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FreeType on OpenGL ES (iPhone)

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24 Nov 2010CPOL4 min read 86.8K   3K   27  
Faster, smarter and better looking fonts rendered with OpenGL ES
/***************************************************************************/
/*                                                                         */
/*  ttload.c                                                               */
/*                                                                         */
/*    Load the basic TrueType tables, i.e., tables that can be either in   */
/*    TTF or OTF fonts (body).                                             */
/*                                                                         */
/*  Copyright 1996-2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,   */
/*            2010 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.                                        */
/*                                                                         */
/***************************************************************************/


#include <ft2build.h>
#include FT_INTERNAL_DEBUG_H
#include FT_INTERNAL_STREAM_H
#include FT_TRUETYPE_TAGS_H
#include "ttload.h"

#include "sferrors.h"


  /*************************************************************************/
  /*                                                                       */
  /* The macro FT_COMPONENT is used in trace mode.  It is an implicit      */
  /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log  */
  /* messages during execution.                                            */
  /*                                                                       */
#undef  FT_COMPONENT
#define FT_COMPONENT  trace_ttload


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_lookup_table                                               */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Looks for a TrueType table by name.                                */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face :: A face object handle.                                      */
  /*                                                                       */
  /*    tag  :: The searched tag.                                          */
  /*                                                                       */
  /* <Return>                                                              */
  /*    A pointer to the table directory entry.  0 if not found.           */
  /*                                                                       */
  FT_LOCAL_DEF( TT_Table  )
  tt_face_lookup_table( TT_Face   face,
                        FT_ULong  tag  )
  {
    TT_Table  entry;
    TT_Table  limit;
#ifdef FT_DEBUG_LEVEL_TRACE
    FT_Bool   zero_length = FALSE;
#endif


    FT_TRACE4(( "tt_face_lookup_table: %08p, `%c%c%c%c' -- ",
                face,
                (FT_Char)( tag >> 24 ),
                (FT_Char)( tag >> 16 ),
                (FT_Char)( tag >> 8  ),
                (FT_Char)( tag       ) ));

    entry = face->dir_tables;
    limit = entry + face->num_tables;

    for ( ; entry < limit; entry++ )
    {
      /* For compatibility with Windows, we consider    */
      /* zero-length tables the same as missing tables. */
      if ( entry->Tag == tag )
      {
        if ( entry->Length != 0 )
        {
          FT_TRACE4(( "found table.\n" ));
          return entry;
        }
#ifdef FT_DEBUG_LEVEL_TRACE
        zero_length = TRUE;
#endif
      }
    }

#ifdef FT_DEBUG_LEVEL_TRACE
    if ( zero_length )
      FT_TRACE4(( "ignoring empty table\n" ));
    else
      FT_TRACE4(( "could not find table\n" ));
#endif

    return NULL;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_goto_table                                                 */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Looks for a TrueType table by name, then seek a stream to it.      */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face   :: A face object handle.                                    */
  /*                                                                       */
  /*    tag    :: The searched tag.                                        */
  /*                                                                       */
  /*    stream :: The stream to seek when the table is found.              */
  /*                                                                       */
  /* <Output>                                                              */
  /*    length :: The length of the table if found, undefined otherwise.   */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_LOCAL_DEF( FT_Error )
  tt_face_goto_table( TT_Face    face,
                      FT_ULong   tag,
                      FT_Stream  stream,
                      FT_ULong*  length )
  {
    TT_Table  table;
    FT_Error  error;


    table = tt_face_lookup_table( face, tag );
    if ( table )
    {
      if ( length )
        *length = table->Length;

      if ( FT_STREAM_SEEK( table->Offset ) )
        goto Exit;
    }
    else
      error = SFNT_Err_Table_Missing;

