1 /* 2 * Copyright 2006 The Android Open Source Project 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "SkRegionPriv.h" 9 #include "SkBlitter.h" 10 #include "SkScan.h" 11 #include "SkTSort.h" 12 #include "SkTDArray.h" 13 #include "SkPath.h" 14 15 // The rgnbuilder caller *seems* to pass short counts, possible often seens early failure, so 16 // we may not want to promote this to a "std" routine just yet. 17 static bool sk_memeq32(const int32_t* SK_RESTRICT a, const int32_t* SK_RESTRICT b, int count) { 18 for (int i = 0; i < count; ++i) { 19 if (a[i] != b[i]) { 20 return false; 21 } 22 } 23 return true; 24 } 25 26 class SkRgnBuilder : public SkBlitter { 27 public: 28 SkRgnBuilder(); 29 ~SkRgnBuilder() override; 30 31 // returns true if it could allocate the working storage needed 32 bool init(int maxHeight, int maxTransitions, bool pathIsInverse); 33 34 void done() { 35 if (fCurrScanline != nullptr) { 36 fCurrScanline->fXCount = (SkRegion::RunType)((int)(fCurrXPtr - fCurrScanline->firstX())); 37 if (!this->collapsWithPrev()) { // flush the last line 38 fCurrScanline = fCurrScanline->nextScanline(); 39 } 40 } 41 } 42 43 int computeRunCount() const; 44 void copyToRect(SkIRect*) const; 45 void copyToRgn(SkRegion::RunType runs[]) const; 46 47 void blitH(int x, int y, int width) override; 48 void blitAntiH(int x, int y, const SkAlpha antialias[], const int16_t runs[]) override { 49 SkDEBUGFAIL("blitAntiH not implemented"); 50 } 51 52 #ifdef SK_DEBUG 53 void dump() const { 54 SkDebugf("SkRgnBuilder: Top = %d\n", fTop); 55 const Scanline* line = (Scanline*)fStorage; 56 while (line < fCurrScanline) { 57 SkDebugf("SkRgnBuilder::Scanline: LastY=%d, fXCount=%d", line->fLastY, line->fXCount); 58 for (int i = 0; i < line->fXCount; i++) { 59 SkDebugf(" %d", line->firstX()[i]); 60 } 61 SkDebugf("\n"); 62 63 line = line->nextScanline(); 64 } 65 } 66 #endif 67 private: 68 /* 69 * Scanline mimics a row in the region, nearly. A row in a region is: 70 * [Bottom IntervalCount [L R]... Sentinel] 71 * while a Scanline is 72 * [LastY XCount [L R]... uninitialized] 73 * The two are the same length (which is good), but we have to transmute 74 * the scanline a little when we convert it to a region-row. 75 * 76 * Potentially we could recode this to exactly match the row format, in 77 * which case copyToRgn() could be a single memcpy. Not sure that is worth 78 * the effort. 79 */ 80 struct Scanline { 81 SkRegion::RunType fLastY; 82 SkRegion::RunType fXCount; 83 84 SkRegion::RunType* firstX() const { return (SkRegion::RunType*)(this + 1); } 85 Scanline* nextScanline() const { 86 // add final +1 for the x-sentinel 87 return (Scanline*)((SkRegion::RunType*)(this + 1) + fXCount + 1); 88 } 89 }; 90 SkRegion::RunType* fStorage; 91 Scanline* fCurrScanline; 92 Scanline* fPrevScanline; 93 // points at next avialable x[] in fCurrScanline 94 SkRegion::RunType* fCurrXPtr; 95 SkRegion::RunType fTop; // first Y value 96 97 int fStorageCount; 98 99 bool collapsWithPrev() { 100 if (fPrevScanline != nullptr && 101 fPrevScanline->fLastY + 1 == fCurrScanline->fLastY && 102 fPrevScanline->fXCount == fCurrScanline->fXCount && 103 sk_memeq32(fPrevScanline->firstX(), fCurrScanline->firstX(), fCurrScanline->fXCount)) 104 { 105 // update the height of fPrevScanline 106 fPrevScanline->fLastY = fCurrScanline->fLastY; 107 return true; 108 } 109 return false; 110 } 111 }; 112 113 SkRgnBuilder::SkRgnBuilder() 114 : fStorage(nullptr) { 115 } 116 117 SkRgnBuilder::~SkRgnBuilder() { 118 sk_free(fStorage); 119 } 120 121 bool SkRgnBuilder::init(int maxHeight, int maxTransitions, bool pathIsInverse) { 122 if ((maxHeight | maxTransitions) < 0) { 123 return false; 124 } 125 126 if (pathIsInverse) { 127 // allow for additional X transitions to "invert" each scanline 128 // [ L' ... normal transitions ... R' ] 129 // 130 maxTransitions += 2; 131 } 132 133 // compute the count with +1 and +3 slop for the working buffer 134 int64_t count = sk_64_mul(maxHeight + 1, 3 + maxTransitions); 135 136 if (pathIsInverse) { 137 // allow for two "empty" rows for the top and bottom 138 // [ Y, 1, L, R, S] == 5 (*2 for top and bottom) 139 count += 10; 140 } 141 142 if (count < 0 || !sk_64_isS32(count)) { 143 return false; 144 } 145 fStorageCount = sk_64_asS32(count); 146 147 fStorage = (SkRegion::RunType*)sk_malloc_canfail(fStorageCount, sizeof(SkRegion::RunType)); 148 if (nullptr == fStorage) { 149 return false; 150 } 151 152 fCurrScanline = nullptr; // signal empty collection 153 fPrevScanline = nullptr; // signal first scanline 154 return true; 155 } 156 157 void SkRgnBuilder::blitH(int x, int y, int width) { 158 if (fCurrScanline == nullptr) { // first time 159 fTop = (SkRegion::RunType)(y); 160 fCurrScanline = (Scanline*)fStorage; 161 fCurrScanline->fLastY = (SkRegion::RunType)(y); 162 fCurrXPtr = fCurrScanline->firstX(); 163 } else { 164 SkASSERT(y >= fCurrScanline->fLastY); 165 166 if (y > fCurrScanline->fLastY) { 167 // if we get here, we're done with fCurrScanline 168 fCurrScanline->fXCount = (SkRegion::RunType)((int)(fCurrXPtr - fCurrScanline->firstX())); 169 170 int prevLastY = fCurrScanline->fLastY; 171 if (!this->collapsWithPrev()) { 172 fPrevScanline = fCurrScanline; 173 fCurrScanline = fCurrScanline->nextScanline(); 174 175 } 176 if (y - 1 > prevLastY) { // insert empty run 177 fCurrScanline->fLastY = (SkRegion::RunType)(y - 1); 178 fCurrScanline->fXCount = 0; 179 fCurrScanline = fCurrScanline->nextScanline(); 180 } 181 // setup for the new curr line 182 fCurrScanline->fLastY = (SkRegion::RunType)(y); 183 fCurrXPtr = fCurrScanline->firstX(); 184 } 185 } 186 // check if we should extend the current run, or add a new one 187 if (fCurrXPtr > fCurrScanline->firstX() && fCurrXPtr[-1] == x) { 188 fCurrXPtr[-1] = (SkRegion::RunType)(x + width); 189 } else { 190 fCurrXPtr[0] = (SkRegion::RunType)(x); 191 fCurrXPtr[1] = (SkRegion::RunType)(x + width); 192 fCurrXPtr += 2; 193 } 194 SkASSERT(fCurrXPtr - fStorage < fStorageCount); 195 } 196 197 int