ftxgpos.c

Trolltech公司发布的基于C++图形开发环境

/*******************************************************************
 *
 *  ftxgpos.c
 *
 *    TrueType Open GPOS 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 7 and 8), 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 :-)                                  */

#define TTAG_GPOS  FT_MAKE_TAG( 'G', 'P', 'O', 'S' )

#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 "ftxgsub.h"
#include "ftxopenf.h"


  struct  GPOS_Instance_
  {
    TTO_GPOSHeader*  gpos;
    FT_Face          face;
    FT_Bool          dvi;
    FT_UShort        load_flags;  /* how the glyph should be loaded */
    FT_Bool          r2l;

    FT_UShort        first;       /* the first glyph in a chain of
                                     cursive connections           */
    FT_UShort        last;        /* the last valid glyph -- used
                                     with cursive positioning     */
    FT_Pos           anchor_x;    /* the coordinates of the anchor point */
    FT_Pos           anchor_y;    /* of the last valid glyph             */
  };

  typedef struct GPOS_Instance_  GPOS_Instance;


  static FT_Error  GPos_Do_Glyph_Lookup( GPOS_Instance*    gpi,
                                    FT_UShort         lookup_index,
                                    TTO_GSUB_String*  in,
                                    TTO_GPOS_Data*    out,
                                    FT_UShort         context_length,
                                    int               nesting_level );


  /* the client application must replace this with something more
     meaningful if multiple master fonts are to be supported.     */
static FT_Error  default_mmfunc( FT_Face      face,
				 FT_UShort    metric_id,
				 FT_Pos*      metric_value,
				 void*        data )
{
    (void)face;
    (void)metric_id;
    (void)metric_value;
    (void)data;
    return TTO_Err_No_MM_Interpreter;
}


#if 0
#define GPOS_ID  Build_Extension_ID( 'G', 'P', 'O', 'S' )

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

  static FT_Error  GPOS_Create( void*      ext,
                                FT_Stream stream )
  {
    FT_Error  error;
    FT_Memory memory = stream->memory;

    TTO_GPOSHeader*  gpos = (TTO_GPOSHeader*)ext;
    FT_Long          table;


    /* by convention */

    if ( !gpos )
      return TT_Err_Ok;

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

    gpos->offset = 0;

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

    table = face->lookup_table ( face, TTAG_GPOS );
    if ( table < 0 )
      return TT_Err_Ok;             /* The table is optional */

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

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

    FORGET_Frame();

    /* a default mmfunc() handler which just returns an error */

    gpos->mmfunc = default_mmfunc;

    /* the default glyph function is TT_Load_Glyph() */

    gpos->gfunc = FT_Load_Glyph;

    gpos->loaded = FALSE;

    return TT_Err_Ok;
  }


  static FT_Error  GPOS_Destroy( void*  ext,
                                 PFace  face )
  {
    TTO_GPOSHeader*  gpos = (TTO_GPOSHeader*)ext;


    /* by convention */

    if ( !gpos )
      return TT_Err_Ok;

    if ( gpos->loaded )
    {
      Free_LookupList( &gpos->LookupList, GPOS );
      Free_FeatureList( &gpos->FeatureList );
      Free_ScriptList( &gpos->ScriptList );
    }

    return TT_Err_Ok;
  }


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


    if ( !_engine )
      return TT_Err_Invalid_Engine;

    return  TT_Register_Extension( _engine,
                                   GPOS_ID,
                                   sizeof ( TTO_GPOSHeader ),
                                   GPOS_Create,
                                   GPOS_Destroy );
  }
#endif

  EXPORT_FUNC
  FT_Error  TT_Load_GPOS_Table( FT_Face          face,
                                TTO_GPOSHeader** retptr,
                                TTO_GDEFHeader*  gdef )
  {
    FT_ULong         cur_offset, new_offset, base_offset;

    /*    FT_UShort        i, num_lookups; */
    TTO_GPOSHeader*  gpos;
    /*    TTO_Lookup*      lo; */
    TT_Face          tt_face = (TT_Face)face;

    FT_Stream  stream = face->stream;
    FT_Error   error;
    FT_Memory  memory = face->memory;


    if ( !retptr )
      return TT_Err_Invalid_Argument;

    if ( !stream )
      return TT_Err_Invalid_Face_Handle;

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

    base_offset = FILE_Pos();

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

    gpos->memory = memory;
    gpos->gfunc = FT_Load_Glyph;
    gpos->mmfunc = default_mmfunc;

    /* 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( &gpos->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( &gpos->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( &gpos->LookupList,
                                    stream, GPOS ) ) != TT_Err_Ok )
      goto Fail2;

    gpos->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          = gpos->LookupList.Lookup;
      num_lookups = gpos->LookupList.LookupCount;

      for ( i = 0; i < num_lookups; i++ )
      {
        if ( lo[i].LookupFlag & IGNORE_SPECIAL_MARKS )
        {
          if ( FILE_Seek( gdef->MarkAttachClassDef_offset ) ||
               ACCESS_Frame( 2L ) )
            goto Fail1;

          new_offset = GET_UShort();

          FORGET_Frame();

          if ( !new_offset )
            return TTO_Err_Invalid_GDEF_SubTable;

          new_offset += base_offset;

          if ( FILE_Seek( new_offset ) ||
               ( error = Load_ClassDefinition( &gdef->MarkAttachClassDef,
                                               256, stream ) ) != TT_Err_Ok )
            goto Fail1;

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

    return TT_Err_Ok;

