GrTessellator.cpp revision 2e2cb9bc768bd13e1beeafc9acf8b8f19bea3215
1/* 2 * Copyright 2015 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 "GrTessellator.h" 9 10#include "GrDefaultGeoProcFactory.h" 11#include "GrPathUtils.h" 12 13#include "SkChunkAlloc.h" 14#include "SkGeometry.h" 15#include "SkPath.h" 16 17#include <stdio.h> 18 19/* 20 * There are six stages to the basic algorithm: 21 * 22 * 1) Linearize the path contours into piecewise linear segments (path_to_contours()). 23 * 2) Build a mesh of edges connecting the vertices (build_edges()). 24 * 3) Sort the vertices in Y (and secondarily in X) (merge_sort()). 25 * 4) Simplify the mesh by inserting new vertices at intersecting edges (simplify()). 26 * 5) Tessellate the simplified mesh into monotone polygons (tessellate()). 27 * 6) Triangulate the monotone polygons directly into a vertex buffer (polys_to_triangles()). 28 * 29 * For screenspace antialiasing, the algorithm is modified as follows: 30 * 31 * Run steps 1-5 above to produce polygons. 32 * 5b) Apply fill rules to extract boundary contours from the polygons (extract_boundaries()). 33 * 5c) Simplify boundaries to remove "pointy" vertices which cause inversions (simplify_boundary()). 34 * 5d) Displace edges by half a pixel inward and outward along their normals. Intersect to find 35 * new vertices, and set zero alpha on the exterior and one alpha on the interior. Build a new 36 * antialiased mesh from those vertices (boundary_to_aa_mesh()). 37 * Run steps 3-6 above on the new mesh, and produce antialiased triangles. 38 * 39 * The vertex sorting in step (3) is a merge sort, since it plays well with the linked list 40 * of vertices (and the necessity of inserting new vertices on intersection). 41 * 42 * Stages (4) and (5) use an active edge list, which a list of all edges for which the 43 * sweep line has crossed the top vertex, but not the bottom vertex. It's sorted 44 * left-to-right based on the point where both edges are active (when both top vertices 45 * have been seen, so the "lower" top vertex of the two). If the top vertices are equal 46 * (shared), it's sorted based on the last point where both edges are active, so the 47 * "upper" bottom vertex. 48 * 49 * The most complex step is the simplification (4). It's based on the Bentley-Ottman 50 * line-sweep algorithm, but due to floating point inaccuracy, the intersection points are 51 * not exact and may violate the mesh topology or active edge list ordering. We 52 * accommodate this by adjusting the topology of the mesh and AEL to match the intersection 53 * points. This occurs in three ways: 54 * 55 * A) Intersections may cause a shortened edge to no longer be ordered with respect to its 56 * neighbouring edges at the top or bottom vertex. This is handled by merging the 57 * edges (merge_collinear_edges()). 58 * B) Intersections may cause an edge to violate the left-to-right ordering of the 59 * active edge list. This is handled by splitting the neighbour edge on the 60 * intersected vertex (cleanup_active_edges()). 61 * C) Shortening an edge may cause an active edge to become inactive or an inactive edge 62 * to become active. This is handled by removing or inserting the edge in the active 63 * edge list (fix_active_state()). 64 * 65 * The tessellation steps (5) and (6) are based on "Triangulating Simple Polygons and 66 * Equivalent Problems" (Fournier and Montuno); also a line-sweep algorithm. Note that it 67 * currently uses a linked list for the active edge list, rather than a 2-3 tree as the 68 * paper describes. The 2-3 tree gives O(lg N) lookups, but insertion and removal also 69 * become O(lg N). In all the test cases, it was found that the cost of frequent O(lg N) 70 * insertions and removals was greater than the cost of infrequent O(N) lookups with the 71 * linked list implementation. With the latter, all removals are O(1), and most insertions 72 * are O(1), since we know the adjacent edge in the active edge list based on the topology. 73 * Only type 2 vertices (see paper) require the O(N) lookups, and these are much less 74 * frequent. There may be other data structures worth investigating, however. 75 * 76 * Note that the orientation of the line sweep algorithms is determined by the aspect ratio of the 77 * path bounds. When the path is taller than it is wide, we sort vertices based on increasing Y 78 * coordinate, and secondarily by increasing X coordinate. When the path is wider than it is tall, 79 * we sort by increasing X coordinate, but secondarily by *decreasing* Y coordinate. This is so 80 * that the "left" and "right" orientation in the code remains correct (edges to the left are 81 * increasing in Y; edges to the right are decreasing in Y). That is, the setting rotates 90 82 * degrees counterclockwise, rather that transposing. 83 */ 84 85#define LOGGING_ENABLED 0 86 87#if LOGGING_ENABLED 88#define LOG printf 89#else 90#define LOG(...) 91#endif 92 93#define ALLOC_NEW(Type, args, alloc) new (alloc.allocThrow(sizeof(Type))) Type args 94 95namespace { 96 97struct Vertex; 98struct Edge; 99struct Poly; 100 101template <class T, T* T::*Prev, T* T::*Next> 102void list_insert(T* t, T* prev, T* next, T** head, T** tail) { 103 t->*Prev = prev; 104 t->*Next = next; 105 if (prev) { 106 prev->*Next = t; 107 } else if (head) { 108 *head = t; 109 } 110 if (next) { 111 next->*Prev = t; 112 } else if (tail) { 113 *tail = t; 114 } 115} 116 117template <class T, T* T::*Prev, T* T::*Next> 118void list_remove(T* t, T** head, T** tail) { 119 if (t->*Prev) { 120 t->*Prev->*Next = t->*Next; 121 } else if (head) { 122 *head = t->*Next; 123 } 124 if (t->*Next) { 125 t->*Next->*Prev = t->*Prev; 126 } else if (tail) { 127 *tail = t->*Prev; 128 } 129 t->*Prev = t->*Next = nullptr; 130} 131 132/** 133 * Vertices are used in three ways: first, the path contours are converted into a 134 * circularly-linked list of Vertices for each contour. After edge construction, the same Vertices 135 * are re-ordered by the merge sort according to the sweep_lt comparator (usually, increasing 136 * in Y) using the same fPrev/fNext pointers that were used for the contours, to avoid 137 * reallocation. Finally, MonotonePolys are built containing a circularly-linked list of 138 * Vertices. (Currently, those Vertices are newly-allocated for the MonotonePolys, since 139 * an individual Vertex from the path mesh may belong to multiple 140 * MonotonePolys, so the original Vertices cannot be re-used. 141 */ 142 143struct Vertex { 144 Vertex(const SkPoint& point, uint8_t alpha) 145 : fPoint(point), fPrev(nullptr), fNext(nullptr) 146 , fFirstEdgeAbove(nullptr), fLastEdgeAbove(nullptr) 147 , fFirstEdgeBelow(nullptr), fLastEdgeBelow(nullptr) 148 , fProcessed(false) 149 , fAlpha(alpha) 150#if LOGGING_ENABLED 151 , fID (-1.0f) 152#endif 153 {} 154 SkPoint fPoint; // Vertex position 155 Vertex* fPrev; // Linked list of contours, then Y-sorted vertices. 156 Vertex* fNext; // " 157 Edge* fFirstEdgeAbove; // Linked list of edges above this vertex. 158 Edge* fLastEdgeAbove; // " 159 Edge* fFirstEdgeBelow; // Linked list of edges below this vertex. 160 Edge* fLastEdgeBelow; // " 161 bool fProcessed; // Has this vertex been seen in simplify()? 162 uint8_t fAlpha; 163#if LOGGING_ENABLED 164 float fID; // Identifier used for logging. 