1 /***************************************************************************/
2 /* */
3 /* aftypes.h */
4 /* */
5 /* Auto-fitter types (specification only). */
6 /* */
7 /* Copyright 2003-2018 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 /*************************************************************************
20 *
21 * The auto-fitter is a complete rewrite of the old auto-hinter.
22 * Its main feature is the ability to differentiate between different
23 * writing systems and scripts in order to apply specific rules.
24 *
25 * The code has also been compartmentalized into several entities that
26 * should make algorithmic experimentation easier than with the old
27 * code.
28 *
29 *************************************************************************/
30
31
32 #ifndef AFTYPES_H_
33 #define AFTYPES_H_
34
35 #include <ft2build.h>
36
37 #include FT_FREETYPE_H
38 #include FT_OUTLINE_H
39 #include FT_INTERNAL_OBJECTS_H
40 #include FT_INTERNAL_DEBUG_H
41
42 #include "afblue.h"
43
44 #ifdef FT_DEBUG_AUTOFIT
45 #include FT_CONFIG_STANDARD_LIBRARY_H
46 #endif
47
48
49 FT_BEGIN_HEADER
50
51 /*************************************************************************/
52 /*************************************************************************/
53 /***** *****/
54 /***** D E B U G G I N G *****/
55 /***** *****/
56 /*************************************************************************/
57 /*************************************************************************/
58
59 #ifdef FT_DEBUG_AUTOFIT
60
61 extern int _af_debug_disable_horz_hints;
62 extern int _af_debug_disable_vert_hints;
63 extern int _af_debug_disable_blue_hints;
64 extern void* _af_debug_hints;
65
66 #endif /* FT_DEBUG_AUTOFIT */
67
68
69 /*************************************************************************/
70 /*************************************************************************/
71 /***** *****/
72 /***** U T I L I T Y S T U F F *****/
73 /***** *****/
74 /*************************************************************************/
75 /*************************************************************************/
76
77 typedef struct AF_WidthRec_
78 {
79 FT_Pos org; /* original position/width in font units */
80 FT_Pos cur; /* current/scaled position/width in device subpixels */
81 FT_Pos fit; /* current/fitted position/width in device subpixels */
82
83 } AF_WidthRec, *AF_Width;
84
85
86 FT_LOCAL( void )
87 af_sort_pos( FT_UInt count,
88 FT_Pos* table );
89
90 FT_LOCAL( void )
91 af_sort_and_quantize_widths( FT_UInt* count,
92 AF_Width widths,
93 FT_Pos threshold );
94
95
96 /*************************************************************************/
97 /*************************************************************************/
98 /***** *****/
99 /***** A N G L E T Y P E S *****/
100 /***** *****/
101 /*************************************************************************/
102 /*************************************************************************/
103
104 /*
105 * The auto-fitter doesn't need a very high angular accuracy;
106 * this allows us to speed up some computations considerably with a
107 * light Cordic algorithm (see afangles.c).
108 */
109
110 typedef FT_Int AF_Angle;
111
112
113 #define AF_ANGLE_PI 256
114 #define AF_ANGLE_2PI ( AF_ANGLE_PI * 2 )
115 #define AF_ANGLE_PI2 ( AF_ANGLE_PI / 2 )
116 #define AF_ANGLE_PI4 ( AF_ANGLE_PI / 4 )
117
118
119 #if 0
120 /*
121 * compute the angle of a given 2-D vector
122 */
123 FT_LOCAL( AF_Angle )
124 af_angle_atan( FT_Pos dx,
125 FT_Pos dy );
126
127
128 /*
129 * compute `angle2 - angle1'; the result is always within
130 * the range [-AF_ANGLE_PI .. AF_ANGLE_PI - 1]
131 */
132 FT_LOCAL( AF_Angle )
133 af_angle_diff( AF_Angle angle1,
134 AF_Angle angle2 );
135 #endif /* 0 */
136
137
138 #define AF_ANGLE_DIFF( result, angle1, angle2 ) \
139 FT_BEGIN_STMNT \
140 AF_Angle _delta = (angle2) - (angle1); \
141 \
142 \
143 while ( _delta <= -AF_ANGLE_PI ) \
144 _delta += AF_ANGLE_2PI; \
145 \
146 while ( _delta > AF_ANGLE_PI ) \
147 _delta -= AF_ANGLE_2PI; \
148 \
149 result = _delta; \
150 FT_END_STMNT
151
152
153 /* opaque handle to glyph-specific hints -- see `afhints.h' for more
154 * details
155 */
156 typedef struct AF_GlyphHintsRec_* AF_GlyphHints;
157
158
159 /*************************************************************************/
160 /*************************************************************************/
161 /***** *****/
162 /***** S C A L E R S *****/
163 /***** *****/
164 /*************************************************************************/
165 /*************************************************************************/
166
167 /*
168 * A scaler models the target pixel device that will receive the
169 * auto-hinted glyph image.