SkRgnBuilder::computeRunCount() const { 198 if (fCurrScanline == nullptr) { 199 return 0; 200 } 201 202 const SkRegion::RunType* line = fStorage; 203 const SkRegion::RunType* stop = (const SkRegion::RunType*)fCurrScanline; 204 205 return 2 + (int)(stop - line); 206 } 207 208 void SkRgnBuilder::copyToRect(SkIRect* r) const { 209 SkASSERT(fCurrScanline != nullptr); 210 // A rect's scanline is [bottom intervals left right sentinel] == 5 211 SkASSERT((const SkRegion::RunType*)fCurrScanline - fStorage == 5); 212 213 const Scanline* line = (const Scanline*)fStorage; 214 SkASSERT(line->fXCount == 2); 215 216 r->set(line->firstX()[0], fTop, line->firstX()[1], line->fLastY + 1); 217 } 218 219 void SkRgnBuilder::copyToRgn(SkRegion::RunType runs[]) const { 220 SkASSERT(fCurrScanline != nullptr); 221 SkASSERT((const SkRegion::RunType*)fCurrScanline - fStorage > 4); 222 223 const Scanline* line = (const Scanline*)fStorage; 224 const Scanline* stop = fCurrScanline; 225 226 *runs++ = fTop; 227 do { 228 *runs++ = (SkRegion::RunType)(line->fLastY + 1); 229 int count = line->fXCount; 230 *runs++ = count >> 1; // intervalCount 231 if (count) { 232 memcpy(runs, line->firstX(), count * sizeof(SkRegion::RunType)); 233 runs += count; 234 } 235 *runs++ = SkRegion::kRunTypeSentinel; 236 line = line->nextScanline(); 237 } while (line < stop); 238 SkASSERT(line == stop); 239 *runs = SkRegion::kRunTypeSentinel; 240 } 241 242 static unsigned verb_to_initial_last_index(unsigned verb) { 243 static const uint8_t gPathVerbToInitialLastIndex[] = { 244 0, // kMove_Verb 245 1, // kLine_Verb 246 2, // kQuad_Verb 247 2, // kConic_Verb 248 3, // kCubic_Verb 249 0, // kClose_Verb 250 0 // kDone_Verb 251 }; 252 SkASSERT((unsigned)verb < SK_ARRAY_COUNT(gPathVerbToInitialLastIndex)); 253 return gPathVerbToInitialLastIndex[verb]; 254 } 255 256 static unsigned verb_to_max_edges(unsigned verb) { 257 static const uint8_t gPathVerbToMaxEdges[] = { 258 0, // kMove_Verb 259 1, // kLine_Verb 260 2, // kQuad_VerbB 261 2, // kConic_VerbB 262 3, // kCubic_Verb 263 0, // kClose_Verb 264 0 // kDone_Verb 265 }; 266 SkASSERT((unsigned)verb < SK_ARRAY_COUNT(gPathVerbToMaxEdges)); 267 return gPathVerbToMaxEdges[verb]; 268 } 269 270 // If returns 0, ignore itop and ibot 271 static int count_path_runtype_values(const SkPath& path, int* itop, int* ibot) { 272 SkPath::Iter iter(path, true); 273 SkPoint pts[4]; 274 SkPath::Verb verb; 275 276 int maxEdges = 0; 277 SkScalar top = SkIntToScalar(SK_MaxS16); 278 SkScalar bot = SkIntToScalar(SK_MinS16); 279 280 while ((verb = iter.next(pts, false)) != SkPath::kDone_Verb) { 281 maxEdges += verb_to_max_edges(verb); 282 283 int lastIndex = verb_to_initial_last_index(verb); 284 if (lastIndex > 0) { 285 for (int i = 1; i <= lastIndex; i++) { 286 if (top > pts[i].fY) { 287 top = pts[i].fY; 288 } else if (bot < pts[i].fY) { 289 bot = pts[i].fY; 290 } 291 } 292 } else if (SkPath::kMove_Verb == verb) { 293 if (top > pts[0].fY) { 294 top = pts[0].fY; 295 } else if (bot < pts[0].fY) { 296 bot = pts[0].fY; 297 } 298 } 299 } 300 if (0 == maxEdges) { 301 return 0; // we have only moves+closes 302 } 303 304 SkASSERT(top <= bot); 305 *itop = SkScalarRoundToInt(top); 306 *ibot = SkScalarRoundToInt(bot); 307 return maxEdges; 308 } 309 310 static bool check_inverse_on_empty_return(SkRegion* dst, const SkPath& path, const SkRegion& clip) { 311 if (path.isInverseFillType()) { 312 return dst->set(clip); 313 } else { 314 return dst->setEmpty(); 315 } 316 } 317 318 bool SkRegion::setPath(const SkPath& path, const SkRegion& clip) { 319 SkDEBUGCODE(this->validate();) 320 321 if (clip.isEmpty() || !path.isFinite()) { 322 return this->setEmpty(); 323 } 324 325 if (path.isEmpty()) { 326 return check_inverse_on_empty_return(this, path, clip); 327 } 328 329 // compute worst-case rgn-size for the path 330 int pathTop, pathBot; 331 int pathTransitions = count_path_runtype_values(path, &pathTop, &pathBot); 332 if (0 == pathTransitions) { 333 return check_inverse_on_empty_return(this, path, clip); 334 } 335 336 int clipTop, clipBot; 337 int clipTransitions = clip.count_runtype_values(&clipTop, &clipBot); 338 339 int top = SkMax32(pathTop, clipTop); 340 int bot = SkMin32(pathBot, clipBot); 341 if (top >= bot) { 342 return check_inverse_on_empty_return(this, path, clip); 343 } 344 345 SkRgnBuilder builder; 346 347 if (!builder.init(bot - top, 348 SkMax32(pathTransitions, clipTransitions), 349 path.isInverseFillType())) { 350 // can't allocate working space, so return false 351 return this->setEmpty(); 352 } 353 354 SkScan::FillPath(path, clip, &builder); 355 builder.done(); 356 357 int count = builder.computeRunCount(); 358 if (count == 0) { 359 return this->setEmpty(); 360 } else if (count == kRectRegionRuns) { 361 builder.copyToRect(&fBounds); 362 this->setRect(fBounds); 363 } else { 364 SkRegion tmp; 365 366 tmp.fRunHead = RunHead::Alloc(count); 367 builder.copyToRgn(tmp.fRunHead->writable_runs()); 368 tmp.fRunHead->computeRunBounds(&tmp.fBounds); 369 this->swap(tmp); 370 } 371 SkDEBUGCODE(this->validate();) 372 return true; 373 } 374 375 ///////////////////////////////////////////////////////////////////////////////////////////////// 376 ///////////////////////////////////////////////////////////////////////////////////////////////// 377 378 struct Edge { 379 enum { 380 kY0Link = 0x01, 381 kY1Link = 0x02, 382 383 kCompleteLink = (kY0Link | kY1Link) 384 }; 385 386 SkRegion::RunType fX; 387 SkRegion::RunType fY0, fY1; 388 uint8_t fFlags; 389 Edge* fNext; 390 391 void set(int x, int y0, int y1) { 392 SkASSERT(y0 != y1); 393 394 fX = (SkRegion::RunType)(x); 395 fY0 = (SkRegion::RunType)(y0); 396 fY1 = (SkRegion::RunType)(y1); 397 fFlags = 0; 398 SkDEBUGCODE(fNext = nullptr;) 399 } 400 401 int top() const { 402 return SkFastMin32(fY0, fY1); 403 } 404 }; 405 406 static void find_link(Edge* base, Edge* stop) { 407 SkASSERT(base < stop); 408 409 if (base->fFlags == Edge::kCompleteLink) { 410 SkASSERT(base->fNext); 411 return; 412 } 413 414 