1 /****************************************************************************
2 *
3 * psblues.c
4 *
5 * Adobe's code for handling Blue Zones (body).
6 *
7 * Copyright 2009-2014 Adobe Systems Incorporated.
8 *
9 * This software, and all works of authorship, whether in source or
10 * object code form as indicated by the copyright notice(s) included
11 * herein (collectively, the "Work") is made available, and may only be
12 * used, modified, and distributed under the FreeType Project License,
13 * LICENSE.TXT. Additionally, subject to the terms and conditions of the
14 * FreeType Project License, each contributor to the Work hereby grants
15 * to any individual or legal entity exercising permissions granted by
16 * the FreeType Project License and this section (hereafter, "You" or
17 * "Your") a perpetual, worldwide, non-exclusive, no-charge,
18 * royalty-free, irrevocable (except as stated in this section) patent
19 * license to make, have made, use, offer to sell, sell, import, and
20 * otherwise transfer the Work, where such license applies only to those
21 * patent claims licensable by such contributor that are necessarily
22 * infringed by their contribution(s) alone or by combination of their
23 * contribution(s) with the Work to which such contribution(s) was
24 * submitted. If You institute patent litigation against any entity
25 * (including a cross-claim or counterclaim in a lawsuit) alleging that
26 * the Work or a contribution incorporated within the Work constitutes
27 * direct or contributory patent infringement, then any patent licenses
28 * granted to You under this License for that Work shall terminate as of
29 * the date such litigation is filed.
30 *
31 * By using, modifying, or distributing the Work you indicate that you
32 * have read and understood the terms and conditions of the
33 * FreeType Project License as well as those provided in this section,
34 * and you accept them fully.
35 *
36 */
37
38
39 #include "psft.h"
40 #include <freetype/internal/ftdebug.h>
41
42 #include "psblues.h"
43 #include "pshints.h"
44 #include "psfont.h"
45
46
47 /**************************************************************************
48 *
49 * The macro FT_COMPONENT is used in trace mode. It is an implicit
50 * parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log
51 * messages during execution.
52 */
53 #undef FT_COMPONENT
54 #define FT_COMPONENT cf2blues
55
56
57 /*
58 * For blue values, the FreeType parser produces an array of integers,
59 * while the Adobe CFF engine produces an array of fixed.
60 * Define a macro to convert FreeType to fixed.
61 */
62 #define cf2_blueToFixed( x ) cf2_intToFixed( x )
63
64
65 FT_LOCAL_DEF( void )
66 cf2_blues_init( CF2_Blues blues,
67 CF2_Font font )
68 {
69 /* pointer to parsed font object */
70 PS_Decoder* decoder = font->decoder;
71
72 CF2_Fixed zoneHeight;
73 CF2_Fixed maxZoneHeight = 0;
74 CF2_Fixed csUnitsPerPixel;
75
76 size_t numBlueValues;
77 size_t numOtherBlues;
78 size_t numFamilyBlues;
79 size_t numFamilyOtherBlues;
80
81 FT_Pos* blueValues;
82 FT_Pos* otherBlues;
83 FT_Pos* familyBlues;
84 FT_Pos* familyOtherBlues;
85
86 size_t i;
87 CF2_Fixed emBoxBottom, emBoxTop;
88
89 #if 0
90 CF2_Int unitsPerEm = font->unitsPerEm;
91
92
93 if ( unitsPerEm == 0 )
94 unitsPerEm = 1000;
95 #endif
96
97 FT_ZERO( blues );
98 blues->scale = font->innerTransform.d;
99
100 cf2_getBlueMetrics( decoder,
101 &blues->blueScale,
102 &blues->blueShift,
103 &blues->blueFuzz );
104
105 cf2_getBlueValues( decoder, &numBlueValues, &blueValues );
106 cf2_getOtherBlues( decoder, &numOtherBlues, &otherBlues );
107 cf2_getFamilyBlues( decoder, &numFamilyBlues, &familyBlues );
108 cf2_getFamilyOtherBlues( decoder, &numFamilyOtherBlues, &familyOtherBlues );
109
110 /*
111 * synthetic em box hint heuristic
112 *
113 * Apply this when ideographic dictionary (LanguageGroup 1) has no
114 * real alignment zones. Adobe tools generate dummy zones at -250 and
115 * 1100 for a 1000 unit em. Fonts with ICF-based alignment zones
116 * should not enable the heuristic. When the heuristic is enabled,
117 * the font's blue zones are ignored.