170 */
171
172 #define AF_SCALER_FLAG_NO_HORIZONTAL 1U /* disable horizontal hinting */
173 #define AF_SCALER_FLAG_NO_VERTICAL 2U /* disable vertical hinting */
174 #define AF_SCALER_FLAG_NO_ADVANCE 4U /* disable advance hinting */
175 #define AF_SCALER_FLAG_NO_WARPER 8U /* disable warper */
176
177
178 typedef struct AF_ScalerRec_
179 {
180 FT_Face face; /* source font face */
181 FT_Fixed x_scale; /* from font units to 1/64th device pixels */
182 FT_Fixed y_scale; /* from font units to 1/64th device pixels */
183 FT_Pos x_delta; /* in 1/64th device pixels */
184 FT_Pos y_delta; /* in 1/64th device pixels */
185 FT_Render_Mode render_mode; /* monochrome, anti-aliased, LCD, etc. */
186 FT_UInt32 flags; /* additional control flags, see above */
187
188 } AF_ScalerRec, *AF_Scaler;
189
190
191 #define AF_SCALER_EQUAL_SCALES( a, b ) \
192 ( (a)->x_scale == (b)->x_scale && \
193 (a)->y_scale == (b)->y_scale && \
194 (a)->x_delta == (b)->x_delta && \
195 (a)->y_delta == (b)->y_delta )
196
197
198 typedef struct AF_StyleMetricsRec_* AF_StyleMetrics;
199
200 /* This function parses an FT_Face to compute global metrics for
201 * a specific style.
202 */
203 typedef FT_Error
204 (*AF_WritingSystem_InitMetricsFunc)( AF_StyleMetrics metrics,
205 FT_Face face );
206
207 typedef void
208 (*AF_WritingSystem_ScaleMetricsFunc)( AF_StyleMetrics metrics,
209 AF_Scaler scaler );
210
211 typedef void
212 (*AF_WritingSystem_DoneMetricsFunc)( AF_StyleMetrics metrics );
213
214 typedef void
215 (*AF_WritingSystem_GetStdWidthsFunc)( AF_StyleMetrics metrics,
216 FT_Pos* stdHW,
217 FT_Pos* stdVW );
218
219
220 typedef FT_Error
221 (*AF_WritingSystem_InitHintsFunc)( AF_GlyphHints hints,
222 AF_StyleMetrics metrics );
223
224 typedef FT_Error
225 (*AF_WritingSystem_ApplyHintsFunc)( FT_UInt glyph_index,
226 AF_GlyphHints hints,
227 FT_Outline* outline,
228 AF_StyleMetrics metrics );
229
230
231 /*************************************************************************/
232 /*************************************************************************/
233 /***** *****/
234 /***** W R I T I N G S Y S T E M S *****/
235 /***** *****/
236 /*************************************************************************/
237 /*************************************************************************/
238
239 /*
240 * For the auto-hinter, a writing system consists of multiple scripts that
241 * can be handled similarly *in a typographical way*; the relationship is
242 * not based on history. For example, both the Greek and the unrelated
243 * Armenian scripts share the same features like ascender, descender,
244 * x-height, etc. Essentially, a writing system is covered by a
245 * submodule of the auto-fitter; it contains
246 *
247 * - a specific global analyzer that computes global metrics specific to
248 * the script (based on script-specific characters to identify ascender
249 * height, x-height, etc.),
250 *
251 * - a specific glyph analyzer that computes segments and edges for each
252 * glyph covered by the script,
253 *
254 * - a specific grid-fitting algorithm that distorts the scaled glyph
255 * outline according to the results of the glyph analyzer.