  Exit:
    return error;
  }


  /* Here, we                                                         */
  /*                                                                  */
  /* - check that `num_tables' is valid (and adjust it if necessary)  */
  /*                                                                  */
  /* - look for a `head' table, check its size, and parse it to check */
  /*   whether its `magic' field is correctly set                     */
  /*                                                                  */
  /* - errors (except errors returned by stream handling)             */
  /*                                                                  */
  /*     SFNT_Err_Unknown_File_Format:                                */
  /*       no table is defined in directory, it is not sfnt-wrapped   */
  /*       data                                                       */
  /*     SFNT_Err_Table_Missing:                                      */
  /*       table directory is valid, but essential tables             */
  /*       (head/bhed/SING) are missing                               */
  /*                                                                  */
  static FT_Error
  check_table_dir( SFNT_Header  sfnt,
                   FT_Stream    stream )
  {
    FT_Error   error;
    FT_UShort  nn, valid_entries = 0;
    FT_UInt    has_head = 0, has_sing = 0, has_meta = 0;
    FT_ULong   offset = sfnt->offset + 12;

    static const FT_Frame_Field  table_dir_entry_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_TableRec

      FT_FRAME_START( 16 ),
        FT_FRAME_ULONG( Tag ),
        FT_FRAME_ULONG( CheckSum ),
        FT_FRAME_ULONG( Offset ),
        FT_FRAME_ULONG( Length ),
      FT_FRAME_END
    };


    if ( FT_STREAM_SEEK( offset ) )
      goto Exit;

    for ( nn = 0; nn < sfnt->num_tables; nn++ )
    {
      TT_TableRec  table;


      if ( FT_STREAM_READ_FIELDS( table_dir_entry_fields, &table ) )
      {
        nn--;
        FT_TRACE2(( "check_table_dir:"
                    " can read only %d table%s in font (instead of %d)\n",
                    nn, nn == 1 ? "" : "s", sfnt->num_tables ));
        sfnt->num_tables = nn;
        break;
      }

      /* we ignore invalid tables */
      if ( table.Offset + table.Length > stream->size )
      {
        FT_TRACE2(( "check_table_dir: table entry %d invalid\n", nn ));
        continue;
      }
      else
        valid_entries++;

      if ( table.Tag == TTAG_head || table.Tag == TTAG_bhed )
      {
        FT_UInt32  magic;


#ifndef TT_CONFIG_OPTION_EMBEDDED_BITMAPS
        if ( table.Tag == TTAG_head )
#endif
          has_head = 1;

        /*
         * The table length should be 0x36, but certain font tools make it
         * 0x38, so we will just check that it is greater.
         *
         * Note that according to the specification, the table must be
         * padded to 32-bit lengths, but this doesn't apply to the value of
         * its `Length' field!
         *
         */
        if ( table.Length < 0x36 )
        {
          FT_TRACE2(( "check_table_dir: `head' table too small\n" ));
          error = SFNT_Err_Table_Missing;
          goto Exit;
        }

        if ( FT_STREAM_SEEK( table.Offset + 12 ) ||
             FT_READ_ULONG( magic )              )
          goto Exit;

        if ( magic != 0x5F0F3CF5UL )
        {
          FT_TRACE2(( "check_table_dir:"
                      " no magic number found in `head' table\n"));
          error = SFNT_Err_Table_Missing;
          goto Exit;
        }

        if ( FT_STREAM_SEEK( offset + ( nn + 1 ) * 16 ) )
          goto Exit;
      }
      else if ( table.Tag == TTAG_SING )
        has_sing = 1;
      else if ( table.Tag == TTAG_META )
        has_meta = 1;
    }

    sfnt->num_tables = valid_entries;

    if ( sfnt->num_tables == 0 )
    {
      FT_TRACE2(( "check_table_dir: no tables found\n" ));
      error = SFNT_Err_Unknown_File_Format;
      goto Exit;
    }

    /* if `sing' and `meta' tables are present, there is no `head' table */
    if ( has_head || ( has_sing && has_meta ) )
    {
      error = SFNT_Err_Ok;
      goto Exit;
    }
    else
    {
      FT_TRACE2(( "check_table_dir:" ));
#ifdef TT_CONFIG_OPTION_EMBEDDED_BITMAPS
      FT_TRACE2(( " neither `head', `bhed', nor `sing' table found\n" ));
#else
      FT_TRACE2(( " neither `head' nor `sing' table found\n" ));
#endif
      error = SFNT_Err_Table_Missing;
    }