118 *
119 */
120
121 /* get em box from OS/2 typoAscender/Descender */
122 /* TODO: FreeType does not parse these metrics. Skip them for now. */
123 #if 0
124 FCM_getHorizontalLineMetrics( &e,
125 font->font,
126 &ascender,
127 &descender,
128 &linegap );
129 if ( ascender - descender == unitsPerEm )
130 {
131 emBoxBottom = cf2_intToFixed( descender );
132 emBoxTop = cf2_intToFixed( ascender );
133 }
134 else
135 #endif
136 {
137 emBoxBottom = CF2_ICF_Bottom;
138 emBoxTop = CF2_ICF_Top;
139 }
140
141 if ( cf2_getLanguageGroup( decoder ) == 1 &&
142 ( numBlueValues == 0 ||
143 ( numBlueValues == 4 &&
144 cf2_blueToFixed( blueValues[0] ) < emBoxBottom &&
145 cf2_blueToFixed( blueValues[1] ) < emBoxBottom &&
146 cf2_blueToFixed( blueValues[2] ) > emBoxTop &&
147 cf2_blueToFixed( blueValues[3] ) > emBoxTop ) ) )
148 {
149 /*
150 * Construct hint edges suitable for synthetic ghost hints at top
151 * and bottom of em box. +-CF2_MIN_COUNTER allows for unhinted
152 * features above or below the last hinted edge. This also gives a
153 * net 1 pixel boost to the height of ideographic glyphs.
154 *
155 * Note: Adjust synthetic hints outward by epsilon (0x.0001) to
156 * avoid interference. E.g., some fonts have real hints at
157 * 880 and -120.
158 */
159
160 blues->emBoxBottomEdge.csCoord = emBoxBottom - CF2_FIXED_EPSILON;
161 blues->emBoxBottomEdge.dsCoord = cf2_fixedRound(
162 FT_MulFix(
163 blues->emBoxBottomEdge.csCoord,
164 blues->scale ) ) -
165 CF2_MIN_COUNTER;
166 blues->emBoxBottomEdge.scale = blues->scale;
167 blues->emBoxBottomEdge.flags = CF2_GhostBottom |
168 CF2_Locked |
169 CF2_Synthetic;
170
171 blues->emBoxTopEdge.csCoord = emBoxTop + CF2_FIXED_EPSILON +
172 2 * font->darkenY;
173 blues->emBoxTopEdge.dsCoord = cf2_fixedRound(
174 FT_MulFix(
175 blues->emBoxTopEdge.csCoord,
176 blues->scale ) ) +
177 CF2_MIN_COUNTER;
178 blues->emBoxTopEdge.scale = blues->scale;
179 blues->emBoxTopEdge.flags = CF2_GhostTop |
180 CF2_Locked |
181 CF2_Synthetic;
182
183 blues->doEmBoxHints = TRUE; /* enable the heuristic */
184
185 return;
186 }
187
188 /* copy `BlueValues' and `OtherBlues' to a combined array of top and */
189 /* bottom zones */
190 for ( i = 0; i < numBlueValues; i += 2 )
191 {
192 blues->zone[blues->count].csBottomEdge =
193 cf2_blueToFixed( blueValues[i] );
194 blues->zone[blues->count].csTopEdge =
195 cf2_blueToFixed( blueValues[i + 1] );
196
197 zoneHeight = SUB_INT32( blues->zone[blues->count].csTopEdge,
198 blues->zone[blues->count].csBottomEdge );
199
200 if ( zoneHeight < 0 )
201 {
202 FT_TRACE4(( "cf2_blues_init: ignoring negative zone height\n" ));
203 continue; /* reject this zone */
204 }
205
206 if ( zoneHeight > maxZoneHeight )
207 {
208 /* take maximum before darkening adjustment */
209 /* so overshoot suppression point doesn't change */
210 maxZoneHeight = zoneHeight;
211 }
212
213 /* adjust both edges of top zone upward by twice darkening amount */
214 if ( i != 0 )
215 {
216 blues->zone[blues->count].csTopEdge += 2 * font->darkenY;
217 blues->zone[blues->count].csBottomEdge += 2 * font->darkenY;
218 }
219
220 /* first `BlueValue' is bottom zone; others are top */
221 if ( i == 0 )
222 {
223 blues->zone[blues->count].bottomZone =
224 TRUE;
225 blues->zone[blues->count].csFlatEdge =
226 blues->zone[blues->count].csTopEdge;
