1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
|
/****************************************************************************
*
* ftgasp.h
*
* Access of TrueType's 'gasp' table (specification).
*
* Copyright (C) 2007-2019 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.
*
*/
#ifndef FTGASP_H_
#define FTGASP_H_
#include <ft2build.h>
#include FT_FREETYPE_H
#ifdef FREETYPE_H
#error "freetype.h of FreeType 1 has been loaded!"
#error "Please fix the directory search order for header files"
#error "so that freetype.h of FreeType 2 is found first."
#endif
FT_BEGIN_HEADER
/**************************************************************************
*
* @section:
* gasp_table
*
* @title:
* Gasp Table
*
* @abstract:
* Retrieving TrueType 'gasp' table entries.
*
* @description:
* The function @FT_Get_Gasp can be used to query a TrueType or OpenType
* font for specific entries in its 'gasp' table, if any. This is mainly
* useful when implementing native TrueType hinting with the bytecode
* interpreter to duplicate the Windows text rendering results.
*/
/**************************************************************************
*
* @enum:
* FT_GASP_XXX
*
* @description:
* A list of values and/or bit-flags returned by the @FT_Get_Gasp
* function.
*
* @values:
* FT_GASP_NO_TABLE ::
* This special value means that there is no GASP table in this face.
* It is up to the client to decide what to do.
*
* FT_GASP_DO_GRIDFIT ::
* Grid-fitting and hinting should be performed at the specified ppem.
* This **really** means TrueType bytecode interpretation. If this bit
* is not set, no hinting gets applied.
*
* FT_GASP_DO_GRAY ::
* Anti-aliased rendering should be performed at the specified ppem.
* If not set, do monochrome rendering.
*
* FT_GASP_SYMMETRIC_SMOOTHING ::
* If set, smoothing along multiple axes must be used with ClearType.
*
* FT_GASP_SYMMETRIC_GRIDFIT ::
* Grid-fitting must be used with ClearType's symmetric smoothing.
*
* @note:
* The bit-flags `FT_GASP_DO_GRIDFIT` and `FT_GASP_DO_GRAY` are to be
* used for standard font rasterization only. Independently of that,
* `FT_GASP_SYMMETRIC_SMOOTHING` and `FT_GASP_SYMMETRIC_GRIDFIT` are to
* be used if ClearType is enabled (and `FT_GASP_DO_GRIDFIT` and
* `FT_GASP_DO_GRAY` are consequently ignored).
*
* 'ClearType' is Microsoft's implementation of LCD rendering, partly
* protected by patents.
*
* @since:
* 2.3.0
*/
#define FT_GASP_NO_TABLE -1
#define FT_GASP_DO_GRIDFIT 0x01
#define FT_GASP_DO_GRAY 0x02
#define FT_GASP_SYMMETRIC_GRIDFIT 0x04
#define FT_GASP_SYMMETRIC_SMOOTHING 0x08
/**************************************************************************
*
* @function:
* FT_Get_Gasp
*
* @description:
* For a TrueType or OpenType font file, return the rasterizer behaviour
* flags from the font's 'gasp' table corresponding to a given character
* pixel size.
*
* @input:
* face ::
* The source face handle.
*
* ppem ::
* The vertical character pixel size.
*
* @return:
* Bit flags (see @FT_GASP_XXX), or @FT_GASP_NO_TABLE if there is no
* 'gasp' table in the face.
*
* @note:
* If you want to use the MM functionality of OpenType variation fonts
* (i.e., using @FT_Set_Var_Design_Coordinates and friends), call this
* function **after** setting an instance since the return values can
* change.
*
* @since:
* 2.3.0
*/
FT_EXPORT( FT_Int )
FT_Get_Gasp( FT_Face face,
FT_UInt ppem );
/* */
FT_END_HEADER
#endif /* FTGASP_H_ */
/* END */
|