  Exit:
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_font_dir                                              */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the header of a SFNT font file.                              */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face       :: A handle to the target face object.                  */
  /*                                                                       */
  /*    stream     :: The input stream.                                    */
  /*                                                                       */
  /* <Output>                                                              */
  /*    sfnt       :: The SFNT header.                                     */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    The stream cursor must be at the beginning of the font directory.  */
  /*                                                                       */
  FT_LOCAL_DEF( FT_Error )
  tt_face_load_font_dir( TT_Face    face,
                         FT_Stream  stream )
  {
    SFNT_HeaderRec  sfnt;
    FT_Error        error;
    FT_Memory       memory = stream->memory;
    TT_TableRec*    entry;
    FT_Int          nn;

    static const FT_Frame_Field  offset_table_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  SFNT_HeaderRec

      FT_FRAME_START( 8 ),
        FT_FRAME_USHORT( num_tables ),
        FT_FRAME_USHORT( search_range ),
        FT_FRAME_USHORT( entry_selector ),
        FT_FRAME_USHORT( range_shift ),
      FT_FRAME_END
    };


    FT_TRACE2(( "tt_face_load_font_dir: %08p\n", face ));

    /* read the offset table */

    sfnt.offset = FT_STREAM_POS();

    if ( FT_READ_ULONG( sfnt.format_tag )                    ||
         FT_STREAM_READ_FIELDS( offset_table_fields, &sfnt ) )
      goto Exit;

    /* many fonts don't have these fields set correctly */
#if 0
    if ( sfnt.search_range != 1 << ( sfnt.entry_selector + 4 )        ||
         sfnt.search_range + sfnt.range_shift != sfnt.num_tables << 4 )
      return SFNT_Err_Unknown_File_Format;
#endif

    /* load the table directory */

    FT_TRACE2(( "-- Number of tables: %10u\n",    sfnt.num_tables ));
    FT_TRACE2(( "-- Format version:   0x%08lx\n", sfnt.format_tag ));

    /* check first */
    error = check_table_dir( &sfnt, stream );
    if ( error )
    {
      FT_TRACE2(( "tt_face_load_font_dir:"
                  " invalid table directory for TrueType\n" ));

      goto Exit;
    }

    face->num_tables = sfnt.num_tables;
    face->format_tag = sfnt.format_tag;

    if ( FT_QNEW_ARRAY( face->dir_tables, face->num_tables ) )
      goto Exit;

    if ( FT_STREAM_SEEK( sfnt.offset + 12 )       ||
         FT_FRAME_ENTER( face->num_tables * 16L ) )
      goto Exit;

    entry = face->dir_tables;

    for ( nn = 0; nn < sfnt.num_tables; nn++ )
    {
      entry->Tag      = FT_GET_TAG4();
      entry->CheckSum = FT_GET_ULONG();
      entry->Offset   = FT_GET_LONG();
      entry->Length   = FT_GET_LONG();

      /* ignore invalid tables */
      if ( entry->Offset + entry->Length > stream->size )
        continue;
      else
      {
        FT_TRACE2(( "  %c%c%c%c  -  %08lx  -  %08lx\n",
                    (FT_Char)( entry->Tag >> 24 ),
                    (FT_Char)( entry->Tag >> 16 ),
                    (FT_Char)( entry->Tag >> 8  ),
                    (FT_Char)( entry->Tag       ),
                    entry->Offset,
                    entry->Length ));
        entry++;
      }
    }

    FT_FRAME_EXIT();

    FT_TRACE2(( "table directory loaded\n\n" ));

