src/third_party/skia/src/core/SkPathRef.cpp

   1 /*
   2  * Copyright 2013 Google Inc.
   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 "SkBuffer.h"
   9 #include "SkLazyPtr.h"
  10 #include "SkPath.h"
  11 #include "SkPathRef.h"
  12
  13 //////////////////////////////////////////////////////////////////////////////
  14 SkPathRef::Editor::Editor(SkAutoTUnref<SkPathRef>* pathRef,
  15                           int incReserveVerbs,
  16                           int incReservePoints)
  17 {
  18     if ((*pathRef)->unique()) {
  19         (*pathRef)->incReserve(incReserveVerbs, incReservePoints);
  20     } else {
  21         SkPathRef* copy = SkNEW(SkPathRef);
  22         copy->copy(**pathRef, incReserveVerbs, incReservePoints);
  23         pathRef->reset(copy);
  24     }
  25     fPathRef = *pathRef;
  26     fPathRef->fGenerationID = 0;
  27     SkDEBUGCODE(sk_atomic_inc(&fPathRef->fEditorsAttached);)
  28 }
  29
  30 //////////////////////////////////////////////////////////////////////////////
  31
  32 // As a template argument, this must have external linkage.
  33 SkPathRef* sk_create_empty_pathref() {
  34     SkPathRef* empty = SkNEW(SkPathRef);
  35     empty->computeBounds();   // Avoids races later to be the first to do this.
  36     return empty;
  37 }
  38
  39 SK_DECLARE_STATIC_LAZY_PTR(SkPathRef, empty, sk_create_empty_pathref);
  40
  41 SkPathRef* SkPathRef::CreateEmpty() {
  42     return SkRef(empty.get());
  43 }
  44
  45 void SkPathRef::CreateTransformedCopy(SkAutoTUnref<SkPathRef>* dst,
  46                                       const SkPathRef& src,
  47                                       const SkMatrix& matrix) {
  48     SkDEBUGCODE(src.validate();)
  49     if (matrix.isIdentity()) {
  50         if (*dst != &src) {
  51             src.ref();
  52             dst->reset(const_cast<SkPathRef*>(&src));
  53             SkDEBUGCODE((*dst)->validate();)
  54         }
  55         return;
  56     }
  57
  58     if (!(*dst)->unique()) {
  59         dst->reset(SkNEW(SkPathRef));
  60     }
  61
  62     if (*dst != &src) {
  63         (*dst)->resetToSize(src.fVerbCnt, src.fPointCnt, src.fConicWeights.count());
  64         memcpy((*dst)->verbsMemWritable(), src.verbsMemBegin(), src.fVerbCnt * sizeof(uint8_t));
  65         (*dst)->fConicWeights = src.fConicWeights;
  66     }
  67
  68     SkASSERT((*dst)->countPoints() == src.countPoints());
  69     SkASSERT((*dst)->countVerbs() == src.countVerbs());
  70     SkASSERT((*dst)->fConicWeights.count() == src.fConicWeights.count());
  71
  72     // Need to check this here in case (&src == dst)
  73     bool canXformBounds = !src.fBoundsIsDirty && matrix.rectStaysRect() && src.countPoints() > 1;
  74
  75     matrix.mapPoints((*dst)->fPoints, src.points(), src.fPointCnt);
  76
  77     /*
  78         *  Here we optimize the bounds computation, by noting if the bounds are
  79         *  already known, and if so, we just transform those as well and mark
  80         *  them as "known", rather than force the transformed path to have to
  81         *  recompute them.
  82         *
  83         *  Special gotchas if the path is effectively empty (<= 1 point) or
  84         *  if it is non-finite. In those cases bounds need to stay empty,
  85         *  regardless of the matrix.
  86         */
  87     if (canXformBounds) {
  88         (*dst)->fBoundsIsDirty = false;
  89         if (src.fIsFinite) {
  90             matrix.mapRect((*dst)->fBounds.get(), src.fBounds);
  91             if (!((*dst)->fIsFinite = (*dst)->fBounds->isFinite())) {
  92                 (*dst)->fBounds->setEmpty();
  93             }
  94         } else {
  95             (*dst)->fIsFinite = false;
  96             (*dst)->fBounds->setEmpty();
  97         }
  98     } else {
  99         (*dst)->fBoundsIsDirty = true;
 100     }
 101
 102     (*dst)->fSegmentMask = src.fSegmentMask;
 103
 104     // It's an oval only if it stays a rect.
