GrTessellator.cpp revision d4b21552481a6d313dfa9bc14b624c9ec94b56ce
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 close() { 249 if (fHead && fTail) { 250 fTail->fNext = fHead; 251 fHead->fPrev = fTail; 252 } 253 } 254}; 255 256// Round to nearest quarter-pixel. This is used for screenspace tessellation. 257 258inline void round(SkPoint* p) { 259 p->fX = SkScalarRoundToScalar(p->fX * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); 260 p->fY = SkScalarRoundToScalar(p->fY * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); 261} 262 263// A line equation in implicit form. fA * x + fB * y + fC = 0, for all points (x, y) on the line. 264struct Line { 265 Line(Vertex* p, Vertex* q) : Line(p->fPoint, q->fPoint) {} 266 Line(const SkPoint& p, const SkPoint& q) 267 : fA(static_cast<double>(q.fY) - p.fY) // a = dY 268 , fB(static_cast<double>(p.fX) - q.fX) // b = -dX 269 , fC(static_cast<double>(p.fY) * q.fX - // c = cross(q, p) 270 static_cast<double>(p.fX) * q.fY) {} 271 double dist(const SkPoint& p) const { 272 return fA * p.fX + fB * p.fY + fC; 273 } 274 double magSq() const { 275 return fA * fA + fB * fB; 276 } 277 278 // Compute the intersection of two (infinite) Lines. 279 bool intersect(const Line& other, SkPoint* point) { 280 double denom = fA * other.fB - fB * other.fA; 281 if (denom == 0.0) { 282 return false; 283 } 284 double scale = 1.0f / denom; 285 point->fX = SkDoubleToScalar((fB * other.fC - other.fB * fC) * scale); 286 point->fY = SkDoubleToScalar((other.fA * fC - fA * other.fC) * scale); 287 round(point); 288 return true; 289 } 290 double fA, fB, fC; 291}; 292 293/** 294 * An Edge joins a top Vertex to a bottom Vertex. Edge ordering for the list of "edges above" and 295 * "edge below" a vertex as well as for the active edge list is handled by isLeftOf()/isRightOf(). 296 * Note that an Edge will give occasionally dist() != 0 for its own endpoints (because floating 297 * point). For speed, that case is only tested by the callers which require it (e.g., 298 * cleanup_active_edges()). Edges also handle checking for intersection with other edges. 299 * Currently, this converts the edges to the parametric form, in order to avoid doing a division 300 * until an intersection has been confirmed. This is slightly slower in the "found" case, but 301 * a lot faster in the "not found" case. 302 * 303 * The coefficients of the line equation stored in double precision to avoid catastrphic 304 * cancellation in the isLeftOf() and isRightOf() checks. Using doubles ensures that the result is 305 * correct in float, since it's a polynomial of degree 2. The intersect() function, being 306 * degree 5, is still subject to catastrophic cancellation. We deal with that by assuming its 307 * output may be incorrect, and adjusting the mesh topology to match (see comment at the top of 308 * this file). 309 */ 310 311struct Edge { 312 enum class Type { kInner, kOuter, kConnector }; 313 Edge(Vertex* top, Vertex* bottom, int winding, Type type) 314 : fWinding(winding) 315 , fTop(top) 316 , fBottom(bottom) 317 , fType(type) 318 , fLeft(nullptr) 319 , fRight(nullptr) 320 , fPrevEdgeAbove(nullptr) 321 , fNextEdgeAbove(nullptr) 322 , fPrevEdgeBelow(nullptr) 323 , fNextEdgeBelow(nullptr) 324 , fLeftPoly(nullptr) 325 , fRightPoly(nullptr) 326 , fLeftPolyPrev(nullptr) 327 , fLeftPolyNext(nullptr) 328 , fRightPolyPrev(nullptr) 329 , fRightPolyNext(nullptr) 330 , fUsedInLeftPoly(false) 331 , fUsedInRightPoly(false) 332 , fLine(top, bottom) { 333 } 334 int fWinding; // 1 == edge goes downward; -1 = edge goes upward. 335 Vertex* fTop; // The top vertex in vertex-sort-order (sweep_lt). 336 Vertex* fBottom; // The bottom vertex in vertex-sort-order. 337 Type fType; 338 Edge* fLeft; // The linked list of edges in the active edge list. 339 Edge* fRight; // " 340 Edge* fPrevEdgeAbove; // The linked list of edges in the bottom Vertex's "edges above". 341 Edge* fNextEdgeAbove; // " 342 Edge* fPrevEdgeBelow; // The linked list of edges in the top Vertex's "edges below". 343 Edge* fNextEdgeBelow; // " 344 Poly* fLeftPoly; // The Poly to the left of this edge, if any. 345 Poly* fRightPoly; // The Poly to the right of this edge, if any. 346 Edge* fLeftPolyPrev; 347 Edge* fLeftPolyNext; 348 Edge* fRightPolyPrev; 349 Edge* fRightPolyNext; 350 bool fUsedInLeftPoly; 351 bool fUsedInRightPoly; 352 Line fLine; 353 double dist(const SkPoint& p) const { 354 return fLine.dist(p); 355 } 356 bool isRightOf(Vertex* v) const { 357 return fLine.dist(v->fPoint) < 0.0; 358 } 359 bool isLeftOf(Vertex* v) const { 360 return fLine.dist(v->fPoint) > 0.0; 361 } 362 void recompute() { 363 fLine = Line(fTop, fBottom); 364 } 365 bool intersect(const Edge& other, SkPoint* p) { 366 LOG("intersecting %g -> %g with %g -> %g\n", 367 fTop->fID, fBottom->fID, 368 other.fTop->fID, other.fBottom->fID); 369 if (fTop == other.fTop || fBottom == other.fBottom) { 370 return false; 371 } 372 double denom = fLine.fA * other.fLine.fB - fLine.fB * other.fLine.fA; 373 if (denom == 0.0) { 374 return false; 375 } 376 double dx = static_cast<double>(fTop->fPoint.fX) - other.fTop->fPoint.fX; 377 double dy = static_cast<double>(fTop->fPoint.fY) - other.fTop->fPoint.fY; 378 double sNumer = -dy * other.fLine.fB - dx * other.fLine.fA; 379 double tNumer = -dy * fLine.fB - dx * fLine.fA; 380 // If (sNumer / denom) or (tNumer / denom) is not in [0..1], exit early. 381 // This saves us doing the divide below unless absolutely necessary. 382 if (denom > 0.0 ? (sNumer < 0.0 || sNumer > denom || tNumer < 0.0 || tNumer > denom) 383 : (sNumer > 0.0 || sNumer < denom || tNumer > 0.0 || tNumer < denom)) { 384 return false; 385 } 386 double s = sNumer / denom; 387 SkASSERT(s >= 0.0 && s <= 1.0); 388 p->fX = SkDoubleToScalar(fTop->fPoint.fX - s * fLine.fB); 389 p->fY = SkDoubleToScalar(fTop->fPoint.fY + s * fLine.fA); 390 return true; 391 } 392}; 393 394struct EdgeList { 395 EdgeList() : fHead(nullptr), fTail(nullptr), fNext(nullptr), fCount(0) {} 396 Edge* fHead; 397 Edge* fTail; 398 EdgeList* fNext; 399 int fCount; 400 void insert(Edge* edge, Edge* prev, Edge* next) { 401 list_insert<Edge, &Edge::fLeft, &Edge::fRight>(edge, prev, next, &fHead, &fTail); 402 fCount++; 403 } 404 void append(Edge* e) { 405 insert(e, fTail, nullptr); 406 } 407 void remove(Edge* edge) { 408 list_remove<Edge, &Edge::fLeft, &Edge::fRight>(edge, &fHead, &fTail); 409 fCount--; 410 } 411 void close() { 412 if (fHead && fTail) { 413 fTail->fRight = fHead; 414 fHead->fLeft = fTail; 415 } 416 } 417 bool contains(Edge* edge) const { 418 return edge->fLeft || edge->fRight || fHead == edge; 419 } 420}; 421 422/***************************************************************************************/ 423 424struct Poly { 425 Poly(Vertex* v, int winding) 426 : fFirstVertex(v) 427 , fWinding(winding) 428 , fHead(nullptr) 429 , fTail(nullptr) 430 , fNext(nullptr) 431 , fPartner(nullptr) 432 , fCount(0) 433 { 434#if LOGGING_ENABLED 435 static int gID = 0; 436 fID = gID++; 437 LOG("*** created Poly %d\n", fID); 438#endif 439 } 440 typedef enum { kLeft_Side, kRight_Side } Side; 441 struct MonotonePoly { 442 MonotonePoly(Edge* edge, Side side) 443 : fSide(side) 444 , fFirstEdge(nullptr) 445 , fLastEdge(nullptr) 446 , fPrev(nullptr) 447 , fNext(nullptr) { 448 this->addEdge(edge); 449 } 450 Side fSide; 451 Edge* fFirstEdge; 452 Edge* fLastEdge; 453 MonotonePoly* fPrev; 454 MonotonePoly* fNext; 455 void addEdge(Edge* edge) { 456 if (fSide == kRight_Side) { 457 SkASSERT(!edge->fUsedInRightPoly); 458 list_insert<Edge, &Edge::fRightPolyPrev, &Edge::fRightPolyNext>( 459 edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); 460 edge->fUsedInRightPoly = true; 461 } else { 462 SkASSERT(!edge->fUsedInLeftPoly); 463 list_insert<Edge, &Edge::fLeftPolyPrev, &Edge::fLeftPolyNext>( 464 edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); 465 edge->fUsedInLeftPoly = true; 466 } 467 } 468 469 void* emit(const AAParams* aaParams, void* data) { 470 Edge* e = fFirstEdge; 471 e->fTop->fPrev = e->fTop->fNext = nullptr; 472 VertexList vertices; 473 vertices.append(e->fTop); 474 while (e != nullptr) { 475 e->fBottom->fPrev = e->fBottom->fNext = nullptr; 476 if (kRight_Side == fSide) { 477 vertices.append(e->fBottom); 478 e = e->fRightPolyNext; 479 } else { 480 vertices.prepend(e->fBottom); 481 e = e->fLeftPolyNext; 482 } 483 } 484 Vertex* first = vertices.fHead; 485 Vertex* v = first->fNext; 486 while (v != vertices.fTail) { 487 SkASSERT(v && v->fPrev && v->fNext); 488 Vertex* prev = v->fPrev; 489 Vertex* curr = v; 490 Vertex* next = v->fNext; 491 double ax = static_cast<double>(curr->fPoint.fX) - prev->fPoint.fX; 492 double ay = static_cast<double>(curr->fPoint.fY) - prev->fPoint.fY; 493 double bx = static_cast<double>(next->fPoint.fX) - curr->fPoint.fX; 494 double by = static_cast<double>(next->fPoint.fY) - curr->fPoint.fY; 495 if (ax * by - ay * bx >= 0.0) { 496 data = emit_triangle(prev, curr, next, aaParams, data); 497 v->fPrev->fNext = v->fNext; 498 v->fNext->fPrev = v->fPrev; 499 if (v->fPrev == first) { 500 v = v->fNext; 501 } else { 502 v = v->fPrev; 503 } 504 } else { 505 v = v->fNext; 506 } 507 } 508 return data; 509 } 510 }; 511 Poly* addEdge(Edge* e, Side side, SkChunkAlloc& alloc) { 512 LOG("addEdge (%g -> %g) to poly %d, %s side\n", 513 e->fTop->fID, e->fBottom->fID, fID, side == kLeft_Side ? "left" : "right"); 514 Poly* partner = fPartner; 515 Poly* poly = this; 516 if (side == kRight_Side) { 517 if (e->fUsedInRightPoly) { 518 return this; 519 } 520 } else { 521 if (e->fUsedInLeftPoly) { 522 return this; 523 } 524 } 525 if (partner) { 526 fPartner = partner->fPartner = nullptr; 527 } 528 if (!fTail) { 529 fHead = fTail = ALLOC_NEW(MonotonePoly, (e, side), alloc); 530 fCount += 2; 531 } else if (e->fBottom == fTail->fLastEdge->fBottom) { 532 return poly; 533 } else if (side == fTail->fSide) { 534 fTail->addEdge(e); 535 fCount++; 536 } else { 537 e = ALLOC_NEW(Edge, (fTail->fLastEdge->fBottom, e->fBottom, 1, Edge::Type::kInner), 538 alloc); 539 fTail->addEdge(e); 540 fCount++; 541 if (partner) { 542 partner->addEdge(e, side, alloc); 543 poly = partner; 544 } else { 545 MonotonePoly* m = ALLOC_NEW(MonotonePoly, (e, side), alloc); 546 m->fPrev = fTail; 547 fTail->fNext = m; 548 fTail = m; 549 } 550 } 551 return poly; 552 } 553 void* emit(const AAParams* aaParams, void *data) { 554 if (fCount < 3) { 555 return data; 556 } 557 LOG("emit() %d, size %d\n", fID, fCount); 558 for (MonotonePoly* m = fHead; m != nullptr; m = m->fNext) { 559 data = m->emit(aaParams, data); 560 } 561 return data; 562 } 563 Vertex* lastVertex() const { return fTail ? fTail->fLastEdge->fBottom : fFirstVertex; } 564 Vertex* fFirstVertex; 565 int fWinding; 566 MonotonePoly* fHead; 567 MonotonePoly* fTail; 568 Poly* fNext; 569 Poly* fPartner; 570 int fCount; 571#if LOGGING_ENABLED 572 int fID; 573#endif 574}; 575 576/***************************************************************************************/ 577 578bool coincident(const SkPoint& a, const SkPoint& b) { 579 return a == b; 580} 581 582Poly* new_poly(Poly** head, Vertex* v, int winding, SkChunkAlloc& alloc) { 583 Poly* poly = ALLOC_NEW(Poly, (v, winding), alloc); 584 poly->fNext = *head; 585 *head = poly; 586 return poly; 587} 588 589EdgeList* new_contour(EdgeList** head, SkChunkAlloc& alloc) { 590 EdgeList* contour = ALLOC_NEW(EdgeList, (), alloc); 591 contour->fNext = *head; 592 *head = contour; 593 return contour; 594} 595 596Vertex* append_point_to_contour(const SkPoint& p, Vertex* prev, Vertex** head, 597 SkChunkAlloc& alloc) { 598 Vertex* v = ALLOC_NEW(Vertex, (p, 255), alloc); 599#if LOGGING_ENABLED 600 static float gID = 0.0f; 601 v->fID = gID++; 602#endif 603 if (prev) { 604 prev->fNext = v; 605 v->fPrev = prev; 606 } else { 607 *head = v; 608 } 609 return v; 610} 611 612Vertex* generate_quadratic_points(const SkPoint& p0, 613 const SkPoint& p1, 614 const SkPoint& p2, 615 SkScalar tolSqd, 616 Vertex* prev, 617 Vertex** head, 618 int pointsLeft, 619 SkChunkAlloc& alloc) { 620 SkScalar d = p1.distanceToLineSegmentBetweenSqd(p0, p2); 621 if (pointsLeft < 2 || d < tolSqd || !SkScalarIsFinite(d)) { 622 return append_point_to_contour(p2, prev, head, alloc); 623 } 624 625 const SkPoint q[] = { 626 { SkScalarAve(p0.fX, p1.fX), SkScalarAve(p0.fY, p1.fY) }, 627 { SkScalarAve(p1.fX, p2.fX), SkScalarAve(p1.fY, p2.fY) }, 628 }; 629 const SkPoint r = { SkScalarAve(q[0].fX, q[1].fX), SkScalarAve(q[0].fY, q[1].fY) }; 630 631 pointsLeft >>= 1; 632 prev = generate_quadratic_points(p0, q[0], r, tolSqd, prev, head, pointsLeft, alloc); 633 prev = generate_quadratic_points(r, q[1], p2, tolSqd, prev, head, pointsLeft, alloc); 634 return prev; 635} 636 637Vertex* generate_cubic_points(const SkPoint& p0, 638 const SkPoint& p1, 639 const SkPoint& p2, 640 const SkPoint& p3, 641 SkScalar tolSqd, 642 Vertex* prev, 643 Vertex** head, 644 int pointsLeft, 645 SkChunkAlloc& alloc) { 646 SkScalar d1 = p1.distanceToLineSegmentBetweenSqd(p0, p3); 647 SkScalar d2 = p2.distanceToLineSegmentBetweenSqd(p0, p3); 648 if (pointsLeft < 2 || (d1 < tolSqd && d2 < tolSqd) || 649 !SkScalarIsFinite(d1) || !SkScalarIsFinite(d2)) { 650 return append_point_to_contour(p3, prev, head, alloc); 651 } 652 const SkPoint q[] = { 653 { SkScalarAve(p0.fX, p1.fX), SkScalarAve(p0.fY, p1.fY) }, 654 { SkScalarAve(p1.fX, p2.fX), SkScalarAve(p1.fY, p2.fY) }, 655 { SkScalarAve(p2.fX, p3.fX), SkScalarAve(p2.fY, p3.fY) } 656 }; 657 const SkPoint r[] = { 658 { SkScalarAve(q[0].fX, q[1].fX), SkScalarAve(q[0].fY, q[1].fY) }, 659 { SkScalarAve(q[1].fX, q[2].fX), SkScalarAve(q[1].fY, q[2].fY) } 660 }; 661 const SkPoint s = { SkScalarAve(r[0].fX, r[1].fX), SkScalarAve(r[0].fY, r[1].fY) }; 662 pointsLeft >>= 1; 663 prev = generate_cubic_points(p0, q[0], r[0], s, tolSqd, prev, head, pointsLeft, alloc); 664 prev = generate_cubic_points(s, r[1], q[2], p3, tolSqd, prev, head, pointsLeft, alloc); 665 return prev; 666} 667 668// Stage 1: convert the input path to a set of linear contours (linked list of Vertices). 