  Exit:
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_any                                                   */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads any font table into client memory.                           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face   :: The face object to look for.                             */
  /*                                                                       */
  /*    tag    :: The tag of table to load.  Use the value 0 if you want   */
  /*              to access the whole font file, else set this parameter   */
  /*              to a valid TrueType table tag that you can forge with    */
  /*              the MAKE_TT_TAG macro.                                   */
  /*                                                                       */
  /*    offset :: The starting offset in the table (or the file if         */
  /*              tag == 0).                                               */
  /*                                                                       */
  /*    length :: The address of the decision variable:                    */
  /*                                                                       */
  /*                If length == NULL:                                     */
  /*                  Loads the whole table.  Returns an error if          */
  /*                  `offset' == 0!                                       */
  /*                                                                       */
  /*                If *length == 0:                                       */
  /*                  Exits immediately; returning the length of the given */
  /*                  table or of the font file, depending on the value of */
  /*                  `tag'.                                               */
  /*                                                                       */
  /*                If *length != 0:                                       */
  /*                  Loads the next `length' bytes of table or font,      */
  /*                  starting at offset `offset' (in table or font too).  */
  /*                                                                       */
  /* <Output>                                                              */
  /*    buffer :: The address of target buffer.                            */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_LOCAL_DEF( FT_Error )
  tt_face_load_any( TT_Face    face,
                    FT_ULong   tag,
                    FT_Long    offset,
                    FT_Byte*   buffer,
                    FT_ULong*  length )
  {
    FT_Error   error;
    FT_Stream  stream;
    TT_Table   table;
    FT_ULong   size;


    if ( tag != 0 )
    {
      /* look for tag in font directory */
      table = tt_face_lookup_table( face, tag );
      if ( !table )
      {
        error = SFNT_Err_Table_Missing;
        goto Exit;
      }

      offset += table->Offset;
      size    = table->Length;
    }
    else
      /* tag == 0 -- the user wants to access the font file directly */
      size = face->root.stream->size;

    if ( length && *length == 0 )
    {
      *length = size;

      return SFNT_Err_Ok;
    }

    if ( length )
      size = *length;

    stream = face->root.stream;
    /* the `if' is syntactic sugar for picky compilers */
    if ( FT_STREAM_READ_AT( offset, buffer, size ) )
      goto Exit;

  Exit:
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_generic_header                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the TrueType table `head' or `bhed'.                         */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face   :: A handle to the target face object.                      */
  /*                                                                       */
  /*    stream :: The input stream.                                        */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  static FT_Error
  tt_face_load_generic_header( TT_Face    face,
                               FT_Stream  stream,
                               FT_ULong   tag )
  {
    FT_Error    error;
    TT_Header*  header;

    static const FT_Frame_Field  header_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_Header

      FT_FRAME_START( 54 ),
        FT_FRAME_ULONG ( Table_Version ),
        FT_FRAME_ULONG ( Font_Revision ),
        FT_FRAME_LONG  ( CheckSum_Adjust ),
        FT_FRAME_LONG  ( Magic_Number ),
        FT_FRAME_USHORT( Flags ),
        FT_FRAME_USHORT( Units_Per_EM ),
        FT_FRAME_LONG  ( Created[0] ),
        FT_FRAME_LONG  ( Created[1] ),
        FT_FRAME_LONG  ( Modified[0] ),
        FT_FRAME_LONG  ( Modified[1] ),
        FT_FRAME_SHORT ( xMin ),
        FT_FRAME_SHORT ( yMin ),
        FT_FRAME_SHORT ( xMax ),
        FT_FRAME_SHORT ( yMax ),
        FT_FRAME_USHORT( Mac_Style ),
        FT_FRAME_USHORT( Lowest_Rec_PPEM ),
        FT_FRAME_SHORT ( Font_Direction ),
        FT_FRAME_SHORT ( Index_To_Loc_Format ),
        FT_FRAME_SHORT ( Glyph_Data_Format ),
      FT_FRAME_END
    };


    error = face->goto_table( face, tag, stream, 0 );
    if ( error )
      goto Exit;

    header = &face->header;

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

    FT_TRACE3(( "Units per EM: %4u\n", header->Units_Per_EM ));
    FT_TRACE3(( "IndexToLoc:   %4d\n", header->Index_To_Loc_Format ));

  Exit:
    return error;
  }


  FT_LOCAL_DEF( FT_Error )
  tt_face_load_head( TT_Face    face,
                     FT_Stream  stream )
  {
    return tt_face_load_generic_header( face, stream, TTAG_head );
  }