165#endif 166}; 167 168/***************************************************************************************/ 169 170struct AAParams { 171 bool fTweakAlpha; 172 GrColor fColor; 173}; 174 175typedef bool (*CompareFunc)(const SkPoint& a, const SkPoint& b); 176 177struct Comparator { 178 CompareFunc sweep_lt; 179 CompareFunc sweep_gt; 180}; 181 182bool sweep_lt_horiz(const SkPoint& a, const SkPoint& b) { 183 return a.fX == b.fX ? a.fY > b.fY : a.fX < b.fX; 184} 185 186bool sweep_lt_vert(const SkPoint& a, const SkPoint& b) { 187 return a.fY == b.fY ? a.fX < b.fX : a.fY < b.fY; 188} 189 190bool sweep_gt_horiz(const SkPoint& a, const SkPoint& b) { 191 return a.fX == b.fX ? a.fY < b.fY : a.fX > b.fX; 192} 193 194bool sweep_gt_vert(const SkPoint& a, const SkPoint& b) { 195 return a.fY == b.fY ? a.fX > b.fX : a.fY > b.fY; 196} 197 198inline void* emit_vertex(Vertex* v, const AAParams* aaParams, void* data) { 199 if (!aaParams) { 200 SkPoint* d = static_cast<SkPoint*>(data); 201 *d++ = v->fPoint; 202 return d; 203 } 204 if (aaParams->fTweakAlpha) { 205 auto d = static_cast<GrDefaultGeoProcFactory::PositionColorAttr*>(data); 206 d->fPosition = v->fPoint; 207 d->fColor = SkAlphaMulQ(aaParams->fColor, SkAlpha255To256(v->fAlpha)); 208 d++; 209 return d; 210 } 211 auto d = static_cast<GrDefaultGeoProcFactory::PositionColorCoverageAttr*>(data); 212 d->fPosition = v->fPoint; 213 d->fColor = aaParams->fColor; 214 d->fCoverage = GrNormalizeByteToFloat(v->fAlpha); 215 d++; 216 return d; 217} 218 219void* emit_triangle(Vertex* v0, Vertex* v1, Vertex* v2, const AAParams* aaParams, void* data) { 220#if TESSELLATOR_WIREFRAME 221 data = emit_vertex(v0, aaParams, data); 222 data = emit_vertex(v1, aaParams, data); 223 data = emit_vertex(v1, aaParams, data); 224 data = emit_vertex(v2, aaParams, data); 225 data = emit_vertex(v2, aaParams, data); 226 data = emit_vertex(v0, aaParams, data); 227#else 228 data = emit_vertex(v0, aaParams, data); 229 data = emit_vertex(v1, aaParams, data); 230 data = emit_vertex(v2, aaParams, data); 231#endif 232 return data; 233} 234 235struct VertexList { 236 VertexList() : fHead(nullptr), fTail(nullptr) {} 237 Vertex* fHead; 238 Vertex* fTail; 239 void insert(Vertex* v, Vertex* prev, Vertex* next) { 240 list_insert<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, prev, next, &fHead, &fTail); 241 } 242 void append(Vertex* v) { 243 insert(v, fTail, nullptr); 244 } 245 void prepend(Vertex* v) { 246 insert(v, nullptr, fHead); 247 } 248 void remove(Vertex* v) { 249 list_remove<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, &fHead, &fTail); 250 } 251 void close() { 252 if (fHead && fTail) { 253 fTail->fNext = fHead; 254 fHead->fPrev = fTail; 255 } 256 } 257}; 258 259// Round to nearest quarter-pixel. This is used for screenspace tessellation. 260 261inline void round(SkPoint* p) { 262 p->fX = SkScalarRoundToScalar(p->fX * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); 263 p->fY = SkScalarRoundToScalar(p->fY * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); 264} 265 266// A line equation in implicit form. fA * x + fB * y + fC = 0, for all points (x, y) on the line. 267struct Line { 268 Line(Vertex* p, Vertex* q) : Line(p->fPoint, q->fPoint) {} 269 Line(const SkPoint& p, const SkPoint& q) 270 : fA(static_cast<double>(q.fY) - p.fY) // a = dY 271 , fB(static_cast<double>(p.fX) - q.fX) // b = -dX 272 , fC(static_cast<double>(p.fY) * q.fX - // c = cross(q, p) 273 static_cast<double>(p.fX) * q.fY) {} 274 double dist(const SkPoint& p) const { 275 return fA * p.fX + fB * p.fY + fC; 276 } 277 double magSq() const { 278 return fA * fA + fB * fB; 279 } 280 281 // Compute the intersection of two (infinite) Lines. 282 bool intersect(const Line& other, SkPoint* point) { 283 double denom = fA * other.fB - fB * other.fA; 284 if (denom == 0.0) { 285 return false; 286 } 287 double scale = 1.0f / denom; 288 point->fX = SkDoubleToScalar((fB * other.fC - other.fB * fC) * scale); 289 point->fY = SkDoubleToScalar((other.fA * fC - fA * other.fC) * scale); 290 round(point); 291 return true; 292 } 293 double fA, fB, fC; 294}; 295 296/** 297 * An Edge joins a top Vertex to a bottom Vertex. Edge ordering for the list of "edges above" and 298 * "edge below" a vertex as well as for the active edge list is handled by isLeftOf()/isRightOf(). 299 * Note that an Edge will give occasionally dist() != 0 for its own endpoints (because floating 300 * point). For speed, that case is only tested by the callers which require it (e.g., 301 * cleanup_active_edges()). Edges also handle checking for intersection with other edges. 302 * Currently, this converts the edges to the parametric form, in order to avoid doing a division 303 * until an intersection has been confirmed. This is slightly slower in the "found" case, but 304 * a lot faster in the "not found" case. 305 * 306 * The coefficients of the line equation stored in double precision to avoid catastrphic 307 * cancellation in the isLeftOf() and isRightOf() checks. Using doubles ensures that the result is 308 * correct in float, since it's a polynomial of degree 2. The intersect() function, being 309 * degree 5, is still subject to catastrophic cancellation. We deal with that by assuming its 310 * output may be incorrect, and adjusting the mesh topology to match (see comment at the top of 311 * this file). 312 */ 313 314struct Edge { 315 enum class Type { kInner, kOuter, kConnector }; 316 Edge(Vertex* top, Vertex* bottom, int winding, Type type) 317 : fWinding(winding) 318 , fTop(top) 319 , fBottom(bottom) 320 , fType(type) 321 , fLeft(nullptr) 322 , fRight(nullptr) 323 , fPrevEdgeAbove(nullptr) 324 , fNextEdgeAbove(nullptr) 325 , fPrevEdgeBelow(nullptr) 326 , fNextEdgeBelow(nullptr) 327 , fLeftPoly(nullptr) 328 , fRightPoly(nullptr) 329 , fLeftPolyPrev(nullptr) 330 , fLeftPolyNext(nullptr) 331 , fRightPolyPrev(nullptr) 332 , fRightPolyNext(nullptr) 333 , fUsedInLeftPoly(false) 334 , fUsedInRightPoly(false) 335 , fLine(top, bottom) { 336 } 337 int fWinding; // 1 == edge goes downward; -1 = edge goes upward. 338 Vertex* fTop; // The top vertex in vertex-sort-order (sweep_lt). 339 Vertex* fBottom; // The bottom vertex in vertex-sort-order. 340 Type fType; 341 Edge* fLeft; // The linked list of edges in the active edge list. 342 Edge* fRight; // " 343 Edge* fPrevEdgeAbove; // The linked list of edges in the bottom Vertex's "edges above". 344 Edge* fNextEdgeAbove; // " 345 Edge* fPrevEdgeBelow; // The linked list of edges in the top Vertex's "edges below". 346 Edge* fNextEdgeBelow; // " 347 Poly* fLeftPoly; // The Poly to the left of this edge, if any. 348 Poly* fRightPoly; // The Poly to the right of this edge, if any. 349 Edge* fLeftPolyPrev; 350 Edge* fLeftPolyNext; 351 Edge* fRightPolyPrev; 352 Edge* fRightPolyNext; 353 bool fUsedInLeftPoly; 354 bool fUsedInRightPoly; 355 Line fLine; 356 double dist(const SkPoint& p) const { 357 return fLine.dist(p); 358 } 359 bool isRightOf(Vertex* v) const { 360 return fLine.dist(v->fPoint) < 0.0; 361 } 362 bool isLeftOf(Vertex* v) const { 363 return fLine.dist(v->fPoint) > 0.0; 364 } 365 void recompute() { 366 fLine = Line(fTop, fBottom); 367 } 368 bool intersect(const Edge& other, SkPoint* p) { 369 LOG("intersecting %g -> %g with %g -> %g\n", 370 fTop->fID, fBottom->fID, 371 other.fTop->fID, other.fBottom->fID); 372 if (fTop == other.fTop || fBottom == other.fBottom) { 373 return false; 374 } 375 double denom = fLine.fA * other.fLine.fB - fLine.fB * other.fLine.fA; 376 if (denom == 0.0) { 377 return false; 378 } 379 double dx = static_cast<double>(fTop->fPoint.fX) - other.fTop->fPoint.fX; 380 double dy = static_cast<double>(fTop->fPoint.fY) - other.fTop->fPoint.fY; 381 double sNumer = -dy * other.fLine.fB - dx * other.fLine.fA; 382 double tNumer = -dy * fLine.fB - dx * fLine.fA; 383 // If (sNumer / denom) or (tNumer / denom) is not in [0..1], exit early. 384 // This saves us doing the divide below unless absolutely necessary. 