ftxgsub.c

Trolltech公司发布的基于C++图形开发环境

/*******************************************************************
 *
 *  ftxgsub.c
 *
 *    TrueType Open GSUB table support.
 *
 *  Copyright 1996-2000 by
 *  David Turner, Robert Wilhelm, and Werner Lemberg.
 *
 *  This file is part of the FreeType project, and may only be used
 *  modified and distributed under the terms of the FreeType project
 *  license, LICENSE.TXT.  By continuing to use, modify, or distribute
 *  this file you indicate that you have read the license and
 *  understand and accept it fully.
 *
 ******************************************************************/

/* XXX There is *a lot* of duplicated code (cf. formats 5 and 6), but
       I don't care currently.  I believe that it would be possible to
       save about 50% of TTO code by carefully designing the structures,
       sharing as much as possible with extensive use of macros.  This
       is something for a volunteer :-)                                  */

#ifndef EXPORT_FUNC
#define EXPORT_FUNC
#endif

#include <freetype/tttags.h>

#include <freetype/internal/ftstream.h>
#include <freetype/internal/ftmemory.h>
#include <freetype/internal/tttypes.h>

#include "fterrcompat.h"

#include "ftxopen.h"
#include "ftxopenf.h"

#include <assert.h>

#define GSUB_ID  Build_Extension_ID( 'G', 'S', 'U', 'B' )


#define ADD_String( in, num_in, out, num_out, glyph_data, component ) \
          ( ( error = TT_GSUB_Add_String( (in), (num_in),                    \
                                          (out), (num_out),                  \
                                          (glyph_data), (component) \
                                        ) ) != TT_Err_Ok )


  static FT_Error  GSub_Do_Glyph_Lookup( TTO_GSUBHeader*   gsub,
                                    FT_UShort         lookup_index,
                                    TTO_GSUB_String*  in,
                                    TTO_GSUB_String*  out,
                                    FT_UShort         context_length,
                                    int               nesting_level );



  /**********************
   * Auxiliary functions
   **********************/


  /* The following function copies `num_out' elements from `glyph_data'
     to `out', advancing the array pointer in the `in' structure by
     `num_in' elements, and in `out' by `num_out' elements.  If the
     string (resp. the properties) array in `out' is empty or too
     small, it allocates resp. reallocates the string (and properties)
     array.  Finally, it sets the `length' field of `out' equal to
     `pos' of the `out' structure.

     If `component' is 0xFFFF, the value `in->component[in->pos]'
     will be copied `num_out' times, otherwise `component' itself will
     be used to fill `out->component'.

     If `ligID' is 0xFFFF, the value `in->lig_IDs[in->pos]' will be
     copied `num_out' times, otherwise `ligID' itself will be used to
     fill `out->ligIDs'.

     The properties (if defined) for all replaced glyphs are taken
     from the glyph at position `in->pos'.

     The logClusters[] value for the glyph at position in->pos is used
     for all replacement glyphs */

  EXPORT_FUNC
  FT_Error  TT_GSUB_Add_String( TTO_GSUB_String*  in,
                                FT_UShort         num_in,
                                TTO_GSUB_String*  out,
                                FT_UShort         num_out,
                                FT_UShort*        glyph_data,
                                FT_UShort         component)
  {

    /* sanity check */
      /*assert( !( !in || !out || in->length == 0 || in->pos >= in->length || in->length < in->pos + num_in ) );*/

    if ( out->pos + num_out > out->allocated )
	TT_GSUB_String_Allocate( out, out->pos + num_out );

    if ( num_out )
    {
      int n = num_out;
      FT_UShort *dest_glyph = out->string + out->pos;
      TTO_Glyph_property *dest_prop = out->glyph_properties + out->pos;
      FT_Int *dest_ci = out->character_index + out->pos;
      FT_Int src_ci = in->character_index[in->pos];

      if ( component == 0xFFFF )
        component = in->glyph_properties[in->pos].component;

      while ( n-- ) {
	  *(dest_glyph++) = *(glyph_data++);
	  (dest_prop++)->component = component;
	  *(dest_ci++) = src_ci;
      }

      out->pos += num_out;
    }

    in->pos  += num_in;
    out->length = out->pos;

    return TT_Err_Ok;
  }



/* optimised function for the common case of copying copying 1 glyph to out, replacing n in glyphs */
static inline void glyph_copy( TTO_GSUB_String*  in,
                                FT_UShort         num_in,
                                TTO_GSUB_String*  out,
                                FT_UShort        glyph,
                                FT_UShort         component)
{