#ifdef TT_CONFIG_OPTION_EMBEDDED_BITMAPS

  FT_LOCAL_DEF( FT_Error )
  tt_face_load_bhed( TT_Face    face,
                     FT_Stream  stream )
  {
    return tt_face_load_generic_header( face, stream, TTAG_bhed );
  }

#endif /* TT_CONFIG_OPTION_EMBEDDED_BITMAPS */


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_max_profile                                           */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the maximum profile into a face object.                      */
  /*                                                                       */
  /* <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_face_load_maxp( TT_Face    face,
                     FT_Stream  stream )
  {
    FT_Error        error;
    TT_MaxProfile*  maxProfile = &face->max_profile;

    const FT_Frame_Field  maxp_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_MaxProfile

      FT_FRAME_START( 6 ),
        FT_FRAME_LONG  ( version ),
        FT_FRAME_USHORT( numGlyphs ),
      FT_FRAME_END
    };

    const FT_Frame_Field  maxp_fields_extra[] =
    {
      FT_FRAME_START( 26 ),
        FT_FRAME_USHORT( maxPoints ),
        FT_FRAME_USHORT( maxContours ),
        FT_FRAME_USHORT( maxCompositePoints ),
        FT_FRAME_USHORT( maxCompositeContours ),
        FT_FRAME_USHORT( maxZones ),
        FT_FRAME_USHORT( maxTwilightPoints ),
        FT_FRAME_USHORT( maxStorage ),
        FT_FRAME_USHORT( maxFunctionDefs ),
        FT_FRAME_USHORT( maxInstructionDefs ),
        FT_FRAME_USHORT( maxStackElements ),
        FT_FRAME_USHORT( maxSizeOfInstructions ),
        FT_FRAME_USHORT( maxComponentElements ),
        FT_FRAME_USHORT( maxComponentDepth ),
      FT_FRAME_END
    };


    error = face->goto_table( face, TTAG_maxp, stream, 0 );
    if ( error )
      goto Exit;

    if ( FT_STREAM_READ_FIELDS( maxp_fields, maxProfile ) )
      goto Exit;

    maxProfile->maxPoints             = 0;
    maxProfile->maxContours           = 0;
    maxProfile->maxCompositePoints    = 0;
    maxProfile->maxCompositeContours  = 0;
    maxProfile->maxZones              = 0;
    maxProfile->maxTwilightPoints     = 0;
    maxProfile->maxStorage            = 0;
    maxProfile->maxFunctionDefs       = 0;
    maxProfile->maxInstructionDefs    = 0;
    maxProfile->maxStackElements      = 0;
    maxProfile->maxSizeOfInstructions = 0;
    maxProfile->maxComponentElements  = 0;
    maxProfile->maxComponentDepth     = 0;

    if ( maxProfile->version >= 0x10000L )
    {
      if ( FT_STREAM_READ_FIELDS( maxp_fields_extra, maxProfile ) )
        goto Exit;

      /* XXX: an adjustment that is necessary to load certain */
      /*      broken fonts like `Keystrokes MT' :-(           */
      /*                                                      */
      /*   We allocate 64 function entries by default when    */
      /*   the maxFunctionDefs value is smaller.              */

      if ( maxProfile->maxFunctionDefs < 64 )
        maxProfile->maxFunctionDefs = 64;

      /* we add 4 phantom points later */
      if ( maxProfile->maxTwilightPoints > ( 0xFFFFU - 4 ) )
      {
        FT_TRACE0(( "tt_face_load_maxp:"
                    " too much twilight points in `maxp' table;\n"
                    "                  "
                    " some glyphs might be rendered incorrectly\n" ));

        maxProfile->maxTwilightPoints = 0xFFFFU - 4;
      }

      /* we arbitrarily limit recursion to avoid stack exhaustion */
      if ( maxProfile->maxComponentDepth > 100 )
      {
        FT_TRACE0(( "tt_face_load_maxp:"
                    " abnormally large component depth (%d) set to 100\n",
                    maxProfile->maxComponentDepth ));
        maxProfile->maxComponentDepth = 100;
      }
    }