669 670void path_to_contours(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 671 Vertex** contours, SkChunkAlloc& alloc, bool *isLinear) { 672 SkScalar toleranceSqd = tolerance * tolerance; 673 674 SkPoint pts[4]; 675 bool done = false; 676 *isLinear = true; 677 SkPath::Iter iter(path, false); 678 Vertex* prev = nullptr; 679 Vertex* head = nullptr; 680 if (path.isInverseFillType()) { 681 SkPoint quad[4]; 682 clipBounds.toQuad(quad); 683 for (int i = 3; i >= 0; i--) { 684 prev = append_point_to_contour(quad[i], prev, &head, alloc); 685 } 686 head->fPrev = prev; 687 prev->fNext = head; 688 *contours++ = head; 689 head = prev = nullptr; 690 } 691 SkAutoConicToQuads converter; 692 while (!done) { 693 SkPath::Verb verb = iter.next(pts); 694 switch (verb) { 695 case SkPath::kConic_Verb: { 696 SkScalar weight = iter.conicWeight(); 697 const SkPoint* quadPts = converter.computeQuads(pts, weight, toleranceSqd); 698 for (int i = 0; i < converter.countQuads(); ++i) { 699 int pointsLeft = GrPathUtils::quadraticPointCount(quadPts, tolerance); 700 prev = generate_quadratic_points(quadPts[0], quadPts[1], quadPts[2], 701 toleranceSqd, prev, &head, pointsLeft, alloc); 702 quadPts += 2; 703 } 704 *isLinear = false; 705 break; 706 } 707 case SkPath::kMove_Verb: 708 if (head) { 709 head->fPrev = prev; 710 prev->fNext = head; 711 *contours++ = head; 712 } 713 head = prev = nullptr; 714 prev = append_point_to_contour(pts[0], prev, &head, alloc); 715 break; 716 case SkPath::kLine_Verb: { 717 prev = append_point_to_contour(pts[1], prev, &head, alloc); 718 break; 719 } 720 case SkPath::kQuad_Verb: { 721 int pointsLeft = GrPathUtils::quadraticPointCount(pts, tolerance); 722 prev = generate_quadratic_points(pts[0], pts[1], pts[2], toleranceSqd, prev, 723 &head, pointsLeft, alloc); 724 *isLinear = false; 725 break; 726 } 727 case SkPath::kCubic_Verb: { 728 int pointsLeft = GrPathUtils::cubicPointCount(pts, tolerance); 729 prev = generate_cubic_points(pts[0], pts[1], pts[2], pts[3], 730 toleranceSqd, prev, &head, pointsLeft, alloc); 731 *isLinear = false; 732 break; 733 } 734 case SkPath::kClose_Verb: 735 if (head) { 736 head->fPrev = prev; 737 prev->fNext = head; 738 *contours++ = head; 739 } 740 head = prev = nullptr; 741 break; 742 case SkPath::kDone_Verb: 743 if (head) { 744 head->fPrev = prev; 745 prev->fNext = head; 746 *contours++ = head; 747 } 748 done = true; 749 break; 750 } 751 } 752} 753 754inline bool apply_fill_type(SkPath::FillType fillType, Poly* poly) { 755 if (!poly) { 756 return false; 757 } 758 int winding = poly->fWinding; 759 switch (fillType) { 760 case SkPath::kWinding_FillType: 761 return winding != 0; 762 case SkPath::kEvenOdd_FillType: 763 return (winding & 1) != 0; 764 case SkPath::kInverseWinding_FillType: 765 return winding == 1; 766 case SkPath::kInverseEvenOdd_FillType: 767 return (winding & 1) == 1; 768 default: 769 SkASSERT(false); 770 return false; 771 } 772} 773 774Edge* new_edge(Vertex* prev, Vertex* next, SkChunkAlloc& alloc, Comparator& c, Edge::Type type) { 775 int winding = c.sweep_lt(prev->fPoint, next->fPoint) ? 1 : -1; 776 Vertex* top = winding < 0 ? next : prev; 777 Vertex* bottom = winding < 0 ? prev : next; 778 return ALLOC_NEW(Edge, (top, bottom, winding, type), alloc); 779} 780 781void remove_edge(Edge* edge, EdgeList* edges) { 782 LOG("removing edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); 783 SkASSERT(edges->contains(edge)); 784 edges->remove(edge); 785} 786 787void insert_edge(Edge* edge, Edge* prev, EdgeList* edges) { 788 LOG("inserting edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); 789 SkASSERT(!edges->contains(edge)); 790 Edge* next = prev ? prev->fRight : edges->fHead; 791 edges->insert(edge, prev, next); 792} 793 794void find_enclosing_edges(Vertex* v, EdgeList* edges, Edge** left, Edge** right) { 795 if (v->fFirstEdgeAbove) { 796 *left = v->fFirstEdgeAbove->fLeft; 797 *right = v->fLastEdgeAbove->fRight; 798 return; 799 } 800 Edge* next = nullptr; 801 Edge* prev; 802 for (prev = edges->fTail; prev != nullptr; prev = prev->fLeft) { 803 if (prev->isLeftOf(v)) { 804 break; 805 } 806 next = prev; 807 } 808 *left = prev; 809 *right = next; 810} 811 812void find_enclosing_edges(Edge* edge, EdgeList* edges, Comparator& c, Edge** left, Edge** right) { 813 Edge* prev = nullptr; 814 Edge* next; 815 for (next = edges->fHead; next != nullptr; next = next->fRight) { 816 if ((c.sweep_gt(edge->fTop->fPoint, next->fTop->fPoint) && next->isRightOf(edge->fTop)) || 817 (c.sweep_gt(next->fTop->fPoint, edge->fTop->fPoint) && edge->isLeftOf(next->fTop)) || 818 (c.sweep_lt(edge->fBottom->fPoint, next->fBottom->fPoint) && 819 next->isRightOf(edge->fBottom)) || 820 (c.sweep_lt(next->fBottom->fPoint, edge->fBottom->fPoint) && 821 edge->isLeftOf(next->fBottom))) { 822 break; 823 } 824 prev = next; 825 } 826 *left = prev; 827 *right = next; 828} 829 830void fix_active_state(Edge* edge, EdgeList* activeEdges, Comparator& c) { 831 if (!activeEdges) { 832 return; 833 } 834 if (activeEdges->contains(edge)) { 835 if (edge->fBottom->fProcessed || !edge->fTop->fProcessed) { 836 remove_edge(edge, activeEdges); 837 } 838 } else if (edge->fTop->fProcessed && !edge->fBottom->fProcessed) { 839 Edge* left; 840 Edge* right; 841 find_enclosing_edges(edge, activeEdges, c, &left, &right); 842 insert_edge(edge, left, activeEdges); 843 } 844} 845 846void insert_edge_above(Edge* edge, Vertex* v, Comparator& c) { 847 if (edge->fTop->fPoint == edge->fBottom->fPoint || 848 c.sweep_gt(edge->fTop->fPoint, edge->fBottom->fPoint)) { 849 return; 850 } 851 LOG("insert edge (%g -> %g) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); 852 Edge* prev = nullptr; 853 Edge* next; 854 for (next = v->fFirstEdgeAbove; next; next = next->fNextEdgeAbove) { 855 if (next->isRightOf(edge->fTop)) { 856 break; 857 } 858 prev = next; 859 } 860 list_insert<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( 861 edge, prev, next, &v->fFirstEdgeAbove, &v->fLastEdgeAbove); 862} 863 864void insert_edge_below(Edge* edge, Vertex* v, Comparator& c) { 865 if (edge->fTop->fPoint == edge->fBottom->fPoint || 866 c.sweep_gt(edge->fTop->fPoint, edge->fBottom->fPoint)) { 867 return; 868 } 869 LOG("insert edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); 870 Edge* prev = nullptr; 871 Edge* next; 872 for (next = v->fFirstEdgeBelow; next; next = next->fNextEdgeBelow) { 873 if (next->isRightOf(edge->fBottom)) { 874 break; 875 } 876 prev = next; 877 } 878 list_insert<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( 879 edge, prev, next, &v->fFirstEdgeBelow, &v->fLastEdgeBelow); 