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ftadvanc.h
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1 /***************************************************************************/
2 /* */
3 /* ftadvanc.h */
4 /* */
5 /* Quick computation of advance widths (specification only). */
6 /* */
7 /* Copyright 2008-2018 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 FTADVANC_H_
20 #define FTADVANC_H_
21 
22 
23 #include <ft2build.h>
24 #include FT_FREETYPE_H
25 
26 #ifdef FREETYPE_H
27 #error "freetype.h of FreeType 1 has been loaded!"
28 #error "Please fix the directory search order for header files"
29 #error "so that freetype.h of FreeType 2 is found first."
30 #endif
31 
32 
33 FT_BEGIN_HEADER
34 
35 
36  /**************************************************************************
37  *
38  * @section:
39  * quick_advance
40  *
41  * @title:
42  * Quick retrieval of advance values
43  *
44  * @abstract:
45  * Retrieve horizontal and vertical advance values without processing
46  * glyph outlines, if possible.
47  *
48  * @description:
49  * This section contains functions to quickly extract advance values
50  * without handling glyph outlines, if possible.
51  *
52  * @order:
53  * FT_Get_Advance
54  * FT_Get_Advances
55  *
56  */
57 
58 
59  /*************************************************************************/
60  /* */
61  /* <Const> */
62  /* FT_ADVANCE_FLAG_FAST_ONLY */
63  /* */
64  /* <Description> */
65  /* A bit-flag to be OR-ed with the `flags' parameter of the */
66  /* @FT_Get_Advance and @FT_Get_Advances functions. */
67  /* */
68  /* If set, it indicates that you want these functions to fail if the */
69  /* corresponding hinting mode or font driver doesn't allow for very */
70  /* quick advance computation. */
71  /* */
72  /* Typically, glyphs that are either unscaled, unhinted, bitmapped, */
73  /* or light-hinted can have their advance width computed very */
74  /* quickly. */
75  /* */
76  /* Normal and bytecode hinted modes that require loading, scaling, */
77  /* and hinting of the glyph outline, are extremely slow by */
78  /* comparison. */
79  /* */
80 #define FT_ADVANCE_FLAG_FAST_ONLY 0x20000000L
81 
82 
83  /*************************************************************************/
84  /* */
85  /* <Function> */
86  /* FT_Get_Advance */
87  /* */
88  /* <Description> */
89  /* Retrieve the advance value of a given glyph outline in an */
90  /* @FT_Face. */
91  /* */
92  /* <Input> */
93  /* face :: The source @FT_Face handle. */
94  /* */
95  /* gindex :: The glyph index. */
96  /* */
97  /* load_flags :: A set of bit flags similar to those used when */
98  /* calling @FT_Load_Glyph, used to determine what kind */
99  /* of advances you need. */
100  /* <Output> */
101  /* padvance :: The advance value. If scaling is performed (based on */
102  /* the value of `load_flags'), the advance value is in */
103  /* 16.16 format. Otherwise, it is in font units. */
104  /* */
105  /* If @FT_LOAD_VERTICAL_LAYOUT is set, this is the */
106  /* vertical advance corresponding to a vertical layout. */
107  /* Otherwise, it is the horizontal advance in a */
108  /* horizontal layout. */
109  /* */
110  /* <Return> */
111  /* FreeType error code. 0 means success. */
112  /* */
113  /* <Note> */
114  /* This function may fail if you use @FT_ADVANCE_FLAG_FAST_ONLY and */
115  /* if the corresponding font backend doesn't have a quick way to */
116  /* retrieve the advances. */
117  /* */
118  /* A scaled advance is returned in 16.16 format but isn't transformed */
119  /* by the affine transformation specified by @FT_Set_Transform. */
120  /* */
121  FT_EXPORT( FT_Error )
122  FT_Get_Advance( FT_Face face,
123  FT_UInt gindex,
124  FT_Int32 load_flags,
125  FT_Fixed *padvance );
126 
127 
128  /*************************************************************************/
129  /* */
130  /* <Function> */
131  /* FT_Get_Advances */
132  /* */
133  /* <Description> */
134  /* Retrieve the advance values of several glyph outlines in an */
135  /* @FT_Face. */
136  /* */
137  /* <Input> */
138  /* face :: The source @FT_Face handle. */
139  /* */
140  /* start :: The first glyph index. */
141  /* */
142  /* count :: The number of advance values you want to retrieve. */
143  /* */
144  /* load_flags :: A set of bit flags similar to those used when */
145  /* calling @FT_Load_Glyph. */
146  /* */
147  /* <Output> */
148  /* padvance :: The advance values. This array, to be provided by the */
149  /* caller, must contain at least `count' elements. */
150  /* */
151  /* If scaling is performed (based on the value of */
152  /* `load_flags'), the advance values are in 16.16 format. */
153  /* Otherwise, they are in font units. */
154  /* */
155  /* If @FT_LOAD_VERTICAL_LAYOUT is set, these are the */
156  /* vertical advances corresponding to a vertical layout. */
157  /* Otherwise, they are the horizontal advances in a */
158  /* horizontal layout. */
159  /* */
160  /* <Return> */
161  /* FreeType error code. 0 means success. */
162  /* */
163  /* <Note> */
164  /* This function may fail if you use @FT_ADVANCE_FLAG_FAST_ONLY and */
165  /* if the corresponding font backend doesn't have a quick way to */
166  /* retrieve the advances. */
167  /* */
168  /* Scaled advances are returned in 16.16 format but aren't */
169  /* transformed by the affine transformation specified by */
170  /* @FT_Set_Transform. */
171  /* */
172  FT_EXPORT( FT_Error )
173  FT_Get_Advances( FT_Face face,
174  FT_UInt start,
175  FT_UInt count,
176  FT_Int32 load_flags,
177  FT_Fixed *padvances );
178 
179  /* */
180 
181 
182 FT_END_HEADER
183 
184 #endif /* FTADVANC_H_ */
185 
186 
187 /* END */
FT_Error
int FT_Error
Definition: fttypes.h:300
FT_END_HEADER
#define FT_END_HEADER
Definition: ftheader.h:54
count
GLuint GLuint GLsizei count
Definition: gl.h:1545
FT_BEGIN_HEADER
#define FT_BEGIN_HEADER
Definition: ftheader.h:36
FT_Get_Advance
FT_Get_Advance(FT_Face face, FT_UInt gindex, FT_Int32 load_flags, FT_Fixed *padvance)
Definition: ftadvanc.c:75
FT_Get_Advances
FT_Get_Advances(FT_Face face, FT_UInt start, FT_UInt count, FT_Int32 load_flags, FT_Fixed *padvances)
Definition: ftadvanc.c:113
FT_Fixed
signed long FT_Fixed
Definition: fttypes.h:288
FT_UInt
unsigned int FT_UInt
Definition: fttypes.h:231
start
GLuint start
Definition: gl.h:1545
FT_EXPORT
#define FT_EXPORT(x)
Definition: ftconfig.h:461
FT_FaceRec_
Definition: freetype.h:1068
face
GLenum GLuint GLint GLenum face
Definition: glext.h:7025