ttload.c

a very goog book

                                              face ));

    if ( vertical )
    {
      /* The table is optional, quit silently if it wasn't found       */
      /*                                                               */
      /* XXX: Some fonts have a valid vertical header with a non-null  */
      /*      `number_of_VMetrics' fields, but no corresponding `vmtx' */
      /*      table to get the metrics from (e.g. mingliu).            */
      /*                                                               */
      /*      For safety, we set the field to 0!                       */
      /*                                                               */
      error = face->goto_table( face, TTAG_vmtx, stream, &table_len );
      if ( error )
      {
        /* Set number_Of_VMetrics to 0! */
        FT_TRACE2(( "  no vertical header in file.\n" ));
        face->vertical.number_Of_VMetrics = 0;
        error = SFNT_Err_Ok;
        goto Exit;
      }

      num_longs = face->vertical.number_Of_VMetrics;
      longs     = (TT_LongMetrics *)&face->vertical.long_metrics;
      shorts    = (TT_ShortMetrics**)&face->vertical.short_metrics;
    }
    else
    {
      error = face->goto_table( face, TTAG_hmtx, stream, &table_len );
      if ( error )
      {
        FT_ERROR(( " no horizontal metrics in file!\n" ));
        error = SFNT_Err_Hmtx_Table_Missing;
        goto Exit;
      }

      num_longs = face->horizontal.number_Of_HMetrics;
      longs     = (TT_LongMetrics *)&face->horizontal.long_metrics;
      shorts    = (TT_ShortMetrics**)&face->horizontal.short_metrics;
    }

    /* never trust derived values */

    num_shorts         = face->max_profile.numGlyphs - num_longs;
    num_shorts_checked = ( table_len - num_longs * 4L ) / 2;

    if ( num_shorts < 0 )
    {
      FT_ERROR(( "TT_Load_%s_Metrics: more metrics than glyphs!\n",
                 vertical ? "Vertical"
                          : "Horizontal" ));

      error = vertical ? SFNT_Err_Invalid_Vert_Metrics
                       : SFNT_Err_Invalid_Horiz_Metrics;
      goto Exit;
    }

    if ( FT_NEW_ARRAY( *longs,  num_longs  ) ||
         FT_NEW_ARRAY( *shorts, num_shorts ) )
      goto Exit;

    if ( FT_FRAME_ENTER( table_len ) )
      goto Exit;

    {
      TT_LongMetrics  cur   = *longs;
      TT_LongMetrics  limit = cur + num_longs;


      for ( ; cur < limit; cur++ )
      {
        cur->advance = FT_GET_USHORT();
        cur->bearing = FT_GET_SHORT();
      }
    }

    /* do we have an inconsistent number of metric values? */
    {
      TT_ShortMetrics*  cur   = *shorts;
      TT_ShortMetrics*  limit = cur + MIN( num_shorts, num_shorts_checked );


      for ( ; cur < limit; cur++ )
        *cur = FT_GET_SHORT();

      /* we fill up the missing left side bearings with the     */
      /* last valid value.  Since this will occur for buggy CJK */
      /* fonts usually only, nothing serious will happen        */
      if ( num_shorts > num_shorts_checked && num_shorts_checked > 0 )
      {
        FT_Short  val = (*shorts)[num_shorts_checked - 1];


        limit = *shorts + num_shorts;
        for ( ; cur < limit; cur++ )
          *cur = val;
      }
    }

    FT_FRAME_EXIT();

    FT_TRACE2(( "loaded\n" ));

  Exit:
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    TT_Load_Metrics_Header                                             */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the horizontal or vertical header in a face object.          */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face     :: A handle to the target face object.                    */
  /*                                                                       */
  /*    stream   :: The input stream.                                      */
  /*                                                                       */
  /*    vertical :: A boolean flag.  If set, load vertical metrics.        */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_LOCAL_DEF( FT_Error )
  TT_Load_Metrics_Header( TT_Face    face,
                          FT_Stream  stream,
                          FT_Bool    vertical )
  {
    FT_Error        error;
    TT_HoriHeader*  header;

    const FT_Frame_Field  metrics_header_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_HoriHeader

      FT_FRAME_START( 36 ),
        FT_FRAME_ULONG ( Version ),
        FT_FRAME_SHORT ( Ascender ),
        FT_FRAME_SHORT ( Descender ),
        FT_FRAME_SHORT ( Line_Gap ),
        FT_FRAME_USHORT( advance_Width_Max ),
        FT_FRAME_SHORT ( min_Left_Side_Bearing ),
        FT_FRAME_SHORT ( min_Right_Side_Bearing ),
        FT_FRAME_SHORT ( xMax_Extent ),
        FT_FRAME_SHORT ( caret_Slope_Rise ),
        FT_FRAME_SHORT ( caret_Slope_Run ),
        FT_FRAME_SHORT ( caret_Offset ),
        FT_FRAME_SHORT ( Reserved[0] ),
        FT_FRAME_SHORT ( Reserved[1] ),
        FT_FRAME_SHORT ( Reserved[2] ),
        FT_FRAME_SHORT ( Reserved[3] ),
        FT_FRAME_SHORT ( metric_Data_Format ),
        FT_FRAME_USHORT( number_Of_HMetrics ),
      FT_FRAME_END
    };