SkASSERT(base + 1 < stop); 415 416 int y0 = base->fY0; 417 int y1 = base->fY1; 418 419 Edge* e = base; 420 if ((base->fFlags & Edge::kY0Link) == 0) { 421 for (;;) { 422 e += 1; 423 if ((e->fFlags & Edge::kY1Link) == 0 && y0 == e->fY1) { 424 SkASSERT(nullptr == e->fNext); 425 e->fNext = base; 426 e->fFlags = SkToU8(e->fFlags | Edge::kY1Link); 427 break; 428 } 429 } 430 } 431 432 e = base; 433 if ((base->fFlags & Edge::kY1Link) == 0) { 434 for (;;) { 435 e += 1; 436 if ((e->fFlags & Edge::kY0Link) == 0 && y1 == e->fY0) { 437 SkASSERT(nullptr == base->fNext); 438 base->fNext = e; 439 e->fFlags = SkToU8(e->fFlags | Edge::kY0Link); 440 break; 441 } 442 } 443 } 444 445 base->fFlags = Edge::kCompleteLink; 446 } 447 448 static int extract_path(Edge* edge, Edge* stop, SkPath* path) { 449 while (0 == edge->fFlags) { 450 edge++; // skip over "used" edges 451 } 452 453 SkASSERT(edge < stop); 454 455 Edge* base = edge; 456 Edge* prev = edge; 457 edge = edge->fNext; 458 SkASSERT(edge != base); 459 460 int count = 1; 461 path->moveTo(SkIntToScalar(prev->fX), SkIntToScalar(prev->fY0)); 462 prev->fFlags = 0; 463 do { 464 if (prev->fX != edge->fX || prev->fY1 != edge->fY0) { // skip collinear 465 path->lineTo(SkIntToScalar(prev->fX), SkIntToScalar(prev->fY1)); // V 466 path->lineTo(SkIntToScalar(edge->fX), SkIntToScalar(edge->fY0)); // H 467 } 468 prev = edge; 469 edge = edge->fNext; 470 count += 1; 471 prev->fFlags = 0; 472 } while (edge != base); 473 path->lineTo(SkIntToScalar(prev->fX), SkIntToScalar(prev->fY1)); // V 474 path->close(); 475 return count; 476 } 477 478 struct EdgeLT { 479 bool operator()(const Edge& a, const Edge& b) const { 480 return (a.fX == b.fX) ? a.top() < b.top() : a.fX < b.fX; 481 } 482 }; 483 484 bool SkRegion::getBoundaryPath(SkPath* path) const { 485 // path could safely be nullptr if we're empty, but the caller shouldn't 486 // *know* that 487 SkASSERT(path); 488 489 if (this->isEmpty()) { 490 return false; 491 } 492 493 const SkIRect& bounds = this->getBounds(); 494 495 if (this->isRect()) { 496 SkRect r; 497 r.set(bounds); // this converts the ints to scalars 498 path->addRect(r); 499 return true; 500 } 501 502 SkRegion::Iterator iter(*this); 503 SkTDArray<Edge> edges; 504 505 for (const SkIRect& r = iter.rect(); !iter.done(); iter.next()) { 506 Edge* edge = edges.append(2); 507 edge[0].set(r.fLeft, r.fBottom, r.fTop); 508 edge[1].set(r.fRight, r.fTop, r.fBottom); 509 } 510 511 int count = edges.count(); 512 Edge* start = edges.begin(); 513 Edge* stop = start + count; 514 SkTQSort<Edge>(start, stop - 1, EdgeLT()); 515 516 Edge* e; 517 for (e = start; e != stop; e++) { 518 find_link(e, stop); 519 } 520 521 #ifdef SK_DEBUG 522 for (e = start; e != stop; e++) { 523 SkASSERT(e->fNext != nullptr); 524 SkASSERT(e->fFlags == Edge::kCompleteLink); 525 } 526 #endif 527 528 path->incReserve(count << 1); 529 do { 530 SkASSERT(count > 1); 531 count -= extract_path(start, stop, path); 532 } while (count > 0); 533 534 return true; 535 } 536