880} 881 882void remove_edge_above(Edge* edge) { 883 LOG("removing edge (%g -> %g) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, 884 edge->fBottom->fID); 885 list_remove<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( 886 edge, &edge->fBottom->fFirstEdgeAbove, &edge->fBottom->fLastEdgeAbove); 887} 888 889void remove_edge_below(Edge* edge) { 890 LOG("removing edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, 891 edge->fTop->fID); 892 list_remove<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( 893 edge, &edge->fTop->fFirstEdgeBelow, &edge->fTop->fLastEdgeBelow); 894} 895 896void erase_edge_if_zero_winding(Edge* edge, EdgeList* edges) { 897 if (edge->fWinding != 0) { 898 return; 899 } 900 LOG("erasing edge (%g -> %g)\n", edge->fTop->fID, edge->fBottom->fID); 901 remove_edge_above(edge); 902 remove_edge_below(edge); 903 if (edges && edges->contains(edge)) { 904 remove_edge(edge, edges); 905 } 906} 907 908void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Comparator& c); 909 910void set_top(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c) { 911 remove_edge_below(edge); 912 edge->fTop = v; 913 edge->recompute(); 914 insert_edge_below(edge, v, c); 915 fix_active_state(edge, activeEdges, c); 916 merge_collinear_edges(edge, activeEdges, c); 917} 918 919void set_bottom(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c) { 920 remove_edge_above(edge); 921 edge->fBottom = v; 922 edge->recompute(); 923 insert_edge_above(edge, v, c); 924 fix_active_state(edge, activeEdges, c); 925 merge_collinear_edges(edge, activeEdges, c); 926} 927 928void merge_edges_above(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c) { 929 if (coincident(edge->fTop->fPoint, other->fTop->fPoint)) { 930 LOG("merging coincident above edges (%g, %g) -> (%g, %g)\n", 931 edge->fTop->fPoint.fX, edge->fTop->fPoint.fY, 932 edge->fBottom->fPoint.fX, edge->fBottom->fPoint.fY); 933 other->fWinding += edge->fWinding; 934 erase_edge_if_zero_winding(other, activeEdges); 935 edge->fWinding = 0; 936 erase_edge_if_zero_winding(edge, activeEdges); 937 } else if (c.sweep_lt(edge->fTop->fPoint, other->fTop->fPoint)) { 938 other->fWinding += edge->fWinding; 939 erase_edge_if_zero_winding(other, activeEdges); 940 set_bottom(edge, other->fTop, activeEdges, c); 941 } else { 942 edge->fWinding += other->fWinding; 943 erase_edge_if_zero_winding(edge, activeEdges); 944 set_bottom(other, edge->fTop, activeEdges, c); 945 } 946} 947 948void merge_edges_below(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c) { 949 if (coincident(edge->fBottom->fPoint, other->fBottom->fPoint)) { 950 LOG("merging coincident below edges (%g, %g) -> (%g, %g)\n", 951 edge->fTop->fPoint.fX, edge->fTop->fPoint.fY, 952 edge->fBottom->fPoint.fX, edge->fBottom->fPoint.fY); 953 other->fWinding += edge->fWinding; 954 erase_edge_if_zero_winding(other, activeEdges); 955 edge->fWinding = 0; 956 erase_edge_if_zero_winding(edge, activeEdges); 957 } else if (c.sweep_lt(edge->fBottom->fPoint, other->fBottom->fPoint)) { 958 edge->fWinding += other->fWinding; 959 erase_edge_if_zero_winding(edge, activeEdges); 960 set_top(other, edge->fBottom, activeEdges, c); 961 } else { 962 other->fWinding += edge->fWinding; 963 erase_edge_if_zero_winding(other, activeEdges); 964 set_top(edge, other->fBottom, activeEdges, c); 965 } 966} 967 968void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Comparator& c) { 969 if (edge->fPrevEdgeAbove && (edge->fTop == edge->fPrevEdgeAbove->fTop || 970 !edge->fPrevEdgeAbove->isLeftOf(edge->fTop))) { 971 merge_edges_above(edge, edge->fPrevEdgeAbove, activeEdges, c); 972 } else if (edge->fNextEdgeAbove && (edge->fTop == edge->fNextEdgeAbove->fTop || 973 !edge->isLeftOf(edge->fNextEdgeAbove->fTop))) { 974 merge_edges_above(edge, edge->fNextEdgeAbove, activeEdges, c); 975 } 976 if (edge->fPrevEdgeBelow && (edge->fBottom == edge->fPrevEdgeBelow->fBottom || 977 !edge->fPrevEdgeBelow->isLeftOf(edge->fBottom))) { 978 merge_edges_below(edge, edge->fPrevEdgeBelow, activeEdges, c); 979 } else if (edge->fNextEdgeBelow && (edge->fBottom == edge->fNextEdgeBelow->fBottom || 980 !edge->isLeftOf(edge->fNextEdgeBelow->fBottom))) { 981 merge_edges_below(edge, edge->fNextEdgeBelow, activeEdges, c); 982 } 983} 984 985void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, SkChunkAlloc& alloc); 986 987void cleanup_active_edges(Edge* edge, EdgeList* activeEdges, Comparator& c, SkChunkAlloc& alloc) { 988 Vertex* top = edge->fTop; 989 Vertex* bottom = edge->fBottom; 990 if (edge->fLeft) { 991 Vertex* leftTop = edge->fLeft->fTop; 992 Vertex* leftBottom = edge->fLeft->fBottom; 993 if (c.sweep_gt(top->fPoint, leftTop->fPoint) && !edge->fLeft->isLeftOf(top)) { 994 split_edge(edge->fLeft, edge->fTop, activeEdges, c, alloc); 995 } else if (c.sweep_gt(leftTop->fPoint, top->fPoint) && !edge->isRightOf(leftTop)) { 996 split_edge(edge, leftTop, activeEdges, c, alloc); 997 } else if (c.sweep_lt(bottom->fPoint, leftBottom->fPoint) && 998 !edge->fLeft->isLeftOf(bottom)) { 999 split_edge(edge->fLeft, bottom, activeEdges, c, alloc); 1000 } else if (c.sweep_lt(leftBottom->fPoint, bottom->fPoint) && !edge->isRightOf(leftBottom)) { 1001 split_edge(edge, leftBottom, activeEdges, c, alloc); 1002 } 1003 } 1004 if (edge->fRight) { 1005 Vertex* rightTop = edge->fRight->fTop; 1006 Vertex* rightBottom = edge->fRight->fBottom; 1007 if (c.sweep_gt(top->fPoint, rightTop->fPoint) && !edge->fRight->isRightOf(top)) { 1008 split_edge(edge->fRight, top, activeEdges, c, alloc); 1009 } else if (c.sweep_gt(rightTop->fPoint, top->fPoint) && !edge->isLeftOf(rightTop)) { 1010 split_edge(edge, rightTop, activeEdges, c, alloc); 1011 } else if (c.sweep_lt(bottom->fPoint, rightBottom->fPoint) && 1012 !edge->fRight->isRightOf(bottom)) { 1013 split_edge(edge->fRight, bottom, activeEdges, c, alloc); 1014 } else if (c.sweep_lt(rightBottom->fPoint, bottom->fPoint) && 1015 !edge->isLeftOf(rightBottom)) { 1016 split_edge(edge, rightBottom, activeEdges, c, alloc); 1017 } 1018 } 1019} 1020 1021void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, SkChunkAlloc& alloc) { 1022 LOG("splitting edge (%g -> %g) at vertex %g (%g, %g)\n", 1023 edge->fTop->fID, edge->fBottom->fID, 1024 v->fID, v->fPoint.fX, v->fPoint.fY); 1025 if (c.sweep_lt(v->fPoint, edge->fTop->fPoint)) { 1026 set_top(edge, v, activeEdges, c); 1027 } else if (c.sweep_gt(v->fPoint, edge->fBottom->fPoint)) { 1028 set_bottom(edge, v, activeEdges, c); 1029 } else { 1030 Edge* newEdge = ALLOC_NEW(Edge, (v, edge->fBottom, edge->fWinding, edge->fType), alloc); 1031 insert_edge_below(newEdge, v, c); 1032 insert_edge_above(newEdge, edge->fBottom, c); 1033 set_bottom(edge, v, activeEdges, c); 1034 cleanup_active_edges(edge, activeEdges, c, alloc); 1035 fix_active_state(newEdge, activeEdges, c); 1036 merge_collinear_edges(newEdge, activeEdges, c); 