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

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

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

  Fail4:
    FREE( gpos );

    return error;
  }

  EXPORT_FUNC
  FT_Error  TT_Done_GPOS_Table( TTO_GPOSHeader* gpos )
  {
    FT_Memory memory = gpos->memory;

    Free_LookupList( &gpos->LookupList, GPOS, memory );
    Free_FeatureList( &gpos->FeatureList, memory );
    Free_ScriptList( &gpos->ScriptList, memory );

    return FT_Err_Ok;
  }


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

  /* shared tables */

  /* ValueRecord */

  /* There is a subtle difference in the specs between a `table' and a
     `record' -- offsets for device tables in ValueRecords are taken from
     the parent table and not the parent record.                          */

  static FT_Error  Load_ValueRecord( TTO_ValueRecord*  vr,
                                     FT_UShort         format,
                                     FT_ULong          base_offset,
                                     FT_Stream         stream )
  {
    FT_Error  error;
    FT_Memory memory = stream->memory;

    FT_ULong cur_offset, new_offset;


    if ( format & HAVE_X_PLACEMENT )
    {
      if ( ACCESS_Frame( 2L ) )
        return error;

      vr->XPlacement = GET_Short();

      FORGET_Frame();
    }
    else
      vr->XPlacement = 0;

    if ( format & HAVE_Y_PLACEMENT )
    {
      if ( ACCESS_Frame( 2L ) )
        return error;

      vr->YPlacement = GET_Short();

      FORGET_Frame();
    }
    else
      vr->YPlacement = 0;

    if ( format & HAVE_X_ADVANCE )
    {
      if ( ACCESS_Frame( 2L ) )
        return error;

      vr->XAdvance = GET_Short();

      FORGET_Frame();
    }
    else
      vr->XAdvance = 0;

    if ( format & HAVE_Y_ADVANCE )
    {
      if ( ACCESS_Frame( 2L ) )
        return error;

      vr->YAdvance = GET_Short();

      FORGET_Frame();
    }
    else
      vr->YAdvance = 0;

    if ( format & HAVE_X_PLACEMENT_DEVICE )
    {
      if ( ACCESS_Frame( 2L ) )
        return error;

      new_offset = GET_UShort();

      FORGET_Frame();

      if ( new_offset )
      {
        new_offset += base_offset;

        cur_offset = FILE_Pos();
        if ( FILE_Seek( new_offset ) ||
             ( error = Load_Device( &vr->XPlacementDevice,
                                    stream ) ) != TT_Err_Ok )
          return error;
        (void)FILE_Seek( cur_offset );
      }
      else
        goto empty1;
    }
    else
    {
    empty1:
      vr->XPlacementDevice.StartSize  = 0;
      vr->XPlacementDevice.EndSize    = 0;
      vr->XPlacementDevice.DeltaValue = NULL;
    }

    if ( format & HAVE_Y_PLACEMENT_DEVICE )
    {
      if ( ACCESS_Frame( 2L ) )
        goto Fail3;

      new_offset = GET_UShort();

      FORGET_Frame();

      if ( new_offset )
      {
        new_offset += base_offset;

        cur_offset = FILE_Pos();
        if ( FILE_Seek( new_offset ) ||
             ( error = Load_Device( &vr->YPlacementDevice,
                                    stream ) ) != TT_Err_Ok )
          goto Fail3;
        (void)FILE_Seek( cur_offset );
      }
      else
        goto empty2;
    }
    else
    {
    empty2:
      vr->YPlacementDevice.StartSize  = 0;
      vr->YPlacementDevice.EndSize    = 0;
      vr->YPlacementDevice.DeltaValue = NULL;
    }

    if ( format & HAVE_X_ADVANCE_DEVICE )
    {
      if ( ACCESS_Frame( 2L ) )
        goto Fail2;

      new_offset = GET_UShort();

      FORGET_Frame();

      if ( new_offset )
      {
        new_offset += base_offset;

        cur_offset = FILE_Pos();
        if ( FILE_Seek( new_offset ) ||
             ( error = Load_Device( &vr->XAdvanceDevice,
                                    stream ) ) != TT_Err_Ok )
          goto Fail2;
        (void)FILE_Seek( cur_offset );
      }
      else
        goto empty3;
    }
    else
    {
    empty3:
      vr->XAdvanceDevice.StartSize  = 0;
      vr->XAdvanceDevice.EndSize    = 0;
      vr->XAdvanceDevice.DeltaValue = NULL;
    }

    if ( format & HAVE_Y_ADVANCE_DEVICE )
    {
      if ( ACCESS_Frame( 2L ) )
        goto Fail1;

      new_offset = GET_UShort();

      FORGET_Frame();

      if ( new_offset )
      {
        new_offset += base_offset;

        cur_offset = FILE_Pos();
        if ( FILE_Seek( new_offset ) ||
             ( error = Load_Device( &vr->YAdvanceDevice,
                                    stream ) ) != TT_Err_Ok )
          goto Fail1;
        (void)FILE_Seek( cur_offset );
      }
      else
        goto empty4;
    }
    else
    {
    empty4:
      vr->YAdvanceDevice.StartSize  = 0;
      vr->YAdvanceDevice.EndSize    = 0;
      vr->YAdvanceDevice.DeltaValue = NULL;
    }

    if ( format & HAVE_X_ID_PLACEMENT )
    {
      if ( ACCESS_Frame( 2L ) )
        goto Fail1;

      vr->XIdPlacement = GET_UShort();

      FORGET_Frame();
    }
    else
      vr->XIdPlacement = 0;