227 }
228 else
229 {
230 blues->zone[blues->count].bottomZone =
231 FALSE;
232 blues->zone[blues->count].csFlatEdge =
233 blues->zone[blues->count].csBottomEdge;
234 }
235
236 blues->count += 1;
237 }
238
239 for ( i = 0; i < numOtherBlues; i += 2 )
240 {
241 blues->zone[blues->count].csBottomEdge =
242 cf2_blueToFixed( otherBlues[i] );
243 blues->zone[blues->count].csTopEdge =
244 cf2_blueToFixed( otherBlues[i + 1] );
245
246 zoneHeight = SUB_INT32( blues->zone[blues->count].csTopEdge,
247 blues->zone[blues->count].csBottomEdge );
248
249 if ( zoneHeight < 0 )
250 {
251 FT_TRACE4(( "cf2_blues_init: ignoring negative zone height\n" ));
252 continue; /* reject this zone */
253 }
254
255 if ( zoneHeight > maxZoneHeight )
256 {
257 /* take maximum before darkening adjustment */
258 /* so overshoot suppression point doesn't change */
259 maxZoneHeight = zoneHeight;
260 }
261
262 /* Note: bottom zones are not adjusted for darkening amount */
263
264 /* all OtherBlues are bottom zone */
265 blues->zone[blues->count].bottomZone =
266 TRUE;
267 blues->zone[blues->count].csFlatEdge =
268 blues->zone[blues->count].csTopEdge;
269
270 blues->count += 1;
271 }
272
273 /* Adjust for FamilyBlues */
274
275 /* Search for the nearest flat edge in `FamilyBlues' or */
276 /* `FamilyOtherBlues'. According to the Black Book, any matching edge */
277 /* must be within one device pixel */
278
279 csUnitsPerPixel = FT_DivFix( cf2_intToFixed( 1 ), blues->scale );
280
281 /* loop on all zones in this font */
282 for ( i = 0; i < blues->count; i++ )
283 {
284 size_t j;
285 CF2_Fixed minDiff;
286 CF2_Fixed flatFamilyEdge, diff;
287 /* value for this font */
288 CF2_Fixed flatEdge = blues->zone[i].csFlatEdge;
289
290
291 if ( blues->zone[i].bottomZone )
292 {
293 /* In a bottom zone, the top edge is the flat edge. */
294 /* Search `FamilyOtherBlues' for bottom zones; look for closest */
295 /* Family edge that is within the one pixel threshold. */
296
297 minDiff = CF2_FIXED_MAX;
298
299 for ( j = 0; j < numFamilyOtherBlues; j += 2 )
300 {
301 /* top edge */
302 flatFamilyEdge = cf2_blueToFixed( familyOtherBlues[j + 1] );
303
304 diff = cf2_fixedAbs( SUB_INT32( flatEdge, flatFamilyEdge ) );
305
306 if ( diff < minDiff && diff < csUnitsPerPixel )
307 {
308 blues->zone[i].csFlatEdge = flatFamilyEdge;
309 minDiff = diff;
310
311 if ( diff == 0 )
312 break;
313 }
314 }
315
316 /* check the first member of FamilyBlues, which is a bottom zone */
317 if ( numFamilyBlues >= 2 )
318 {
319 /* top edge */
320 flatFamilyEdge = cf2_blueToFixed( familyBlues[1] );
321
322 diff = cf2_fixedAbs( SUB_INT32( flatEdge, flatFamilyEdge ) );
323
324 if ( diff < minDiff && diff < csUnitsPerPixel )
325 blues->zone[i].csFlatEdge = flatFamilyEdge;
326 }
327 }
328 else
329 {
330 /* In a top zone, the bottom edge is the flat edge. */
331 /* Search `FamilyBlues' for top zones; skip first zone, which is a */
332 /* bottom zone; look for closest Family edge that is within the */
333 /* one pixel threshold */
334
335 minDiff = CF2_FIXED_MAX;
336
337 for ( j = 2; j < numFamilyBlues; j += 2 )
338 {
339 /* bottom edge */
340 flatFamilyEdge = cf2_blueToFixed( familyBlues[j] );
341
342 /* adjust edges of top zone upward by twice darkening amount */
343 flatFamilyEdge += 2 * font->darkenY; /* bottom edge */
344
