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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   /*
154    * opaque handle to glyph-specific hints -- see `afhints.h' for more
155    * details
156    */
157   typedef struct AF_GlyphHintsRec_*  AF_GlyphHints;
158 
159 
160   /*************************************************************************/
161   /*************************************************************************/
162   /*****                                                               *****/
163   /*****                       S C A L E R S                           *****/
164   /*****                                                               *****/
165   /*************************************************************************/
166   /*************************************************************************/
167 
168   /*
169    * A scaler models the target pixel device that will receive the
170    * auto-hinted glyph image.
171    */
172 
173 #define AF_SCALER_FLAG_NO_HORIZONTAL  1U /* disable horizontal hinting */
174 #define AF_SCALER_FLAG_NO_VERTICAL    2U /* disable vertical hinting   */
175 #define AF_SCALER_FLAG_NO_ADVANCE     4U /* disable advance hinting    */
176 #define AF_SCALER_FLAG_NO_WARPER      8U /* disable warper             */
177 
178 
179   typedef struct  AF_ScalerRec_
180   {
181     FT_Face         face;        /* source font face                        */
182     FT_Fixed        x_scale;     /* from font units to 1/64th device pixels */
183     FT_Fixed        y_scale;     /* from font units to 1/64th device pixels */
184     FT_Pos          x_delta;     /* in 1/64th device pixels                 */
185     FT_Pos          y_delta;     /* in 1/64th device pixels                 */
186     FT_Render_Mode  render_mode; /* monochrome, anti-aliased, LCD, etc.     */
187     FT_UInt32       flags;       /* additional control flags, see above     */
188 
189   } AF_ScalerRec, *AF_Scaler;
190 
191 
192 #define AF_SCALER_EQUAL_SCALES( a, b )      \
193           ( (a)->x_scale == (b)->x_scale && \
194             (a)->y_scale == (b)->y_scale && \
195             (a)->x_delta == (b)->x_delta && \
196             (a)->y_delta == (b)->y_delta )
197 
198 
199   typedef struct AF_StyleMetricsRec_*  AF_StyleMetrics;
200 
201   /*
202    * This function parses an FT_Face to compute global metrics for
203    * a specific style.
204    */
205   typedef FT_Error
206   (*AF_WritingSystem_InitMetricsFunc)( AF_StyleMetrics  metrics,
207                                        FT_Face          face );
208 
209   typedef void
210   (*AF_WritingSystem_ScaleMetricsFunc)( AF_StyleMetrics  metrics,
211                                         AF_Scaler        scaler );
212 
213   typedef void
214   (*AF_WritingSystem_DoneMetricsFunc)( AF_StyleMetrics  metrics );
215 
216   typedef void
217   (*AF_WritingSystem_GetStdWidthsFunc)( AF_StyleMetrics  metrics,
218                                         FT_Pos*          stdHW,
219                                         FT_Pos*          stdVW );
220 
221 
222   typedef FT_Error
223   (*AF_WritingSystem_InitHintsFunc)( AF_GlyphHints    hints,
224                                      AF_StyleMetrics  metrics );
225 
226   typedef FT_Error
227   (*AF_WritingSystem_ApplyHintsFunc)( FT_UInt          glyph_index,
228                                       AF_GlyphHints    hints,
229                                       FT_Outline*      outline,
230                                       AF_StyleMetrics  metrics );
231 
232 
233   /*************************************************************************/
234   /*************************************************************************/
235   /*****                                                               *****/
236   /*****                W R I T I N G   S Y S T E M S                  *****/
237   /*****                                                               *****/
238   /*************************************************************************/
239   /*************************************************************************/
240 
241   /*
242    * For the auto-hinter, a writing system consists of multiple scripts that
243    * can be handled similarly *in a typographical way*; the relationship is
244    * not based on history.  For example, both the Greek and the unrelated
245    * Armenian scripts share the same features like ascender, descender,
246    * x-height, etc.  Essentially, a writing system is covered by a
247    * submodule of the auto-fitter; it contains
248    *
249    * - a specific global analyzer that computes global metrics specific to
250    *   the script (based on script-specific characters to identify ascender
251    *   height, x-height, etc.),
252    *
253    * - a specific glyph analyzer that computes segments and edges for each
254    *   glyph covered by the script,
255    *
256    * - a specific grid-fitting algorithm that distorts the scaled glyph
257    *   outline according to the results of the glyph analyzer.
