Generalize the concept of `tricky' fonts by introducing

FT_FACE_FLAG_TRICKY to indicate that the font format's hinting
engine is necessary for correct rendering.

At the same time, slightly modify the behaviour of tricky fonts:
FT_LOAD_NO_HINTING is now ignored.  To really force raw loading
of tricky fonts (without hinting), both FT_LOAD_NO_HINTING and
FT_LOAD_NO_AUTOHINT must be used.

Finally, tricky TrueType fonts always use the bytecode interpreter
even if the patented code is used.

* include/freetype/freetype.h (FT_FACE_FLAG_TRICKY, FT_IS_TRICKY):
New macros.

* src/truetype/ttdriver.c (Load_Glyph): Handle new load flags
semantics as described above.

* src/truetype/ttobjs.c (tt_check_trickyness): New function, using
code of ...
(tt_face_init): This function, now simplified and updated to new
semantics.

* src/base/ftobjs.c (FT_Load_Glyph): Don't use autohinter for tricky
fonts.

* docs/CHANGES: Document it.

4 files changed, 78 insertions, 59 deletions

diff --git a/src/base/ftobjs.c b/src/base/ftobjs.c
index cb5ed42f3..fb750fb6c 100644
--- a/src/base/ftobjs.c
+++ b/src/base/ftobjs.c
@@ -41,6 +41,7 @@
 
 #define GRID_FIT_METRICS
 
+
   FT_BASE_DEF( FT_Pointer )
   ft_service_list_lookup( FT_ServiceDesc  service_descriptors,
                           const char*     service_id )
@@ -552,7 +553,7 @@
     FT_Driver     driver;
     FT_GlyphSlot  slot;
     FT_Library    library;
-    FT_Bool       autohint = 0;
+    FT_Bool       autohint = FALSE;
     FT_Module     hinter;
 
 
@@ -596,22 +597,22 @@
      *
      * - Otherwise, auto-hint for LIGHT hinting mode.
      *
-     * - Exception: The font requires the unpatented
-     *   bytecode interpreter to load properly.
+     * - Exception: The font is `tricky' and requires
+     *   the native hinter to load properly.
      */
 
-    autohint = 0;
-    if ( hinter                                    &&
-         ( load_flags & FT_LOAD_NO_HINTING  ) == 0 &&
-         ( load_flags & FT_LOAD_NO_AUTOHINT ) == 0 &&
-         FT_DRIVER_IS_SCALABLE( driver )           &&
-         FT_DRIVER_USES_OUTLINES( driver )         &&
-         face->internal->transform_matrix.yy > 0   &&
-         face->internal->transform_matrix.yx == 0  )
+    if ( hinter                                   &&
+         !( load_flags & FT_LOAD_NO_HINTING )     &&
+         !( load_flags & FT_LOAD_NO_AUTOHINT )    &&
+         FT_DRIVER_IS_SCALABLE( driver )          &&
+         FT_DRIVER_USES_OUTLINES( driver )        &&
+         !FT_IS_TRICKY( face )                    &&
+         face->internal->transform_matrix.yy > 0  &&
+         face->internal->transform_matrix.yx == 0 )
     {
-      if ( ( load_flags & FT_LOAD_FORCE_AUTOHINT ) != 0 ||
-           !FT_DRIVER_HAS_HINTER( driver )              )
-        autohint = 1;
+      if ( ( load_flags & FT_LOAD_FORCE_AUTOHINT ) ||
+           !FT_DRIVER_HAS_HINTER( driver )         )
+        autohint = TRUE;
       else
       {
         FT_Render_Mode  mode = FT_LOAD_TARGET_MODE( load_flags );
@@ -619,7 +620,7 @@
 
         if ( mode == FT_RENDER_MODE_LIGHT             ||
              face->internal->ignore_unpatented_hinter )
-          autohint = 1;
+          autohint = TRUE;
       }
     }
 
