1 /****************************************************************************
2 *
3 * psfont.c
4 *
5 * Adobe's code for font instances (body).
6 *
7 * Copyright 2007-2014 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 <freetype/internal/ftcalc.h>
40
41 #include "psft.h"
42
43 #include "psglue.h"
44 #include "psfont.h"
45 #include "pserror.h"
46 #include "psintrp.h"
47
48
49 /* Compute a stem darkening amount in character space. */
50 static void
51 cf2_computeDarkening( CF2_Fixed emRatio,
52 CF2_Fixed ppem,
53 CF2_Fixed stemWidth,
54 CF2_Fixed* darkenAmount,
55 CF2_Fixed boldenAmount,
56 FT_Bool stemDarkened,
57 FT_Int* darkenParams )
58 {
59 /*
60 * Total darkening amount is computed in 1000 unit character space
61 * using the modified 5 part curve as Adobe's Avalon rasterizer.
62 * The darkening amount is smaller for thicker stems.
63 * It becomes zero when the stem is thicker than 2.333 pixels.
64 *
65 * By default, we use
66 *
67 * darkenAmount = 0.4 pixels if scaledStem <= 0.5 pixels,
68 * darkenAmount = 0.275 pixels if 1 <= scaledStem <= 1.667 pixels,
69 * darkenAmount = 0 pixel if scaledStem >= 2.333 pixels,
70 *
71 * and piecewise linear in-between:
72 *
73 *
74 * darkening
75 * ^
76 * |
77 * | (x1,y1)
78 * |--------+
79 * | \
80 * | \
81 * | \ (x3,y3)
82 * | +----------+
83 * | (x2,y2) \
84 * | \
85 * | \
86 * | +-----------------
87 * | (x4,y4)
88 * +---------------------------------------------> stem
89 * thickness
90 *
91 *
92 * This corresponds to the following values for the
93 * `darkening-parameters' property:
94 *
95 * (x1, y1) = (500, 400)
96 * (x2, y2) = (1000, 275)
97 * (x3, y3) = (1667, 275)
98 * (x4, y4) = (2333, 0)
99 *
100 */
101
102 /* Internal calculations are done in units per thousand for */
103 /* convenience. The x axis is scaled stem width in */
104 /* thousandths of a pixel. That is, 1000 is 1 pixel. */
105 /* The y axis is darkening amount in thousandths of a pixel.*/
106 /* In the code, below, dividing by ppem and */
107 /* adjusting for emRatio converts darkenAmount to character */
108 /* space (font units). */
109 CF2_Fixed stemWidthPer1000, scaledStem;
110 FT_Int logBase2;
111
112
113 *darkenAmount = 0;
114
115 if ( boldenAmount == 0 && !stemDarkened )
116 return;
117
118 /* protect against range problems and divide by zero */
119 if ( emRatio < cf2_doubleToFixed( .01 ) )
120 return;
121
122 if ( stemDarkened )
123 {
124 FT_Int x1 = darkenParams[0];
125 FT_Int y1 = darkenParams[1];
126 FT_Int x2 = darkenParams[2];
127 FT_Int y2 = darkenParams[3];
128 FT_Int x3 = darkenParams[4];
129 FT_Int y3 = darkenParams[5];
130 FT_Int x4 = darkenParams[6];
131 FT_Int y4 = darkenParams[7];
132
133
134 /* convert from true character space to 1000 unit character space; */
135 /* add synthetic emboldening effect */
136
137 /* `stemWidthPer1000' will not overflow for a legitimate font */
138
139 stemWidthPer1000 = FT_MulFix( stemWidth + boldenAmount, emRatio );
140
141 /* `scaledStem' can easily overflow, so we must clamp its maximum */
142 /* value; the test doesn't need to be precise, but must be */
143 /* conservative. The clamp value (default 2333) where */
144 /* `darkenAmount' is zero is well below the overflow value of */
145 /* 32767. */
146 /* */
147 /* FT_MSB computes the integer part of the base 2 logarithm. The */
148 /* number of bits for the product is 1 or 2 more than the sum of */
149 /* logarithms; remembering that the 16 lowest bits of the fraction */
150 /* are dropped this is correct to within a factor of almost 4. */
151 /* For example, 0x80.0000 * 0x80.0000 = 0x4000.0000 is 23+23 and */
152 /* is flagged as possible overflow because 0xFF.FFFF * 0xFF.FFFF = */
153 /* 0xFFFF.FE00 is also 23+23. */
154
