GrTessellator.cpp revision 16a40cb65adeb4d94b84479f9946c360ed73e1bb
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 "SkArenaAlloc.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 93namespace { 94 95const int kArenaChunkSize = 16 * 1024; 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 177bool sweep_lt_horiz(const SkPoint& a, const SkPoint& b) { 178 return a.fX < b.fX || (a.fX == b.fX && a.fY > b.fY); 179} 180 181bool sweep_lt_vert(const SkPoint& a, const SkPoint& b) { 182 return a.fY < b.fY || (a.fY == b.fY && a.fX < b.fX); 183} 184 185bool sweep_gt_horiz(const SkPoint& a, const SkPoint& b) { 186 return a.fX > b.fX || (a.fX == b.fX && a.fY < b.fY); 187} 188 189bool sweep_gt_vert(const SkPoint& a, const SkPoint& b) { 190 return a.fY > b.fY || (a.fY == b.fY && a.fX > b.fX); 191} 192 193struct Comparator { 194 enum class Direction { kVertical, kHorizontal }; 195 Comparator(Direction direction) : fDirection(direction) {} 196 bool sweep_lt(const SkPoint& a, const SkPoint& b) const { 197 return fDirection == Direction::kHorizontal ? sweep_lt_horiz(a, b) : sweep_lt_vert(a, b); 198 } 199 bool sweep_gt(const SkPoint& a, const SkPoint& b) const { 200 return fDirection == Direction::kHorizontal ? sweep_gt_horiz(a, b) : sweep_gt_vert(a, b); 201 } 202 Direction fDirection; 203}; 204 205inline void* emit_vertex(Vertex* v, const AAParams* aaParams, void* data) { 206 if (!aaParams) { 207 SkPoint* d = static_cast<SkPoint*>(data); 208 *d++ = v->fPoint; 209 return d; 210 } 211 if (aaParams->fTweakAlpha) { 212 auto d = static_cast<GrDefaultGeoProcFactory::PositionColorAttr*>(data); 213 d->fPosition = v->fPoint; 214 d->fColor = SkAlphaMulQ(aaParams->fColor, SkAlpha255To256(v->fAlpha)); 215 d++; 216 return d; 217 } 218 auto d = static_cast<GrDefaultGeoProcFactory::PositionColorCoverageAttr*>(data); 219 d->fPosition = v->fPoint; 220 d->fColor = aaParams->fColor; 221 d->fCoverage = GrNormalizeByteToFloat(v->fAlpha); 222 d++; 223 return d; 224} 225 226void* emit_triangle(Vertex* v0, Vertex* v1, Vertex* v2, const AAParams* aaParams, void* data) { 227 LOG("emit_triangle (%g, %g) %d\n", v0->fPoint.fX, v0->fPoint.fY, v0->fAlpha); 228 LOG(" (%g, %g) %d\n", v1->fPoint.fX, v1->fPoint.fY, v1->fAlpha); 229 LOG(" (%g, %g) %d\n", v2->fPoint.fX, v2->fPoint.fY, v2->fAlpha); 230#if TESSELLATOR_WIREFRAME 231 data = emit_vertex(v0, aaParams, data); 232 data = emit_vertex(v1, aaParams, data); 233 data = emit_vertex(v1, aaParams, data); 234 data = emit_vertex(v2, aaParams, data); 235 data = emit_vertex(v2, aaParams, data); 236 data = emit_vertex(v0, aaParams, data); 237#else 238 data = emit_vertex(v0, aaParams, data); 239 data = emit_vertex(v1, aaParams, data); 240 data = emit_vertex(v2, aaParams, data); 241#endif 242 return data; 243} 244 245struct VertexList { 246 VertexList() : fHead(nullptr), fTail(nullptr) {} 247 VertexList(Vertex* head, Vertex* tail) : fHead(head), fTail(tail) {} 248 Vertex* fHead; 249 Vertex* fTail; 250 void insert(Vertex* v, Vertex* prev, Vertex* next) { 251 list_insert<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, prev, next, &fHead, &fTail); 252 } 253 void append(Vertex* v) { 254 insert(v, fTail, nullptr); 255 } 256 void prepend(Vertex* v) { 257 insert(v, nullptr, fHead); 258 } 259 void remove(Vertex* v) { 260 list_remove<Vertex, &Vertex::fPrev, &Vertex::fNext>(v, &fHead, &fTail); 261 } 262 void close() { 263 if (fHead && fTail) { 264 fTail->fNext = fHead; 265 fHead->fPrev = fTail; 266 } 267 } 268}; 269 270// Round to nearest quarter-pixel. This is used for screenspace tessellation. 271 272inline void round(SkPoint* p) { 273 p->fX = SkScalarRoundToScalar(p->fX * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); 274 p->fY = SkScalarRoundToScalar(p->fY * SkFloatToScalar(4.0f)) * SkFloatToScalar(0.25f); 275} 276 277// A line equation in implicit form. fA * x + fB * y + fC = 0, for all points (x, y) on the line. 278struct Line { 279 Line(Vertex* p, Vertex* q) : Line(p->fPoint, q->fPoint) {} 280 Line(const SkPoint& p, const SkPoint& q) 281 : fA(static_cast<double>(q.fY) - p.fY) // a = dY 282 , fB(static_cast<double>(p.fX) - q.fX) // b = -dX 283 , fC(static_cast<double>(p.fY) * q.fX - // c = cross(q, p) 284 static_cast<double>(p.fX) * q.fY) {} 285 double dist(const SkPoint& p) const { 286 return fA * p.fX + fB * p.fY + fC; 287 } 288 double magSq() const { 289 return fA * fA + fB * fB; 290 } 291 292 // Compute the intersection of two (infinite) Lines. 