    /* sanity check */
    /*assert( !( !in || !out || in->length == 0 || in->pos >= in->length || in->length < in->pos + num_in ) );*/

    if ( out->pos >= out->allocated )
	TT_GSUB_String_Allocate( out, out->pos + 1 );

    out->string[out->pos] = glyph;
    out->glyph_properties[out->pos].component = component;
    out->character_index[out->pos] = in->character_index[in->pos];
    out->pos++;
    in->pos  += num_in;
    out->length = out->pos;
}
#if 0

  /**********************
   * Extension Functions
   **********************/


  static FT_Error  GSUB_Create( void*  ext,
                                PFace  face )
  {
    DEFINE_LOAD_LOCALS( face->stream );

    TTO_GSUBHeader*  gsub = (TTO_GSUBHeader*)ext;
    Long             table;


    /* by convention */

    if ( !gsub )
      return TT_Err_Ok;

    /* a null offset indicates that there is no GSUB table */

    gsub->offset = 0;

    /* we store the start offset and the size of the subtable */

    table = TT_LookUp_Table( face, TTAG_GSUB );
    if ( table < 0 )
      return TT_Err_Ok;             /* The table is optional */

    if ( FILE_Seek( face->dirTables[table].Offset ) ||
         ACCESS_Frame( 4L ) )
      return error;

    gsub->offset  = FILE_Pos() - 4L;    /* undo ACCESS_Frame() */
    gsub->Version = GET_ULong();

    FORGET_Frame();

    gsub->loaded = FALSE;

    return TT_Err_Ok;
  }


  static FT_Error  GSUB_Destroy( void*  ext,
                                 PFace  face )
  {
    TTO_GSUBHeader*  gsub = (TTO_GSUBHeader*)ext;


    /* by convention */

    if ( !gsub )
      return TT_Err_Ok;

    if ( gsub->loaded )
    {
      Free_LookupList( &gsub->LookupList, GSUB, memory );
      Free_FeatureList( &gsub->FeatureList, memory );
      Free_ScriptList( &gsub->ScriptList, memory );
    }

    return TT_Err_Ok;
  }


  EXPORT_FUNC
  FT_Error  TT_Init_GSUB_Extension( TT_Engine  engine )
  {
    PEngine_Instance  _engine = HANDLE_Engine( engine );


    if ( !_engine )
      return TT_Err_Invalid_Engine;

    return  TT_Register_Extension( _engine,
                                   GSUB_ID,
                                   sizeof ( TTO_GSUBHeader ),
                                   GSUB_Create,
                                   GSUB_Destroy );
  }
#endif

  EXPORT_FUNC
  FT_Error  TT_Load_GSUB_Table( FT_Face          face,
                                TTO_GSUBHeader** retptr,
                                TTO_GDEFHeader*  gdef )
  {
    FT_Stream        stream = face->stream;
    FT_Memory        memory = face->memory;
    FT_Error         error;
    FT_ULong         cur_offset, new_offset, base_offset;
    TT_Face          tt_face = (TT_Face)face;

    /*    FT_UShort        i, num_lookups; */
    TTO_GSUBHeader*  gsub;
    /*    TTO_Lookup*      lo; */

    if ( !retptr )
      return TT_Err_Invalid_Argument;

    if (( error = tt_face->goto_table( tt_face, TTAG_GSUB, stream, 0 ) ))
      return error;

    base_offset = FILE_Pos();

    if ( ALLOC ( gsub, sizeof( *gsub ) ) )
      return error;

    gsub->memory = memory;

