ftgasp.h revision ec0bab5697bb31ba980810145f62e3799946ec60 
1/***************************************************************************/
2/*                                                                         */
3/*  ftgasp.h                                                               */
4/*                                                                         */
5/*    Access of TrueType's `gasp' table (specification).                   */
6/*                                                                         */
7/*  Copyright 2007, 2008, 2011 by                                          */
8/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
9/*                                                                         */
10/*  This file is part of the FreeType project, and may only be used,       */
11/*  modified, and distributed under the terms of the FreeType project      */
12/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
13/*  this file you indicate that you have read the license and              */
14/*  understand and accept it fully.                                        */
15/*                                                                         */
16/***************************************************************************/
17
18
19#ifndef _FT_GASP_H_
20#define _FT_GASP_H_
21
22#include <ft2build.h>
23#include FT_FREETYPE_H
24
25#ifdef FREETYPE_H
26#error "freetype.h of FreeType 1 has been loaded!"
27#error "Please fix the directory search order for header files"
28#error "so that freetype.h of FreeType 2 is found first."
29#endif
30
31
32  /***************************************************************************
33   *
34   * @section:
35   *   gasp_table
36   *
37   * @title:
38   *   Gasp Table
39   *
40   * @abstract:
41   *   Retrieving TrueType `gasp' table entries.
42   *
43   * @description:
44   *   The function @FT_Get_Gasp can be used to query a TrueType or OpenType
45   *   font for specific entries in its `gasp' table, if any.  This is
46   *   mainly useful when implementing native TrueType hinting with the
47   *   bytecode interpreter to duplicate the Windows text rendering results.
48   */
49
50  /*************************************************************************
51   *
52   * @enum:
53   *   FT_GASP_XXX
54   *
55   * @description:
56   *   A list of values and/or bit-flags returned by the @FT_Get_Gasp
57   *   function.
58   *
59   * @values:
60   *   FT_GASP_NO_TABLE ::
61   *     This special value means that there is no GASP table in this face.
62   *     It is up to the client to decide what to do.
63   *
64   *   FT_GASP_DO_GRIDFIT ::
65   *     Grid-fitting and hinting should be performed at the specified ppem.
66   *     This *really* means TrueType bytecode interpretation.  If this bit
67   *     is not set, no hinting gets applied.
68   *
69   *   FT_GASP_DO_GRAY ::
70   *     Anti-aliased rendering should be performed at the specified ppem.
71   *     If not set, do monochrome rendering.
72   *
73   *   FT_GASP_SYMMETRIC_SMOOTHING ::
74   *     If set, smoothing along multiple axes must be used with ClearType.
75   *
76   *   FT_GASP_SYMMETRIC_GRIDFIT ::
77   *     Grid-fitting must be used with ClearType's symmetric smoothing.
78   *
79   * @note:
80   *   The bit-flags `FT_GASP_DO_GRIDFIT' and `FT_GASP_DO_GRAY' are to be
81   *   used for standard font rasterization only.  Independently of that,
82   *   `FT_GASP_SYMMETRIC_SMOOTHING' and `FT_GASP_SYMMETRIC_GRIDFIT' are to
83   *   be used if ClearType is enabled (and `FT_GASP_DO_GRIDFIT' and
84   *   `FT_GASP_DO_GRAY' are consequently ignored).
85   *
86   *   `ClearType' is Microsoft's implementation of LCD rendering, partly
87   *   protected by patents.
88   *
89   * @since:
90   *   2.3.0
91   */
92#define FT_GASP_NO_TABLE               -1
93#define FT_GASP_DO_GRIDFIT           0x01
94#define FT_GASP_DO_GRAY              0x02
95#define FT_GASP_SYMMETRIC_SMOOTHING  0x08
96#define FT_GASP_SYMMETRIC_GRIDFIT    0x10
97
98
99  /*************************************************************************
100   *
101   * @func:
102   *   FT_Get_Gasp
103   *
104   * @description:
105   *   Read the `gasp' table from a TrueType or OpenType font file and
106   *   return the entry corresponding to a given character pixel size.
107   *
108   * @input:
109   *   face :: The source face handle.
110   *   ppem :: The vertical character pixel size.
111   *
112   * @return:
113   *   Bit flags (see @FT_GASP_XXX), or @FT_GASP_NO_TABLE if there is no
114   *   `gasp' table in the face.
115   *
116   * @since:
117   *   2.3.0
118   */
119  FT_EXPORT( FT_Int )
120  FT_Get_Gasp( FT_Face  face,
121               FT_UInt  ppem );
122
123/* */
124
125#endif /* _FT_GASP_H_ */
126
127
128/* END */
129