ftglue.h revision 2c393a42 
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
51FT_BEGIN_HEADER
52
53
54/* utility macros */
55#define  TT_Err_Ok                   FT_Err_Ok
56#define  TT_Err_Invalid_Argument     FT_Err_Invalid_Argument
57#define  TT_Err_Invalid_Face_Handle  FT_Err_Invalid_Face_Handle
58#define  TT_Err_Table_Missing        FT_Err_Table_Missing
59
60#define  SET_ERR(c)   ( (error = (c)) != 0 )
61
62#ifndef FTGLUE_API
63#define FTGLUE_API(x)  extern FcPrivate x
64#endif
65
66#ifndef FTGLUE_APIDEF
67#define FTGLUE_APIDEF(x)  x
68#endif
69
70/* stream macros used by the OpenType parser */
71#define  FILE_Pos()      ftglue_stream_pos( stream )
72#define  FILE_Seek(pos)  SET_ERR( ftglue_stream_seek( stream, pos ) )
73#define  ACCESS_Frame(size)  SET_ERR( ftglue_stream_frame_enter( stream, size ) )
74#define  FORGET_Frame()      ftglue_stream_frame_exit( stream )
75
76#define  GET_Byte()      (*stream->cursor++)
77#define  GET_Short()     (stream->cursor += 2, (FT_Short)( \
78				(*(((FT_Byte*)stream->cursor)-2) << 8) | \
79				 *(((FT_Byte*)stream->cursor)-1) \
80			 ))
81#define  GET_Long()      (stream->cursor += 4, (FT_Long)( \
82				(*(((FT_Byte*)stream->cursor)-4) << 24) | \
83				(*(((FT_Byte*)stream->cursor)-3) << 16) | \
84				(*(((FT_Byte*)stream->cursor)-2) << 8) | \
85				 *(((FT_Byte*)stream->cursor)-1) \
86			 ))
87
88#define  GET_Char()      ((FT_Char)GET_Byte())
89#define  GET_UShort()    ((FT_UShort)GET_Short())
90#define  GET_ULong()     ((FT_ULong)GET_Long())
91#define  GET_Tag4()      GET_ULong()
92
93#define FT_SET_ERROR( expression ) \
94          ( ( error = (expression) ) != 0 )
95
96FTGLUE_API( FT_Long )
97ftglue_stream_pos( FT_Stream   stream );
98
99FTGLUE_API( FT_Error )
100ftglue_stream_seek( FT_Stream   stream,
101                    FT_Long     pos );
102
103FTGLUE_API( FT_Error )
104ftglue_stream_frame_enter( FT_Stream   stream,
105                           FT_ULong    size );
106
107FTGLUE_API( void )
108ftglue_stream_frame_exit( FT_Stream  stream );
109
110FTGLUE_API( FT_Byte )
111ftglue_stream_get_byte( FT_Stream  stream );
112
113FTGLUE_API( FT_Short )
114ftglue_stream_get_short( FT_Stream  stream );
115
116FTGLUE_API( FT_Long )
117ftglue_stream_get_long( FT_Stream   stream );
118
119FTGLUE_API( FT_Error )
120ftglue_face_goto_table( FT_Face    face,
121                        FT_ULong   tag,
122                        FT_Stream  stream );
123
124FTGLUE_API( FT_Pointer )
125ftglue_alloc( FT_Memory  memory,
126              FT_ULong   size,
127              FT_Error  *perror_ );
128
129FTGLUE_API( FT_Pointer )
130ftglue_realloc( FT_Memory   memory,
131                FT_Pointer  block,
132                FT_ULong    old_size,
133                FT_ULong    new_size,
134                FT_Error   *perror_ );
135
136FTGLUE_API( void )
137ftglue_free( FT_Memory   memory,
138             FT_Pointer  block );
139
140/* */
141
142FT_END_HEADER
143
144#endif /* __OPENTYPE_FTGLUE_H__ */
145