src/ftglue.h

   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_Byte*)stream->cursor)-2) << 8) | \
  73                                  *(((FT_Byte*)stream->cursor)-1) \
  74                          ))
  75 #define  GET_Long()      (stream->cursor += 4, (FT_Long)( \
  76                                 (*(((FT_Byte*)stream->cursor)-4) << 24) | \
  77                                 (*(((FT_Byte*)stream->cursor)-3) << 16) | \
  78                                 (*(((FT_Byte*)stream->cursor)-2) << 8) | \
  79                                  *(((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__ */