1037 } 1038} 1039 1040Edge* connect(Vertex* prev, Vertex* next, SkChunkAlloc& alloc, Comparator c, Edge::Type type) { 1041 Edge* edge = new_edge(prev, next, alloc, c, type); 1042 if (edge->fWinding > 0) { 1043 insert_edge_below(edge, prev, c); 1044 insert_edge_above(edge, next, c); 1045 } else { 1046 insert_edge_below(edge, next, c); 1047 insert_edge_above(edge, prev, c); 1048 } 1049 merge_collinear_edges(edge, nullptr, c); 1050 return edge; 1051} 1052 1053void merge_vertices(Vertex* src, Vertex* dst, Vertex** head, Comparator& c, SkChunkAlloc& alloc) { 1054 LOG("found coincident verts at %g, %g; merging %g into %g\n", src->fPoint.fX, src->fPoint.fY, 1055 src->fID, dst->fID); 1056 dst->fAlpha = SkTMax(src->fAlpha, dst->fAlpha); 1057 for (Edge* edge = src->fFirstEdgeAbove; edge;) { 1058 Edge* next = edge->fNextEdgeAbove; 1059 set_bottom(edge, dst, nullptr, c); 1060 edge = next; 1061 } 1062 for (Edge* edge = src->fFirstEdgeBelow; edge;) { 1063 Edge* next = edge->fNextEdgeBelow; 1064 set_top(edge, dst, nullptr, c); 1065 edge = next; 1066 } 1067 list_remove<Vertex, &Vertex::fPrev, &Vertex::fNext>(src, head, nullptr); 1068} 1069 1070uint8_t max_edge_alpha(Edge* a, Edge* b) { 1071 if (a->fType == Edge::Type::kInner && b->fType == Edge::Type::kInner) { 1072 return 255; 1073 } else if (a->fType == Edge::Type::kOuter && b->fType == Edge::Type::kOuter) { 1074 return 0; 1075 } else { 1076 return SkTMax(SkTMax(a->fTop->fAlpha, a->fBottom->fAlpha), 1077 SkTMax(b->fTop->fAlpha, b->fBottom->fAlpha)); 1078 } 1079} 1080 1081Vertex* check_for_intersection(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c, 1082 SkChunkAlloc& alloc) { 1083 SkPoint p; 1084 if (!edge || !other) { 1085 return nullptr; 1086 } 1087 if (edge->intersect(*other, &p)) { 1088 Vertex* v; 1089 LOG("found intersection, pt is %g, %g\n", p.fX, p.fY); 1090 if (p == edge->fTop->fPoint || c.sweep_lt(p, edge->fTop->fPoint)) { 1091 split_edge(other, edge->fTop, activeEdges, c, alloc); 1092 v = edge->fTop; 1093 } else if (p == edge->fBottom->fPoint || c.sweep_gt(p, edge->fBottom->fPoint)) { 1094 split_edge(other, edge->fBottom, activeEdges, c, alloc); 1095 v = edge->fBottom; 1096 } else if (p == other->fTop->fPoint || c.sweep_lt(p, other->fTop->fPoint)) { 1097 split_edge(edge, other->fTop, activeEdges, c, alloc); 1098 v = other->fTop; 1099 } else if (p == other->fBottom->fPoint || c.sweep_gt(p, other->fBottom->fPoint)) { 1100 split_edge(edge, other->fBottom, activeEdges, c, alloc); 1101 v = other->fBottom; 1102 } else { 1103 Vertex* nextV = edge->fTop; 1104 while (c.sweep_lt(p, nextV->fPoint)) { 1105 nextV = nextV->fPrev; 1106 } 1107 while (c.sweep_lt(nextV->fPoint, p)) { 1108 nextV = nextV->fNext; 1109 } 1110 Vertex* prevV = nextV->fPrev; 1111 if (coincident(prevV->fPoint, p)) { 1112 v = prevV; 1113 } else if (coincident(nextV->fPoint, p)) { 1114 v = nextV; 1115 } else { 1116 uint8_t alpha = max_edge_alpha(edge, other); 1117 v = ALLOC_NEW(Vertex, (p, alpha), alloc); 1118 LOG("inserting between %g (%g, %g) and %g (%g, %g)\n", 1119 prevV->fID, prevV->fPoint.fX, prevV->fPoint.fY, 1120 nextV->fID, nextV->fPoint.fX, nextV->fPoint.fY); 1121#if LOGGING_ENABLED 1122 v->fID = (nextV->fID + prevV->fID) * 0.5f; 1123#endif 1124 v->fPrev = prevV; 1125 v->fNext = nextV; 1126 prevV->fNext = v; 1127 nextV->fPrev = v; 1128 } 1129 split_edge(edge, v, activeEdges, c, alloc); 1130 split_edge(other, v, activeEdges, c, alloc); 1131 } 1132 return v; 1133 } 1134 return nullptr; 1135} 1136 1137void sanitize_contours(Vertex** contours, int contourCnt, bool approximate) { 1138 for (int i = 0; i < contourCnt; ++i) { 1139 SkASSERT(contours[i]); 1140 for (Vertex* v = contours[i];;) { 1141 if (approximate) { 1142 round(&v->fPoint); 1143 } 1144 if (coincident(v->fPrev->fPoint, v->fPoint)) { 1145 LOG("vertex %g,%g coincident; removing\n", v->fPoint.fX, v->fPoint.fY); 1146 if (v->fPrev == v) { 1147 contours[i] = nullptr; 1148 break; 1149 } 1150 v->fPrev->fNext = v->fNext; 1151 v->fNext->fPrev = v->fPrev; 1152 if (contours[i] == v) { 1153 contours[i] = v->fNext; 1154 } 1155 v = v->fPrev; 1156 } else { 1157 v = v->fNext; 1158 if (v == contours[i]) break; 1159 } 1160 } 1161 } 1162} 1163 1164void merge_coincident_vertices(Vertex** vertices, Comparator& c, SkChunkAlloc& alloc) { 1165 for (Vertex* v = (*vertices)->fNext; v != nullptr; v = v->fNext) { 1166 if (c.sweep_lt(v->fPoint, v->fPrev->fPoint)) { 1167 v->fPoint = v->fPrev->fPoint; 1168 } 1169 if (coincident(v->fPrev->fPoint, v->fPoint)) { 1170 merge_vertices(v->fPrev, v, vertices, c, alloc); 1171 } 1172 } 1173} 1174 1175// Stage 2: convert the contours to a mesh of edges connecting the vertices. 1176 1177Vertex* build_edges(Vertex** contours, int contourCnt, Comparator& c, SkChunkAlloc& alloc) { 1178 Vertex* vertices = nullptr; 1179 Vertex* prev = nullptr; 1180 for (int i = 0; i < contourCnt; ++i) { 1181 for (Vertex* v = contours[i]; v != nullptr;) { 1182 Vertex* vNext = v->fNext; 1183 connect(v->fPrev, v, alloc, c, Edge::Type::kInner); 1184 if (prev) { 1185 prev->fNext = v; 1186 v->fPrev = prev; 1187 } else { 1188 vertices = v; 1189 } 1190 prev = v; 1191 v = vNext; 1192 if (v == contours[i]) break; 1193 } 1194 } 1195 if (prev) { 1196 prev->fNext = vertices->fPrev = nullptr; 1197 } 1198 return vertices; 1199} 1200 1201// Stage 3: sort the vertices by increasing sweep direction. 1202 1203Vertex* sorted_merge(Vertex* a, Vertex* b, Comparator& c); 1204 1205void front_back_split(Vertex* v, Vertex** pFront, Vertex** pBack) { 1206 Vertex* fast; 1207 Vertex* slow; 1208 if (!v || !v->fNext) { 1209 *pFront = v; 1210 *pBack = nullptr; 1211 } else { 1212 slow = v; 1213 fast = v->fNext; 1214 1215 while (fast != nullptr) { 1216 fast = fast->fNext; 1217 if (fast != nullptr) { 1218 slow = slow->fNext; 1219 fast = fast->fNext; 1220 } 1221 } 1222 1223 *pFront = v; 1224 *pBack = slow->fNext; 1225 slow->fNext->fPrev = nullptr; 1226 slow->fNext = nullptr; 1227 } 1228} 1229 1230void merge_sort(Vertex** head, Comparator& c) { 1231 if (!*head || !(*head)->fNext) { 1232 return; 1233 } 1234 1235 Vertex* a; 1236 Vertex* b; 1237 front_back_split(*head, &a, &b); 1238 1239 merge_sort(&a, c); 1240 merge_sort(&b, c); 1241 1242 *head = sorted_merge(a, b, c); 1243} 1244 1245Vertex* sorted_merge(Vertex* a, Vertex* b, Comparator& c) { 1246 VertexList vertices; 1247 1248 while (a && b) { 1249 if (c.sweep_lt(a->fPoint, b->fPoint)) { 1250 Vertex* next = a->fNext; 1251 vertices.append(a); 1252 a = next; 1253 } else { 1254 Vertex* next = b->fNext; 1255 vertices.append(b); 1256 b = next; 1257 } 1258 } 1259 if (a) { 1260 vertices.insert(a, vertices.fTail, a->fNext); 1261 } 1262 if (b) { 1263 vertices.insert(b, vertices.fTail, b->fNext); 1264 } 1265 return vertices.fHead; 1266} 1267 1268// Stage 4: Simplify the mesh by inserting new vertices at intersecting edges. 