385 if (denom > 0.0 ? (sNumer < 0.0 || sNumer > denom || tNumer < 0.0 || tNumer > denom) 386 : (sNumer > 0.0 || sNumer < denom || tNumer > 0.0 || tNumer < denom)) { 387 return false; 388 } 389 double s = sNumer / denom; 390 SkASSERT(s >= 0.0 && s <= 1.0); 391 p->fX = SkDoubleToScalar(fTop->fPoint.fX - s * fLine.fB); 392 p->fY = SkDoubleToScalar(fTop->fPoint.fY + s * fLine.fA); 393 return true; 394 } 395}; 396 397struct EdgeList { 398 EdgeList() : fHead(nullptr), fTail(nullptr), fNext(nullptr), fCount(0) {} 399 Edge* fHead; 400 Edge* fTail; 401 EdgeList* fNext; 402 int fCount; 403 void insert(Edge* edge, Edge* prev, Edge* next) { 404 list_insert<Edge, &Edge::fLeft, &Edge::fRight>(edge, prev, next, &fHead, &fTail); 405 fCount++; 406 } 407 void append(Edge* e) { 408 insert(e, fTail, nullptr); 409 } 410 void remove(Edge* edge) { 411 list_remove<Edge, &Edge::fLeft, &Edge::fRight>(edge, &fHead, &fTail); 412 fCount--; 413 } 414 void close() { 415 if (fHead && fTail) { 416 fTail->fRight = fHead; 417 fHead->fLeft = fTail; 418 } 419 } 420 bool contains(Edge* edge) const { 421 return edge->fLeft || edge->fRight || fHead == edge; 422 } 423}; 424 425/***************************************************************************************/ 426 427struct Poly { 428 Poly(Vertex* v, int winding) 429 : fFirstVertex(v) 430 , fWinding(winding) 431 , fHead(nullptr) 432 , fTail(nullptr) 433 , fNext(nullptr) 434 , fPartner(nullptr) 435 , fCount(0) 436 { 437#if LOGGING_ENABLED 438 static int gID = 0; 439 fID = gID++; 440 LOG("*** created Poly %d\n", fID); 441#endif 442 } 443 typedef enum { kLeft_Side, kRight_Side } Side; 444 struct MonotonePoly { 445 MonotonePoly(Edge* edge, Side side) 446 : fSide(side) 447 , fFirstEdge(nullptr) 448 , fLastEdge(nullptr) 449 , fPrev(nullptr) 450 , fNext(nullptr) { 451 this->addEdge(edge); 452 } 453 Side fSide; 454 Edge* fFirstEdge; 455 Edge* fLastEdge; 456 MonotonePoly* fPrev; 457 MonotonePoly* fNext; 458 void addEdge(Edge* edge) { 459 if (fSide == kRight_Side) { 460 SkASSERT(!edge->fUsedInRightPoly); 461 list_insert<Edge, &Edge::fRightPolyPrev, &Edge::fRightPolyNext>( 462 edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); 463 edge->fUsedInRightPoly = true; 464 } else { 465 SkASSERT(!edge->fUsedInLeftPoly); 466 list_insert<Edge, &Edge::fLeftPolyPrev, &Edge::fLeftPolyNext>( 467 edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); 468 edge->fUsedInLeftPoly = true; 469 } 470 } 471 472 void* emit(const AAParams* aaParams, void* data) { 473 Edge* e = fFirstEdge; 474 e->fTop->fPrev = e->fTop->fNext = nullptr; 475 VertexList vertices; 476 vertices.append(e->fTop); 477 while (e != nullptr) { 478 e->fBottom->fPrev = e->fBottom->fNext = nullptr; 479 if (kRight_Side == fSide) { 480 vertices.append(e->fBottom); 481 e = e->fRightPolyNext; 482 } else { 483 vertices.prepend(e->fBottom); 484 e = e->fLeftPolyNext; 485 } 486 } 487 Vertex* first = vertices.fHead; 488 Vertex* v = first->fNext; 489 while (v != vertices.fTail) { 490 SkASSERT(v && v->fPrev && v->fNext); 491 Vertex* prev = v->fPrev; 492 Vertex* curr = v; 493 Vertex* next = v->fNext; 494 double ax = static_cast<double>(curr->fPoint.fX) - prev->fPoint.fX; 495 double ay = static_cast<double>(curr->fPoint.fY) - prev->fPoint.fY; 496 double bx = static_cast<double>(next->fPoint.fX) - curr->fPoint.fX; 497 double by = static_cast<double>(next->fPoint.fY) - curr->fPoint.fY; 498 if (ax * by - ay * bx >= 0.0) { 499 data = emit_triangle(prev, curr, next, aaParams, data); 500 v->fPrev->fNext = v->fNext; 501 v->fNext->fPrev = v->fPrev; 502 if (v->fPrev == first) { 503 v = v->fNext; 504 } else { 505 v = v->fPrev; 506 } 507 } else { 508 v = v->fNext; 509 } 510 } 511 return data; 512 } 513 }; 514 Poly* addEdge(Edge* e, Side side, SkChunkAlloc& alloc) { 515 LOG("addEdge (%g -> %g) to poly %d, %s side\n", 516 e->fTop->fID, e->fBottom->fID, fID, side == kLeft_Side ? "left" : "right"); 517 Poly* partner = fPartner; 518 Poly* poly = this; 519 if (side == kRight_Side) { 520 if (e->fUsedInRightPoly) { 521 return this; 522 } 523 } else { 524 if (e->fUsedInLeftPoly) { 525 return this; 526 } 527 } 528 if (partner) { 529 fPartner = partner->fPartner = nullptr; 530 } 531 if (!fTail) { 532 fHead = fTail = ALLOC_NEW(MonotonePoly, (e, side), alloc); 533 fCount += 2; 534 } else if (e->fBottom == fTail->fLastEdge->fBottom) { 535 return poly; 536 } else if (side == fTail->fSide) { 537 fTail->addEdge(e); 538 fCount++; 539 } else { 540 e = ALLOC_NEW(Edge, (fTail->fLastEdge->fBottom, e->fBottom, 1, Edge::Type::kInner), 541 alloc); 542 fTail->addEdge(e); 543 fCount++; 544 if (partner) { 545 partner->addEdge(e, side, alloc); 546 poly = partner; 547 } else { 548 MonotonePoly* m = ALLOC_NEW(MonotonePoly, (e, side), alloc); 549 m->fPrev = fTail; 550 fTail->fNext = m; 551 fTail = m; 552 } 553 } 554 return poly; 555 } 556 void* emit(const AAParams* aaParams, void *data) { 557 if (fCount < 3) { 558 return data; 559 } 560 LOG("emit() %d, size %d\n", fID, fCount); 561 for (MonotonePoly* m = fHead; m != nullptr; m = m->fNext) { 562 data = m->emit(aaParams, data); 563 } 564 return data; 565 } 566 Vertex* lastVertex() const { return fTail ? fTail->fLastEdge->fBottom : fFirstVertex; } 567 Vertex* fFirstVertex; 568 int fWinding; 569 MonotonePoly* fHead; 570 MonotonePoly* fTail; 571 Poly* fNext; 572 Poly* fPartner; 573 int fCount; 574#if LOGGING_ENABLED 575 int fID; 576#endif 577}; 578 579/***************************************************************************************/ 580 581bool coincident(const SkPoint& a, const SkPoint& b) { 582 return a == b; 583} 584 585Poly* new_poly(Poly** head, Vertex* v, int winding, SkChunkAlloc& alloc) { 586 Poly* poly = ALLOC_NEW(Poly, (v, winding), alloc); 587 poly->fNext = *head; 588 *head = poly; 589 return poly; 590} 591 592EdgeList* new_contour(EdgeList** head, SkChunkAlloc& alloc) { 593 EdgeList* contour = ALLOC_NEW(EdgeList, (), alloc); 594 contour->fNext = *head; 595 *head = contour; 596 return contour; 597} 598 599Vertex* append_point_to_contour(const SkPoint& p, Vertex* prev, Vertex** head, 600 SkChunkAlloc& alloc) { 601 Vertex* v = ALLOC_NEW(Vertex, (p, 255), alloc); 602#if LOGGING_ENABLED 603 static float gID = 0.0f; 604 v->fID = gID++; 605#endif 606 if (prev) { 607 prev->fNext = v; 608 v->fPrev = prev; 609 } else { 610 *head = v; 611 } 612 return v; 613} 614 615Vertex* generate_quadratic_points(const SkPoint& p0, 616 const SkPoint& p1, 617 const SkPoint& p2, 618 SkScalar tolSqd, 619 Vertex* prev, 620 Vertex** head, 621 int pointsLeft, 622 SkChunkAlloc& alloc) { 623 SkScalar d = p1.distanceToLineSegmentBetweenSqd(p0, p2); 624 if (pointsLeft < 2 || d < tolSqd || !SkScalarIsFinite(d)) { 625 return append_point_to_contour(p2, prev, head, alloc); 626 } 627 628 const SkPoint q[] = { 629 { SkScalarAve(p0.fX, p1.fX), SkScalarAve(p0.fY, p1.fY) }, 630 { SkScalarAve(p1.fX, p2.fX), SkScalarAve(p1.fY, p2.fY) }, 631 }; 632 const SkPoint r = { SkScalarAve(q[0].fX, q[1].fX), SkScalarAve(q[0].fY, q[1].fY) }; 633 634 pointsLeft >>= 1; 635 prev = generate_quadratic_points(p0, q[0], r, tolSqd, prev, head, pointsLeft, alloc); 636 prev = generate_quadratic_points(r, q[1], p2, tolSqd, prev, head, pointsLeft, alloc); 637 return prev; 638} 639 640Vertex* generate_cubic_points(const SkPoint& p0, 641 const SkPoint& p1, 642 const SkPoint& p2, 643 const SkPoint& p3, 644 SkScalar tolSqd, 645 Vertex* prev, 646 Vertex** head, 647 int pointsLeft, 648 SkChunkAlloc& alloc) { 649 SkScalar d1 = p1.distanceToLineSegmentBetweenSqd(p0, p3); 650 SkScalar d2 = p2.distanceToLineSegmentBetweenSqd(p0, p3); 651 if (pointsLeft < 2 || (d1 < tolSqd && d2 < tolSqd) || 652 !SkScalarIsFinite(d1) || !SkScalarIsFinite(d2)) { 653 return append_point_to_contour(p3, prev, head, alloc); 654 } 655 const SkPoint q[] = { 656 { SkScalarAve(p0.fX, p1.fX), SkScalarAve(p0.fY, p1.fY) }, 657 { SkScalarAve(p1.fX, p2.fX), SkScalarAve(p1.fY, p2.fY) }, 658 { SkScalarAve(p2.fX, p3.fX), SkScalarAve(p2.fY, p3.fY) } 659 }; 660 const SkPoint r[] = { 661 { SkScalarAve(q[0].fX, q[1].fX), SkScalarAve(q[0].fY, q[1].fY) }, 662 { SkScalarAve(q[1].fX, q[2].fX), SkScalarAve(q[1].fY, q[2].fY) } 663 }; 664 const SkPoint s = { SkScalarAve(r[0].fX, r[1].fX), SkScalarAve(r[0].fY, r[1].fY) }; 665 pointsLeft >>= 1; 666 prev = generate_cubic_points(p0, q[0], r[0], s, tolSqd, prev, head, pointsLeft, alloc); 667 prev = generate_cubic_points(s, r[1], q[2], p3, tolSqd, prev, head, pointsLeft, alloc); 668 return prev; 669} 670 671// Stage 1: convert the input path to a set of linear contours (linked list of Vertices). 