 105     (*dst)->fIsOval = src.fIsOval && matrix.rectStaysRect();
 106
 107     SkDEBUGCODE((*dst)->validate();)
 108 }
 109
 110 SkPathRef* SkPathRef::CreateFromBuffer(SkRBuffer* buffer) {
 111     SkPathRef* ref = SkNEW(SkPathRef);
 112     bool isOval;
 113     uint8_t segmentMask;
 114
 115     int32_t packed;
 116     if (!buffer->readS32(&packed)) {
 117         SkDELETE(ref);
 118         return NULL;
 119     }
 120
 121     ref->fIsFinite = (packed >> kIsFinite_SerializationShift) & 1;
 122     segmentMask = (packed >> kSegmentMask_SerializationShift) & 0xF;
 123     isOval  = (packed >> kIsOval_SerializationShift) & 1;
 124
 125     int32_t verbCount, pointCount, conicCount;
 126     if (!buffer->readU32(&(ref->fGenerationID)) ||
 127         !buffer->readS32(&verbCount) ||
 128         !buffer->readS32(&pointCount) ||
 129         !buffer->readS32(&conicCount)) {
 130         SkDELETE(ref);
 131         return NULL;
 132     }
 133
 134     ref->resetToSize(verbCount, pointCount, conicCount);
 135     SkASSERT(verbCount == ref->countVerbs());
 136     SkASSERT(pointCount == ref->countPoints());
 137     SkASSERT(conicCount == ref->fConicWeights.count());
 138
 139     if (!buffer->read(ref->verbsMemWritable(), verbCount * sizeof(uint8_t)) ||
 140         !buffer->read(ref->fPoints, pointCount * sizeof(SkPoint)) ||
 141         !buffer->read(ref->fConicWeights.begin(), conicCount * sizeof(SkScalar)) ||
 142         !buffer->read(&ref->fBounds, sizeof(SkRect))) {
 143         SkDELETE(ref);
 144         return NULL;
 145     }
 146     ref->fBoundsIsDirty = false;
 147
 148     // resetToSize clears fSegmentMask and fIsOval
 149     ref->fSegmentMask = segmentMask;
 150     ref->fIsOval = isOval;
 151     return ref;
 152 }
 153
 154 void SkPathRef::Rewind(SkAutoTUnref<SkPathRef>* pathRef) {
 155     if ((*pathRef)->unique()) {
 156         SkDEBUGCODE((*pathRef)->validate();)
 157         (*pathRef)->fBoundsIsDirty = true;  // this also invalidates fIsFinite
 158         (*pathRef)->fVerbCnt = 0;
 159         (*pathRef)->fPointCnt = 0;
 160         (*pathRef)->fFreeSpace = (*pathRef)->currSize();
 161         (*pathRef)->fGenerationID = 0;
 162         (*pathRef)->fConicWeights.rewind();
 163         (*pathRef)->fSegmentMask = 0;
 164         (*pathRef)->fIsOval = false;
 165         SkDEBUGCODE((*pathRef)->validate();)
 166     } else {
 167         int oldVCnt = (*pathRef)->countVerbs();
 168         int oldPCnt = (*pathRef)->countPoints();
 169         pathRef->reset(SkNEW(SkPathRef));
 170         (*pathRef)->resetToSize(0, 0, 0, oldVCnt, oldPCnt);
 171     }
 172 }
 173
 174 bool SkPathRef::operator== (const SkPathRef& ref) const {
 175     SkDEBUGCODE(this->validate();)
 176     SkDEBUGCODE(ref.validate();)
 177
 178     // We explicitly check fSegmentMask as a quick-reject. We could skip it,
 179     // since it is only a cache of info in the fVerbs, but its a fast way to
 180     // notice a difference
 181     if (fSegmentMask != ref.fSegmentMask) {
 182         return false;
 183     }
 184
 185     bool genIDMatch = fGenerationID && fGenerationID == ref.fGenerationID;
 186 #ifdef SK_RELEASE
 187     if (genIDMatch) {
 188         return true;
 189     }
 190 #endif
 191     if (fPointCnt != ref.fPointCnt ||
 192         fVerbCnt != ref.fVerbCnt) {
 193         SkASSERT(!genIDMatch);
 194         return false;
 195     }
 196     if (0 != memcmp(this->verbsMemBegin(),
 197                     ref.verbsMemBegin(),
 198                     ref.fVerbCnt * sizeof(uint8_t))) {
 199         SkASSERT(!genIDMatch);
 200         return false;
 201     }
 202     if (0 != memcmp(this->points(),
 203                     ref.points(),
 204                     ref.fPointCnt * sizeof(SkPoint))) {
 205         SkASSERT(!genIDMatch);
 206         return false;
 207     }
 208     if (fConicWeights != ref.fConicWeights) {
 209         SkASSERT(!genIDMatch);
 210         return false;
 211     }
 212     // We've done the work to determine that these are equal. If either has a zero genID, copy
 213     // the other's. If both are 0 then genID() will compute the next ID.