155 logBase2 = FT_MSB( (FT_UInt32)stemWidthPer1000 ) +
156 FT_MSB( (FT_UInt32)ppem );
157
158 if ( logBase2 >= 46 )
159 /* possible overflow */
160 scaledStem = cf2_intToFixed( x4 );
161 else
162 scaledStem = FT_MulFix( stemWidthPer1000, ppem );
163
164 /* now apply the darkening parameters */
165
166 if ( scaledStem < cf2_intToFixed( x1 ) )
167 *darkenAmount = FT_DivFix( cf2_intToFixed( y1 ), ppem );
168
169 else if ( scaledStem < cf2_intToFixed( x2 ) )
170 {
171 FT_Int xdelta = x2 - x1;
172 FT_Int ydelta = y2 - y1;
173 FT_Int x = stemWidthPer1000 -
174 FT_DivFix( cf2_intToFixed( x1 ), ppem );
175
176
177 if ( !xdelta )
178 goto Try_x3;
179
180 *darkenAmount = FT_MulDiv( x, ydelta, xdelta ) +
181 FT_DivFix( cf2_intToFixed( y1 ), ppem );
182 }
183
184 else if ( scaledStem < cf2_intToFixed( x3 ) )
185 {
186 Try_x3:
187 {
188 FT_Int xdelta = x3 - x2;
189 FT_Int ydelta = y3 - y2;
190 FT_Int x = stemWidthPer1000 -
191 FT_DivFix( cf2_intToFixed( x2 ), ppem );
192
193
194 if ( !xdelta )
195 goto Try_x4;
196
197 *darkenAmount = FT_MulDiv( x, ydelta, xdelta ) +
198 FT_DivFix( cf2_intToFixed( y2 ), ppem );
199 }
200 }
201
202 else if ( scaledStem < cf2_intToFixed( x4 ) )
203 {
204 Try_x4:
205 {
206 FT_Int xdelta = x4 - x3;
207 FT_Int ydelta = y4 - y3;
208 FT_Int x = stemWidthPer1000 -
209 FT_DivFix( cf2_intToFixed( x3 ), ppem );
210
211
212 if ( !xdelta )
213 goto Use_y4;
214
215 *darkenAmount = FT_MulDiv( x, ydelta, xdelta ) +
216 FT_DivFix( cf2_intToFixed( y3 ), ppem );
217 }
218 }
219
220 else
221 {
222 Use_y4:
223 *darkenAmount = FT_DivFix( cf2_intToFixed( y4 ), ppem );
224 }
225
226 /* use half the amount on each side and convert back to true */
227 /* character space */
228 *darkenAmount = FT_DivFix( *darkenAmount, 2 * emRatio );
229 }
230
231 /* add synthetic emboldening effect in character space */
232 *darkenAmount += boldenAmount / 2;
233 }
234
235
236 /* set up values for the current FontDict and matrix; */
237 /* called for each glyph to be rendered */
238
239 /* caller's transform is adjusted for subpixel positioning */
240 static void
241 cf2_font_setup( CF2_Font font,
242 const CF2_Matrix* transform )
243 {
244 /* pointer to parsed font object */
245 PS_Decoder* decoder = font->decoder;
246
247 FT_Bool needExtraSetup = FALSE;
248
249 CFF_VStoreRec* vstore;
250 FT_Bool hasVariations = FALSE;
251
252 /* character space units */
253 CF2_Fixed boldenX = font->syntheticEmboldeningAmountX;
254 CF2_Fixed boldenY = font->syntheticEmboldeningAmountY;
255
256 CFF_SubFont subFont;
257 CF2_Fixed ppem;
258
259 CF2_UInt lenNormalizedV = 0;
260 FT_Fixed* normalizedV = NULL;
261
262 /* clear previous error */
263 font->error = FT_Err_Ok;
264
265 /* if a CID fontDict has changed, we need to recompute some cached */
266 /* data */
267 subFont = cf2_getSubfont( decoder );
268 if ( font->lastSubfont != subFont )
269 {
270 font->lastSubfont = subFont;
271 needExtraSetup = TRUE;
272 }
273
274 if ( !font->isT1 )
275 {
276 /* check for variation vectors */
277 vstore = cf2_getVStore( decoder );
278 hasVariations = ( vstore->dataCount != 0 );
279
280 if ( hasVariations )
281 {
282 #ifdef TT_CONFIG_OPTION_GX_VAR_SUPPORT
283 FT_Service_CFFLoad cffload = (FT_Service_CFFLoad)font->cffload;
284
285
286 /* check whether Private DICT in this subfont needs to be reparsed */
287 font->error = cf2_getNormalizedVector( decoder,
288 &lenNormalizedV,
289 &normalizedV );
290 if ( font->error )
291 return;
292
293 if ( cffload->blend_check_vector( &subFont->blend,
294 subFont->private_dict.vsindex,
295 lenNormalizedV,
296 normalizedV ) )
297 {
298 /* blend has changed, reparse */
299 cffload->load_private_dict( decoder->cff,
300 subFont,
301 lenNormalizedV,
302 normalizedV );
303 needExtraSetup = TRUE;
