1 /****************************************************************************
2 *
3 * ftdrv.h
4 *
5 * FreeType internal font driver interface (specification).
6 *
7 * Copyright (C) 1996-2019 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 FTDRV_H_
20 #define FTDRV_H_
21
22
23 #include <ft2build.h>
24 #include FT_MODULE_H
25
26
27 FT_BEGIN_HEADER
28
29
30 typedef FT_Error
31 (*FT_Face_InitFunc)( FT_Stream stream,
32 FT_Face face,
33 FT_Int typeface_index,
34 FT_Int num_params,
35 FT_Parameter* parameters );
36
37 typedef void
38 (*FT_Face_DoneFunc)( FT_Face face );
39
40
41 typedef FT_Error
42 (*FT_Size_InitFunc)( FT_Size size );
43
44 typedef void
45 (*FT_Size_DoneFunc)( FT_Size size );
46
47
48 typedef FT_Error
49 (*FT_Slot_InitFunc)( FT_GlyphSlot slot );
50
51 typedef void
52 (*FT_Slot_DoneFunc)( FT_GlyphSlot slot );
53
54
55 typedef FT_Error
56 (*FT_Size_RequestFunc)( FT_Size size,
57 FT_Size_Request req );
58
59 typedef FT_Error
60 (*FT_Size_SelectFunc)( FT_Size size,
61 FT_ULong size_index );
62
63 typedef FT_Error
64 (*FT_Slot_LoadFunc)( FT_GlyphSlot slot,
65 FT_Size size,
66 FT_UInt glyph_index,
67 FT_Int32 load_flags );
68
69
70 typedef FT_Error
71 (*FT_Face_GetKerningFunc)( FT_Face face,
72 FT_UInt left_glyph,
73 FT_UInt right_glyph,
74 FT_Vector* kerning );
75
76
77 typedef FT_Error
78 (*FT_Face_AttachFunc)( FT_Face face,
79 FT_Stream stream );
80
81
82 typedef FT_Error
83 (*FT_Face_GetAdvancesFunc)( FT_Face face,
84 FT_UInt first,
85 FT_UInt count,
86 FT_Int32 flags,
87 FT_Fixed* advances );
88
89
90 /**************************************************************************
91 *
92 * @struct:
93 * FT_Driver_ClassRec
94 *
95 * @description:
96 * The font driver class. This structure mostly contains pointers to
97 * driver methods.
98 *
99 * @fields:
100 * root ::
101 * The parent module.
102 *
103 * face_object_size ::
104 * The size of a face object in bytes.
105 *
106 * size_object_size ::
107 * The size of a size object in bytes.
108 *
109 * slot_object_size ::
110 * The size of a glyph object in bytes.
111 *
112 * init_face ::
113 * The format-specific face constructor.
114 *
115 * done_face ::
116 * The format-specific face destructor.
117 *
118 * init_size ::
119 * The format-specific size constructor.
120 *
121 * done_size ::
122 * The format-specific size destructor.
123 *
124 * init_slot ::
125 * The format-specific slot constructor.
126 *
127 * done_slot ::
128 * The format-specific slot destructor.
129 *
130 *
131 * load_glyph ::
132 * A function handle to load a glyph to a slot. This field is
133 * mandatory!
134 *
135 * get_kerning ::
136 * A function handle to return the unscaled kerning for a given pair of
137 * glyphs. Can be set to 0 if the format doesn't support kerning.
138 *
139 * attach_file ::
140 * This function handle is used to read additional data for a face from
141 * another file/stream. For example, this can be used to add data from
142 * AFM or PFM files on a Type 1 face, or a CIDMap on a CID-keyed face.
143 *
144 * get_advances ::
145 * A function handle used to return advance widths of 'count' glyphs
146 * (in font units), starting at 'first'. The 'vertical' flag must be
147 * set to get vertical advance heights. The 'advances' buffer is
148 * caller-allocated. The idea of this function is to be able to
149 * perform device-independent text layout without loading a single
150 * glyph image.