672 673void path_to_contours(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 674 Vertex** contours, SkChunkAlloc& alloc, bool *isLinear) { 675 SkScalar toleranceSqd = tolerance * tolerance; 676 677 SkPoint pts[4]; 678 bool done = false; 679 *isLinear = true; 680 SkPath::Iter iter(path, false); 681 Vertex* prev = nullptr; 682 Vertex* head = nullptr; 683 if (path.isInverseFillType()) { 684 SkPoint quad[4]; 685 clipBounds.toQuad(quad); 686 for (int i = 3; i >= 0; i--) { 687 prev = append_point_to_contour(quad[i], prev, &head, alloc); 688 } 689 head->fPrev = prev; 690 prev->fNext = head; 691 *contours++ = head; 692 head = prev = nullptr; 693 } 694 SkAutoConicToQuads converter; 695 while (!done) { 696 SkPath::Verb verb = iter.next(pts); 697 switch (verb) { 698 case SkPath::kConic_Verb: { 699 SkScalar weight = iter.conicWeight(); 700 const SkPoint* quadPts = converter.computeQuads(pts, weight, toleranceSqd); 701 for (int i = 0; i < converter.countQuads(); ++i) { 702 int pointsLeft = GrPathUtils::quadraticPointCount(quadPts, tolerance); 703 prev = generate_quadratic_points(quadPts[0], quadPts[1], quadPts[2], 704 toleranceSqd, prev, &head, pointsLeft, alloc); 705 quadPts += 2; 706 } 707 *isLinear = false; 708 break; 709 } 710 case SkPath::kMove_Verb: 711 if (head) { 712 head->fPrev = prev; 713 prev->fNext = head; 714 *contours++ = head; 715 } 716 head = prev = nullptr; 717 prev = append_point_to_contour(pts[0], prev, &head, alloc); 718 break; 719 case SkPath::kLine_Verb: { 720 prev = append_point_to_contour(pts[1], prev, &head, alloc); 721 break; 722 } 723 case SkPath::kQuad_Verb: { 724 int pointsLeft = GrPathUtils::quadraticPointCount(pts, tolerance); 725 prev = generate_quadratic_points(pts[0], pts[1], pts[2], toleranceSqd, prev, 726 &head, pointsLeft, alloc); 727 *isLinear = false; 728 break; 729 } 730 case SkPath::kCubic_Verb: { 731 int pointsLeft = GrPathUtils::cubicPointCount(pts, tolerance); 732 prev = generate_cubic_points(pts[0], pts[1], pts[2], pts[3], 733 toleranceSqd, prev, &head, pointsLeft, alloc); 734 *isLinear = false; 735 break; 736 } 737 case SkPath::kClose_Verb: 738 if (head) { 739 head->fPrev = prev; 740 prev->fNext = head; 741 *contours++ = head; 742 } 743 head = prev = nullptr; 744 break; 745 case SkPath::kDone_Verb: 746 if (head) { 747 head->fPrev = prev; 748 prev->fNext = head; 749 *contours++ = head; 750 } 751 done = true; 752 break; 753 } 754 } 755} 756 757inline bool apply_fill_type(SkPath::FillType fillType, Poly* poly) { 758 if (!poly) { 759 return false; 760 } 761 int winding = poly->fWinding; 762 switch (fillType) { 763 case SkPath::kWinding_FillType: 764 return winding != 0; 765 case SkPath::kEvenOdd_FillType: 766 return (winding & 1) != 0; 767 case SkPath::kInverseWinding_FillType: 768 return winding == 1; 769 case SkPath::kInverseEvenOdd_FillType: 770 return (winding & 1) == 1; 771 default: 772 SkASSERT(false); 773 return false; 774 } 775} 776 777Edge* new_edge(Vertex* prev, Vertex* next, Edge::Type type, Comparator& c, SkChunkAlloc& alloc) { 778 int winding = c.sweep_lt(prev->fPoint, next->fPoint) ? 1 : -1; 779 Vertex* top = winding < 0 ? next : prev; 780 Vertex* bottom = winding < 0 ? prev : next; 781 return ALLOC_NEW(Edge, (top, bottom, winding, type), alloc); 782} 783 784void remove_edge(Edge* edge, EdgeList* edges) { 785 LOG("removing edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); 786 SkASSERT(edges->contains(edge)); 787 edges->remove(edge); 788} 789 790void insert_edge(Edge* edge, Edge* prev, EdgeList* edges) { 791 LOG("inserting edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); 792 SkASSERT(!edges->contains(edge)); 793 Edge* next = prev ? prev->fRight : edges->fHead; 794 edges->insert(edge, prev, next); 795} 796 797void find_enclosing_edges(Vertex* v, EdgeList* edges, Edge** left, Edge** right) { 798 if (v->fFirstEdgeAbove) { 799 *left = v->fFirstEdgeAbove->fLeft; 800 *right = v->fLastEdgeAbove->fRight; 801 return; 802 } 803 Edge* next = nullptr; 804 Edge* prev; 805 for (prev = edges->fTail; prev != nullptr; prev = prev->fLeft) { 806 if (prev->isLeftOf(v)) { 807 break; 808 } 809 next = prev; 810 } 811 *left = prev; 812 *right = next; 813} 814 815void find_enclosing_edges(Edge* edge, EdgeList* edges, Comparator& c, Edge** left, Edge** right) { 816 Edge* prev = nullptr; 817 Edge* next; 818 for (next = edges->fHead; next != nullptr; next = next->fRight) { 819 if ((c.sweep_gt(edge->fTop->fPoint, next->fTop->fPoint) && next->isRightOf(edge->fTop)) || 820 (c.sweep_gt(next->fTop->fPoint, edge->fTop->fPoint) && edge->isLeftOf(next->fTop)) || 821 (c.sweep_lt(edge->fBottom->fPoint, next->fBottom->fPoint) && 822 next->isRightOf(edge->fBottom)) || 823 (c.sweep_lt(next->fBottom->fPoint, edge->fBottom->fPoint) && 824 edge->isLeftOf(next->fBottom))) { 825 break; 826 } 827 prev = next; 828 } 829 *left = prev; 830 *right = next; 831} 832 833void fix_active_state(Edge* edge, EdgeList* activeEdges, Comparator& c) { 834 if (!activeEdges) { 835 return; 836 } 837 if (activeEdges->contains(edge)) { 838 if (edge->fBottom->fProcessed || !edge->fTop->fProcessed) { 839 remove_edge(edge, activeEdges); 840 } 841 } else if (edge->fTop->fProcessed && !edge->fBottom->fProcessed) { 842 Edge* left; 843 Edge* right; 844 find_enclosing_edges(edge, activeEdges, c, &left, &right); 845 insert_edge(edge, left, activeEdges); 846 } 847} 848 849void insert_edge_above(Edge* edge, Vertex* v, Comparator& c) { 850 if (edge->fTop->fPoint == edge->fBottom->fPoint || 851 c.sweep_gt(edge->fTop->fPoint, edge->fBottom->fPoint)) { 852 return; 853 } 854 LOG("insert edge (%g -> %g) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); 855 Edge* prev = nullptr; 856 Edge* next; 857 for (next = v->fFirstEdgeAbove; next; next = next->fNextEdgeAbove) { 858 if (next->isRightOf(edge->fTop)) { 859 break; 860 } 861 prev = next; 862 } 863 list_insert<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( 864 edge, prev, next, &v->fFirstEdgeAbove, &v->fLastEdgeAbove); 865} 866 867void insert_edge_below(Edge* edge, Vertex* v, Comparator& c) { 868 if (edge->fTop->fPoint == edge->fBottom->fPoint || 869 c.sweep_gt(edge->fTop->fPoint, edge->fBottom->fPoint)) { 870 return; 871 } 872 LOG("insert edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); 873 Edge* prev = nullptr; 874 Edge* next; 875 for (next = v->fFirstEdgeBelow; next; next = next->fNextEdgeBelow) { 876 if (next->isRightOf(edge->fBottom)) { 877 break; 878 } 879 prev = next; 880 } 881 list_insert<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( 882 edge, prev, next, &v->fFirstEdgeBelow, &v->fLastEdgeBelow); 883} 884 885void remove_edge_above(Edge* edge) { 886 LOG("removing edge (%g -> %g) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, 887 edge->fBottom->fID); 888 list_remove<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( 889 edge, &edge->fBottom->fFirstEdgeAbove, &edge->fBottom->fLastEdgeAbove); 890} 891 892void remove_edge_below(Edge* edge) { 893 LOG("removing edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, 894 edge->fTop->fID); 895 list_remove<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( 896 edge, &edge->fTop->fFirstEdgeBelow, &edge->fTop->fLastEdgeBelow); 897} 898 899void erase_edge_if_zero_winding(Edge* edge, EdgeList* edges) { 900 if (edge->fWinding != 0) { 901 return; 902 } 903 LOG("erasing edge (%g -> %g)\n", edge->fTop->fID, edge->fBottom->fID); 904 remove_edge_above(edge); 905 remove_edge_below(edge); 906 if (edges && edges->contains(edge)) { 907 remove_edge(edge, edges); 908 } 909} 910 911void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Comparator& c); 912 913void set_top(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c) { 914 remove_edge_below(edge); 915 edge->fTop = v; 916 edge->recompute(); 917 insert_edge_below(edge, v, c); 918 fix_active_state(edge, activeEdges, c); 919 merge_collinear_edges(edge, activeEdges, c); 920} 921 922void set_bottom(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c) { 923 remove_edge_above(edge); 924 edge->fBottom = v; 925 edge->recompute(); 926 insert_edge_above(edge, v, c); 927 fix_active_state(edge, activeEdges, c); 928 merge_collinear_edges(edge, activeEdges, c); 929} 930 931void merge_edges_above(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c) { 932 if (coincident(edge->fTop->fPoint, other->fTop->fPoint)) { 933 LOG("merging coincident above edges (%g, %g) -> (%g, %g)\n", 934 edge->fTop->fPoint.fX, edge->fTop->fPoint.fY, 935 edge->fBottom->fPoint.fX, edge->fBottom->fPoint.fY); 936 other->fWinding += edge->fWinding; 937 erase_edge_if_zero_winding(other, activeEdges); 938 