zenilib  0.5.3.0
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Properties Friends Macros Groups Pages
autohint.h
Go to the documentation of this file.
1 /***************************************************************************/
2 /* */
3 /* autohint.h */
4 /* */
5 /* High-level `autohint' module-specific interface (specification). */
6 /* */
7 /* Copyright 1996-2001, 2002, 2007 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  /*************************************************************************/
20  /* */
21  /* The auto-hinter is used to load and automatically hint glyphs if a */
22  /* format-specific hinter isn't available. */
23  /* */
24  /*************************************************************************/
25 
26 
27 #ifndef __AUTOHINT_H__
28 #define __AUTOHINT_H__
29 
30 
31  /*************************************************************************/
32  /* */
33  /* A small technical note regarding automatic hinting in order to */
34  /* clarify this module interface. */
35  /* */
36  /* An automatic hinter might compute two kinds of data for a given face: */
37  /* */
38  /* - global hints: Usually some metrics that describe global properties */
39  /* of the face. It is computed by scanning more or less */
40  /* aggressively the glyphs in the face, and thus can be */
41  /* very slow to compute (even if the size of global */
42  /* hints is really small). */
43  /* */
44  /* - glyph hints: These describe some important features of the glyph */
45  /* outline, as well as how to align them. They are */
46  /* generally much faster to compute than global hints. */
47  /* */
48  /* The current FreeType auto-hinter does a pretty good job while */
49  /* performing fast computations for both global and glyph hints. */
50  /* However, we might be interested in introducing more complex and */
51  /* powerful algorithms in the future, like the one described in the John */
52  /* D. Hobby paper, which unfortunately requires a lot more horsepower. */
53  /* */
54  /* Because a sufficiently sophisticated font management system would */
55  /* typically implement an LRU cache of opened face objects to reduce */
56  /* memory usage, it is a good idea to be able to avoid recomputing */
57  /* global hints every time the same face is re-opened. */
58  /* */
59  /* We thus provide the ability to cache global hints outside of the face */
60  /* object, in order to speed up font re-opening time. Of course, this */
61  /* feature is purely optional, so most client programs won't even notice */
62  /* it. */
63  /* */
64  /* I initially thought that it would be a good idea to cache the glyph */
65  /* hints too. However, my general idea now is that if you really need */
66  /* to cache these too, you are simply in need of a new font format, */
67  /* where all this information could be stored within the font file and */
68  /* decoded on the fly. */
69  /* */
70  /*************************************************************************/
71 
72 
73 #include <ft2build.h>
74 #include FT_FREETYPE_H
75 
76 
77 FT_BEGIN_HEADER
78 
79 
80  typedef struct FT_AutoHinterRec_ *FT_AutoHinter;
81 
82 
83  /*************************************************************************/
84  /* */
85  /* <FuncType> */
86  /* FT_AutoHinter_GlobalGetFunc */
87  /* */
88  /* <Description> */
89  /* Retrieves the global hints computed for a given face object the */
90  /* resulting data is dissociated from the face and will survive a */
91  /* call to FT_Done_Face(). It must be discarded through the API */
92  /* FT_AutoHinter_GlobalDoneFunc(). */
93  /* */
94  /* <Input> */
95  /* hinter :: A handle to the source auto-hinter. */
96  /* */
97  /* face :: A handle to the source face object. */
98  /* */
99  /* <Output> */
100  /* global_hints :: A typeless pointer to the global hints. */
101  /* */
102  /* global_len :: The size in bytes of the global hints. */
103  /* */
104  typedef void
105  (*FT_AutoHinter_GlobalGetFunc)( FT_AutoHinter hinter,
106  FT_Face face,
107  void** global_hints,
108  long* global_len );
109 
110 
111  /*************************************************************************/
112  /* */
113  /* <FuncType> */
114  /* FT_AutoHinter_GlobalDoneFunc */
115  /* */
116  /* <Description> */
117  /* Discards the global hints retrieved through */
118  /* FT_AutoHinter_GlobalGetFunc(). This is the only way these hints */
119  /* are freed from memory. */
120  /* */
121  /* <Input> */
122  /* hinter :: A handle to the auto-hinter module. */
123  /* */
124  /* global :: A pointer to retrieved global hints to discard. */
125  /* */
126  typedef void
127  (*FT_AutoHinter_GlobalDoneFunc)( FT_AutoHinter hinter,
128  void* global );
129 
130 
131  /*************************************************************************/
132  /* */
133  /* <FuncType> */
134  /* FT_AutoHinter_GlobalResetFunc */