304 }
305 #endif
306
307 /* copy from subfont */
308 font->blend.font = subFont->blend.font;
309
310 /* clear state of charstring blend */
311 font->blend.usedBV = FALSE;
312
313 /* initialize value for charstring */
314 font->vsindex = subFont->private_dict.vsindex;
315
316 /* store vector inputs for blends in charstring */
317 font->lenNDV = lenNormalizedV;
318 font->NDV = normalizedV;
319 }
320 }
321
322 /* if ppem has changed, we need to recompute some cached data */
323 /* note: because of CID font matrix concatenation, ppem and transform */
324 /* do not necessarily track. */
325 ppem = cf2_getPpemY( decoder );
326 if ( font->ppem != ppem )
327 {
328 font->ppem = ppem;
329 needExtraSetup = TRUE;
330 }
331
332 /* copy hinted flag on each call */
333 font->hinted = FT_BOOL( font->renderingFlags & CF2_FlagsHinted );
334
335 /* determine if transform has changed; */
336 /* include Fontmatrix but ignore translation */
337 if ( ft_memcmp( transform,
338 &font->currentTransform,
339 4 * sizeof ( CF2_Fixed ) ) != 0 )
340 {
341 /* save `key' information for `cache of one' matrix data; */
342 /* save client transform, without the translation */
343 font->currentTransform = *transform;
344 font->currentTransform.tx =
345 font->currentTransform.ty = cf2_intToFixed( 0 );
346
347 /* TODO: FreeType transform is simple scalar; for now, use identity */
348 /* for outer */
349 font->innerTransform = *transform;
350 font->outerTransform.a =
351 font->outerTransform.d = cf2_intToFixed( 1 );
352 font->outerTransform.b =
353 font->outerTransform.c = cf2_intToFixed( 0 );
354
355 needExtraSetup = TRUE;
356 }
357
358 /*
359 * font->darkened is set to true if there is a stem darkening request or
360 * the font is synthetic emboldened.
361 * font->darkened controls whether to adjust blue zones, winding order,
362 * and hinting.
363 *
364 */
365 if ( font->stemDarkened != ( font->renderingFlags & CF2_FlagsDarkened ) )
366 {
367 font->stemDarkened =
368 FT_BOOL( font->renderingFlags & CF2_FlagsDarkened );
369
370 /* blue zones depend on darkened flag */
371 needExtraSetup = TRUE;
372 }
373
374 /* recompute variables that are dependent on transform or FontDict or */
375 /* darken flag */
376 if ( needExtraSetup )
377 {
378 /* StdVW is found in the private dictionary; */
379 /* recompute darkening amounts whenever private dictionary or */
380 /* transform change */
381 /* Note: a rendering flag turns darkening on or off, so we want to */
382 /* store the `on' amounts; */
383 /* darkening amount is computed in character space */
384 /* TODO: testing size-dependent darkening here; */
385 /* what to do for rotations? */
386
387 CF2_Fixed emRatio;
388 CF2_Fixed stdHW;
389 CF2_Int unitsPerEm = font->unitsPerEm;
390
391
392 if ( unitsPerEm == 0 )
393 unitsPerEm = 1000;
394
395 ppem = FT_MAX( cf2_intToFixed( 4 ),
396 font->ppem ); /* use minimum ppem of 4 */
397
398 #if 0
399 /* since vstem is measured in the x-direction, we use the `a' member */
400 /* of the fontMatrix */
401 emRatio = cf2_fixedFracMul( cf2_intToFixed( 1000 ), fontMatrix->a );
402 #endif
403
404 /* Freetype does not preserve the fontMatrix when parsing; use */
405 /* unitsPerEm instead. */
406 /* TODO: check precision of this */
407 emRatio = cf2_intToFixed( 1000 ) / unitsPerEm;
408 font->stdVW = cf2_getStdVW( decoder );
409
410 if ( font->stdVW <= 0 )
411 font->stdVW = FT_DivFix( cf2_intToFixed( 75 ), emRatio );
412
413 if ( boldenX > 0 )
414 {
415 /* Ensure that boldenX is at least 1 pixel for synthetic bold font */
416 /* (similar to what Avalon does) */
417 boldenX = FT_MAX( boldenX,
418 FT_DivFix( cf2_intToFixed( unitsPerEm ), ppem ) );
419
420 /* Synthetic emboldening adds at least 1 pixel to darkenX, while */