    FT_TRACE3(( "numGlyphs: %u\n", maxProfile->numGlyphs ));

  Exit:
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_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_face_load_name( 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;

    error = face->goto_table( face, TTAG_name, stream, &table_len );
    if ( error )
      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_face_load_name: 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 = (FT_UInt)( entry - table->names );
    }

    FT_FRAME_EXIT();

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

  Exit:
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_free_names                                                 */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Frees the name records.                                            */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face :: A handle to the target face object.                        */
  /*                                                                       */
  FT_LOCAL_DEF( void )
  tt_face_free_name( TT_Face  face )
  {
    FT_Memory     memory = face->root.driver->root.memory;
    TT_NameTable  table  = &face->name_table;
    TT_NameEntry  entry  = table->names;
    FT_UInt       count  = table->numNameRecords;


    if ( table->names )
    {
      for ( ; count > 0; count--, entry++ )
      {
        FT_FREE( entry->string );
        entry->stringLength = 0;
      }

      /* free strings table */
      FT_FREE( table->names );
    }

    table->numNameRecords = 0;
    table->format         = 0;
    table->storageOffset  = 0;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_cmap                                                  */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the cmap directory in a face object.  The cmaps themselves   */
  /*    are loaded on demand in the `ttcmap.c' module.                     */
  /*                                                                       */
  /* <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_cmap( TT_Face    face,
                     FT_Stream  stream )
  {
    FT_Error  error;


    error = face->goto_table( face, TTAG_cmap, stream, &face->cmap_size );
    if ( error )
      goto Exit;

    if ( FT_FRAME_EXTRACT( face->cmap_size, face->cmap_table ) )
      face->cmap_size = 0;

  Exit:
    return error;
  }



  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_os2                                                   */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the OS2 table.                                               */
  /*                                                                       */
  /* <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_os2( TT_Face    face,
                    FT_Stream  stream )
  {
    FT_Error  error;
    TT_OS2*   os2;

    const FT_Frame_Field  os2_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_OS2

      FT_FRAME_START( 78 ),
        FT_FRAME_USHORT( version ),
        FT_FRAME_SHORT ( xAvgCharWidth ),
        FT_FRAME_USHORT( usWeightClass ),
        FT_FRAME_USHORT( usWidthClass ),
        FT_FRAME_SHORT ( fsType ),
        FT_FRAME_SHORT ( ySubscriptXSize ),
        FT_FRAME_SHORT ( ySubscriptYSize ),
        FT_FRAME_SHORT ( ySubscriptXOffset ),
        FT_FRAME_SHORT ( ySubscriptYOffset ),
        FT_FRAME_SHORT ( ySuperscriptXSize ),
        FT_FRAME_SHORT ( ySuperscriptYSize ),
        FT_FRAME_SHORT ( ySuperscriptXOffset ),
        FT_FRAME_SHORT ( ySuperscriptYOffset ),
        FT_FRAME_SHORT ( yStrikeoutSize ),
        FT_FRAME_SHORT ( yStrikeoutPosition ),
        FT_FRAME_SHORT ( sFamilyClass ),
        FT_FRAME_BYTE  ( panose[0] ),
        FT_FRAME_BYTE  ( panose[1] ),
        FT_FRAME_BYTE  ( panose[2] ),
        FT_FRAME_BYTE  ( panose[3] ),
        FT_FRAME_BYTE  ( panose[4] ),
        FT_FRAME_BYTE  ( panose[5] ),
        FT_FRAME_BYTE  ( panose[6] ),
        FT_FRAME_BYTE  ( panose[7] ),
        FT_FRAME_BYTE  ( panose[8] ),
        FT_FRAME_BYTE  ( panose[9] ),
        FT_FRAME_ULONG ( ulUnicodeRange1 ),
        FT_FRAME_ULONG ( ulUnicodeRange2 ),
        FT_FRAME_ULONG ( ulUnicodeRange3 ),
        FT_FRAME_ULONG ( ulUnicodeRange4 ),
        FT_FRAME_BYTE  ( achVendID[0] ),
        FT_FRAME_BYTE  ( achVendID[1] ),
        FT_FRAME_BYTE  ( achVendID[2] ),
        FT_FRAME_BYTE  ( achVendID[3] ),

