cf2blues.c revision 9c745321260bb728ab1cd1c8fd5f075854b2ad49
1/***************************************************************************/ 2/* */ 3/* cf2blues.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 "cf2ft.h" 40#include FT_INTERNAL_DEBUG_H 41 42#include "cf2blues.h" 43#include "cf2hints.h" 44#include "cf2font.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 trace_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 CFF_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 = 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 = 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( 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( 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( 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_floatToFixed( .6 ) - 412 FT_MulDiv( cf2_floatToFixed ( .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 ( ( blues->zone[i].csBottomEdge - csFuzz ) <= 493 bottomHintEdge->csCoord && 494 bottomHintEdge->csCoord <= 495 ( 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 ( ( blues->zone[i].csTopEdge - bottomHintEdge->csCoord ) >= 503 blues->blueShift ) 504 { 505 /* guarantee minimum of 1 pixel overshoot */ 506 dsNew = FT_MIN( 507 cf2_fixedRound( bottomHintEdge->dsCoord ), 508 blues->zone[i].dsFlatEdge - cf2_intToFixed( 1 ) ); 509 } 510 511 else 512 { 513 /* simply round captured edge */ 514 dsNew = cf2_fixedRound( bottomHintEdge->dsCoord ); 515 } 516 517 dsMove = dsNew - bottomHintEdge->dsCoord; 518 captured = TRUE; 519 520 break; 521 } 522 } 523 524 if ( !blues->zone[i].bottomZone && cf2_hint_isTop( topHintEdge ) ) 525 { 526 if ( ( blues->zone[i].csBottomEdge - csFuzz ) <= 527 topHintEdge->csCoord && 528 topHintEdge->csCoord <= 529 ( blues->zone[i].csTopEdge + csFuzz ) ) 530 { 531 /* top edge captured by top zone */ 532 533 if ( blues->suppressOvershoot ) 534 dsNew = blues->zone[i].dsFlatEdge; 535 536 else if ( ( topHintEdge->csCoord - blues->zone[i].csBottomEdge ) >= 537 blues->blueShift ) 538 { 539 /* guarantee minimum of 1 pixel overshoot */ 540 dsNew = FT_MAX( 541 cf2_fixedRound( topHintEdge->dsCoord ), 542 blues->zone[i].dsFlatEdge + cf2_intToFixed( 1 ) ); 543 } 544 545 else 546 { 547 /* simply round captured edge */ 548 dsNew = cf2_fixedRound( topHintEdge->dsCoord ); 549 } 550 551 dsMove = dsNew - topHintEdge->dsCoord; 552 captured = TRUE; 553 554 break; 555 } 556 } 557 } 558 559 if ( captured ) 560 { 561 /* move both edges and flag them `locked' */ 562 if ( cf2_hint_isValid( bottomHintEdge ) ) 563 { 564 bottomHintEdge->dsCoord += dsMove; 565 cf2_hint_lock( bottomHintEdge ); 566 } 567 568 if ( cf2_hint_isValid( topHintEdge ) ) 569 { 570 topHintEdge->dsCoord += dsMove; 571 cf2_hint_lock( topHintEdge ); 572 } 573 } 574 575 return captured; 576 } 577 578 579/* END */ 580