258    */
259 
260 #define AFWRTSYS_H_  /* don't load header files */
261 #undef  WRITING_SYSTEM
262 #define WRITING_SYSTEM( ws, WS )    \
263           AF_WRITING_SYSTEM_ ## WS,
264 
265   /* The list of known writing systems. */
266   typedef enum  AF_WritingSystem_
267   {
268 
269 #include "afwrtsys.h"
270 
271     AF_WRITING_SYSTEM_MAX   /* do not remove */
272 
273   } AF_WritingSystem;
274 
275 #undef  AFWRTSYS_H_
276 
277 
278   typedef struct  AF_WritingSystemClassRec_
279   {
280     AF_WritingSystem  writing_system;
281 
282     FT_Offset                          style_metrics_size;
283     AF_WritingSystem_InitMetricsFunc   style_metrics_init;
284     AF_WritingSystem_ScaleMetricsFunc  style_metrics_scale;
285     AF_WritingSystem_DoneMetricsFunc   style_metrics_done;
286     AF_WritingSystem_GetStdWidthsFunc  style_metrics_getstdw;
287 
288     AF_WritingSystem_InitHintsFunc     style_hints_init;
289     AF_WritingSystem_ApplyHintsFunc    style_hints_apply;
290 
291   } AF_WritingSystemClassRec;
292 
293   typedef const AF_WritingSystemClassRec*  AF_WritingSystemClass;
294 
295 
296   /*************************************************************************/
297   /*************************************************************************/
298   /*****                                                               *****/
299   /*****                        S C R I P T S                          *****/
300   /*****                                                               *****/
301   /*************************************************************************/
302   /*************************************************************************/
303 
304   /*
305    * Each script is associated with two sets of Unicode ranges to test
306    * whether the font face supports the script, and which non-base
307    * characters the script contains.
308    *
309    * We use four-letter script tags from the OpenType specification,
310    * extended by `NONE', which indicates `no script'.
311    */
312 
313 #undef  SCRIPT
314 #define SCRIPT( s, S, d, h, H, ss ) \
315           AF_SCRIPT_ ## S,
316 
317   /* The list of known scripts. */
318   typedef enum  AF_Script_
319   {
320 
321 #include "afscript.h"
322 
323     AF_SCRIPT_MAX   /* do not remove */
324 
325   } AF_Script;
326 
327 
328   typedef struct  AF_Script_UniRangeRec_
329   {
330     FT_UInt32  first;
331     FT_UInt32  last;
332 
333   } AF_Script_UniRangeRec;
334 
335 #define AF_UNIRANGE_REC( a, b ) { (FT_UInt32)(a), (FT_UInt32)(b) }
336 
337   typedef const AF_Script_UniRangeRec*  AF_Script_UniRange;
338 
339 
340   typedef struct  AF_ScriptClassRec_
341   {
342     AF_Script  script;
343 
344     /* last element in the ranges must be { 0, 0 } */
345     AF_Script_UniRange  script_uni_ranges;
346     AF_Script_UniRange  script_uni_nonbase_ranges;
347 
348     FT_Bool  top_to_bottom_hinting;
349 
350     const char*  standard_charstring;      /* for default width and height */
351 
352   } AF_ScriptClassRec;
353 
354   typedef const AF_ScriptClassRec*  AF_ScriptClass;
355 
356 
357   /*************************************************************************/
358   /*************************************************************************/
359   /*****                                                               *****/
360   /*****                      C O V E R A G E S                        *****/
361   /*****                                                               *****/
362   /*************************************************************************/
363   /*************************************************************************/
364 
365   /*
366    * Usually, a font contains more glyphs than can be addressed by its
367    * character map.
368    *
369    * In the PostScript font world, encoding vectors specific to a given
370    * task are used to select such glyphs, and these glyphs can be often
371    * recognized by having a suffix in its glyph names.  For example, a
372    * superscript glyph `A' might be called `A.sup'.  Unfortunately, this
373    * naming scheme is not standardized and thus unusable for us.