1269 1270void simplify(Vertex* vertices, Comparator& c, SkChunkAlloc& alloc) { 1271 LOG("simplifying complex polygons\n"); 1272 EdgeList activeEdges; 1273 for (Vertex* v = vertices; v != nullptr; v = v->fNext) { 1274 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1275 continue; 1276 } 1277#if LOGGING_ENABLED 1278 LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); 1279#endif 1280 Edge* leftEnclosingEdge = nullptr; 1281 Edge* rightEnclosingEdge = nullptr; 1282 bool restartChecks; 1283 do { 1284 restartChecks = false; 1285 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1286 if (v->fFirstEdgeBelow) { 1287 for (Edge* edge = v->fFirstEdgeBelow; edge != nullptr; edge = edge->fNextEdgeBelow) { 1288 if (check_for_intersection(edge, leftEnclosingEdge, &activeEdges, c, alloc)) { 1289 restartChecks = true; 1290 break; 1291 } 1292 if (check_for_intersection(edge, rightEnclosingEdge, &activeEdges, c, alloc)) { 1293 restartChecks = true; 1294 break; 1295 } 1296 } 1297 } else { 1298 if (Vertex* pv = check_for_intersection(leftEnclosingEdge, rightEnclosingEdge, 1299 &activeEdges, c, alloc)) { 1300 if (c.sweep_lt(pv->fPoint, v->fPoint)) { 1301 v = pv; 1302 } 1303 restartChecks = true; 1304 } 1305 1306 } 1307 } while (restartChecks); 1308 if (v->fAlpha == 0) { 1309 if ((leftEnclosingEdge && leftEnclosingEdge->fWinding > 0) && 1310 (rightEnclosingEdge && rightEnclosingEdge->fWinding < 0)) { 1311 v->fAlpha = max_edge_alpha(leftEnclosingEdge, rightEnclosingEdge); 1312 } 1313 } 1314 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 1315 remove_edge(e, &activeEdges); 1316 } 1317 Edge* leftEdge = leftEnclosingEdge; 1318 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1319 insert_edge(e, leftEdge, &activeEdges); 1320 leftEdge = e; 1321 } 1322 v->fProcessed = true; 1323 } 1324} 1325 1326// Stage 5: Tessellate the simplified mesh into monotone polygons. 1327 1328Poly* tessellate(Vertex* vertices, SkChunkAlloc& alloc) { 1329 LOG("tessellating simple polygons\n"); 1330 EdgeList activeEdges; 1331 Poly* polys = nullptr; 1332 for (Vertex* v = vertices; v != nullptr; v = v->fNext) { 1333 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1334 continue; 1335 } 1336#if LOGGING_ENABLED 1337 LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); 1338#endif 1339 Edge* leftEnclosingEdge = nullptr; 1340 Edge* rightEnclosingEdge = nullptr; 1341 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1342 Poly* leftPoly = nullptr; 1343 Poly* rightPoly = nullptr; 1344 if (v->fFirstEdgeAbove) { 1345 leftPoly = v->fFirstEdgeAbove->fLeftPoly; 1346 rightPoly = v->fLastEdgeAbove->fRightPoly; 1347 } else { 1348 leftPoly = leftEnclosingEdge ? leftEnclosingEdge->fRightPoly : nullptr; 1349 rightPoly = rightEnclosingEdge ? rightEnclosingEdge->fLeftPoly : nullptr; 1350 } 1351#if LOGGING_ENABLED 1352 LOG("edges above:\n"); 1353 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 1354 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1355 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1356 } 1357 LOG("edges below:\n"); 1358 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1359 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1360 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1361 } 1362#endif 1363 if (v->fFirstEdgeAbove) { 1364 if (leftPoly) { 1365 leftPoly = leftPoly->addEdge(v->fFirstEdgeAbove, Poly::kRight_Side, alloc); 1366 } 1367 if (rightPoly) { 1368 rightPoly = rightPoly->addEdge(v->fLastEdgeAbove, Poly::kLeft_Side, alloc); 1369 } 1370 for (Edge* e = v->fFirstEdgeAbove; e != v->fLastEdgeAbove; e = e->fNextEdgeAbove) { 1371 Edge* leftEdge = e; 1372 Edge* rightEdge = e->fNextEdgeAbove; 1373 SkASSERT(rightEdge->isRightOf(leftEdge->fTop)); 1374 remove_edge(leftEdge, &activeEdges); 1375 if (leftEdge->fRightPoly) { 1376 leftEdge->fRightPoly->addEdge(e, Poly::kLeft_Side, alloc); 1377 } 1378 if (rightEdge->fLeftPoly) { 1379 rightEdge->fLeftPoly->addEdge(e, Poly::kRight_Side, alloc); 1380 } 1381 } 1382 remove_edge(v->fLastEdgeAbove, &activeEdges); 1383 if (!v->fFirstEdgeBelow) { 1384 if (leftPoly && rightPoly && leftPoly != rightPoly) { 1385 SkASSERT(leftPoly->fPartner == nullptr && rightPoly->fPartner == nullptr); 1386 rightPoly->fPartner = leftPoly; 1387 leftPoly->fPartner = rightPoly; 1388 } 1389 } 1390 } 1391 if (v->fFirstEdgeBelow) { 1392 if (!v->fFirstEdgeAbove) { 1393 if (leftPoly && rightPoly) { 1394 if (leftPoly == rightPoly) { 1395 if (leftPoly->fTail && leftPoly->fTail->fSide == Poly::kLeft_Side) { 1396 leftPoly = new_poly(&polys, leftPoly->lastVertex(), 1397 leftPoly->fWinding, alloc); 1398 leftEnclosingEdge->fRightPoly = leftPoly; 1399 } else { 1400 rightPoly = new_poly(&polys, rightPoly->lastVertex(), 1401 rightPoly->fWinding, alloc); 1402 rightEnclosingEdge->fLeftPoly = rightPoly; 1403 } 1404 } 1405 Edge* join = ALLOC_NEW(Edge, 1406 (leftPoly->lastVertex(), v, 1, Edge::Type::kInner), alloc); 1407 leftPoly = leftPoly->addEdge(join, Poly::kRight_Side, alloc); 1408 rightPoly = rightPoly->addEdge(join, Poly::kLeft_Side, alloc); 1409 } 1410 } 1411 Edge* leftEdge = v->fFirstEdgeBelow; 1412 leftEdge->fLeftPoly = leftPoly; 1413 insert_edge(leftEdge, leftEnclosingEdge, &activeEdges); 1414 for (Edge* rightEdge = leftEdge->fNextEdgeBelow; rightEdge; 1415 rightEdge = rightEdge->fNextEdgeBelow) { 1416 insert_edge(rightEdge, leftEdge, &activeEdges); 1417 int winding = leftEdge->fLeftPoly ? leftEdge->fLeftPoly->fWinding : 0; 1418 winding += leftEdge->fWinding; 1419 if (winding != 0) { 1420 Poly* poly = new_poly(&polys, v, winding, alloc); 1421 leftEdge->fRightPoly = rightEdge->fLeftPoly = poly; 1422 } 1423 leftEdge = rightEdge; 1424 } 1425 v->fLastEdgeBelow->fRightPoly = rightPoly; 1426 } 1427#if LOGGING_ENABLED 1428 LOG("\nactive edges:\n"); 1429 for (Edge* e = activeEdges.fHead; e != nullptr; e = e->fRight) { 1430 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1431 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1432 } 1433#endif 1434 } 1435 return polys; 1436} 1437 1438bool is_boundary_edge(Edge* edge, SkPath::FillType fillType) { 1439 return apply_fill_type(fillType, edge->fLeftPoly) != 1440 apply_fill_type(fillType, edge->fRightPoly); 1441} 1442 1443bool is_boundary_start(Edge* edge, SkPath::FillType fillType) { 1444 return !apply_fill_type(fillType, edge->fLeftPoly) && 1445 apply_fill_type(fillType, edge->fRightPoly); 1446} 1447 1448Vertex* remove_non_boundary_edges(Vertex* vertices, SkPath::FillType fillType, 1449 SkChunkAlloc& alloc) { 1450 for (Vertex* v = vertices; v != nullptr; v = v->fNext) { 1451 for (Edge* e = v->fFirstEdgeBelow; e != nullptr;) { 1452 Edge* next = e->fNextEdgeBelow; 1453 if (!is_boundary_edge(e, fillType)) { 1454 remove_edge_above(e); 1455 remove_edge_below(e); 1456 } 1457 e = next; 1458 } 1459 } 1460 return vertices; 1461} 1462 1463void get_edge_normal(const Edge* e, SkVector* normal) { 1464 normal->setNormalize(SkDoubleToScalar(-e->fLine.fB) * e->fWinding, 1465 SkDoubleToScalar(e->fLine.fA) * e->fWinding); 1466} 1467 1468// Stage 5c: detect and remove "pointy" vertices whose edge normals point in opposite directions 1469// and whose adjacent vertices are less than a quarter pixel from an edge. These are guaranteed to 1470// invert on stroking. 