edge->fWinding = 0; 939 erase_edge_if_zero_winding(edge, activeEdges); 940 } else if (c.sweep_lt(edge->fTop->fPoint, other->fTop->fPoint)) { 941 other->fWinding += edge->fWinding; 942 erase_edge_if_zero_winding(other, activeEdges); 943 set_bottom(edge, other->fTop, activeEdges, c); 944 } else { 945 edge->fWinding += other->fWinding; 946 erase_edge_if_zero_winding(edge, activeEdges); 947 set_bottom(other, edge->fTop, activeEdges, c); 948 } 949} 950 951void merge_edges_below(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c) { 952 if (coincident(edge->fBottom->fPoint, other->fBottom->fPoint)) { 953 LOG("merging coincident below edges (%g, %g) -> (%g, %g)\n", 954 edge->fTop->fPoint.fX, edge->fTop->fPoint.fY, 955 edge->fBottom->fPoint.fX, edge->fBottom->fPoint.fY); 956 other->fWinding += edge->fWinding; 957 erase_edge_if_zero_winding(other, activeEdges); 958 edge->fWinding = 0; 959 erase_edge_if_zero_winding(edge, activeEdges); 960 } else if (c.sweep_lt(edge->fBottom->fPoint, other->fBottom->fPoint)) { 961 edge->fWinding += other->fWinding; 962 erase_edge_if_zero_winding(edge, activeEdges); 963 set_top(other, edge->fBottom, activeEdges, c); 964 } else { 965 other->fWinding += edge->fWinding; 966 erase_edge_if_zero_winding(other, activeEdges); 967 set_top(edge, other->fBottom, activeEdges, c); 968 } 969} 970 971void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Comparator& c) { 972 if (edge->fPrevEdgeAbove && (edge->fTop == edge->fPrevEdgeAbove->fTop || 973 !edge->fPrevEdgeAbove->isLeftOf(edge->fTop))) { 974 merge_edges_above(edge, edge->fPrevEdgeAbove, activeEdges, c); 975 } else if (edge->fNextEdgeAbove && (edge->fTop == edge->fNextEdgeAbove->fTop || 976 !edge->isLeftOf(edge->fNextEdgeAbove->fTop))) { 977 merge_edges_above(edge, edge->fNextEdgeAbove, activeEdges, c); 978 } 979 if (edge->fPrevEdgeBelow && (edge->fBottom == edge->fPrevEdgeBelow->fBottom || 980 !edge->fPrevEdgeBelow->isLeftOf(edge->fBottom))) { 981 merge_edges_below(edge, edge->fPrevEdgeBelow, activeEdges, c); 982 } else if (edge->fNextEdgeBelow && (edge->fBottom == edge->fNextEdgeBelow->fBottom || 983 !edge->isLeftOf(edge->fNextEdgeBelow->fBottom))) { 984 merge_edges_below(edge, edge->fNextEdgeBelow, activeEdges, c); 985 } 986} 987 988void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, SkChunkAlloc& alloc); 989 990void cleanup_active_edges(Edge* edge, EdgeList* activeEdges, Comparator& c, SkChunkAlloc& alloc) { 991 Vertex* top = edge->fTop; 992 Vertex* bottom = edge->fBottom; 993 if (edge->fLeft) { 994 Vertex* leftTop = edge->fLeft->fTop; 995 Vertex* leftBottom = edge->fLeft->fBottom; 996 if (c.sweep_gt(top->fPoint, leftTop->fPoint) && !edge->fLeft->isLeftOf(top)) { 997 split_edge(edge->fLeft, edge->fTop, activeEdges, c, alloc); 998 } else if (c.sweep_gt(leftTop->fPoint, top->fPoint) && !edge->isRightOf(leftTop)) { 999 split_edge(edge, leftTop, activeEdges, c, alloc); 1000 } else if (c.sweep_lt(bottom->fPoint, leftBottom->fPoint) && 1001 !edge->fLeft->isLeftOf(bottom)) { 1002 split_edge(edge->fLeft, bottom, activeEdges, c, alloc); 1003 } else if (c.sweep_lt(leftBottom->fPoint, bottom->fPoint) && !edge->isRightOf(leftBottom)) { 1004 split_edge(edge, leftBottom, activeEdges, c, alloc); 1005 } 1006 } 1007 if (edge->fRight) { 1008 Vertex* rightTop = edge->fRight->fTop; 1009 Vertex* rightBottom = edge->fRight->fBottom; 1010 if (c.sweep_gt(top->fPoint, rightTop->fPoint) && !edge->fRight->isRightOf(top)) { 1011 split_edge(edge->fRight, top, activeEdges, c, alloc); 1012 } else if (c.sweep_gt(rightTop->fPoint, top->fPoint) && !edge->isLeftOf(rightTop)) { 1013 split_edge(edge, rightTop, activeEdges, c, alloc); 1014 } else if (c.sweep_lt(bottom->fPoint, rightBottom->fPoint) && 1015 !edge->fRight->isRightOf(bottom)) { 1016 split_edge(edge->fRight, bottom, activeEdges, c, alloc); 1017 } else if (c.sweep_lt(rightBottom->fPoint, bottom->fPoint) && 1018 !edge->isLeftOf(rightBottom)) { 1019 split_edge(edge, rightBottom, activeEdges, c, alloc); 1020 } 1021 } 1022} 1023 1024void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, SkChunkAlloc& alloc) { 1025 LOG("splitting edge (%g -> %g) at vertex %g (%g, %g)\n", 1026 edge->fTop->fID, edge->fBottom->fID, 1027 v->fID, v->fPoint.fX, v->fPoint.fY); 1028 if (c.sweep_lt(v->fPoint, edge->fTop->fPoint)) { 1029 set_top(edge, v, activeEdges, c); 1030 } else if (c.sweep_gt(v->fPoint, edge->fBottom->fPoint)) { 1031 set_bottom(edge, v, activeEdges, c); 1032 } else { 1033 Edge* newEdge = ALLOC_NEW(Edge, (v, edge->fBottom, edge->fWinding, edge->fType), alloc); 1034 insert_edge_below(newEdge, v, c); 1035 insert_edge_above(newEdge, edge->fBottom, c); 1036 set_bottom(edge, v, activeEdges, c); 1037 cleanup_active_edges(edge, activeEdges, c, alloc); 1038 fix_active_state(newEdge, activeEdges, c); 1039 merge_collinear_edges(newEdge, activeEdges, c); 1040 } 1041} 1042 1043Edge* connect(Vertex* prev, Vertex* next, Edge::Type type, Comparator& c, SkChunkAlloc& alloc) { 1044 Edge* edge = new_edge(prev, next, type, c, alloc); 1045 if (edge->fWinding > 0) { 1046 insert_edge_below(edge, prev, c); 1047 insert_edge_above(edge, next, c); 1048 } else { 1049 insert_edge_below(edge, next, c); 1050 insert_edge_above(edge, prev, c); 1051 } 1052 merge_collinear_edges(edge, nullptr, c); 1053 return edge; 1054} 1055 1056void merge_vertices(Vertex* src, Vertex* dst, VertexList* mesh, Comparator& c, 1057 SkChunkAlloc& alloc) { 1058 LOG("found coincident verts at %g, %g; merging %g into %g\n", src->fPoint.fX, src->fPoint.fY, 1059 src->fID, dst->fID); 1060 dst->fAlpha = SkTMax(src->fAlpha, dst->fAlpha); 1061 for (Edge* edge = src->fFirstEdgeAbove; edge;) { 1062 Edge* next = edge->fNextEdgeAbove; 1063 set_bottom(edge, dst, nullptr, c); 1064 edge = next; 1065 } 1066 for (Edge* edge = src->fFirstEdgeBelow; edge;) { 1067 Edge* next = edge->fNextEdgeBelow; 1068 set_top(edge, dst, nullptr, c); 1069 edge = next; 1070 } 1071 mesh->remove(src); 1072} 1073 1074uint8_t max_edge_alpha(Edge* a, Edge* b) { 1075 if (a->fType == Edge::Type::kInner && b->fType == Edge::Type::kInner) { 1076 return 255; 1077 } else if (a->fType == Edge::Type::kOuter && b->fType == Edge::Type::kOuter) { 1078 return 0; 1079 } else { 1080 return SkTMax(SkTMax(a->fTop->fAlpha, a->fBottom->fAlpha), 1081 SkTMax(b->fTop->fAlpha, b->fBottom->fAlpha)); 1082 } 1083} 1084 1085Vertex* check_for_intersection(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c, 1086 SkChunkAlloc& alloc) { 1087 SkPoint p; 1088 if (!edge || !other) { 1089 return nullptr; 1090 } 1091 if (edge->intersect(*other, &p)) { 1092 Vertex* v; 1093 LOG("found intersection, pt is %g, %g\n", p.fX, p.fY); 1094 if (p == edge->fTop->fPoint || c.sweep_lt(p, edge->fTop->fPoint)) { 1095 split_edge(other, edge->fTop, activeEdges, c, alloc); 1096 v = edge->fTop; 1097 } else if (p == edge->fBottom->fPoint || c.sweep_gt(p, edge->fBottom->fPoint)) { 1098 split_edge(other, edge->fBottom, activeEdges, c, alloc); 1099 v = edge->fBottom; 1100 } else if (p == other->fTop->fPoint || c.sweep_lt(p, other->fTop->fPoint)) { 1101 split_edge(edge, other->fTop, activeEdges, c, alloc); 1102 v = other->fTop; 1103 } else if (p == other->fBottom->fPoint || c.sweep_gt(p, other->fBottom->fPoint)) { 1104 split_edge(edge, other->fBottom, activeEdges, c, alloc); 1105 v = other->fBottom; 1106 } else { 1107 Vertex* nextV = edge->fTop; 1108 while (c.sweep_lt(p, nextV->fPoint)) { 1109 nextV = nextV->fPrev; 1110 } 1111 while (c.sweep_lt(nextV->fPoint, p)) { 1112 nextV = nextV->fNext; 1113 } 1114 Vertex* prevV = nextV->fPrev; 1115 if (coincident(prevV->fPoint, p)) { 1116 v = prevV; 1117 } else if (coincident(nextV->fPoint, p)) { 1118 v = nextV; 1119 } else { 1120 uint8_t alpha = max_edge_alpha(edge, other); 1121 v = ALLOC_NEW(Vertex, (p, alpha), alloc); 1122 LOG("inserting between %g (%g, %g) and %g (%g, %g)\n", 1123 prevV->fID, prevV->fPoint.fX, prevV->fPoint.fY, 1124 nextV->fID, nextV->fPoint.fX, nextV->fPoint.fY); 1125#if LOGGING_ENABLED 1126 v->fID = (nextV->fID + prevV->fID) * 0.5f; 1127#endif 1128 v->fPrev = prevV; 1129 v->fNext = nextV; 1130 prevV->fNext = v; 1131 nextV->fPrev = v; 1132 } 1133 split_edge(edge, v, activeEdges, c, alloc); 1134 split_edge(other, v, activeEdges, c, alloc); 1135 } 1136 return v; 1137 } 1138 return nullptr; 1139} 1140 1141void sanitize_contours(Vertex** contours, int contourCnt, bool approximate) { 1142 for (int i = 0; i < contourCnt; ++i) { 1143 SkASSERT(contours[i]); 1144 for (Vertex* v = contours[i];;) { 1145 if (approximate) { 1146 round(&v->fPoint); 1147 } 1148 if (coincident(v->fPrev->fPoint, v->fPoint)) { 1149 LOG("vertex %g,%g coincident; removing\n", v->fPoint.fX, v->fPoint.fY); 1150 if (v->fPrev == v) { 1151 contours[i] = nullptr; 1152 break; 1153 } 1154 v->fPrev->fNext = v->fNext; 1155 v->fNext->fPrev = v->fPrev; 1156 if (contours[i] == v) { 1157 contours[i] = v->fNext; 1158 } 1159 v = v->fPrev; 1160 } else { 1161 v = v->fNext; 1162 if (v == contours[i]) break; 1163 } 1164 } 1165 } 1166} 1167 1168void merge_coincident_vertices(VertexList* mesh, Comparator& c, SkChunkAlloc& alloc) { 1169 for (Vertex* v = mesh->fHead->fNext; v != nullptr; v = v->fNext) { 1170 if (c.sweep_lt(v->fPoint, v->fPrev->fPoint)) { 1171 v->fPoint = v->fPrev->fPoint; 1172 } 1173 if (coincident(v->fPrev->fPoint, v->fPoint)) { 1174 merge_vertices(v->fPrev, v, mesh, c, alloc); 1175 } 1176 } 1177} 1178 1179// Stage 2: convert the contours to a mesh of edges connecting the vertices. 1180 1181void build_edges(Vertex** contours, int contourCnt, VertexList* mesh, Comparator& c, 1182 SkChunkAlloc& alloc) { 1183 Vertex* prev = nullptr; 1184 for (int i = 0; i < contourCnt; ++i) { 1185 for (Vertex* v = contours[i]; v != nullptr;) { 1186 Vertex* vNext = v->fNext; 1187 connect(v->fPrev, v, Edge::Type::kInner, c, alloc); 1188 if (prev) { 1189 prev->fNext = v; 1190 v->fPrev = prev; 1191 } else { 1192 mesh->fHead = v; 1193 } 1194 prev = v; 1195 v = vNext; 1196 if (v == contours[i]) break; 1197 } 1198 } 1199 if (prev) { 1200 prev->fNext = mesh->fHead->fPrev = nullptr; 1201 } 1202 mesh->fTail = prev; 1203} 1204 1205// Stage 3: sort the vertices by increasing sweep direction. 1206 1207void sorted_merge(Vertex* a, Vertex* b, VertexList* result, Comparator& c); 1208 1209void front_back_split(VertexList* v, VertexList* front, VertexList* back) { 1210 Vertex* fast; 1211 Vertex* slow; 1212 if (!v->fHead || !v->fHead->fNext) { 1213 *front = *v; 1214 } else { 1215 slow = v->fHead; 1216 fast = v->fHead->fNext; 1217 1218 while (fast != nullptr) { 1219 fast = fast->fNext; 1220 if (fast != nullptr) { 1221 slow = slow->fNext; 1222 fast = fast->fNext; 1223 } 1224 } 1225 front->fHead = v->fHead; 1226 front->fTail = slow; 1227 back->fHead = slow->fNext; 1228 back->fTail = v->fTail; 1229 slow->fNext->fPrev = nullptr; 1230 slow->fNext = nullptr; 1231 } 1232 v->fHead = v->fTail = nullptr; 1233} 1234 1235void merge_sort(VertexList* mesh, Comparator& c) { 1236 if (!mesh->fHead || !mesh->fHead->fNext) { 1237 return; 1238 } 1239 1240 VertexList a; 1241 VertexList b; 1242 front_back_split(mesh, &a, &b); 1243 1244 merge_sort(&a, c); 1245 merge_sort(&b, c); 1246 1247 sorted_merge(a.fHead, b.fHead, mesh, c); 1248} 1249 1250void sorted_merge(Vertex* a, Vertex* b, VertexList* result, Comparator& c) { 1251 VertexList vertices; 1252 while (a && b) { 1253 if (c.sweep_lt(a->fPoint, b->fPoint)) { 1254 Vertex* next = a->fNext; 1255 vertices.append(a); 1256 a = next; 1257 } else { 1258 Vertex* next = b->fNext; 1259 vertices.append(b); 1260 b = next; 1261 } 1262 } 1263 if (a) { 1264 vertices.insert(a, vertices.fTail, a->fNext); 1265 } 1266 if (b) { 1267 vertices.insert(b, vertices.fTail, b->fNext); 1268 } 1269 *result = vertices; 1270} 1271 1272// Stage 4: Simplify the mesh by inserting new vertices at intersecting edges. 1273 1274void simplify(const VertexList& vertices, Comparator& c, SkChunkAlloc& alloc) { 1275 LOG("simplifying complex polygons\n"); 1276 EdgeList activeEdges; 1277 for (Vertex* v = vertices.fHead; v != nullptr; v = v->fNext) { 1278 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1279 continue; 1280 } 1281#if LOGGING_ENABLED 1282 LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); 1283#endif 1284 Edge* leftEnclosingEdge = nullptr; 1285 Edge* rightEnclosingEdge = nullptr; 1286 bool restartChecks; 1287 do { 1288 restartChecks = false; 1289 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1290 if (v->fFirstEdgeBelow) { 1291 for (Edge* edge = v->fFirstEdgeBelow; edge; edge = edge->fNextEdgeBelow) { 1292 if (check_for_intersection(edge, leftEnclosingEdge, &activeEdges, c, alloc)) { 1293 restartChecks = true; 1294 break; 1295 } 1296 if (check_for_intersection(edge, rightEnclosingEdge, &activeEdges, c, alloc)) { 1297 restartChecks = true; 1298 break; 1299 } 1300 } 1301 } else { 1302 if (Vertex* pv = check_for_intersection(leftEnclosingEdge, rightEnclosingEdge, 1303 &activeEdges, c, alloc)) { 1304 if (c.sweep_lt(pv->fPoint, v->fPoint)) { 1305 v = pv; 1306 } 1307 restartChecks = true; 1308 } 1309 1310 } 1311 } while (restartChecks); 1312 if (v->fAlpha == 0) { 1313 if ((leftEnclosingEdge && leftEnclosingEdge->fWinding > 0) && 1314 (rightEnclosingEdge && rightEnclosingEdge->fWinding < 0)) { 1315 v->fAlpha = max_edge_alpha(leftEnclosingEdge, rightEnclosingEdge); 1316 } 1317 } 1318 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 1319 remove_edge(e, &activeEdges); 1320 } 1321 Edge* leftEdge = leftEnclosingEdge; 1322 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1323 insert_edge(e, leftEdge, &activeEdges); 1324 leftEdge = e; 1325 } 1326 v->fProcessed = true; 1327 } 1328} 1329 1330// Stage 5: Tessellate the simplified mesh into monotone polygons. 1331 1332Poly* tessellate(const VertexList& vertices, SkChunkAlloc& alloc) { 1333 LOG("tessellating simple polygons\n"); 1334 EdgeList activeEdges; 1335 Poly* polys = nullptr; 1336 for (Vertex* v = vertices.fHead; v != nullptr; v = v->fNext) { 1337 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1338 continue; 1339 } 1340#if LOGGING_ENABLED 1341 LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); 1342#endif 1343 Edge* leftEnclosingEdge = nullptr; 1344 Edge* rightEnclosingEdge = nullptr; 1345 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1346 Poly* leftPoly = nullptr; 1347 Poly* rightPoly = nullptr; 1348 if (v->fFirstEdgeAbove) { 1349 leftPoly = v->fFirstEdgeAbove->fLeftPoly; 1350 rightPoly = v->fLastEdgeAbove->fRightPoly; 1351 } else { 1352 leftPoly = leftEnclosingEdge ? leftEnclosingEdge->fRightPoly : nullptr; 1353 rightPoly = rightEnclosingEdge ? rightEnclosingEdge->fLeftPoly : nullptr; 1354 } 1355#if LOGGING_ENABLED 1356 LOG("edges above:\n"); 1357 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 1358 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1359 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1360 } 1361 LOG("edges below:\n"); 1362 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1363 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1364 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1365 } 1366#endif 1367 if (v->fFirstEdgeAbove) { 1368 if (leftPoly) { 1369 leftPoly = leftPoly->addEdge(v->fFirstEdgeAbove, Poly::kRight_Side, alloc); 1370 } 1371 if (rightPoly) { 1372 rightPoly = rightPoly->addEdge(v->fLastEdgeAbove, Poly::kLeft_Side, alloc); 1373 } 1374 for (Edge* e = v->fFirstEdgeAbove; e != v->fLastEdgeAbove; e = e->fNextEdgeAbove) { 1375 Edge* leftEdge = e; 1376 Edge* rightEdge = e->fNextEdgeAbove; 1377 SkASSERT(rightEdge->isRightOf(leftEdge->fTop)); 1378 remove_edge(leftEdge, &activeEdges); 1379 if (leftEdge->fRightPoly) { 1380 leftEdge->fRightPoly->addEdge(e, Poly::kLeft_Side, alloc); 1381 } 1382 if (rightEdge->fLeftPoly) { 1383 rightEdge->fLeftPoly->addEdge(e, Poly::kRight_Side, alloc); 1384 } 1385 } 1386 remove_edge(v->fLastEdgeAbove, &activeEdges); 1387 if (!v->fFirstEdgeBelow) { 1388 if (leftPoly && rightPoly && leftPoly != rightPoly) { 1389 SkASSERT(leftPoly->fPartner == nullptr && rightPoly->fPartner == nullptr); 1390 rightPoly->fPartner = leftPoly; 1391 leftPoly->fPartner = rightPoly; 1392 } 1393 } 1394 } 1395 if (v->fFirstEdgeBelow) { 1396 if (!v->fFirstEdgeAbove) { 1397 if (leftPoly && rightPoly) { 1398 if (leftPoly == rightPoly) { 