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 <ft2build.h>
  47 #include FT_FREETYPE_H
  48
  49 FT_BEGIN_HEADER
  50
  51
  52 /* utility macros */
  53 #define  TT_Err_Ok                   FT_Err_Ok
  54 #define  TT_Err_Invalid_Argument     FT_Err_Invalid_Argument
  55 #define  TT_Err_Invalid_Face_Handle  FT_Err_Invalid_Face_Handle
  56 #define  TT_Err_Table_Missing        FT_Err_Table_Missing
  57
  58 #define  SET_ERR(c)   ( (error = (c)) != 0 )
  59
  60 #ifndef FTGLUE_API
  61 #define FTGLUE_API(x)  extern x
  62 #endif
  63
  64 #ifndef FTGLUE_APIDEF
  65 #define FTGLUE_APIDEF(x)  x
  66 #endif
  67
  68 /* stream macros used by the OpenType parser */
  69 #define  FILE_Pos()      ftglue_stream_pos( stream )
  70 #define  FILE_Seek(pos)  SET_ERR( ftglue_stream_seek( stream, pos ) )
  71 #define  ACCESS_Frame(size)  SET_ERR( ftglue_stream_frame_enter( stream, size ) )
  72 #define  FORGET_Frame()      ftglue_stream_frame_exit( stream )
  73
  74 #define  GET_Byte()      (*stream->cursor++)
  75 #define  GET_Short()     (stream->cursor += 2, (FT_Short)( \
  76                                 (*(((FT_Byte*)stream->cursor)-2) << 8) | \
  77                                  *(((FT_Byte*)stream->cursor)-1) \
  78                          ))
  79 #define  GET_Long()      (stream->cursor += 4, (FT_Long)( \
  80                                 (*(((FT_Byte*)stream->cursor)-4) << 24) | \
  81                                 (*(((FT_Byte*)stream->cursor)-3) << 16) | \
  82                                 (*(((FT_Byte*)stream->cursor)-2) << 8) | \
  83                                  *(((FT_Byte*)stream->cursor)-1) \
  84                          ))
  85
  86 #define  GET_Char()      ((FT_Char)GET_Byte())
  87 #define  GET_UShort()    ((FT_UShort)GET_Short())
  88 #define  GET_ULong()     ((FT_ULong)GET_Long())
  89 #define  GET_Tag4()      GET_ULong()
  90
  91 #define FT_SET_ERROR( expression ) \
  92           ( ( error = (expression) ) != 0 )
  93
  94 FTGLUE_API( FT_Long )
  95 ftglue_stream_pos( FT_Stream   stream );
  96
  97 FTGLUE_API( FT_Error )
  98 ftglue_stream_seek( FT_Stream   stream,
  99                     FT_Long     pos );
 100
 101 FTGLUE_API( FT_Error )
 102 ftglue_stream_frame_enter( FT_Stream   stream,
 103                            FT_ULong    size );
 104
 105 FTGLUE_API( void )
 106 ftglue_stream_frame_exit( FT_Stream  stream );
 107
 108 FTGLUE_API( FT_Byte )
 109 ftglue_stream_get_byte( FT_Stream  stream );
 110
 111 FTGLUE_API( FT_Short )
 112 ftglue_stream_get_short( FT_Stream  stream );
 113
 114 FTGLUE_API( FT_Long )
 115 ftglue_stream_get_long( FT_Stream   stream );
 116
 117 FTGLUE_API( FT_Error )
 118 ftglue_face_goto_table( FT_Face    face,
 119                         FT_ULong   tag,
 120                         FT_Stream  stream );
 121
 122 FTGLUE_API( FT_Pointer )
 123 ftglue_alloc( FT_Memory  memory,
 124               FT_ULong   size,
 125               FT_Error  *perror_ );
 126
 127 FTGLUE_API( FT_Pointer )
 128 ftglue_realloc( FT_Memory   memory,
 129                 FT_Pointer  block,
 130                 FT_ULong    old_size,
 131                 FT_ULong    new_size,
 132                 FT_Error   *perror_ );
 133
 134 FTGLUE_API( void )
 135 ftglue_free( FT_Memory   memory,
 136              FT_Pointer  block );
 137
 138 /* */
 139
 140 FT_END_HEADER
 141
 142 #endif /* __OPENTYPE_FTGLUE_H__ */