ftxgsub.c

字体缩放显示

/*******************************************************************
 *
 *  ftxgsub.c
 *
 *    TrueType Open GSUB table support.
 *
 *  Copyright 1996-2001 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 :-)                                  */

#include "tttypes.h"
#include "tttags.h"
#include "ttload.h"
#include "ttextend.h"
#include "ttmemory.h"
#include "ttfile.h"

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


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


  static TT_Error  Do_Glyph_Lookup( TTO_GSUBHeader*   gsub,
                                    UShort            lookup_index,
                                    TTO_GSUB_String*  in,
                                    TTO_GSUB_String*  out,
                                    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'.                              */

  FT_EXPORT_FUNC( TT_Error )
  TT_GSUB_Add_String( TTO_GSUB_String*  in,
                      UShort            num_in,
                      TTO_GSUB_String*  out,
                      UShort            num_out,
                      UShort*           glyph_data,
                      UShort            component,
                      UShort            ligID )
  {
    TT_Error  error;
    TT_UInt   i;
    UShort    p_in;
    UShort*   p_out;


    /* sanity check */

    if ( !in || !out ||
         in->length == 0 || in->pos >= in->length ||
         in->length < in->pos + num_in )
      return TT_Err_Invalid_Argument;

    if ( out->pos + num_out >= out->allocated )
    {
      ULong  size = out->pos + num_out + 256L;


      /* The following works because all fields in `out' must be
         initialized to zero (including the `string' field) for the
         first use.                                                 */

      if ( REALLOC_ARRAY( out->string, size, UShort ) )
        return error;
      if ( REALLOC_ARRAY( out->components, size, UShort ) )
        return error;
      if ( REALLOC_ARRAY( out->ligIDs, size, UShort ) )
        return error;
      if ( in->properties )
        if ( REALLOC_ARRAY( out->properties, size, UShort ) )
          return error;

      out->allocated = size;
    }

    if ( num_out )
    {
      MEM_Copy( &out->string[out->pos], glyph_data,
                num_out * sizeof ( UShort ) );

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

      p_out = out->components;

      for ( i = out->pos; i < out->pos + num_out; i++ )
        p_out[i] = component;

      p_out = out->ligIDs;

      if ( ligID == 0xFFFF )
        ligID = in->ligIDs[in->pos];

      for ( i = out->pos; i < out->pos + num_out; i++ )
        p_out[i] = ligID;

      if ( in->properties )
      {
        p_in  = in->properties[in->pos];
        p_out = out->properties;

        for ( i = out->pos; i < out->pos + num_out; i++ )
          p_out[i] = p_in;
      }
    }

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

    out->length = out->pos;

    return TT_Err_Ok;
  }



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


  static TT_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 TT_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 );
      Free_FeatureList( &gsub->FeatureList );
      Free_ScriptList( &gsub->ScriptList );
    }

    return TT_Err_Ok;
  }


  FT_EXPORT_FUNC( TT_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 );
  }


  FT_EXPORT_FUNC( TT_Error )
  TT_Load_GSUB_Table( TT_Face          face,
                      TTO_GSUBHeader*  retptr,
                      TTO_GDEFHeader*  gdef )
  {
    ULong            cur_offset, new_offset, base_offset;

    UShort           i, num_lookups;
    TTO_GSUBHeader*  gsub;
    TTO_GDEFHeader*  gdef_reg;
    TTO_Lookup*      lo;

    PFace  faze = HANDLE_Face( face );
    DEFINE_ALL_LOCALS;


    if ( !retptr )
      return TT_Err_Invalid_Argument;

    if ( !faze )
      return TT_Err_Invalid_Face_Handle;

    error = TT_Extension_Get( faze, GSUB_ID, (void**)&gsub );
    if ( error )
      return error;

    if ( gsub->offset == 0 )
      return TT_Err_Table_Missing;      /* no GSUB table; nothing to do */

    /* now access stream */

    if ( USE_Stream( faze->stream, stream ) )
      return error;

    base_offset = gsub->offset;

    /* skip version */

    if ( FILE_Seek( base_offset + 4L ) ||
         ACCESS_Frame( 2L ) )
      return error;

    new_offset = GET_UShort() + base_offset;

    FORGET_Frame();

    cur_offset = FILE_Pos();
    if ( FILE_Seek( new_offset ) ||
         ( error = Load_ScriptList( &gsub->ScriptList,
                                    faze ) ) != TT_Err_Ok )
      return error;
    (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,
                                     faze ) ) != 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,
                                    faze, 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 ( 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 ) ||
               ACCESS_Frame( 2L ) )
            goto Fail1;

          new_offset = GET_UShort();

          FORGET_Frame();

          if ( !new_offset )
            return TTO_Err_Invalid_GDEF_SubTable;

          new_offset += gdef->offset;

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

          /* copy the class definition pointer into the extension structure */

          error = TT_Extension_Get( faze, GDEF_ID, (void**)&gdef_reg );
          if ( error )
            return error;

          *gdef_reg = *gdef;

          break;
        }
      }
    }

    gsub->loaded = TRUE;
    *retptr = *gsub;
    DONE_Stream( stream );

    return TT_Err_Ok;

  Fail1:
    Free_LookupList( &gsub->LookupList, GSUB );

  Fail2:
    Free_FeatureList( &gsub->FeatureList );

  Fail3:
    Free_ScriptList( &gsub->ScriptList );

    /* release stream */

    DONE_Stream( stream );

    return error;
  }



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


  /* LookupType 1 */

  /* SingleSubstFormat1 */
  /* SingleSubstFormat2 */

  TT_Error  Load_SingleSubst( TTO_SingleSubst*  ss,
                              PFace             input )
  {
    DEFINE_LOAD_LOCALS( input->stream );

    UShort   n, count;
    ULong    cur_offset, new_offset, base_offset;

    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, input ) ) != 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, 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 );
    return error;
  }


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

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

    Free_Coverage( &ss->Coverage );
  }


  static TT_Error  Lookup_SingleSubst( TTO_SingleSubst*  ss,
                                       TTO_GSUB_String*  in,
                                       TTO_GSUB_String*  out,
                                       UShort            flags,
                                       UShort            context_length,
                                       TTO_GDEFHeader*   gdef )
  {
    UShort    index, value[1], property;
    TT_Error  error;


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

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

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

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

    case 2:
      if ( index >= ss->ssf.ssf2.GlyphCount )
        return TTO_Err_Invalid_GSUB_SubTable;
      value[0] = ss->ssf.ssf2.Substitute[index];
      if ( ADD_String( in, 1, out, 1, value, 0xFFFF, 0xFFFF ) )
        return error;
      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[0], property );
      if ( error && error != TTO_Err_Not_Covered )
        return error;
    }

    return TT_Err_Ok;
  }


  /* LookupType 2 */

  /* Sequence */

  static TT_Error  Load_Sequence( TTO_Sequence*  s,
                                  PFace          input )
  {
    DEFINE_LOAD_LOCALS( input->stream );

    UShort   n, count;
    UShort*  sub;


    if ( ACCESS_Frame( 2L ) )