374    *
375    * In the OpenType world, a better solution was invented, namely
376    * `features', which cleanly separate a character's input encoding from
377    * the corresponding glyph's appearance, and which don't use glyph names
378    * at all.  For our purposes, and slightly generalized, an OpenType
379    * feature is a name of a mapping that maps character codes to
380    * non-standard glyph indices (features get used for other things also).
381    * For example, the `sups' feature provides superscript glyphs, thus
382    * mapping character codes like `A' or `B' to superscript glyph
383    * representation forms.  How this mapping happens is completely
384    * uninteresting to us.
385    *
386    * For the auto-hinter, a `coverage' represents all glyphs of an OpenType
387    * feature collected in a set (as listed below) that can be hinted
388    * together.  To continue the above example, superscript glyphs must not
389    * be hinted together with normal glyphs because the blue zones
390    * completely differ.
391    *
392    * Note that FreeType itself doesn't compute coverages; it only provides
393    * the glyphs addressable by the default Unicode character map.  Instead,
394    * we use the HarfBuzz library (if available), which has many functions
395    * exactly for this purpose.
396    *
397    * AF_COVERAGE_DEFAULT is special: It should cover everything that isn't
398    * listed separately (including the glyphs addressable by the character
399    * map).  In case HarfBuzz isn't available, it exactly covers the glyphs
400    * addressable by the character map.
401    *
402    */
403 
404 #undef  COVERAGE
405 #define COVERAGE( name, NAME, description, \
406                   tag1, tag2, tag3, tag4 ) \
407           AF_COVERAGE_ ## NAME,
408 
409 
410   typedef enum  AF_Coverage_
411   {
412 #include "afcover.h"
413 
414     AF_COVERAGE_DEFAULT
415 
416   } AF_Coverage;
417 
418 
419   /*************************************************************************/
420   /*************************************************************************/
421   /*****                                                               *****/
422   /*****                         S T Y L E S                           *****/
423   /*****                                                               *****/
424   /*************************************************************************/
425   /*************************************************************************/
426 
427   /*
428    * The topmost structure for modelling the auto-hinter glyph input data
429    * is a `style class', grouping everything together.
430    */
431 
432 #undef  STYLE
433 #define STYLE( s, S, d, ws, sc, ss, c ) \
434           AF_STYLE_ ## S,
435 
436   /* The list of known styles. */
437   typedef enum  AF_Style_
438   {
439 
440 #include "afstyles.h"
441 
442     AF_STYLE_MAX   /* do not remove */
443 
444   } AF_Style;
445 
446 
447   typedef struct  AF_StyleClassRec_
448   {
449     AF_Style  style;
450 
451     AF_WritingSystem   writing_system;
452     AF_Script          script;
453     AF_Blue_Stringset  blue_stringset;
454     AF_Coverage        coverage;
455 
456   } AF_StyleClassRec;
457 
458   typedef const AF_StyleClassRec*  AF_StyleClass;
459 
460 
461   /*************************************************************************/
462   /*************************************************************************/
463   /*****                                                               *****/
464   /*****                   S T Y L E   M E T R I C S                   *****/
465   /*****                                                               *****/
466   /*************************************************************************/
467   /*************************************************************************/
468 
469   typedef struct AF_FaceGlobalsRec_*  AF_FaceGlobals;
470 
471   /* This is the main structure that combines everything.  Autofit modules */
472   /* specific to writing systems derive their structures from it, for      */
473   /* example `AF_LatinMetrics'.                                            */
474 
475   typedef struct  AF_StyleMetricsRec_
476   {
477     AF_StyleClass   style_class;
478     AF_ScalerRec    scaler;
479     FT_Bool         digits_have_same_width;
480 
481     AF_FaceGlobals  globals;    /* to access properties */
482 
483   } AF_StyleMetricsRec;
484 
485 
486 #define AF_HINTING_BOTTOM_TO_TOP  0
487 #define AF_HINTING_TOP_TO_BOTTOM  1
488 
489 
490   /* Declare and define vtables for classes */
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 /* */
566 
567 
568 FT_END_HEADER
569 
570 #endif /* AFTYPES_H_ */
571 
572 
573 /* END */
574