    /* skip version */

    if ( FILE_Seek( base_offset + 4L ) ||
         ACCESS_Frame( 2L ) )
      goto Fail4;

    new_offset = GET_UShort() + base_offset;

    FORGET_Frame();

    cur_offset = FILE_Pos();
    if ( FILE_Seek( new_offset ) ||
         ( error = Load_ScriptList( &gsub->ScriptList,
                                    stream ) ) != TT_Err_Ok )
      goto Fail4;
    (void)FILE_Seek( cur_offset );

    if ( ACCESS_Frame( 2L ) )
      goto Fail3;

    new_offset = GET_UShort() + base_offset;

    FORGET_Frame();

    cur_offset = FILE_Pos();
    if ( FILE_Seek( new_offset ) ||
         ( error = Load_FeatureList( &gsub->FeatureList,
                                     stream ) ) != TT_Err_Ok )
      goto Fail3;
    (void)FILE_Seek( cur_offset );

    if ( ACCESS_Frame( 2L ) )
      goto Fail2;

    new_offset = GET_UShort() + base_offset;

    FORGET_Frame();

    cur_offset = FILE_Pos();
    if ( FILE_Seek( new_offset ) ||
         ( error = Load_LookupList( &gsub->LookupList,
                                    stream, GSUB ) ) != TT_Err_Ok )
      goto Fail2;

    gsub->gdef = gdef;      /* can be NULL */

    /* We now check the LookupFlags for values larger than 0xFF to find
       out whether we need to load the `MarkAttachClassDef' field of the
       GDEF table -- this hack is necessary for OpenType 1.2 tables since
       the version field of the GDEF table hasn't been incremented.

       For constructed GDEF tables, we only load it if
       `MarkAttachClassDef_offset' is not zero (nevertheless, a build of
       a constructed mark attach table is not supported currently).       */

#if 0
    if ( gdef &&
         gdef->MarkAttachClassDef_offset && !gdef->MarkAttachClassDef.loaded )
    {
      lo          = gsub->LookupList.Lookup;
      num_lookups = gsub->LookupList.LookupCount;

      for ( i = 0; i < num_lookups; i++ )
      {

        if ( lo[i].LookupFlag & IGNORE_SPECIAL_MARKS )
        {
          if ( FILE_Seek( gdef->MarkAttachClassDef_offset ) ||
               ( error = Load_ClassDefinition( &gdef->MarkAttachClassDef,
                                               256, stream ) ) != TT_Err_Ok )
            goto Fail1;

          break;
        }
      }
    }
#endif
    *retptr = gsub;

    return TT_Err_Ok;

#if 0
  Fail1:
    Free_LookupList( &gsub->LookupList, GSUB, memory );
#endif

  Fail2:
    Free_FeatureList( &gsub->FeatureList, memory );

  Fail3:
    Free_ScriptList( &gsub->ScriptList, memory );

  Fail4:
    FREE ( gsub );


    return error;
  }

  EXPORT_FUNC
  FT_Error   TT_Done_GSUB_Table( TTO_GSUBHeader* gsub )
  {
    FT_Memory memory = gsub->memory;

    Free_LookupList( &gsub->LookupList, GSUB, memory );
    Free_FeatureList( &gsub->FeatureList, memory );
    Free_ScriptList( &gsub->ScriptList, memory );

    FREE( gsub );

    return TT_Err_Ok;
  }

  /*****************************
   * SubTable related functions
   *****************************/


  /* LookupType 1 */

  /* SingleSubstFormat1 */
  /* SingleSubstFormat2 */

  FT_Error  Load_SingleSubst( TTO_SingleSubst*  ss,
                              FT_Stream         stream )
  {
    FT_Error error;
    FT_Memory memory = stream->memory;

    FT_UShort n, count;
    FT_ULong cur_offset, new_offset, base_offset;

    FT_UShort*  s;


    base_offset = FILE_Pos();

    if ( ACCESS_Frame( 4L ) )
      return error;

    ss->SubstFormat = GET_UShort();
    new_offset      = GET_UShort() + base_offset;