256 */
257
258 #define AFWRTSYS_H_ /* don't load header files */
259 #undef WRITING_SYSTEM
260 #define WRITING_SYSTEM( ws, WS ) \
261 AF_WRITING_SYSTEM_ ## WS,
262
263 /* The list of known writing systems. */
264 typedef enum AF_WritingSystem_
265 {
266
267 #include "afwrtsys.h"
268
269 AF_WRITING_SYSTEM_MAX /* do not remove */
270
271 } AF_WritingSystem;
272
273 #undef AFWRTSYS_H_
274
275
276 typedef struct AF_WritingSystemClassRec_
277 {
278 AF_WritingSystem writing_system;
279
280 FT_Offset style_metrics_size;
281 AF_WritingSystem_InitMetricsFunc style_metrics_init;
282 AF_WritingSystem_ScaleMetricsFunc style_metrics_scale;
283 AF_WritingSystem_DoneMetricsFunc style_metrics_done;
284 AF_WritingSystem_GetStdWidthsFunc style_metrics_getstdw;
285
286 AF_WritingSystem_InitHintsFunc style_hints_init;
287 AF_WritingSystem_ApplyHintsFunc style_hints_apply;
288
289 } AF_WritingSystemClassRec;
290
291 typedef const AF_WritingSystemClassRec* AF_WritingSystemClass;
292
293
294 /*************************************************************************/
295 /*************************************************************************/
296 /***** *****/
297 /***** S C R I P T S *****/
298 /***** *****/
299 /*************************************************************************/
300 /*************************************************************************/
301
302 /*
303 * Each script is associated with two sets of Unicode ranges to test
304 * whether the font face supports the script, and which non-base
305 * characters the script contains.
306 *
307 * We use four-letter script tags from the OpenType specification,
308 * extended by `NONE', which indicates `no script'.
309 */
310
311 #undef SCRIPT
312 #define SCRIPT( s, S, d, h, H, ss ) \
313 AF_SCRIPT_ ## S,
314
315 /* The list of known scripts. */
316 typedef enum AF_Script_
317 {
318
319 #include "afscript.h"
320
321 AF_SCRIPT_MAX /* do not remove */
322
323 } AF_Script;
324
325
326 typedef struct AF_Script_UniRangeRec_
327 {
328 FT_UInt32 first;
329 FT_UInt32 last;
330
331 } AF_Script_UniRangeRec;
332
333 #define AF_UNIRANGE_REC( a, b ) { (FT_UInt32)(a), (FT_UInt32)(b) }
334
335 typedef const AF_Script_UniRangeRec* AF_Script_UniRange;
336
337
338 typedef struct AF_ScriptClassRec_
339 {
340 AF_Script script;
341
342 /* last element in the ranges must be { 0, 0 } */
343 AF_Script_UniRange script_uni_ranges;
344 AF_Script_UniRange script_uni_nonbase_ranges;
345
346 FT_Bool top_to_bottom_hinting;
347
348 const char* standard_charstring; /* for default width and height */
349
350 } AF_ScriptClassRec;
351
352 typedef const AF_ScriptClassRec* AF_ScriptClass;
353
354
355 /*************************************************************************/
356 /*************************************************************************/
357 /***** *****/
358 /***** C O V E R A G E S *****/
359 /***** *****/
360 /*************************************************************************/
361 /*************************************************************************/
362
363 /*
364 * Usually, a font contains more glyphs than can be addressed by its
365 * character map.
366 *
367 * In the PostScript font world, encoding vectors specific to a given
368 * task are used to select such glyphs, and these glyphs can be often
369 * recognized by having a suffix in its glyph names. For example, a
370 * superscript glyph `A' might be called `A.sup'. Unfortunately, this
371 * naming scheme is not standardized and thus unusable for us.
372 *
373 * In the OpenType world, a better solution was invented, namely
374 * `features', which cleanly separate a character's input encoding from
375 * the corresponding glyph's appearance, and which don't use glyph names
376 * at all. For our purposes, and slightly generalized, an OpenType
377 * feature is a name of a mapping that maps character codes to
378 * non-standard glyph indices (features get used for other things also).
379 * For example, the `sups' feature provides superscript glyphs, thus
380 * mapping character codes like `A' or `B' to superscript glyph
381 * representation forms. How this mapping happens is completely
382 * uninteresting to us.