421 /* stem darkening adds at most half pixel. Since the purpose of */
422 /* stem darkening (readability at small sizes) is met with */
423 /* synthetic emboldening, no need to add stem darkening for a */
424 /* synthetic bold font. */
425 cf2_computeDarkening( emRatio,
426 ppem,
427 font->stdVW,
428 &font->darkenX,
429 boldenX,
430 FALSE,
431 font->darkenParams );
432 }
433 else
434 cf2_computeDarkening( emRatio,
435 ppem,
436 font->stdVW,
437 &font->darkenX,
438 0,
439 font->stemDarkened,
440 font->darkenParams );
441
442 #if 0
443 /* since hstem is measured in the y-direction, we use the `d' member */
444 /* of the fontMatrix */
445 /* TODO: use the same units per em as above; check this */
446 emRatio = cf2_fixedFracMul( cf2_intToFixed( 1000 ), fontMatrix->d );
447 #endif
448
449 /* set the default stem width, because it must be the same for all */
450 /* family members; */
451 /* choose a constant for StdHW that depends on font contrast */
452 stdHW = cf2_getStdHW( decoder );
453
454 if ( stdHW > 0 && font->stdVW > MUL_INT32( 2, stdHW ) )
455 font->stdHW = FT_DivFix( cf2_intToFixed( 75 ), emRatio );
456 else
457 {
458 /* low contrast font gets less hstem darkening */
459 font->stdHW = FT_DivFix( cf2_intToFixed( 110 ), emRatio );
460 }
461
462 cf2_computeDarkening( emRatio,
463 ppem,
464 font->stdHW,
465 &font->darkenY,
466 boldenY,
467 font->stemDarkened,
468 font->darkenParams );
469
470 if ( font->darkenX != 0 || font->darkenY != 0 )
471 font->darkened = TRUE;
472 else
473 font->darkened = FALSE;
474
475 font->reverseWinding = FALSE; /* initial expectation is CCW */
476
477 /* compute blue zones for this instance */
478 cf2_blues_init( &font->blues, font );
479
480 } /* needExtraSetup */
481 }
482
483
484 /* equivalent to AdobeGetOutline */
485 FT_LOCAL_DEF( FT_Error )
486 cf2_getGlyphOutline( CF2_Font font,
487 CF2_Buffer charstring,
488 const CF2_Matrix* transform,
489 CF2_F16Dot16* glyphWidth )
490 {
491 FT_Error lastError = FT_Err_Ok;
492
493 FT_Vector translation;
494
495 #if 0
496 FT_Vector advancePoint;
497 #endif
498
499 CF2_Fixed advWidth = 0;
500 FT_Bool needWinding;
501
502
503 /* Note: use both integer and fraction for outlines. This allows bbox */
504 /* to come out directly. */
505
506 translation.x = transform->tx;
507 translation.y = transform->ty;
508
509 /* set up values based on transform */
510 cf2_font_setup( font, transform );
511 if ( font->error )
512 goto exit; /* setup encountered an error */
513
514 /* reset darken direction */
515 font->reverseWinding = FALSE;
516
517 /* winding order only affects darkening */
518 needWinding = font->darkened;
519
520 while ( 1 )
521 {
522 /* reset output buffer */
523 cf2_outline_reset( &font->outline );
524
525 /* build the outline, passing the full translation */
526 cf2_interpT2CharString( font,
527 charstring,
528 (CF2_OutlineCallbacks)&font->outline,
529 &translation,
530 FALSE,
531 0,
532 0,
533 &advWidth );
534
535 if ( font->error )
536 goto exit;
537
538 if ( !needWinding )
539 break;
540
541 /* check winding order */
542 if ( font->outline.root.windingMomentum >= 0 ) /* CFF is CCW */
543 break;
544
545 /* invert darkening and render again */
546 /* TODO: this should be a parameter to getOutline-computeOffset */
547 font->reverseWinding = TRUE;
548
549 needWinding = FALSE; /* exit after next iteration */
550 }
551
552 /* finish storing client outline */
553 cf2_outline_close( &font->outline );
554
555 exit:
556 /* FreeType just wants the advance width; there is no translation */
557 *glyphWidth = advWidth;
558
559 /* free resources and collect errors from objects we've used */
560 cf2_setError( &font->error, lastError );
561
562 return font->error;
563 }
564
565
566 /* END */