151 *
152 * request_size ::
153 * A handle to a function used to request the new character size. Can
154 * be set to 0 if the scaling done in the base layer suffices.
155 *
156 * select_size ::
157 * A handle to a function used to select a new fixed size. It is used
158 * only if @FT_FACE_FLAG_FIXED_SIZES is set. Can be set to 0 if the
159 * scaling done in the base layer suffices.
160 * @note:
161 * Most function pointers, with the exception of `load_glyph`, can be set
162 * to 0 to indicate a default behaviour.
163 */
164 typedef struct FT_Driver_ClassRec_
165 {
166 FT_Module_Class root;
167
168 FT_Long face_object_size;
169 FT_Long size_object_size;
170 FT_Long slot_object_size;
171
172 FT_Face_InitFunc init_face;
173 FT_Face_DoneFunc done_face;
174
175 FT_Size_InitFunc init_size;
176 FT_Size_DoneFunc done_size;
177
178 FT_Slot_InitFunc init_slot;
179 FT_Slot_DoneFunc done_slot;
180
181 FT_Slot_LoadFunc load_glyph;
182
183 FT_Face_GetKerningFunc get_kerning;
184 FT_Face_AttachFunc attach_file;
185 FT_Face_GetAdvancesFunc get_advances;
186
187 /* since version 2.2 */
188 FT_Size_RequestFunc request_size;
189 FT_Size_SelectFunc select_size;
190
191 } FT_Driver_ClassRec, *FT_Driver_Class;
192
193
194 /**************************************************************************
195 *
196 * @macro:
197 * FT_DECLARE_DRIVER
198 *
199 * @description:
200 * Used to create a forward declaration of an FT_Driver_ClassRec struct
201 * instance.
202 *
203 * @macro:
204 * FT_DEFINE_DRIVER
205 *
206 * @description:
207 * Used to initialize an instance of FT_Driver_ClassRec struct.
208 *
209 * `ftinit.c` (ft_create_default_module_classes) already contains a
210 * mechanism to call these functions for the default modules described in
211 * `ftmodule.h`.
212 *
213 * The struct will be allocated in the global scope (or the scope where
214 * the macro is used).
215 */
216 #define FT_DECLARE_DRIVER( class_ ) \
217 FT_CALLBACK_TABLE \
218 const FT_Driver_ClassRec class_;
219
220 #define FT_DEFINE_DRIVER( \
221 class_, \
222 flags_, \
223 size_, \
224 name_, \
225 version_, \
226 requires_, \
227 interface_, \
228 init_, \
229 done_, \
230 get_interface_, \
231 face_object_size_, \
232 size_object_size_, \
233 slot_object_size_, \
234 init_face_, \
235 done_face_, \
236 init_size_, \
237 done_size_, \
238 init_slot_, \
239 done_slot_, \
240 load_glyph_, \
241 get_kerning_, \
242 attach_file_, \
243 get_advances_, \
244 request_size_, \
245 select_size_ ) \
246 FT_CALLBACK_TABLE_DEF \
247 const FT_Driver_ClassRec class_ = \
248 { \
249 FT_DEFINE_ROOT_MODULE( flags_, \
250 size_, \
251 name_, \
252 version_, \
253 requires_, \
254 interface_, \
255 init_, \
256 done_, \
257 get_interface_ ) \
258 \
259 face_object_size_, \
260 size_object_size_, \
261 slot_object_size_, \
262 \
263 init_face_, \
264 done_face_, \
265 \
266 init_size_, \
267 done_size_, \
268 \
269 init_slot_, \
270 done_slot_, \
271 \
272 load_glyph_, \
273 \
274 get_kerning_, \
275 attach_file_, \
276 get_advances_, \
277 \
278 request_size_, \
279 select_size_ \
280 };
281
282
283 FT_END_HEADER
284
285 #endif /* FTDRV_H_ */
286
287
288 /* END */