383 *
384 * For the auto-hinter, a `coverage' represents all glyphs of an OpenType
385 * feature collected in a set (as listed below) that can be hinted
386 * together. To continue the above example, superscript glyphs must not
387 * be hinted together with normal glyphs because the blue zones
388 * completely differ.
389 *
390 * Note that FreeType itself doesn't compute coverages; it only provides
391 * the glyphs addressable by the default Unicode character map. Instead,
392 * we use the HarfBuzz library (if available), which has many functions
393 * exactly for this purpose.
394 *
395 * AF_COVERAGE_DEFAULT is special: It should cover everything that isn't
396 * listed separately (including the glyphs addressable by the character
397 * map). In case HarfBuzz isn't available, it exactly covers the glyphs
398 * addressable by the character map.
399 *
400 */
401
402 #undef COVERAGE
403 #define COVERAGE( name, NAME, description, \
404 tag1, tag2, tag3, tag4 ) \
405 AF_COVERAGE_ ## NAME,
406
407
408 typedef enum AF_Coverage_
409 {
410 #include "afcover.h"
411
412 AF_COVERAGE_DEFAULT
413
414 } AF_Coverage;
415
416
417 /*************************************************************************/
418 /*************************************************************************/
419 /***** *****/
420 /***** S T Y L E S *****/
421 /***** *****/
422 /*************************************************************************/
423 /*************************************************************************/
424
425 /*
426 * The topmost structure for modelling the auto-hinter glyph input data
427 * is a `style class', grouping everything together.
428 */
429
430 #undef STYLE
431 #define STYLE( s, S, d, ws, sc, ss, c ) \
432 AF_STYLE_ ## S,
433
434 /* The list of known styles. */
435 typedef enum AF_Style_
436 {
437
438 #include "afstyles.h"
439
440 AF_STYLE_MAX /* do not remove */
441
442 } AF_Style;
443
444
445 typedef struct AF_StyleClassRec_
446 {
447 AF_Style style;
448
449 AF_WritingSystem writing_system;
450 AF_Script script;
451 AF_Blue_Stringset blue_stringset;
452 AF_Coverage coverage;
453
454 } AF_StyleClassRec;
455
456 typedef const AF_StyleClassRec* AF_StyleClass;
457
458
459 /*************************************************************************/
460 /*************************************************************************/
461 /***** *****/
462 /***** S T Y L E M E T R I C S *****/
463 /***** *****/
464 /*************************************************************************/
465 /*************************************************************************/
466
467 typedef struct AF_FaceGlobalsRec_* AF_FaceGlobals;
468
469 /* This is the main structure that combines everything. Autofit modules */
470 /* specific to writing systems derive their structures from it, for */
471 /* example `AF_LatinMetrics'. */
472
473 typedef struct AF_StyleMetricsRec_
474 {
475 AF_StyleClass style_class;
476 AF_ScalerRec scaler;
477 FT_Bool digits_have_same_width;
478
479 AF_FaceGlobals globals; /* to access properties */
480
481 } AF_StyleMetricsRec;
482
483
484 #define AF_HINTING_BOTTOM_TO_TOP 0
485 #define AF_HINTING_TOP_TO_BOTTOM 1
486
487
488 /* Declare and define vtables for classes */
489 #ifndef FT_CONFIG_OPTION_PIC
490
491 #define AF_DECLARE_WRITING_SYSTEM_CLASS( writing_system_class ) \
492 FT_CALLBACK_TABLE const AF_WritingSystemClassRec \
493 writing_system_class;
494
495 #define AF_DEFINE_WRITING_SYSTEM_CLASS( \
