &bc[i], s_in[j], &index );
         if ( error )
           return error;
       }
@@ -5555,8 +5567,8 @@
         return error;
     }
 
-    /* we are starting for lookahead glyphs right after the last context
-       glyph                                                             */
+    /* we are starting to check for lookahead glyphs right after the
+       last context glyph                                            */
 
     curr_pos = j;
     s_in     = &in->string[curr_pos];
Index: ftxgsub.c
===================================================================
RCS file: /cvs/freetype/freetype/lib/extend/ftxgsub.c,v
retrieving revision 1.46
retrieving revision 1.47
diff -u -p -r1.46 -r1.47
--- ftxgsub.c	2002/01/19 00:23:23	1.46
+++ ftxgsub.c	2002/09/26 08:40:00	1.47
@@ -3387,13 +3387,13 @@
 
       if ( bgc )
       {
-        /* Since we don't know in advance the number of glyphs to inspect,
+        /* since we don't know in advance the number of glyphs to inspect,
            we search backwards for matches in the backtrack glyph array    */
 
         curr_pos = 0;
         s_in     = &in->string[curr_pos];
 
-        for ( i = bgc, j = in->pos - 1; i > 0; i--, j-- )
+        for ( i = 0, j = in->pos - 1; i < bgc; i++, j-- )
         {
           while ( CHECK_Property( gdef, s_in[j], flags, &property ) )
           {
@@ -3406,11 +3406,21 @@
               break;
           }
 
-          if ( s_in[j] != curr_csr.Backtrack[i - 1] )
+          /* In OpenType 1.3, it is undefined whether the offsets of
+             backtrack glyphs is in logical order or not.  Version 1.4
+             will clarify this:
+
+               Logical order -      a  b  c  d  e  f  g  h  i  j
+                                                i
+               Input offsets -                  0  1
+               Backtrack offsets -  3  2  1  0
+               Lookahead offsets -                    0  1  2  3           */
+
+          if ( s_in[j] != curr_csr.Backtrack[i] )
             break;
         }
 
-        if ( i != 0 )
+        if ( i != bgc )
           continue;
       }
 
@@ -3592,7 +3602,7 @@
             known_backtrack_classes = i;
           }
 
-          if ( bc[bgc - 1 - i] != backtrack_classes[i] )
+          if ( bc[i] != backtrack_classes[i] )
             break;
         }
 
@@ -3739,7 +3749,7 @@
       s_in     = &in->string[curr_pos];
       bc       = ccsf3->BacktrackCoverage;
 
-      for ( i = bgc, j = in->pos - 1; i > 0; i--, j-- )
+      for ( i = 0, j = in->pos - 1; i < bgc; i++, j-- )
       {
         while ( CHECK_Property( gdef, s_in[j], flags, &property ) )
         {
@@ -3752,7 +3762,7 @@
             return TTO_Err_Not_Covered;
         }
 
-        error = Coverage_Index( &bc[i - 1], s_in[j], &index );
+        error = Coverage_Index( &bc[i], s_in[j], &index );
         if ( error )
           return error;
       }