1471 1472void simplify_boundary(EdgeList* boundary, Comparator& c, SkChunkAlloc& alloc) { 1473 Edge* prevEdge = boundary->fTail; 1474 SkVector prevNormal; 1475 get_edge_normal(prevEdge, &prevNormal); 1476 for (Edge* e = boundary->fHead; e != nullptr;) { 1477 Vertex* prev = prevEdge->fWinding == 1 ? prevEdge->fTop : prevEdge->fBottom; 1478 Vertex* next = e->fWinding == 1 ? e->fBottom : e->fTop; 1479 double dist = e->dist(prev->fPoint); 1480 SkVector normal; 1481 get_edge_normal(e, &normal); 1482 float denom = 0.25f * static_cast<float>(e->fLine.magSq()); 1483 if (prevNormal.dot(normal) < 0.0 && (dist * dist) <= denom) { 1484 Edge* join = new_edge(prev, next, alloc, c, Edge::Type::kInner); 1485 insert_edge(join, e, boundary); 1486 remove_edge(prevEdge, boundary); 1487 remove_edge(e, boundary); 1488 if (join->fLeft && join->fRight) { 1489 prevEdge = join->fLeft; 1490 e = join; 1491 } else { 1492 prevEdge = boundary->fTail; 1493 e = boundary->fHead; // join->fLeft ? join->fLeft : join; 1494 } 1495 get_edge_normal(prevEdge, &prevNormal); 1496 } else { 1497 prevEdge = e; 1498 prevNormal = normal; 1499 e = e->fRight; 1500 } 1501 } 1502} 1503 1504// Stage 5d: Displace edges by half a pixel inward and outward along their normals. Intersect to 1505// find new vertices, and set zero alpha on the exterior and one alpha on the interior. Build a 1506// new antialiased mesh from those vertices. 1507 1508void boundary_to_aa_mesh(EdgeList* boundary, VertexList* mesh, Comparator& c, SkChunkAlloc& alloc) { 1509 EdgeList outerContour; 1510 Edge* prevEdge = boundary->fTail; 1511 float radius = 0.5f; 1512 double offset = radius * sqrt(prevEdge->fLine.magSq()) * prevEdge->fWinding; 1513 Line prevInner(prevEdge->fTop, prevEdge->fBottom); 1514 prevInner.fC -= offset; 1515 Line prevOuter(prevEdge->fTop, prevEdge->fBottom); 1516 prevOuter.fC += offset; 1517 VertexList innerVertices; 1518 VertexList outerVertices; 1519 SkScalar innerCount = SK_Scalar1, outerCount = SK_Scalar1; 1520 for (Edge* e = boundary->fHead; e != nullptr; e = e->fRight) { 1521 double offset = radius * sqrt(e->fLine.magSq()) * e->fWinding; 1522 Line inner(e->fTop, e->fBottom); 1523 inner.fC -= offset; 1524 Line outer(e->fTop, e->fBottom); 1525 outer.fC += offset; 1526 SkPoint innerPoint, outerPoint; 1527 if (prevInner.intersect(inner, &innerPoint) && 1528 prevOuter.intersect(outer, &outerPoint)) { 1529 Vertex* innerVertex = ALLOC_NEW(Vertex, (innerPoint, 255), alloc); 1530 Vertex* outerVertex = ALLOC_NEW(Vertex, (outerPoint, 0), alloc); 1531 if (innerVertices.fTail && outerVertices.fTail) { 1532 Edge innerEdge(innerVertices.fTail, innerVertex, 1, Edge::Type::kInner); 1533 Edge outerEdge(outerVertices.fTail, outerVertex, 1, Edge::Type::kInner); 1534 SkVector innerNormal; 1535 get_edge_normal(&innerEdge, &innerNormal); 1536 SkVector outerNormal; 1537 get_edge_normal(&outerEdge, &outerNormal); 1538 SkVector normal; 1539 get_edge_normal(prevEdge, &normal); 1540 if (normal.dot(innerNormal) < 0) { 1541 innerPoint += innerVertices.fTail->fPoint * innerCount; 1542 innerCount++; 1543 innerPoint *= SkScalarInvert(innerCount); 1544 innerVertices.fTail->fPoint = innerVertex->fPoint = innerPoint; 1545 } else { 1546 innerCount = SK_Scalar1; 1547 } 1548 if (normal.dot(outerNormal) < 0) { 1549 outerPoint += outerVertices.fTail->fPoint * outerCount; 1550 outerCount++; 1551 outerPoint *= SkScalarInvert(outerCount); 1552 outerVertices.fTail->fPoint = outerVertex->fPoint = outerPoint; 1553 } else { 1554 outerCount = SK_Scalar1; 1555 } 1556 } 1557 innerVertices.append(innerVertex); 1558 outerVertices.append(outerVertex); 1559 prevEdge = e; 1560 } 1561 prevInner = inner; 1562 prevOuter = outer; 1563 } 1564 innerVertices.close(); 1565 outerVertices.close(); 1566 1567 Vertex* innerVertex = innerVertices.fHead; 1568 Vertex* outerVertex = outerVertices.fHead; 1569 // Alternate clockwise and counterclockwise polys, so the tesselator 1570 // doesn't cancel out the interior edges. 1571 if (!innerVertex || !outerVertex) { 1572 return; 1573 } 1574 do { 1575 connect(outerVertex->fPrev, outerVertex, alloc, c, Edge::Type::kOuter); 1576 connect(innerVertex->fPrev, innerVertex, alloc, c, Edge::Type::kInner); 1577 connect(outerVertex, innerVertex, alloc, c, Edge::Type::kConnector)->fWinding = 0; 1578 Vertex* innerNext = innerVertex->fNext; 1579 Vertex* outerNext = outerVertex->fNext; 1580 mesh->append(innerVertex); 1581 mesh->append(outerVertex); 1582 innerVertex = innerNext; 1583 outerVertex = outerNext; 1584 } while (innerVertex != innerVertices.fHead && outerVertex != outerVertices.fHead); 1585} 1586 1587void extract_boundary(EdgeList* boundary, Edge* e, SkPath::FillType fillType, SkChunkAlloc& alloc) { 1588 bool down = is_boundary_start(e, fillType); 1589 while (e) { 1590 e->fWinding = down ? 1 : -1; 1591 Edge* next; 1592 boundary->append(e); 1593 if (down) { 1594 // Find outgoing edge, in clockwise order. 1595 if ((next = e->fNextEdgeAbove)) { 1596 down = false; 1597 } else if ((next = e->fBottom->fLastEdgeBelow)) { 1598 down = true; 1599 } else if ((next = e->fPrevEdgeAbove)) { 1600 down = false; 1601 } 1602 } else { 1603 // Find outgoing edge, in counter-clockwise order. 1604 if ((next = e->fPrevEdgeBelow)) { 1605 down = true; 1606 } else if ((next = e->fTop->fFirstEdgeAbove)) { 1607 down = false; 1608 } else if ((next = e->fNextEdgeBelow)) { 1609 down = true; 1610 } 1611 } 1612 remove_edge_above(e); 1613 remove_edge_below(e); 1614 e = next; 1615 } 1616} 1617 1618// Stage 5b: Extract boundary edges. 1619 1620EdgeList* extract_boundaries(Vertex* vertices, SkPath::FillType fillType, SkChunkAlloc& alloc) { 1621 LOG("extracting boundaries\n"); 1622 vertices = remove_non_boundary_edges(vertices, fillType, alloc); 1623 EdgeList* boundaries = nullptr; 1624 for (Vertex* v = vertices; v != nullptr; v = v->fNext) { 1625 while (v->fFirstEdgeBelow) { 1626 EdgeList* boundary = new_contour(&boundaries, alloc); 1627 extract_boundary(boundary, v->fFirstEdgeBelow, fillType, alloc); 1628 } 1629 } 1630 return boundaries; 1631} 1632 1633// This is a driver function which calls stages 2-5 in turn. 1634 1635Vertex* contours_to_mesh(Vertex** contours, int contourCnt, bool antialias, 1636 Comparator& c, SkChunkAlloc& alloc) { 1637#if LOGGING_ENABLED 1638 for (int i = 0; i < contourCnt; ++i) { 1639 Vertex* v = contours[i]; 1640 SkASSERT(v); 1641 LOG("path.moveTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); 1642 for (v = v->fNext; v != contours[i]; v = v->fNext) { 1643 LOG("path.lineTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); 1644 } 1645 } 1646#endif 1647 sanitize_contours(contours, contourCnt, antialias); 1648 return build_edges(contours, contourCnt, c, alloc); 1649} 1650 1651void sort_and_simplify(Vertex** vertices, Comparator& c, SkChunkAlloc& alloc) { 1652 if (!vertices || !