496 writing_system_class, \
497 system, \
498 m_size, \
499 m_init, \
500 m_scale, \
501 m_done, \
502 m_stdw, \
503 h_init, \
504 h_apply ) \
505 FT_CALLBACK_TABLE_DEF \
506 const AF_WritingSystemClassRec writing_system_class = \
507 { \
508 system, \
509 \
510 m_size, \
511 \
512 m_init, \
513 m_scale, \
514 m_done, \
515 m_stdw, \
516 \
517 h_init, \
518 h_apply \
519 };
520
521
522 #define AF_DECLARE_SCRIPT_CLASS( script_class ) \
523 FT_CALLBACK_TABLE const AF_ScriptClassRec \
524 script_class;
525
526 #define AF_DEFINE_SCRIPT_CLASS( \
527 script_class, \
528 script, \
529 ranges, \
530 nonbase_ranges, \
531 top_to_bottom, \
532 std_charstring ) \
533 FT_CALLBACK_TABLE_DEF \
534 const AF_ScriptClassRec script_class = \
535 { \
536 script, \
537 ranges, \
538 nonbase_ranges, \
539 top_to_bottom, \
540 std_charstring, \
541 };
542
543
544 #define AF_DECLARE_STYLE_CLASS( style_class ) \
545 FT_CALLBACK_TABLE const AF_StyleClassRec \
546 style_class;
547
548 #define AF_DEFINE_STYLE_CLASS( \
549 style_class, \
550 style, \
551 writing_system, \
552 script, \
553 blue_stringset, \
554 coverage ) \
555 FT_CALLBACK_TABLE_DEF \
556 const AF_StyleClassRec style_class = \
557 { \
558 style, \
559 writing_system, \
560 script, \
561 blue_stringset, \
562 coverage \
563 };
564
565 #else /* FT_CONFIG_OPTION_PIC */
566
567 #define AF_DECLARE_WRITING_SYSTEM_CLASS( writing_system_class ) \
568 FT_LOCAL( void ) \
569 FT_Init_Class_ ## writing_system_class( AF_WritingSystemClassRec* ac );
570
571 #define AF_DEFINE_WRITING_SYSTEM_CLASS( \
572 writing_system_class, \
573 system, \
574 m_size, \
575 m_init, \
576 m_scale, \
577 m_done, \
578 m_stdw, \
579 h_init, \
580 h_apply ) \
581 FT_LOCAL_DEF( void ) \
582 FT_Init_Class_ ## writing_system_class( AF_WritingSystemClassRec* ac ) \
583 { \
584 ac->writing_system = system; \
585 \
586 ac->style_metrics_size = m_size; \
587 \
588 ac->style_metrics_init = m_init; \
589 ac->style_metrics_scale = m_scale; \
590 ac->style_metrics_done = m_done; \
591 ac->style_metrics_getstdw = m_stdw; \
592 \
593 ac->style_hints_init = h_init; \
594 ac->style_hints_apply = h_apply; \
595 }
596
597
598 #define AF_DECLARE_SCRIPT_CLASS( script_class ) \
599 FT_LOCAL( void ) \
600 FT_Init_Class_ ## script_class( AF_ScriptClassRec* ac );
601
602 #define AF_DEFINE_SCRIPT_CLASS( \
603 script_class, \
604 script_, \
605 ranges, \
606 nonbase_ranges, \
607 top_to_bottom, \
608 std_charstring ) \
609 FT_LOCAL_DEF( void ) \
610 FT_Init_Class_ ## script_class( AF_ScriptClassRec* ac ) \
611 { \
612 ac->script = script_; \
613 ac->script_uni_ranges = ranges; \
614 ac->script_uni_nonbase_ranges = nonbase_ranges; \
615 ac->top_to_bottom_hinting = top_to_bottom; \
616 ac->standard_charstring = std_charstring; \
617 }
618
619
620 #define AF_DECLARE_STYLE_CLASS( style_class ) \
621 FT_LOCAL( void ) \
622 FT_Init_Class_ ## style_class( AF_StyleClassRec* ac );
623
624 #define AF_DEFINE_STYLE_CLASS( \
625 style_class, \
626 style_, \
627 writing_system_, \
628 script_, \
629 blue_stringset_, \
630 coverage_ ) \
631 FT_LOCAL_DEF( void ) \
632 FT_Init_Class_ ## style_class( AF_StyleClassRec* ac ) \
633 { \
634 ac->style = style_; \
635 ac->writing_system = writing_system_; \
636 ac->script = script_; \
637 ac->blue_stringset = blue_stringset_; \
638 ac->coverage = coverage_; \
639 }
640
641 #endif /* FT_CONFIG_OPTION_PIC */
642
643
644 /* */
645
646 FT_END_HEADER
647
648 #endif /* AFTYPES_H_ */
649
650
651 /* END */