 214     if (0 == fGenerationID) {
 215         fGenerationID = ref.genID();
 216     } else if (0 == ref.fGenerationID) {
 217         ref.fGenerationID = this->genID();
 218     }
 219     return true;
 220 }
 221
 222 void SkPathRef::writeToBuffer(SkWBuffer* buffer) const {
 223     SkDEBUGCODE(this->validate();)
 224     SkDEBUGCODE(size_t beforePos = buffer->pos();)
 225
 226     // Call getBounds() to ensure (as a side-effect) that fBounds
 227     // and fIsFinite are computed.
 228     const SkRect& bounds = this->getBounds();
 229
 230     int32_t packed = ((fIsFinite & 1) << kIsFinite_SerializationShift) |
 231                      ((fIsOval & 1) << kIsOval_SerializationShift) |
 232                      (fSegmentMask << kSegmentMask_SerializationShift);
 233     buffer->write32(packed);
 234
 235     // TODO: write gen ID here. Problem: We don't know if we're cross process or not from
 236     // SkWBuffer. Until this is fixed we write 0.
 237     buffer->write32(0);
 238     buffer->write32(fVerbCnt);
 239     buffer->write32(fPointCnt);
 240     buffer->write32(fConicWeights.count());
 241     buffer->write(verbsMemBegin(), fVerbCnt * sizeof(uint8_t));
 242     buffer->write(fPoints, fPointCnt * sizeof(SkPoint));
 243     buffer->write(fConicWeights.begin(), fConicWeights.bytes());
 244     buffer->write(&bounds, sizeof(bounds));
 245
 246     SkASSERT(buffer->pos() - beforePos == (size_t) this->writeSize());
 247 }
 248
 249 uint32_t SkPathRef::writeSize() const {
 250     return uint32_t(5 * sizeof(uint32_t) +
 251                     fVerbCnt * sizeof(uint8_t) +
 252                     fPointCnt * sizeof(SkPoint) +
 253                     fConicWeights.bytes() +
 254                     sizeof(SkRect));
 255 }
 256
 257 void SkPathRef::copy(const SkPathRef& ref,
 258                      int additionalReserveVerbs,
 259                      int additionalReservePoints) {
 260     SkDEBUGCODE(this->validate();)
 261     this->resetToSize(ref.fVerbCnt, ref.fPointCnt, ref.fConicWeights.count(),
 262                         additionalReserveVerbs, additionalReservePoints);
 263     memcpy(this->verbsMemWritable(), ref.verbsMemBegin(), ref.fVerbCnt * sizeof(uint8_t));
 264     memcpy(this->fPoints, ref.fPoints, ref.fPointCnt * sizeof(SkPoint));
 265     fConicWeights = ref.fConicWeights;
 266     // We could call genID() here to force a real ID (instead of 0). However, if we're making
 267     // a copy then presumably we intend to make a modification immediately afterwards.
 268     fGenerationID = ref.fGenerationID;
 269     fBoundsIsDirty = ref.fBoundsIsDirty;
 270     if (!fBoundsIsDirty) {
 271         fBounds = ref.fBounds;
 272         fIsFinite = ref.fIsFinite;
 273     }
 274     fSegmentMask = ref.fSegmentMask;
 275     fIsOval = ref.fIsOval;
 276     SkDEBUGCODE(this->validate();)
 277 }
 278
 279 SkPoint* SkPathRef::growForRepeatedVerb(int /*SkPath::Verb*/ verb,
 280                                         int numVbs,
 281                                         SkScalar** weights) {
 282     // This value is just made-up for now. When count is 4, calling memset was much
 283     // slower than just writing the loop. This seems odd, and hopefully in the
 284     // future this will appear to have been a fluke...