diff --git a/src/base/ftpatent.c b/src/base/ftpatent.c
index d63f191c3..9f129d8f0 100644
--- a/src/base/ftpatent.c
+++ b/src/base/ftpatent.c
@@ -5,7 +5,7 @@
 /*    FreeType API for checking patented TrueType bytecode instructions    */
 /*    (body).                                                              */
 /*                                                                         */
-/*  Copyright 2007 by David Turner.                                        */
+/*  Copyright 2007, 2008 by David Turner.                                  */
 /*                                                                         */
 /*  This file is part of the FreeType project, and may only be used,       */
 /*  modified, and distributed under the terms of the FreeType project      */
@@ -260,7 +260,7 @@
   FT_Face_SetUnpatentedHinting( FT_Face  face,
                                 FT_Bool  value )
   {
-    FT_Bool  result = 0;
+    FT_Bool  result = FALSE;
 
 
 #if defined( TT_CONFIG_OPTION_UNPATENTED_HINTING ) && \
diff --git a/src/truetype/ttdriver.c b/src/truetype/ttdriver.c
index 9e9133b0b..b2430ba54 100644
--- a/src/truetype/ttdriver.c
+++ b/src/truetype/ttdriver.c
@@ -272,7 +272,7 @@
   /*    glyph_index :: The index of the glyph in the font file.            */
   /*                                                                       */
   /*    load_flags  :: A flag indicating what to load for this glyph.  The */
-  /*                   FTLOAD_??? constants can be used to control the     */
+  /*                   FT_LOAD_XXX constants can be used to control the    */
   /*                   glyph loading process (e.g., whether the outline    */
   /*                   should be scaled, whether to load bitmaps or not,   */
   /*                   whether to hint the outline, etc).                  */
@@ -301,11 +301,24 @@
     if ( !face || glyph_index >= (FT_UInt)face->num_glyphs )
       return TT_Err_Invalid_Argument;
 
+    if ( load_flags & FT_LOAD_NO_HINTING )
+    {
+      /* both FT_LOAD_NO_HINTING and FT_LOAD_NO_AUTOHINT   */
+      /* are necessary to disable hinting for tricky fonts */          
+
+      if ( FT_IS_TRICKY( face ) )
+        load_flags &= ~FT_LOAD_NO_HINTING;
+
+      if ( load_flags & FT_LOAD_NO_AUTOHINT )
+        load_flags |= FT_LOAD_NO_HINTING;
+    }
+
     if ( load_flags & ( FT_LOAD_NO_RECURSE | FT_LOAD_NO_SCALE ) )
     {
-      load_flags |= FT_LOAD_NO_HINTING |
-                    FT_LOAD_NO_BITMAP  |
-                    FT_LOAD_NO_SCALE;
+      load_flags |= FT_LOAD_NO_BITMAP | FT_LOAD_NO_SCALE;
+
+      if ( !FT_IS_TRICKY( face ) )
+        load_flags |= FT_LOAD_NO_HINTING;
     }
 
     /* now load the glyph outline if necessary */
diff --git a/src/truetype/ttobjs.c b/src/truetype/ttobjs.c
index d70da2323..06fd76a5c 100644
--- a/src/truetype/ttobjs.c
+++ b/src/truetype/ttobjs.c
@@ -144,6 +144,38 @@
 #endif /* TT_USE_BYTECODE_INTERPRETER */
 
 
+  /* Compare the face with a list of well-known `tricky' fonts. */
+  /* This list shall be expanded as we find more of them.       */
+
+  static FT_Bool
+  tt_check_trickyness( FT_String*  name )
+  {
+    static const char* const  trick_names[] =
+    {
+      "DFKaiSho-SB",     /* dfkaisb.ttf */
+      "DFKai-SB",        /* kaiu.ttf */
+      "HuaTianSongTi?",  /* htst3.ttf */
+      "MingLiU",         /* mingliu.ttf & mingliu.ttc */
+      "PMingLiU",        /* mingliu.ttc */
+      "MingLi43",        /* mingli.ttf */
+      NULL
+    };
+    int  nn;
+
+
+    if ( !name )
+      return FALSE;
+
+    /* Note that we only check the face name at the moment; it might */
+    /* be worth to do more checks for a few special cases.           */
+    for ( nn = 0; trick_names[nn] != NULL; nn++ )
+      if ( ft_strstr( name, trick_names[nn] ) )
+        return TRUE;
+
+    return FALSE;
+  }
+
+
   /*************************************************************************/
   /*                                                                       */
   /* <Function>                                                            */
@@ -180,7 +212,7 @@
     TT_Face       face = (TT_Face)ttface;
 
