ttpload.c

ReactOS是一些高手根据Windows XP的内核编写出的类XP。内核实现机理和API函数调用几乎相同。甚至可以兼容XP的程序。喜欢研究系统内核的人可以看一看。

#endif
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_fpgm                                                  */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Load the font program.                                             */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    face   :: A handle to the target face object.                      */
  /*                                                                       */
  /* <Input>                                                               */
  /*    stream :: A handle to the input stream.                            */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_LOCAL_DEF( FT_Error )
  tt_face_load_fpgm( TT_Face    face,
                     FT_Stream  stream )
  {
#ifdef TT_USE_BYTECODE_INTERPRETER

    FT_Error  error;
    FT_ULong  table_len;


    FT_TRACE2(( "Font program " ));

    /* The font program is optional */
    error = face->goto_table( face, TTAG_fpgm, stream, &table_len );
    if ( error )
    {
      face->font_program      = NULL;
      face->font_program_size = 0;
      error                   = TT_Err_Ok;

      FT_TRACE2(( "is missing!\n" ));
    }
    else
    {
      face->font_program_size = table_len;
      if ( FT_FRAME_EXTRACT( table_len, face->font_program ) )
        goto Exit;

      FT_TRACE2(( "loaded, %12d bytes\n", face->font_program_size ));
    }

  Exit:
    return error;

#else /* !TT_USE_BYTECODE_INTERPRETER */

    FT_UNUSED( face   );
    FT_UNUSED( stream );

    return TT_Err_Ok;

#endif
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_prep                                                  */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Load the cvt program.                                              */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    face   :: A handle to the target face object.                      */
  /*                                                                       */
  /* <Input>                                                               */
  /*    stream :: A handle to the input stream.                            */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_LOCAL_DEF( FT_Error )
  tt_face_load_prep( TT_Face    face,
                     FT_Stream  stream )
  {
#ifdef TT_USE_BYTECODE_INTERPRETER

    FT_Error  error;
    FT_ULong  table_len;


    FT_TRACE2(( "Prep program " ));

    error = face->goto_table( face, TTAG_prep, stream, &table_len );
    if ( error )
    {
      face->cvt_program      = NULL;
      face->cvt_program_size = 0;
      error                  = TT_Err_Ok;

      FT_TRACE2(( "is missing!\n" ));
    }
    else
    {
      face->cvt_program_size = table_len;
      if ( FT_FRAME_EXTRACT( table_len, face->cvt_program ) )
        goto Exit;

      FT_TRACE2(( "loaded, %12d bytes\n", face->cvt_program_size ));
    }

  Exit:
    return error;

#else /* !TT_USE_BYTECODE_INTERPRETER */

    FT_UNUSED( face   );
    FT_UNUSED( stream );

    return TT_Err_Ok;

#endif
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_hdmx                                                  */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Load the `hdmx' table into the face object.                        */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face   :: A handle to the target face object.                      */
  /*                                                                       */
  /*    stream :: A handle to the input stream.                            */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */

  FT_LOCAL_DEF( FT_Error )
  tt_face_load_hdmx( TT_Face    face,
                     FT_Stream  stream )
  {
    FT_Error   error;
    FT_Memory  memory = stream->memory;
    FT_UInt    version, nn, num_records;
    FT_ULong   table_size, record_size;
    FT_Byte*   p;
    FT_Byte*   limit;


    /* this table is optional */
    error = face->goto_table( face, TTAG_hdmx, stream, &table_size );
    if ( error || table_size < 8 )
      return TT_Err_Ok;

    if ( FT_FRAME_EXTRACT( table_size, face->hdmx_table ) )
      goto Exit;

    p     = face->hdmx_table;
    limit = p + table_size;

    version     = FT_NEXT_USHORT( p );
    num_records = FT_NEXT_USHORT( p );
    record_size = FT_NEXT_ULONG( p );

    /* The maximum number of bytes in an hdmx device record is the */
    /* maximum number of glyphs + 2; this is 0xFFFF + 2; this is   */
    /* the reason why `record_size' is a long (which we read as    */
    /* unsigned long for convenience).  In practice, two bytes     */
    /* sufficient to hold the size value.                          */
    /*                                                             */
    /* There are at least two fonts, HANNOM-A and HANNOM-B version */
    /* 2.0 (2005), which get this wrong: The upper two bytes of    */
    /* the size value are set to 0xFF instead of 0x00.  We catch   */
    /* and fix this.                                               */

    if ( record_size >= 0xFFFF0000UL )
      record_size &= 0xFFFFU;

    /* The limit for `num_records' is a heuristic value. */

    if ( version != 0 || num_records > 255 || record_size > 0x10001L )
    {
      error = TT_Err_Invalid_File_Format;
      goto Fail;
    }

    if ( FT_NEW_ARRAY( face->hdmx_record_sizes, num_records ) )
      goto Fail;

    for ( nn = 0; nn < num_records; nn++ )
    {
      if ( p + record_size > limit )
        break;

      face->hdmx_record_sizes[nn] = p[0];
      p                          += record_size;
    }

    face->hdmx_record_count = nn;
    face->hdmx_table_size   = table_size;
    face->hdmx_record_size  = record_size;

  Exit:
    return error;

  Fail:
    FT_FRAME_RELEASE( face->hdmx_table );
    face->hdmx_table_size = 0;
    goto Exit;
  }


  FT_LOCAL_DEF( void )
  tt_face_free_hdmx( TT_Face  face )
  {
    FT_Stream  stream = face->root.stream;
    FT_Memory  memory = stream->memory;


    FT_FREE( face->hdmx_record_sizes );
    FT_FRAME_RELEASE( face->hdmx_table );
  }


  /*************************************************************************/
  /*                                                                       */
  /* Return the advance width table for a given pixel size if it is found  */
  /* in the font's `hdmx' table (if any).                                  */
  /*                                                                       */
  FT_LOCAL_DEF( FT_Byte* )
  tt_face_get_device_metrics( TT_Face  face,
                              FT_UInt  ppem,
                              FT_UInt  gindex )
  {
    FT_UInt   nn;
    FT_Byte*  result      = NULL;
    FT_ULong  record_size = face->hdmx_record_size;
    FT_Byte*  record      = face->hdmx_table + 8;


    for ( nn = 0; nn < face->hdmx_record_count; nn++ )
      if ( face->hdmx_record_sizes[nn] == ppem )
      {
        gindex += 2;
        if ( gindex < record_size )
          result = record + nn * record_size + gindex;
        break;
      }

    return result;
  }


/* END */