1  /* ftglue.c: Glue code for compiling the OpenType code from
       2   *           FreeType 1 using only the public API of FreeType 2
       3   *
       4   * By David Turner, The FreeType Project (www.freetype.org)
       5   *
       6   * This code is explicitely put in the public domain
       7   *
       8   * ==========================================================================
       9   *
      10   * the OpenType parser codes was originally written as an extension to
      11   * FreeType 1.x. As such, its source code was embedded within the library,
      12   * and used many internal FreeType functions to deal with memory and
      13   * stream i/o.
      14   *
      15   * When it was 'salvaged' for Pango and Qt, the code was "ported" to FreeType 2,
      16   * which basically means that some macro tricks were performed in order to
      17   * directly access FT2 _internal_ functions.
      18   *
      19   * these functions were never part of FT2 public API, and _did_ change between
      20   * various releases. This created chaos for many users: when they upgraded the
      21   * FreeType library on their system, they couldn't run Gnome anymore since
      22   * Pango refused to link.
      23   *
      24   * Very fortunately, it's possible to completely avoid this problem because
      25   * the FT_StreamRec and FT_MemoryRec structure types, which describe how
      26   * memory and stream implementations interface with the rest of the font
      27   * library, have always been part of the public API, and never changed.
      28   *
      29   * What we do thus is re-implement, within the OpenType parser, the few
      30   * functions that depend on them. This only adds one or two kilobytes of
      31   * code, and ensures that the parser can work with _any_ version
      32   * of FreeType installed on your system. How sweet... !
      33   *
      34   * Note that we assume that Pango doesn't use any other internal functions
      35   * from FreeType. It used to in old versions, but this should no longer
      36   * be the case. (crossing my fingers).
      37   *
      38   *  - David Turner
      39   *  - The FreeType Project  (www.freetype.org)
      40   *
      41   * PS: This "glue" code is explicitely put in the public domain
      42   */
      43  #ifndef __OPENTYPE_FTGLUE_H__
      44  #define __OPENTYPE_FTGLUE_H__
      45  
      46  #include "fcint.h"
      47  
      48  #include <ft2build.h>
      49  #include FT_FREETYPE_H
      50  
      51  FT_BEGIN_HEADER
      52  
      53  
      54  #define  SET_ERR(c)   ( (error = (c)) != 0 )
      55  
      56  #ifndef FTGLUE_API
      57  #define FTGLUE_API(x)  extern FcPrivate x
      58  #endif
      59  
      60  #ifndef FTGLUE_APIDEF
      61  #define FTGLUE_APIDEF(x)  x
      62  #endif
      63  
      64  /* stream macros used by the OpenType parser */
      65  #define  FILE_Pos()      ftglue_stream_pos( stream )
      66  #define  FILE_Seek(pos)  SET_ERR( ftglue_stream_seek( stream, pos ) )
      67  #define  ACCESS_Frame(size)  SET_ERR( ftglue_stream_frame_enter( stream, size ) )
      68  #define  FORGET_Frame()      ftglue_stream_frame_exit( stream )
      69  
      70  #define  GET_Byte()      (*stream->cursor++)
      71  #define  GET_Short()     (stream->cursor += 2, (FT_Short)( \
      72  				((FT_ULong)*(((FT_Byte*)stream->cursor)-2) << 8) | \
      73  				 (FT_ULong)*(((FT_Byte*)stream->cursor)-1) \
      74  			 ))
      75  #define  GET_Long()      (stream->cursor += 4, (FT_Long)( \
      76  				((FT_ULong)*(((FT_Byte*)stream->cursor)-4) << 24) | \
      77  				((FT_ULong)*(((FT_Byte*)stream->cursor)-3) << 16) | \
      78  				((FT_ULong)*(((FT_Byte*)stream->cursor)-2) << 8) | \
      79  				 (FT_ULong)*(((FT_Byte*)stream->cursor)-1) \
      80  			 ))
      81  
      82  #define  GET_Char()      ((FT_Char)GET_Byte())
      83  #define  GET_UShort()    ((FT_UShort)GET_Short())
      84  #define  GET_ULong()     ((FT_ULong)GET_Long())
      85  #define  GET_Tag4()      GET_ULong()
      86  
      87  #define FT_SET_ERROR( expression ) \
      88            ( ( error = (expression) ) != 0 )
      89  
      90  FTGLUE_API( FT_Long )
      91  ftglue_stream_pos( FT_Stream   stream );
      92  
      93  FTGLUE_API( FT_Error )
      94  ftglue_stream_seek( FT_Stream   stream,
      95                      FT_Long     pos );
      96  
      97  FTGLUE_API( FT_Error )
      98  ftglue_stream_frame_enter( FT_Stream   stream,
      99                             FT_ULong    size );
     100  
     101  FTGLUE_API( void )
     102  ftglue_stream_frame_exit( FT_Stream  stream );
     103  
     104  FTGLUE_API( FT_Error )
     105  ftglue_face_goto_table( FT_Face    face,
     106                          FT_ULong   tag,
     107                          FT_Stream  stream );
     108  
     109  FT_END_HEADER
     110  
     111  #endif /* __OPENTYPE_FTGLUE_H__ */