1399 if (leftPoly->fTail && leftPoly->fTail->fSide == Poly::kLeft_Side) { 1400 leftPoly = new_poly(&polys, leftPoly->lastVertex(), 1401 leftPoly->fWinding, alloc); 1402 leftEnclosingEdge->fRightPoly = leftPoly; 1403 } else { 1404 rightPoly = new_poly(&polys, rightPoly->lastVertex(), 1405 rightPoly->fWinding, alloc); 1406 rightEnclosingEdge->fLeftPoly = rightPoly; 1407 } 1408 } 1409 Edge* join = ALLOC_NEW(Edge, 1410 (leftPoly->lastVertex(), v, 1, Edge::Type::kInner), alloc); 1411 leftPoly = leftPoly->addEdge(join, Poly::kRight_Side, alloc); 1412 rightPoly = rightPoly->addEdge(join, Poly::kLeft_Side, alloc); 1413 } 1414 } 1415 Edge* leftEdge = v->fFirstEdgeBelow; 1416 leftEdge->fLeftPoly = leftPoly; 1417 insert_edge(leftEdge, leftEnclosingEdge, &activeEdges); 1418 for (Edge* rightEdge = leftEdge->fNextEdgeBelow; rightEdge; 1419 rightEdge = rightEdge->fNextEdgeBelow) { 1420 insert_edge(rightEdge, leftEdge, &activeEdges); 1421 int winding = leftEdge->fLeftPoly ? leftEdge->fLeftPoly->fWinding : 0; 1422 winding += leftEdge->fWinding; 1423 if (winding != 0) { 1424 Poly* poly = new_poly(&polys, v, winding, alloc); 1425 leftEdge->fRightPoly = rightEdge->fLeftPoly = poly; 1426 } 1427 leftEdge = rightEdge; 1428 } 1429 v->fLastEdgeBelow->fRightPoly = rightPoly; 1430 } 1431#if LOGGING_ENABLED 1432 LOG("\nactive edges:\n"); 1433 for (Edge* e = activeEdges.fHead; e != nullptr; e = e->fRight) { 1434 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1435 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1436 } 1437#endif 1438 } 1439 return polys; 1440} 1441 1442bool is_boundary_edge(Edge* edge, SkPath::FillType fillType) { 1443 return apply_fill_type(fillType, edge->fLeftPoly) != 1444 apply_fill_type(fillType, edge->fRightPoly); 1445} 1446 1447bool is_boundary_start(Edge* edge, SkPath::FillType fillType) { 1448 return !apply_fill_type(fillType, edge->fLeftPoly) && 1449 apply_fill_type(fillType, edge->fRightPoly); 1450} 1451 1452void remove_non_boundary_edges(const VertexList& mesh, SkPath::FillType fillType, 1453 SkChunkAlloc& alloc) { 1454 for (Vertex* v = mesh.fHead; v != nullptr; v = v->fNext) { 1455 for (Edge* e = v->fFirstEdgeBelow; e != nullptr;) { 1456 Edge* next = e->fNextEdgeBelow; 1457 if (!is_boundary_edge(e, fillType)) { 1458 remove_edge_above(e); 1459 remove_edge_below(e); 1460 } 1461 e = next; 1462 } 1463 } 1464} 1465 1466void get_edge_normal(const Edge* e, SkVector* normal) { 1467 normal->setNormalize(SkDoubleToScalar(-e->fLine.fB) * e->fWinding, 1468 SkDoubleToScalar(e->fLine.fA) * e->fWinding); 1469} 1470 1471// Stage 5c: detect and remove "pointy" vertices whose edge normals point in opposite directions 1472// and whose adjacent vertices are less than a quarter pixel from an edge. These are guaranteed to 1473// invert on stroking. 1474 1475void simplify_boundary(EdgeList* boundary, Comparator& c, SkChunkAlloc& alloc) { 1476 Edge* prevEdge = boundary->fTail; 1477 SkVector prevNormal; 1478 get_edge_normal(prevEdge, &prevNormal); 1479 for (Edge* e = boundary->fHead; e != nullptr;) { 1480 Vertex* prev = prevEdge->fWinding == 1 ? prevEdge->fTop : prevEdge->fBottom; 1481 Vertex* next = e->fWinding == 1 ? e->fBottom : e->fTop; 1482 double dist = e->dist(prev->fPoint); 1483 SkVector normal; 1484 get_edge_normal(e, &normal); 1485 float denom = 0.25f * static_cast<float>(e->fLine.magSq()); 1486 if (prevNormal.dot(normal) < 0.0 && (dist * dist) <= denom) { 1487 Edge* join = new_edge(prev, next, Edge::Type::kInner, c, alloc); 1488 insert_edge(join, e, boundary); 1489 remove_edge(prevEdge, boundary); 1490 remove_edge(e, boundary); 1491 if (join->fLeft && join->fRight) { 1492 prevEdge = join->fLeft; 1493 e = join; 1494 } else { 1495 prevEdge = boundary->fTail; 1496 e = boundary->fHead; // join->fLeft ? join->fLeft : join; 1497 } 1498 get_edge_normal(prevEdge, &prevNormal); 1499 } else { 1500 prevEdge = e; 1501 prevNormal = normal; 1502 e = e->fRight; 1503 } 1504 } 1505} 1506 1507// Stage 5d: Displace edges by half a pixel inward and outward along their normals. Intersect to 1508// find new vertices, and set zero alpha on the exterior and one alpha on the interior. Build a 1509// new antialiased mesh from those vertices. 1510 1511void boundary_to_aa_mesh(EdgeList* boundary, VertexList* mesh, Comparator& c, SkChunkAlloc& alloc) { 1512 EdgeList outerContour; 1513 Edge* prevEdge = boundary->fTail; 1514 float radius = 0.5f; 1515 double offset = radius * sqrt(prevEdge->fLine.magSq()) * prevEdge->fWinding; 1516 Line prevInner(prevEdge->fTop, prevEdge->fBottom); 1517 prevInner.fC -= offset; 1518 Line prevOuter(prevEdge->fTop, prevEdge->fBottom); 1519 prevOuter.fC += offset; 1520 VertexList innerVertices; 1521 VertexList outerVertices; 1522 SkScalar innerCount = SK_Scalar1, outerCount = SK_Scalar1; 1523 for (Edge* e = boundary->fHead; e != nullptr; e = e->fRight) { 1524 double offset = radius * sqrt(e->fLine.magSq()) * e->fWinding; 1525 Line inner(e->fTop, e->fBottom); 1526 inner.fC -= offset; 1527 Line outer(e->fTop, e->fBottom); 1528 outer.fC += offset; 1529 SkPoint innerPoint, outerPoint; 1530 if (prevInner.intersect(inner, &innerPoint) && 1531 prevOuter.intersect(outer, &outerPoint)) { 1532 Vertex* innerVertex = ALLOC_NEW(Vertex, (innerPoint, 255), alloc); 1533 Vertex* outerVertex = ALLOC_NEW(Vertex, (outerPoint, 0), alloc); 1534 if (innerVertices.fTail && outerVertices.fTail) { 1535 Edge innerEdge(innerVertices.fTail, innerVertex, 1, Edge::Type::kInner); 1536 Edge outerEdge(outerVertices.fTail, outerVertex, 1, Edge::Type::kInner); 1537 SkVector innerNormal; 1538 get_edge_normal(&innerEdge, &innerNormal); 1539 SkVector outerNormal; 1540 get_edge_normal(&outerEdge, &outerNormal); 1541 SkVector normal; 1542 get_edge_normal(prevEdge, &normal); 1543 if (normal.dot(innerNormal) < 0) { 1544 innerPoint += innerVertices.fTail->fPoint * innerCount; 1545 innerCount++; 1546 innerPoint *= SkScalarInvert(innerCount); 1547 innerVertices.fTail->fPoint = innerVertex->fPoint = innerPoint; 1548 } else { 1549 innerCount = SK_Scalar1; 1550 } 1551 if (normal.dot(outerNormal) < 0) { 1552 outerPoint += outerVertices.fTail->fPoint * outerCount; 1553 outerCount++; 1554 outerPoint *= SkScalarInvert(outerCount); 1555 outerVertices.fTail->fPoint = outerVertex->fPoint = outerPoint; 1556 } else { 1557 outerCount = SK_Scalar1; 1558 } 1559 } 1560 innerVertices.append(innerVertex); 1561 outerVertices.append(outerVertex); 1562 prevEdge = e; 1563 } 1564 prevInner = inner; 1565 prevOuter = outer; 1566 } 1567 innerVertices.close(); 1568 outerVertices.close(); 1569 1570 Vertex* innerVertex = innerVertices.fHead; 1571 Vertex* outerVertex = outerVertices.fHead; 1572 // Alternate clockwise and counterclockwise polys, so the tesselator 1573 // doesn't cancel out the interior edges. 1574 if (!innerVertex || !outerVertex) { 1575 return; 1576 } 1577 do { 1578 connect(outerVertex->fPrev, outerVertex, Edge::Type::kOuter, c, alloc); 1579 connect(innerVertex->fPrev, innerVertex, Edge::Type::kInner, c, alloc); 1580 connect(outerVertex, innerVertex, Edge::Type::kConnector, c, alloc)->fWinding = 0; 1581 Vertex* innerNext = innerVertex->fNext; 1582 Vertex* outerNext = outerVertex->fNext; 1583 mesh->append(innerVertex); 1584 mesh->append(outerVertex); 1585 innerVertex = innerNext; 1586 outerVertex = outerNext; 1587 } while (innerVertex != innerVertices.fHead && outerVertex != outerVertices.fHead); 1588} 1589 1590void extract_boundary(EdgeList* boundary, Edge* e, SkPath::FillType fillType, SkChunkAlloc& alloc) { 1591 bool down = is_boundary_start(e, fillType); 1592 while (e) { 1593 e->fWinding = down ? 1 : -1; 1594 Edge* next; 1595 boundary->append(e); 1596 if (down) { 1597 // Find outgoing edge, in clockwise order. 1598 if ((next = e->fNextEdgeAbove)) { 1599 down = false; 1600 } else if ((next = e->fBottom->fLastEdgeBelow)) { 1601 down = true; 1602 } else if ((next = e->fPrevEdgeAbove)) { 1603 down = false; 1604 } 1605 } else { 1606 // Find outgoing edge, in counter-clockwise order. 