    FT_TRACE2(( vertical ? "Vertical header " : "Horizontal header " ));

    if ( vertical )
    {
      face->vertical_info = 0;

      /* The vertical header table is optional, so return quietly if */
      /* we don't find it.                                           */
      error = face->goto_table( face, TTAG_vhea, stream, 0 );
      if ( error )
      {
        error = SFNT_Err_Ok;
        goto Exit;
      }

      face->vertical_info = 1;
      header = (TT_HoriHeader*)&face->vertical;
    }
    else
    {
      /* The horizontal header is mandatory; return an error if we */
      /* don't find it.                                            */
      error = face->goto_table( face, TTAG_hhea, stream, 0 );
      if ( error )
      {
        error = SFNT_Err_Horiz_Header_Missing;
        goto Exit;
      }

      header = &face->horizontal;
    }

    if ( FT_STREAM_READ_FIELDS( metrics_header_fields, header ) )
      goto Exit;

    header->long_metrics  = NULL;
    header->short_metrics = NULL;

    FT_TRACE2(( "loaded\n" ));

    /* Now try to load the corresponding metrics */

    error = TT_Load_Metrics( face, stream, vertical );

  Exit:
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    TT_Load_Names                                                      */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the name records.                                            */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face   :: A handle to the target face object.                      */
  /*                                                                       */
  /*    stream :: The input stream.                                        */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_LOCAL_DEF( FT_Error )
  TT_Load_Names( TT_Face    face,
                 FT_Stream  stream )
  {
    FT_Error      error;
    FT_Memory     memory = stream->memory;
    FT_ULong      table_pos, table_len;
    FT_ULong      storage_start, storage_limit;
    FT_UInt       count;
    TT_NameTable  table;

    static const FT_Frame_Field  name_table_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_NameTableRec

      FT_FRAME_START( 6 ),
        FT_FRAME_USHORT( format ),
        FT_FRAME_USHORT( numNameRecords ),
        FT_FRAME_USHORT( storageOffset ),
      FT_FRAME_END
    };

    static const FT_Frame_Field  name_record_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_NameEntryRec

      /* no FT_FRAME_START */
        FT_FRAME_USHORT( platformID ),
        FT_FRAME_USHORT( encodingID ),
        FT_FRAME_USHORT( languageID ),
        FT_FRAME_USHORT( nameID ),
        FT_FRAME_USHORT( stringLength ),
        FT_FRAME_USHORT( stringOffset ),
      FT_FRAME_END
    };


    table         = &face->name_table;
    table->stream = stream;

    FT_TRACE2(( "Names " ));

    error = face->goto_table( face, TTAG_name, stream, &table_len );
    if ( error )
    {
      /* The name table is required so indicate failure. */
      FT_TRACE2(( "is missing!\n" ));
      error = SFNT_Err_Name_Table_Missing;
      goto Exit;
    }

    table_pos = FT_STREAM_POS();


    if ( FT_STREAM_READ_FIELDS( name_table_fields, table ) )
      goto Exit;

    /* Some popular asian fonts have an invalid `storageOffset' value   */
    /* (it should be at least "6 + 12*num_names").  However, the string */
    /* offsets, computed as "storageOffset + entry->stringOffset", are  */
    /* valid pointers within the name table...                          */
    /*                                                                  */
    /* We thus can't check `storageOffset' right now.                   */
    /*                                                                  */
    storage_start = table_pos + 6 + 12*table->numNameRecords;
    storage_limit = table_pos + table_len;

    if ( storage_start > storage_limit )
    {
      FT_ERROR(( "TT_Load_Names: invalid `name' table\n" ));
      error = SFNT_Err_Name_Table_Missing;
      goto Exit;
    }

    /* Allocate the array of name records. */
    count                 = table->numNameRecords;
    table->numNameRecords = 0;

    if ( FT_NEW_ARRAY( table->names, count ) ||
         FT_FRAME_ENTER( count * 12 )        )
      goto Exit;

    /* Load the name records and determine how much storage is needed */
    /* to hold the strings themselves.                                */
    {
      TT_NameEntryRec*  entry = table->names;


      for ( ; count > 0; count-- )
      {
        if ( FT_STREAM_READ_FIELDS( name_record_fields, entry ) )
          continue;

        /* check that the name is not empty */
        if ( entry->stringLength == 0 )
          continue;

        /* check that the name string is within the table */
        entry->stringOffset += table_pos + table->storageOffset;
        if ( entry->stringOffset                       < storage_start ||
             entry->stringOffset + entry->stringLength > storage_limit )
        {
          /* invalid entry - ignore it */
          entry->stringOffset = 0;
          entry->stringLength = 0;
          continue;
        }

        entry++;
      }

      table->numNameRecords = entry - table->names;
    }

    FT_FRAME_EXIT();

    FT_TRACE2(( "loaded\n" ));

    /* everything went well, update face->num_names */
    face->num_names = (FT_UShort) table->numNameRecords;

  Exit:
    return error;
  }