345 diff = cf2_fixedAbs( SUB_INT32( flatEdge, flatFamilyEdge ) );
346
347 if ( diff < minDiff && diff < csUnitsPerPixel )
348 {
349 blues->zone[i].csFlatEdge = flatFamilyEdge;
350 minDiff = diff;
351
352 if ( diff == 0 )
353 break;
354 }
355 }
356 }
357 }
358
359 /* TODO: enforce separation of zones, including BlueFuzz */
360
361 /* Adjust BlueScale; similar to AdjustBlueScale() in coretype */
362 /* `bcsetup.c'. */
363
364 if ( maxZoneHeight > 0 )
365 {
366 if ( blues->blueScale > FT_DivFix( cf2_intToFixed( 1 ),
367 maxZoneHeight ) )
368 {
369 /* clamp at maximum scale */
370 blues->blueScale = FT_DivFix( cf2_intToFixed( 1 ),
371 maxZoneHeight );
372 }
373
374 /*
375 * TODO: Revisit the bug fix for 613448. The minimum scale
376 * requirement catches a number of library fonts. For
377 * example, with default BlueScale (.039625) and 0.4 minimum,
378 * the test below catches any font with maxZoneHeight < 10.1.
379 * There are library fonts ranging from 2 to 10 that get
380 * caught, including e.g., Eurostile LT Std Medium with
381 * maxZoneHeight of 6.
382 *
383 */
384 #if 0
385 if ( blueScale < .4 / maxZoneHeight )
386 {
387 tetraphilia_assert( 0 );
388 /* clamp at minimum scale, per bug 0613448 fix */
389 blueScale = .4 / maxZoneHeight;
390 }
391 #endif
392
393 }
394
395 /*
396 * Suppress overshoot and boost blue zones at small sizes. Boost
397 * amount varies linearly from 0.5 pixel near 0 to 0 pixel at
398 * blueScale cutoff.
399 * Note: This boost amount is different from the coretype heuristic.
400 *
401 */
402
403 if ( blues->scale < blues->blueScale )
404 {
405 blues->suppressOvershoot = TRUE;
406
407 /* Change rounding threshold for `dsFlatEdge'. */
408 /* Note: constant changed from 0.5 to 0.6 to avoid a problem with */
409 /* 10ppem Arial */
410
411 blues->boost = cf2_doubleToFixed( .6 ) -
412 FT_MulDiv( cf2_doubleToFixed ( .6 ),
413 blues->scale,
414 blues->blueScale );
415 if ( blues->boost > 0x7FFF )
416 {
417 /* boost must remain less than 0.5, or baseline could go negative */
418 blues->boost = 0x7FFF;
419 }
420 }
421
422 /* boost and darkening have similar effects; don't do both */
423 if ( font->stemDarkened )
424 blues->boost = 0;
425
426 /* set device space alignment for each zone; */
427 /* apply boost amount before rounding flat edge */
428
429 for ( i = 0; i < blues->count; i++ )
430 {
431 if ( blues->zone[i].bottomZone )
432 blues->zone[i].dsFlatEdge = cf2_fixedRound(
433 FT_MulFix(
434 blues->zone[i].csFlatEdge,
435 blues->scale ) -
436 blues->boost );
437 else
438 blues->zone[i].dsFlatEdge = cf2_fixedRound(
439 FT_MulFix(
440 blues->zone[i].csFlatEdge,
441 blues->scale ) +
442 blues->boost );
443 }
444 }
445
446
447 /*
448 * Check whether `stemHint' is captured by one of the blue zones.
449 *
450 * Zero, one or both edges may be valid; only valid edges can be
451 * captured. For compatibility with CoolType, search top and bottom
452 * zones in the same pass (see `BlueLock'). If a hint is captured,
453 * return true and position the edge(s) in one of 3 ways:
454 *
455 * 1) If `BlueScale' suppresses overshoot, position the captured edge
456 * at the flat edge of the zone.
457 * 2) If overshoot is not suppressed and `BlueShift' requires
458 * overshoot, position the captured edge a minimum of 1 device pixel
459 * from the flat edge.