1607 if ((next = e->fPrevEdgeBelow)) { 1608 down = true; 1609 } else if ((next = e->fTop->fFirstEdgeAbove)) { 1610 down = false; 1611 } else if ((next = e->fNextEdgeBelow)) { 1612 down = true; 1613 } 1614 } 1615 remove_edge_above(e); 1616 remove_edge_below(e); 1617 e = next; 1618 } 1619} 1620 1621// Stage 5b: Extract boundary edges. 1622 1623EdgeList* extract_boundaries(const VertexList& mesh, SkPath::FillType fillType, 1624 SkChunkAlloc& alloc) { 1625 LOG("extracting boundaries\n"); 1626 remove_non_boundary_edges(mesh, fillType, alloc); 1627 EdgeList* boundaries = nullptr; 1628 for (Vertex* v = mesh.fHead; v != nullptr; v = v->fNext) { 1629 while (v->fFirstEdgeBelow) { 1630 EdgeList* boundary = new_contour(&boundaries, alloc); 1631 extract_boundary(boundary, v->fFirstEdgeBelow, fillType, alloc); 1632 } 1633 } 1634 return boundaries; 1635} 1636 1637// This is a driver function which calls stages 2-5 in turn. 1638 1639void contours_to_mesh(Vertex** contours, int contourCnt, bool antialias, 1640 VertexList* mesh, Comparator& c, SkChunkAlloc& alloc) { 1641#if LOGGING_ENABLED 1642 for (int i = 0; i < contourCnt; ++i) { 1643 Vertex* v = contours[i]; 1644 SkASSERT(v); 1645 LOG("path.moveTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); 1646 for (v = v->fNext; v != contours[i]; v = v->fNext) { 1647 LOG("path.lineTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); 1648 } 1649 } 1650#endif 1651 sanitize_contours(contours, contourCnt, antialias); 1652 build_edges(contours, contourCnt, mesh, c, alloc); 1653} 1654 1655void sort_and_simplify(VertexList* vertices, Comparator& c, SkChunkAlloc& alloc) { 1656 if (!vertices || !vertices->fHead) { 1657 return; 1658 } 1659 1660 // Sort vertices in Y (secondarily in X). 1661 merge_sort(vertices, c); 1662 merge_coincident_vertices(vertices, c, alloc); 1663#if LOGGING_ENABLED 1664 for (Vertex* v = vertices->fHead; v != nullptr; v = v->fNext) { 1665 static float gID = 0.0f; 1666 v->fID = gID++; 1667 } 1668#endif 1669 simplify(*vertices, c, alloc); 1670} 1671 1672Poly* mesh_to_polys(VertexList* vertices, Comparator& c, SkChunkAlloc& alloc) { 1673 sort_and_simplify(vertices, c, alloc); 1674 return tessellate(*vertices, alloc); 1675} 1676 1677Poly* contours_to_polys(Vertex** contours, int contourCnt, SkPath::FillType fillType, 1678 const SkRect& pathBounds, bool antialias, 1679 SkChunkAlloc& alloc) { 1680 Comparator c; 1681 if (pathBounds.width() > pathBounds.height()) { 1682 c.sweep_lt = sweep_lt_horiz; 1683 c.sweep_gt = sweep_gt_horiz; 1684 } else { 1685 c.sweep_lt = sweep_lt_vert; 1686 c.sweep_gt = sweep_gt_vert; 1687 } 1688 VertexList mesh; 1689 contours_to_mesh(contours, contourCnt, antialias, &mesh, c, alloc); 1690 Poly* polys = mesh_to_polys(&mesh, c, alloc); 1691 if (antialias) { 1692 EdgeList* boundaries = extract_boundaries(mesh, fillType, alloc); 1693 VertexList aaMesh; 1694 for (EdgeList* boundary = boundaries; boundary != nullptr; boundary = boundary->fNext) { 1695 simplify_boundary(boundary, c, alloc); 1696 if (boundary->fCount > 2) { 1697 boundary_to_aa_mesh(boundary, &aaMesh, c, alloc); 1698 } 1699 } 1700 sort_and_simplify(&aaMesh, c, alloc); 1701 return tessellate(aaMesh, alloc); 1702 } 1703 return polys; 1704} 1705 1706// Stage 6: Triangulate the monotone polygons into a vertex buffer. 1707void* polys_to_triangles(Poly* polys, SkPath::FillType fillType, const AAParams* aaParams, 1708 void* data) { 1709 for (Poly* poly = polys; poly; poly = poly->fNext) { 1710 if (apply_fill_type(fillType, poly)) { 1711 data = poly->emit(aaParams, data); 1712 } 1713 } 1714 return data; 1715} 1716 1717Poly* path_to_polys(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 1718 int contourCnt, SkChunkAlloc& alloc, bool antialias, bool* isLinear) { 1719 SkPath::FillType fillType = path.getFillType(); 1720 if (SkPath::IsInverseFillType(fillType)) { 1721 contourCnt++; 1722 } 1723 std::unique_ptr<Vertex*[]> contours(new Vertex* [contourCnt]); 1724 1725 path_to_contours(path, tolerance, clipBounds, contours.get(), alloc, isLinear); 1726 return contours_to_polys(contours.get(), contourCnt, path.getFillType(), path.getBounds(), 1727 antialias, alloc); 1728} 1729 1730void get_contour_count_and_size_estimate(const SkPath& path, SkScalar tolerance, int* contourCnt, 1731 int* sizeEstimate) { 1732 int maxPts = GrPathUtils::worstCasePointCount(path, contourCnt, tolerance); 1733 if (maxPts <= 0) { 1734 *contourCnt = 0; 1735 return; 1736 } 1737 if (maxPts > ((int)SK_MaxU16 + 1)) { 1738 SkDebugf("Path not rendered, too many verts (%d)\n", maxPts); 1739 *contourCnt = 0; 1740 return; 1741 } 1742 // For the initial size of the chunk allocator, estimate based on the point count: 1743 // one vertex per point for the initial passes, plus two for the vertices in the 1744 // resulting Polys, since the same point may end up in two Polys. Assume minimal 1745 // connectivity of one Edge per Vertex (will grow for intersections). 1746 *sizeEstimate = maxPts * (3 * sizeof(Vertex) + sizeof(Edge)); 1747} 1748 1749int count_points(Poly* polys, SkPath::FillType fillType) { 1750 int count = 0; 1751 for (Poly* poly = polys; poly; poly = poly->fNext) { 1752 if (apply_fill_type(fillType, poly) && poly->fCount >= 3) { 1753 count += (poly->fCount - 2) * (TESSELLATOR_WIREFRAME ? 6 : 3); 1754 } 1755 } 1756 return count; 1757} 1758 1759} // namespace 1760 1761namespace GrTessellator { 1762 1763// Stage 6: Triangulate the monotone polygons into a vertex buffer. 1764 1765int PathToTriangles(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 1766 VertexAllocator* vertexAllocator, bool antialias, const GrColor& color, 1767 bool canTweakAlphaForCoverage, bool* isLinear) { 1768 int contourCnt; 1769 int sizeEstimate; 1770 get_contour_count_and_size_estimate(path, tolerance, &contourCnt, &sizeEstimate); 1771 if (contourCnt <= 0) { 1772 *isLinear = true; 1773 return 0; 1774 } 1775 SkChunkAlloc alloc(sizeEstimate); 1776 Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, antialias, 1777 isLinear); 1778 SkPath::FillType fillType = antialias ? SkPath::kWinding_FillType : path.getFillType(); 1779 int count = count_points(polys, fillType); 1780 if (0 == count) { 1781 return 0; 1782 } 1783 1784 void* verts = vertexAllocator->lock(count); 1785 if (!verts) { 1786 SkDebugf("Could not allocate vertices\n"); 1787 return 0; 1788 } 1789 1790 LOG("emitting %d verts\n", count); 1791 AAParams aaParams; 1792 aaParams.fTweakAlpha = canTweakAlphaForCoverage; 1793 aaParams.fColor = color; 1794 1795 void* end = polys_to_triangles(polys, fillType, antialias ? &aaParams : nullptr, verts); 1796 int actualCount = static_cast<int>((static_cast<uint8_t*>(end) - static_cast<uint8_t*>(verts)) 1797 / vertexAllocator->stride()); 1798 SkASSERT(actualCount <= count); 1799 vertexAllocator->unlock(actualCount); 1800 return actualCount; 1801} 1802 1803int PathToVertices(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 1804 GrTessellator::WindingVertex** verts) { 1805 int contourCnt; 1806 int sizeEstimate; 1807 get_contour_count_and_size_estimate(path, tolerance, &contourCnt, &sizeEstimate); 1808 if (contourCnt <= 0) { 1809 return 0; 1810 } 1811 SkChunkAlloc alloc(sizeEstimate); 1812 bool isLinear; 1813 Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, false, &isLinear); 1814 SkPath::FillType fillType = path.getFillType(); 1815 int count = count_points(polys, fillType); 1816 if (0 == count) { 1817 *verts = nullptr; 1818 return 0; 1819 } 1820 1821 *verts = new GrTessellator::WindingVertex[count]; 1822 GrTessellator::WindingVertex* vertsEnd = *verts; 1823 SkPoint* points = new SkPoint[count]; 1824 SkPoint* pointsEnd = points; 1825 for (Poly* poly = polys; poly; poly = poly->fNext) { 1826 if (apply_fill_type(fillType, poly)) { 1827 SkPoint* start = pointsEnd; 1828 pointsEnd = static_cast<SkPoint*>(poly->emit(nullptr, pointsEnd)); 1829 while (start != pointsEnd) { 1830 vertsEnd->fPos = *start; 1831 vertsEnd->fWinding = poly->fWinding; 1832 ++start; 1833 ++vertsEnd; 1834 } 1835 } 1836 } 1837 int actualCount = static_cast<int>(vertsEnd - *verts); 1838 SkASSERT(actualCount <= count); 1839 SkASSERT(pointsEnd - points == actualCount); 1840 delete[] points; 1841 return actualCount; 1842} 1843 1844} // namespace 1845