135  /* */
136  /* <Description> */
137  /* This function is used to recompute the global metrics in a given */
138  /* font. This is useful when global font data changes (e.g. Multiple */
139  /* Masters fonts where blend coordinates change). */
140  /* */
141  /* <Input> */
142  /* hinter :: A handle to the source auto-hinter. */
143  /* */
144  /* face :: A handle to the face. */
145  /* */
146  typedef void
147  (*FT_AutoHinter_GlobalResetFunc)( FT_AutoHinter hinter,
148  FT_Face face );
149 
150 
151  /*************************************************************************/
152  /* */
153  /* <FuncType> */
154  /* FT_AutoHinter_GlyphLoadFunc */
155  /* */
156  /* <Description> */
157  /* This function is used to load, scale, and automatically hint a */
158  /* glyph from a given face. */
159  /* */
160  /* <Input> */
161  /* face :: A handle to the face. */
162  /* */
163  /* glyph_index :: The glyph index. */
164  /* */
165  /* load_flags :: The load flags. */
166  /* */
167  /* <Note> */
168  /* This function is capable of loading composite glyphs by hinting */
169  /* each sub-glyph independently (which improves quality). */
170  /* */
171  /* It will call the font driver with FT_Load_Glyph(), with */
172  /* FT_LOAD_NO_SCALE set. */
173  /* */
174  typedef FT_Error
175  (*FT_AutoHinter_GlyphLoadFunc)( FT_AutoHinter hinter,
176  FT_GlyphSlot slot,
177  FT_Size size,
178  FT_UInt glyph_index,
179  FT_Int32 load_flags );
180 
181 
182  /*************************************************************************/
183  /* */
184  /* <Struct> */
185  /* FT_AutoHinter_ServiceRec */
186  /* */
187  /* <Description> */
188  /* The auto-hinter module's interface. */
189  /* */
190  typedef struct FT_AutoHinter_ServiceRec_
191  {
192  FT_AutoHinter_GlobalResetFunc reset_face;
193  FT_AutoHinter_GlobalGetFunc get_global_hints;
194  FT_AutoHinter_GlobalDoneFunc done_global_hints;
195  FT_AutoHinter_GlyphLoadFunc load_glyph;
196 
197  } FT_AutoHinter_ServiceRec, *FT_AutoHinter_Service;
198 
199 #ifndef FT_CONFIG_OPTION_PIC
200 
201 #define FT_DEFINE_AUTOHINTER_SERVICE(class_, reset_face_, get_global_hints_, \
202  done_global_hints_, load_glyph_) \
203  FT_CALLBACK_TABLE_DEF \
204  const FT_AutoHinter_ServiceRec class_ = \
205  { \
206  reset_face_, get_global_hints_, done_global_hints_, load_glyph_ \
207  };
208 
209 #else /* FT_CONFIG_OPTION_PIC */
210 
211 #define FT_DEFINE_AUTOHINTER_SERVICE(class_, reset_face_, get_global_hints_, \
212  done_global_hints_, load_glyph_) \
213  void \
214  FT_Init_Class_##class_( FT_Library library, \
215  FT_AutoHinter_ServiceRec* clazz) \
216  { \
217  FT_UNUSED(library); \
218  clazz->reset_face = reset_face_; \
219  clazz->get_global_hints = get_global_hints_; \
220  clazz->done_global_hints = done_global_hints_; \
221  clazz->load_glyph = load_glyph_; \
222  }
223 
224 #endif /* FT_CONFIG_OPTION_PIC */
225 
226 FT_END_HEADER
227 
228 #endif /* __AUTOHINT_H__ */
229 
230 
231 /* END */
FT_SizeRec_
Definition: freetype.h:1395
FT_Error
int FT_Error
Definition: fttypes.h:296
FT_GlyphSlotRec_
Definition: freetype.h:1605
void
GLvoid **typedef void(GLAPIENTRY *PFNGLGETVERTEXATTRIBDVPROC)(GLuint
Definition: glew.h:1824
FT_END_HEADER
#define FT_END_HEADER
Definition: ftheader.h:54
FT_AutoHinter_GlobalResetFunc
void(* FT_AutoHinter_GlobalResetFunc)(FT_AutoHinter hinter, FT_Face face)
Definition: autohint.h:147
FT_AutoHinter_GlobalGetFunc
void(* FT_AutoHinter_GlobalGetFunc)(FT_AutoHinter hinter, FT_Face face, void **global_hints, long *global_len)
Definition: autohint.h:105
FT_AutoHinter_ServiceRec_::get_global_hints
FT_AutoHinter_GlobalGetFunc get_global_hints
Definition: autohint.h:193
FT_AutoHinter_Service
struct FT_AutoHinter_ServiceRec_ * FT_AutoHinter_Service
FT_BEGIN_HEADER
#define FT_BEGIN_HEADER
Definition: ftheader.h:36
FT_AutoHinter_ServiceRec_
Definition: autohint.h:190
FT_FaceRec_
Definition: freetype.h:912
FT_AutoHinter_ServiceRec_::done_global_hints
FT_AutoHinter_GlobalDoneFunc done_global_hints
Definition: autohint.h:194
face
GLenum face
Definition: gl2ext.h:1490
FT_AutoHinter_ServiceRec
struct FT_AutoHinter_ServiceRec_ FT_AutoHinter_ServiceRec
FT_AutoHinter_GlobalDoneFunc
void(* FT_AutoHinter_GlobalDoneFunc)(FT_AutoHinter hinter, void *global)
Definition: autohint.h:127
FT_AutoHinter_ServiceRec_::reset_face
FT_AutoHinter_GlobalResetFunc reset_face
Definition: autohint.h:192
FT_AutoHinter_GlyphLoadFunc
FT_Error(* FT_AutoHinter_GlyphLoadFunc)(FT_AutoHinter hinter, FT_GlyphSlot slot, FT_Size size, FT_UInt glyph_index, FT_Int32 load_flags)
Definition: autohint.h:175
FT_UInt
unsigned int FT_UInt
Definition: fttypes.h:227
FT_AutoHinter
typedefFT_BEGIN_HEADER struct FT_AutoHinterRec_ * FT_AutoHinter
Definition: autohint.h:80
FT_AutoHinter_ServiceRec_::load_glyph
FT_AutoHinter_GlyphLoadFunc load_glyph
Definition: autohint.h:195
size
GLsizei size
Definition: gl2ext.h:1467