460 * 3) If overshoot is not suppressed or required, position the captured
461 * edge at the nearest device pixel.
462 *
463 */
464 FT_LOCAL_DEF( FT_Bool )
465 cf2_blues_capture( const CF2_Blues blues,
466 CF2_Hint bottomHintEdge,
467 CF2_Hint topHintEdge )
468 {
469 /* TODO: validate? */
470 CF2_Fixed csFuzz = blues->blueFuzz;
471
472 /* new position of captured edge */
473 CF2_Fixed dsNew;
474
475 /* amount that hint is moved when positioned */
476 CF2_Fixed dsMove = 0;
477
478 FT_Bool captured = FALSE;
479 CF2_UInt i;
480
481
482 /* assert edge flags are consistent */
483 FT_ASSERT( !cf2_hint_isTop( bottomHintEdge ) &&
484 !cf2_hint_isBottom( topHintEdge ) );
485
486 /* TODO: search once without blue fuzz for compatibility with coretype? */
487 for ( i = 0; i < blues->count; i++ )
488 {
489 if ( blues->zone[i].bottomZone &&
490 cf2_hint_isBottom( bottomHintEdge ) )
491 {
492 if ( SUB_INT32( blues->zone[i].csBottomEdge, csFuzz ) <=
493 bottomHintEdge->csCoord &&
494 bottomHintEdge->csCoord <=
495 ADD_INT32( blues->zone[i].csTopEdge, csFuzz ) )
496 {
497 /* bottom edge captured by bottom zone */
498
499 if ( blues->suppressOvershoot )
500 dsNew = blues->zone[i].dsFlatEdge;
501
502 else if ( SUB_INT32( blues->zone[i].csTopEdge,
503 bottomHintEdge->csCoord ) >=
504 blues->blueShift )
505 {
506 /* guarantee minimum of 1 pixel overshoot */
507 dsNew = FT_MIN(
508 cf2_fixedRound( bottomHintEdge->dsCoord ),
509 SUB_INT32( blues->zone[i].dsFlatEdge,
510 cf2_intToFixed( 1 ) ) );
511 }
512
513 else
514 {
515 /* simply round captured edge */
516 dsNew = cf2_fixedRound( bottomHintEdge->dsCoord );
517 }
518
519 dsMove = SUB_INT32( dsNew, bottomHintEdge->dsCoord );
520 captured = TRUE;
521
522 break;
523 }
524 }
525
526 if ( !blues->zone[i].bottomZone && cf2_hint_isTop( topHintEdge ) )
527 {
528 if ( SUB_INT32( blues->zone[i].csBottomEdge, csFuzz ) <=
529 topHintEdge->csCoord &&
530 topHintEdge->csCoord <=
531 ADD_INT32( blues->zone[i].csTopEdge, csFuzz ) )
532 {
533 /* top edge captured by top zone */
534
535 if ( blues->suppressOvershoot )
536 dsNew = blues->zone[i].dsFlatEdge;
537
538 else if ( SUB_INT32( topHintEdge->csCoord,
539 blues->zone[i].csBottomEdge ) >=
540 blues->blueShift )
541 {
542 /* guarantee minimum of 1 pixel overshoot */
543 dsNew = FT_MAX(
544 cf2_fixedRound( topHintEdge->dsCoord ),
545 blues->zone[i].dsFlatEdge + cf2_intToFixed( 1 ) );
546 }
547
548 else
549 {
550 /* simply round captured edge */
551 dsNew = cf2_fixedRound( topHintEdge->dsCoord );
552 }
553
554 dsMove = SUB_INT32( dsNew, topHintEdge->dsCoord );
555 captured = TRUE;
556
557 break;
558 }
559 }
560 }
561
562 if ( captured )
563 {
564 /* move both edges and flag them `locked' */
565 if ( cf2_hint_isValid( bottomHintEdge ) )
566 {
567 bottomHintEdge->dsCoord = ADD_INT32( bottomHintEdge->dsCoord,
568 dsMove );
569 cf2_hint_lock( bottomHintEdge );
570 }
571
572 if ( cf2_hint_isValid( topHintEdge ) )
573 {
574 topHintEdge->dsCoord = ADD_INT32( topHintEdge->dsCoord, dsMove );
575 cf2_hint_lock( topHintEdge );
576 }
577 }
578
579 return captured;
580 }
581
582
583 /* END */