        FT_FRAME_USHORT( fsSelection ),
        FT_FRAME_USHORT( usFirstCharIndex ),
        FT_FRAME_USHORT( usLastCharIndex ),
        FT_FRAME_SHORT ( sTypoAscender ),
        FT_FRAME_SHORT ( sTypoDescender ),
        FT_FRAME_SHORT ( sTypoLineGap ),
        FT_FRAME_USHORT( usWinAscent ),
        FT_FRAME_USHORT( usWinDescent ),
      FT_FRAME_END
    };

    const FT_Frame_Field  os2_fields_extra[] =
    {
      FT_FRAME_START( 8 ),
        FT_FRAME_ULONG( ulCodePageRange1 ),
        FT_FRAME_ULONG( ulCodePageRange2 ),
      FT_FRAME_END
    };

    const FT_Frame_Field  os2_fields_extra2[] =
    {
      FT_FRAME_START( 10 ),
        FT_FRAME_SHORT ( sxHeight ),
        FT_FRAME_SHORT ( sCapHeight ),
        FT_FRAME_USHORT( usDefaultChar ),
        FT_FRAME_USHORT( usBreakChar ),
        FT_FRAME_USHORT( usMaxContext ),
      FT_FRAME_END
    };


    /* We now support old Mac fonts where the OS/2 table doesn't  */
    /* exist.  Simply put, we set the `version' field to 0xFFFF   */
    /* and test this value each time we need to access the table. */
    error = face->goto_table( face, TTAG_OS2, stream, 0 );
    if ( error )
      goto Exit;

    os2 = &face->os2;

    if ( FT_STREAM_READ_FIELDS( os2_fields, os2 ) )
      goto Exit;

    os2->ulCodePageRange1 = 0;
    os2->ulCodePageRange2 = 0;
    os2->sxHeight         = 0;
    os2->sCapHeight       = 0;
    os2->usDefaultChar    = 0;
    os2->usBreakChar      = 0;
    os2->usMaxContext     = 0;

    if ( os2->version >= 0x0001 )
    {
      /* only version 1 tables */
      if ( FT_STREAM_READ_FIELDS( os2_fields_extra, os2 ) )
        goto Exit;

      if ( os2->version >= 0x0002 )
      {
        /* only version 2 tables */
        if ( FT_STREAM_READ_FIELDS( os2_fields_extra2, os2 ) )
          goto Exit;
      }
    }

    FT_TRACE3(( "sTypoAscender:  %4d\n",   os2->sTypoAscender ));
    FT_TRACE3(( "sTypoDescender: %4d\n",   os2->sTypoDescender ));
    FT_TRACE3(( "usWinAscent:    %4u\n",   os2->usWinAscent ));
    FT_TRACE3(( "usWinDescent:   %4u\n",   os2->usWinDescent ));
    FT_TRACE3(( "fsSelection:    0x%2x\n", os2->fsSelection ));

  Exit:
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_postscript                                            */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the Postscript table.                                        */
  /*                                                                       */
  /* <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_post( TT_Face    face,
                     FT_Stream  stream )
  {
    FT_Error        error;
    TT_Postscript*  post = &face->postscript;

    static const FT_Frame_Field  post_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_Postscript

      FT_FRAME_START( 32 ),
        FT_FRAME_ULONG( FormatType ),
        FT_FRAME_ULONG( italicAngle ),
        FT_FRAME_SHORT( underlinePosition ),
        FT_FRAME_SHORT( underlineThickness ),
        FT_FRAME_ULONG( isFixedPitch ),
        FT_FRAME_ULONG( minMemType42 ),
        FT_FRAME_ULONG( maxMemType42 ),
        FT_FRAME_ULONG( minMemType1 ),
        FT_FRAME_ULONG( maxMemType1 ),
      FT_FRAME_END
    };


    error = face->goto_table( face, TTAG_post, stream, 0 );
    if ( error )
      return error;

    if ( FT_STREAM_READ_FIELDS( post_fields, post ) )
      return error;