*vertices) { 1653 return; 1654 } 1655 1656 // Sort vertices in Y (secondarily in X). 1657 merge_sort(vertices, c); 1658 merge_coincident_vertices(vertices, c, alloc); 1659#if LOGGING_ENABLED 1660 for (Vertex* v = *vertices; v != nullptr; v = v->fNext) { 1661 static float gID = 0.0f; 1662 v->fID = gID++; 1663 } 1664#endif 1665 simplify(*vertices, c, alloc); 1666} 1667 1668Poly* mesh_to_polys(Vertex** vertices, Comparator& c, SkChunkAlloc& alloc) { 1669 sort_and_simplify(vertices, c, alloc); 1670 return tessellate(*vertices, alloc); 1671} 1672 1673Poly* contours_to_polys(Vertex** contours, int contourCnt, SkPath::FillType fillType, 1674 const SkRect& pathBounds, bool antialias, 1675 SkChunkAlloc& alloc) { 1676 Comparator c; 1677 if (pathBounds.width() > pathBounds.height()) { 1678 c.sweep_lt = sweep_lt_horiz; 1679 c.sweep_gt = sweep_gt_horiz; 1680 } else { 1681 c.sweep_lt = sweep_lt_vert; 1682 c.sweep_gt = sweep_gt_vert; 1683 } 1684 Vertex* mesh = contours_to_mesh(contours, contourCnt, antialias, c, alloc); 1685 Poly* polys = mesh_to_polys(&mesh, c, alloc); 1686 if (antialias) { 1687 EdgeList* boundaries = extract_boundaries(mesh, fillType, alloc); 1688 VertexList aaMesh; 1689 for (EdgeList* boundary = boundaries; boundary != nullptr; boundary = boundary->fNext) { 1690 simplify_boundary(boundary, c, alloc); 1691 if (boundary->fCount > 2) { 1692 boundary_to_aa_mesh(boundary, &aaMesh, c, alloc); 1693 } 1694 } 1695 sort_and_simplify(&aaMesh.fHead, c, alloc); 1696 return tessellate(aaMesh.fHead, alloc); 1697 } 1698 return polys; 1699} 1700 1701// Stage 6: Triangulate the monotone polygons into a vertex buffer. 1702void* polys_to_triangles(Poly* polys, SkPath::FillType fillType, const AAParams* aaParams, 1703 void* data) { 1704 for (Poly* poly = polys; poly; poly = poly->fNext) { 1705 if (apply_fill_type(fillType, poly)) { 1706 data = poly->emit(aaParams, data); 1707 } 1708 } 1709 return data; 1710} 1711 1712Poly* path_to_polys(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 1713 int contourCnt, SkChunkAlloc& alloc, bool antialias, bool* isLinear) { 1714 SkPath::FillType fillType = path.getFillType(); 1715 if (SkPath::IsInverseFillType(fillType)) { 1716 contourCnt++; 1717 } 1718 std::unique_ptr<Vertex*[]> contours(new Vertex* [contourCnt]); 1719 1720 path_to_contours(path, tolerance, clipBounds, contours.get(), alloc, isLinear); 1721 return contours_to_polys(contours.get(), contourCnt, path.getFillType(), path.getBounds(), 1722 antialias, alloc); 1723} 1724 1725void get_contour_count_and_size_estimate(const SkPath& path, SkScalar tolerance, int* contourCnt, 1726 int* sizeEstimate) { 1727 int maxPts = GrPathUtils::worstCasePointCount(path, contourCnt, tolerance); 1728 if (maxPts <= 0) { 1729 *contourCnt = 0; 1730 return; 1731 } 1732 if (maxPts > ((int)SK_MaxU16 + 1)) { 1733 SkDebugf("Path not rendered, too many verts (%d)\n", maxPts); 1734 *contourCnt = 0; 1735 return; 1736 } 1737 // For the initial size of the chunk allocator, estimate based on the point count: 1738 // one vertex per point for the initial passes, plus two for the vertices in the 1739 // resulting Polys, since the same point may end up in two Polys. Assume minimal 1740 // connectivity of one Edge per Vertex (will grow for intersections). 1741 *sizeEstimate = maxPts * (3 * sizeof(Vertex) + sizeof(Edge)); 1742} 1743 1744int count_points(Poly* polys, SkPath::FillType fillType) { 1745 int count = 0; 1746 for (Poly* poly = polys; poly; poly = poly->fNext) { 1747 if (apply_fill_type(fillType, poly) && poly->fCount >= 3) { 1748 count += (poly->fCount - 2) * (TESSELLATOR_WIREFRAME ? 6 : 3); 1749 } 1750 } 1751 return count; 1752} 1753 1754} // namespace 1755 1756namespace GrTessellator { 1757 1758// Stage 6: Triangulate the monotone polygons into a vertex buffer. 1759 1760int PathToTriangles(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 1761 VertexAllocator* vertexAllocator, bool antialias, const GrColor& color, 1762 bool canTweakAlphaForCoverage, bool* isLinear) { 1763 int contourCnt; 1764 int sizeEstimate; 1765 get_contour_count_and_size_estimate(path, tolerance, &contourCnt, &sizeEstimate); 1766 if (contourCnt <= 0) { 1767 *isLinear = true; 1768 return 0; 1769 } 1770 SkChunkAlloc alloc(sizeEstimate); 1771 Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, antialias, 1772 isLinear); 1773 SkPath::FillType fillType = antialias ? SkPath::kWinding_FillType : path.getFillType(); 1774 int count = count_points(polys, fillType); 1775 if (0 == count) { 1776 return 0; 1777 } 1778 1779 void* verts = vertexAllocator->lock(count); 1780 if (!verts) { 1781 SkDebugf("Could not allocate vertices\n"); 1782 return 0; 1783 } 1784 1785 LOG("emitting %d verts\n", count); 1786 AAParams aaParams; 1787 aaParams.fTweakAlpha = canTweakAlphaForCoverage; 1788 aaParams.fColor = color; 1789 1790 void* end = polys_to_triangles(polys, fillType, antialias ? &aaParams : nullptr, verts); 1791 int actualCount = static_cast<int>((static_cast<uint8_t*>(end) - static_cast<uint8_t*>(verts)) 1792 / vertexAllocator->stride()); 1793 SkASSERT(actualCount <= count); 1794 vertexAllocator->unlock(actualCount); 1795 return actualCount; 1796} 1797 1798int PathToVertices(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 1799 GrTessellator::WindingVertex** verts) { 1800 int contourCnt; 1801 int sizeEstimate; 1802 get_contour_count_and_size_estimate(path, tolerance, &contourCnt, &sizeEstimate); 1803 if (contourCnt <= 0) { 1804 return 0; 1805 } 1806 SkChunkAlloc alloc(sizeEstimate); 1807 bool isLinear; 1808 Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, false, &isLinear); 1809 SkPath::FillType fillType = path.getFillType(); 1810 int count = count_points(polys, fillType); 1811 if (0 == count) { 1812 *verts = nullptr; 1813 return 0; 1814 } 1815 1816 *verts = new GrTessellator::WindingVertex[count]; 1817 GrTessellator::WindingVertex* vertsEnd = *verts; 1818 SkPoint* points = new SkPoint[count]; 1819 SkPoint* pointsEnd = points; 1820 for (Poly* poly = polys; poly; poly = poly->fNext) { 1821 if (apply_fill_type(fillType, poly)) { 1822 SkPoint* start = pointsEnd; 1823 pointsEnd = static_cast<SkPoint*>(poly->emit(nullptr, pointsEnd)); 1824 while (start != pointsEnd) { 1825 vertsEnd->fPos = *start; 1826 vertsEnd->fWinding = poly->fWinding; 1827 ++start; 1828 ++vertsEnd; 1829 } 1830 } 1831 } 1832 int actualCount = static_cast<int>(vertsEnd - *verts); 1833 SkASSERT(actualCount <= count); 1834 SkASSERT(pointsEnd - points == actualCount); 1835 delete[] points; 1836 return actualCount; 1837} 1838 1839} // namespace 1840