    FORGET_Frame();

    cur_offset = FILE_Pos();
    if ( FILE_Seek( new_offset ) ||
         ( error = Load_Coverage( &ss->Coverage, stream ) ) != TT_Err_Ok )
      return error;
    (void)FILE_Seek( cur_offset );

    switch ( ss->SubstFormat )
    {
    case 1:
      if ( ACCESS_Frame( 2L ) )
        goto Fail2;

      ss->ssf.ssf1.DeltaGlyphID = GET_UShort();

      FORGET_Frame();

      break;

    case 2:
      if ( ACCESS_Frame( 2L ) )
        goto Fail2;

      count = ss->ssf.ssf2.GlyphCount = GET_UShort();

      FORGET_Frame();

      ss->ssf.ssf2.Substitute = NULL;

      if ( ALLOC_ARRAY( ss->ssf.ssf2.Substitute, count, FT_UShort ) )
        goto Fail2;

      s = ss->ssf.ssf2.Substitute;

      if ( ACCESS_Frame( count * 2L ) )
        goto Fail1;

      for ( n = 0; n < count; n++ )
        s[n] = GET_UShort();

      FORGET_Frame();

      break;

    default:
      return TTO_Err_Invalid_GSUB_SubTable_Format;
    }

    return TT_Err_Ok;

  Fail1:
    FREE( s );

  Fail2:
    Free_Coverage( &ss->Coverage, memory );
    return error;
  }


  void  Free_SingleSubst( TTO_SingleSubst*  ss,
			  FT_Memory         memory )
  {
    switch ( ss->SubstFormat )
    {
    case 1:
      break;

    case 2:
      FREE( ss->ssf.ssf2.Substitute );
      break;
    }

    Free_Coverage( &ss->Coverage, memory );
  }


  static FT_Error  Lookup_SingleSubst( TTO_SingleSubst*  ss,
                                       TTO_GSUB_String*  in,
                                       TTO_GSUB_String*  out,
                                       FT_UShort         flags,
                                       FT_UShort         context_length,
                                       TTO_GDEFHeader*   gdef )
  {
    FT_UShort index, value, property;
    FT_Error  error;


    if ( context_length != 0xFFFF && context_length < 1 )
      return TTO_Err_Not_Covered;

    error = Coverage_Index( &ss->Coverage, in->string[in->pos], &index );
    if ( error )
      return error;

    if ( CHECK_Property( gdef, in->string[in->pos], flags, &property ) )
      return error;

    switch ( ss->SubstFormat )
    {
    case 1:
	value = ( in->string[in->pos] + ss->ssf.ssf1.DeltaGlyphID ) & 0xFFFF;
	glyph_copy( in, 1, out, value,
		    in->glyph_properties[in->pos].component);
      break;

    case 2:
      if ( index >= ss->ssf.ssf2.GlyphCount )
        return TTO_Err_Invalid_GSUB_SubTable;
      value = ss->ssf.ssf2.Substitute[index];
      glyph_copy( in, 1, out, value,
		  in->glyph_properties[in->pos].component);
      break;

    default:
      return TTO_Err_Invalid_GSUB_SubTable;
    }

    if ( gdef && gdef->NewGlyphClasses )
    {
      /* we inherit the old glyph class to the substituted glyph */

      error = Add_Glyph_Property( gdef, value, property );
      if ( error && error != TTO_Err_Not_Covered )
        return error;
    }

    return TT_Err_Ok;
  }


  /* LookupType 2 */

  /* Sequence */

  static FT_Error  Load_Sequence( TTO_Sequence*  s,
                                  FT_Stream      stream )
  {
    FT_Error error;
    FT_Memory memory = stream->memory;

    FT_UShort n, count;
    FT_UShort*  sub;


    if ( ACCESS_Frame( 2L ) )
      return error;

    count = s->GlyphCount = GET_UShort();

    FORGET_Frame();

    s->Substitute = NULL;

    if ( count )
    {
      if ( ALLOC_ARRAY( s->Substitute, count, FT_UShort ) )
        return error;

      sub = s->Substitute;

      if ( ACCESS_Frame( count * 2L ) )