    /* we don't load the glyph names, we do that in another */
    /* module (ttpost).                                     */

    FT_TRACE3(( "FormatType:   0x%x\n", post->FormatType ));
    FT_TRACE3(( "isFixedPitch:   %s\n", post->isFixedPitch
                                        ? "  yes" : "   no" ));

    return SFNT_Err_Ok;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_pclt                                                  */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the PCL 5 Table.                                             */
  /*                                                                       */
  /* <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_pclt( TT_Face    face,
                     FT_Stream  stream )
  {
    static const FT_Frame_Field  pclt_fields[] =
    {
#undef  FT_STRUCTURE
#define FT_STRUCTURE  TT_PCLT

      FT_FRAME_START( 54 ),
        FT_FRAME_ULONG ( Version ),
        FT_FRAME_ULONG ( FontNumber ),
        FT_FRAME_USHORT( Pitch ),
        FT_FRAME_USHORT( xHeight ),
        FT_FRAME_USHORT( Style ),
        FT_FRAME_USHORT( TypeFamily ),
        FT_FRAME_USHORT( CapHeight ),
        FT_FRAME_BYTES ( TypeFace, 16 ),
        FT_FRAME_BYTES ( CharacterComplement, 8 ),
        FT_FRAME_BYTES ( FileName, 6 ),
        FT_FRAME_CHAR  ( StrokeWeight ),
        FT_FRAME_CHAR  ( WidthType ),
        FT_FRAME_BYTE  ( SerifStyle ),
        FT_FRAME_BYTE  ( Reserved ),
      FT_FRAME_END
    };

    FT_Error  error;
    TT_PCLT*  pclt = &face->pclt;


    /* optional table */
    error = face->goto_table( face, TTAG_PCLT, stream, 0 );
    if ( error )
      goto Exit;

    if ( FT_STREAM_READ_FIELDS( pclt_fields, pclt ) )
      goto Exit;

  Exit:
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_face_load_gasp                                                  */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads the `gasp' table into a face object.                         */
  /*                                                                       */
  /* <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_face_load_gasp( TT_Face    face,
                     FT_Stream  stream )
  {
    FT_Error   error;
    FT_Memory  memory = stream->memory;

    FT_UInt        j,num_ranges;
    TT_GaspRange   gaspranges;


    /* the gasp table is optional */
    error = face->goto_table( face, TTAG_gasp, stream, 0 );
    if ( error )
      goto Exit;

    if ( FT_FRAME_ENTER( 4L ) )
      goto Exit;

    face->gasp.version   = FT_GET_USHORT();
    face->gasp.numRanges = FT_GET_USHORT();

    FT_FRAME_EXIT();

    /* only support versions 0 and 1 of the table */
    if ( face->gasp.version >= 2 )
    {
      face->gasp.numRanges = 0;
      error = SFNT_Err_Invalid_Table;
      goto Exit;
    }

    num_ranges = face->gasp.numRanges;
    FT_TRACE3(( "numRanges: %u\n", num_ranges ));

    if ( FT_QNEW_ARRAY( gaspranges, num_ranges ) ||
         FT_FRAME_ENTER( num_ranges * 4L )      )
      goto Exit;

    face->gasp.gaspRanges = gaspranges;

    for ( j = 0; j < num_ranges; j++ )
    {
      gaspranges[j].maxPPEM  = FT_GET_USHORT();
      gaspranges[j].gaspFlag = FT_GET_USHORT();

      FT_TRACE3(( "gaspRange %d: rangeMaxPPEM %5d, rangeGaspBehavior 0x%x\n",
                  j,
                  gaspranges[j].maxPPEM,
                  gaspranges[j].gaspFlag ));
    }

    FT_FRAME_EXIT();

  Exit:
    return error;
  }


/* END */

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License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Software Developer Astronautz
Spain Spain
After working in the software industry for many years, I've started my own games company that specialises in strategy games for mobile platforms.

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