 285     static const unsigned int kMIN_COUNT_FOR_MEMSET_TO_BE_FAST = 16;
 286
 287     SkDEBUGCODE(this->validate();)
 288     int pCnt;
 289     bool dirtyAfterEdit = true;
 290     switch (verb) {
 291         case SkPath::kMove_Verb:
 292             pCnt = numVbs;
 293             dirtyAfterEdit = false;
 294             break;
 295         case SkPath::kLine_Verb:
 296             fSegmentMask |= SkPath::kLine_SegmentMask;
 297             pCnt = numVbs;
 298             break;
 299         case SkPath::kQuad_Verb:
 300             fSegmentMask |= SkPath::kQuad_SegmentMask;
 301             pCnt = 2 * numVbs;
 302             break;
 303         case SkPath::kConic_Verb:
 304             fSegmentMask |= SkPath::kConic_SegmentMask;
 305             pCnt = 2 * numVbs;
 306             break;
 307         case SkPath::kCubic_Verb:
 308             fSegmentMask |= SkPath::kCubic_SegmentMask;
 309             pCnt = 3 * numVbs;
 310             break;
 311         case SkPath::kClose_Verb:
 312             SkDEBUGFAIL("growForRepeatedVerb called for kClose_Verb");
 313             pCnt = 0;
 314             dirtyAfterEdit = false;
 315             break;
 316         case SkPath::kDone_Verb:
 317             SkDEBUGFAIL("growForRepeatedVerb called for kDone");
 318             // fall through
 319         default:
 320             SkDEBUGFAIL("default should not be reached");
 321             pCnt = 0;
 322             dirtyAfterEdit = false;
 323     }
 324
 325     size_t space = numVbs * sizeof(uint8_t) + pCnt * sizeof (SkPoint);
 326     this->makeSpace(space);
 327
 328     SkPoint* ret = fPoints + fPointCnt;
 329     uint8_t* vb = fVerbs - fVerbCnt;
 330
 331     // cast to unsigned, so if kMIN_COUNT_FOR_MEMSET_TO_BE_FAST is defined to
 332     // be 0, the compiler will remove the test/branch entirely.
 333     if ((unsigned)numVbs >= kMIN_COUNT_FOR_MEMSET_TO_BE_FAST) {
 334         memset(vb - numVbs, verb, numVbs);
 335     } else {
 336         for (int i = 0; i < numVbs; ++i) {
 337             vb[~i] = verb;
 338         }
 339     }
 340
 341     fVerbCnt += numVbs;
 342     fPointCnt += pCnt;
 343     fFreeSpace -= space;
 344     fBoundsIsDirty = true;  // this also invalidates fIsFinite
 345     if (dirtyAfterEdit) {
 346         fIsOval = false;
 347     }
 348
 349     if (SkPath::kConic_Verb == verb) {
 350         SkASSERT(weights);
 351         *weights = fConicWeights.append(numVbs);
 352     }
 353
 354     SkDEBUGCODE(this->validate();)
 355     return ret;
 356 }
 357
 358 SkPoint* SkPathRef::growForVerb(int /* SkPath::Verb*/ verb, SkScalar weight) {
 359     SkDEBUGCODE(this->validate();)
 360     int pCnt;
 361     bool dirtyAfterEdit = true;
 362     switch (verb) {
 363         case SkPath::kMove_Verb:
 364             pCnt = 1;
 365             dirtyAfterEdit = false;
 366             break;
 367         case SkPath::kLine_Verb:
 368             fSegmentMask |= SkPath::kLine_SegmentMask;
 369             pCnt = 1;
 370             break;
 371         case SkPath::kQuad_Verb:
 372             fSegmentMask |= SkPath::kQuad_SegmentMask;
 373             pCnt = 2;
 374             break;
 375         case SkPath::kConic_Verb:
 376             fSegmentMask |= SkPath::kConic_SegmentMask;
 377             pCnt = 2;
 378             break;
 379         case SkPath::kCubic_Verb:
 380             fSegmentMask |= SkPath::kCubic_SegmentMask;
 381             pCnt = 3;
 382             break;
 383         case SkPath::kClose_Verb:
 384             pCnt = 0;
 385             dirtyAfterEdit = false;
 386             break;
 387         case SkPath::kDone_Verb:
 388             SkDEBUGFAIL("growForVerb called for kDone");
 389             // fall through
 390         default:
 391             SkDEBUGFAIL("default is not reached");
 392             dirtyAfterEdit = false;
 393             pCnt = 0;