 
-    library = face->root.driver->root.library;
+    library = ttface->driver->root.library;
     sfnt    = (SFNT_Service)FT_Get_Module_Interface( library, "sfnt" );
     if ( !sfnt )
       goto Bad_Format;
@@ -206,7 +238,7 @@
     }
 
 #ifdef TT_USE_BYTECODE_INTERPRETER
-    face->root.face_flags |= FT_FACE_FLAG_HINTER;
+    ttface->face_flags |= FT_FACE_FLAG_HINTER;
 #endif
 
     /* If we are performing a simple font format check, exit immediately. */
@@ -218,16 +250,19 @@
     if ( error )
       goto Exit;
 
+    if ( tt_check_trickyness( ttface->family_name ) )
+      ttface->face_flags |= FT_FACE_FLAG_TRICKY;
+
     error = tt_face_load_hdmx( face, stream );
     if ( error )
       goto Exit;
 
-    if ( face->root.face_flags & FT_FACE_FLAG_SCALABLE )
+    if ( FT_IS_SCALABLE( ttface ) )
     {
 
 #ifdef FT_CONFIG_OPTION_INCREMENTAL
 
-      if ( !face->root.internal->incremental_interface )
+      if ( !ttface->internal->incremental_interface )
         error = tt_face_load_loca( face, stream );
       if ( !error )
         error = tt_face_load_cvt( face, stream );
@@ -267,38 +302,8 @@
         if ( params[i].tag == FT_PARAM_TAG_UNPATENTED_HINTING )
           unpatented_hinting = TRUE;
 
-      /* Compare the face with a list of well-known `tricky' fonts. */
-      /* This list shall be expanded as we find more of them.       */
       if ( !unpatented_hinting )
-      {
-        static const char* const  trick_names[] =
-        {
-          "DFKaiSho-SB",     /* dfkaisb.ttf */
-          "DFKai-SB",        /* kaiu.ttf */
-          "HuaTianSongTi?",  /* htst3.ttf */
-          "MingLiU",         /* mingliu.ttf & mingliu.ttc */
-          "PMingLiU",        /* mingliu.ttc */
-          "MingLi43",        /* mingli.ttf */
-          NULL
-        };
-        int  nn;
-
-
-        /* Note that we only check the face name at the moment; it might */
-        /* be worth to do more checks for a few special cases.           */
-        for ( nn = 0; trick_names[nn] != NULL; nn++ )
-        {
-          if ( ttface->family_name                               &&
-               ft_strstr( ttface->family_name, trick_names[nn] ) )
-          {
-            unpatented_hinting = 1;
-            break;
-          }
-        }
-      }
-
-      ttface->internal->ignore_unpatented_hinter =
-        FT_BOOL( !unpatented_hinting );
+        ttface->internal->ignore_unpatented_hinter = TRUE;
     }
 
 #endif /* TT_CONFIG_OPTION_UNPATENTED_HINTING &&
@@ -339,8 +344,8 @@
     if ( !face )
       return;
 
-    memory = face->root.memory;
-    stream = face->root.stream;
+    memory = ttface->memory;
+    stream = ttface->stream;
     sfnt   = (SFNT_Service)face->sfnt;
 
     /* for `extended TrueType formats' (i.e. compressed versions) */
@@ -680,7 +685,7 @@
     if ( !size->cvt_ready )
     {
       FT_UInt  i;
-      TT_Face  face = (TT_Face) size->root.face;
+      TT_Face  face = (TT_Face)size->root.face;
 
 
       /* Scale the cvt values to the new ppem.          */