 394     }
 395     size_t space = sizeof(uint8_t) + pCnt * sizeof (SkPoint);
 396     this->makeSpace(space);
 397     this->fVerbs[~fVerbCnt] = verb;
 398     SkPoint* ret = fPoints + fPointCnt;
 399     fVerbCnt += 1;
 400     fPointCnt += pCnt;
 401     fFreeSpace -= space;
 402     fBoundsIsDirty = true;  // this also invalidates fIsFinite
 403     if (dirtyAfterEdit) {
 404         fIsOval = false;
 405     }
 406
 407     if (SkPath::kConic_Verb == verb) {
 408         *fConicWeights.append() = weight;
 409     }
 410
 411     SkDEBUGCODE(this->validate();)
 412     return ret;
 413 }
 414
 415 uint32_t SkPathRef::genID() const {
 416     SkASSERT(!fEditorsAttached);
 417     static const uint32_t kMask = (static_cast<int64_t>(1) << SkPath::kPathRefGenIDBitCnt) - 1;
 418     if (!fGenerationID) {
 419         if (0 == fPointCnt && 0 == fVerbCnt) {
 420             fGenerationID = kEmptyGenID;
 421         } else {
 422             static int32_t  gPathRefGenerationID;
 423             // do a loop in case our global wraps around, as we never want to return a 0 or the
 424             // empty ID
 425             do {
 426                 fGenerationID = (sk_atomic_inc(&gPathRefGenerationID) + 1) & kMask;
 427             } while (fGenerationID <= kEmptyGenID);
 428         }
 429     }
 430     return fGenerationID;
 431 }
 432
 433 #ifdef SK_DEBUG
 434 void SkPathRef::validate() const {
 435     this->INHERITED::validate();
 436     SkASSERT(static_cast<ptrdiff_t>(fFreeSpace) >= 0);
 437     SkASSERT(reinterpret_cast<intptr_t>(fVerbs) - reinterpret_cast<intptr_t>(fPoints) >= 0);
 438     SkASSERT((NULL == fPoints) == (NULL == fVerbs));
 439     SkASSERT(!(NULL == fPoints && 0 != fFreeSpace));
 440     SkASSERT(!(NULL == fPoints && 0 != fFreeSpace));
 441     SkASSERT(!(NULL == fPoints && fPointCnt));
 442     SkASSERT(!(NULL == fVerbs && fVerbCnt));
 443     SkASSERT(this->currSize() ==
 444                 fFreeSpace + sizeof(SkPoint) * fPointCnt + sizeof(uint8_t) * fVerbCnt);
 445
 446     if (!fBoundsIsDirty && !fBounds->isEmpty()) {
 447         bool isFinite = true;
 448         for (int i = 0; i < fPointCnt; ++i) {
 449             SkASSERT(!fPoints[i].isFinite() || (
 450                      fBounds->fLeft - fPoints[i].fX   < SK_ScalarNearlyZero &&
 451                      fPoints[i].fX - fBounds->fRight  < SK_ScalarNearlyZero &&
 452                      fBounds->fTop  - fPoints[i].fY   < SK_ScalarNearlyZero &&
 453                      fPoints[i].fY - fBounds->fBottom < SK_ScalarNearlyZero));
 454             if (!fPoints[i].isFinite()) {
 455                 isFinite = false;
 456             }
 457         }
 458         SkASSERT(SkToBool(fIsFinite) == isFinite);
 459     }
 460
 461 #ifdef SK_DEBUG_PATH
 462     uint32_t mask = 0;
 463     for (int i = 0; i < fVerbCnt; ++i) {
 464         switch (fVerbs[~i]) {
 465             case SkPath::kMove_Verb:
 466                 break;
 467             case SkPath::kLine_Verb:
 468                 mask |= SkPath::kLine_SegmentMask;
 469                 break;
 470             case SkPath::kQuad_Verb:
 471                 mask |= SkPath::kQuad_SegmentMask;
 472                 break;
 473             case SkPath::kConic_Verb:
 474                 mask |= SkPath::kConic_SegmentMask;
 475                 break;
 476             case SkPath::kCubic_Verb:
 477                 mask |= SkPath::kCubic_SegmentMask;
 478                 break;
 479             case SkPath::kClose_Verb:
 480                 break;
 481             case SkPath::kDone_Verb:
 482                 SkDEBUGFAIL("Done verb shouldn't be recorded.");
 483                 break;
 484             default:
 485                 SkDEBUGFAIL("Unknown Verb");
 486                 break;
 487         }
 488     }
 489     SkASSERT(mask == fSegmentMask);
 490 #endif // SK_DEBUG_PATH
 491 }
 492 #endif