293 bool intersect(const Line& other, SkPoint* point) { 294 double denom = fA * other.fB - fB * other.fA; 295 if (denom == 0.0) { 296 return false; 297 } 298 double scale = 1.0f / denom; 299 point->fX = SkDoubleToScalar((fB * other.fC - other.fB * fC) * scale); 300 point->fY = SkDoubleToScalar((other.fA * fC - fA * other.fC) * scale); 301 return true; 302 } 303 double fA, fB, fC; 304}; 305 306/** 307 * An Edge joins a top Vertex to a bottom Vertex. Edge ordering for the list of "edges above" and 308 * "edge below" a vertex as well as for the active edge list is handled by isLeftOf()/isRightOf(). 309 * Note that an Edge will give occasionally dist() != 0 for its own endpoints (because floating 310 * point). For speed, that case is only tested by the callers which require it (e.g., 311 * cleanup_active_edges()). Edges also handle checking for intersection with other edges. 312 * Currently, this converts the edges to the parametric form, in order to avoid doing a division 313 * until an intersection has been confirmed. This is slightly slower in the "found" case, but 314 * a lot faster in the "not found" case. 315 * 316 * The coefficients of the line equation stored in double precision to avoid catastrphic 317 * cancellation in the isLeftOf() and isRightOf() checks. Using doubles ensures that the result is 318 * correct in float, since it's a polynomial of degree 2. The intersect() function, being 319 * degree 5, is still subject to catastrophic cancellation. We deal with that by assuming its 320 * output may be incorrect, and adjusting the mesh topology to match (see comment at the top of 321 * this file). 322 */ 323 324struct Edge { 325 enum class Type { kInner, kOuter, kConnector }; 326 Edge(Vertex* top, Vertex* bottom, int winding, Type type) 327 : fWinding(winding) 328 , fTop(top) 329 , fBottom(bottom) 330 , fType(type) 331 , fLeft(nullptr) 332 , fRight(nullptr) 333 , fPrevEdgeAbove(nullptr) 334 , fNextEdgeAbove(nullptr) 335 , fPrevEdgeBelow(nullptr) 336 , fNextEdgeBelow(nullptr) 337 , fLeftPoly(nullptr) 338 , fRightPoly(nullptr) 339 , fLeftPolyPrev(nullptr) 340 , fLeftPolyNext(nullptr) 341 , fRightPolyPrev(nullptr) 342 , fRightPolyNext(nullptr) 343 , fUsedInLeftPoly(false) 344 , fUsedInRightPoly(false) 345 , fLine(top, bottom) { 346 } 347 int fWinding; // 1 == edge goes downward; -1 = edge goes upward. 348 Vertex* fTop; // The top vertex in vertex-sort-order (sweep_lt). 349 Vertex* fBottom; // The bottom vertex in vertex-sort-order. 350 Type fType; 351 Edge* fLeft; // The linked list of edges in the active edge list. 352 Edge* fRight; // " 353 Edge* fPrevEdgeAbove; // The linked list of edges in the bottom Vertex's "edges above". 354 Edge* fNextEdgeAbove; // " 355 Edge* fPrevEdgeBelow; // The linked list of edges in the top Vertex's "edges below". 356 Edge* fNextEdgeBelow; // " 357 Poly* fLeftPoly; // The Poly to the left of this edge, if any. 358 Poly* fRightPoly; // The Poly to the right of this edge, if any. 359 Edge* fLeftPolyPrev; 360 Edge* fLeftPolyNext; 361 Edge* fRightPolyPrev; 362 Edge* fRightPolyNext; 363 bool fUsedInLeftPoly; 364 bool fUsedInRightPoly; 365 Line fLine; 366 double dist(const SkPoint& p) const { 367 return fLine.dist(p); 368 } 369 bool isRightOf(Vertex* v) const { 370 return fLine.dist(v->fPoint) < 0.0; 371 } 372 bool isLeftOf(Vertex* v) const { 373 return fLine.dist(v->fPoint) > 0.0; 374 } 375 void recompute() { 376 fLine = Line(fTop, fBottom); 377 } 378 bool intersect(const Edge& other, SkPoint* p, uint8_t* alpha = nullptr) { 379 LOG("intersecting %g -> %g with %g -> %g\n", 380 fTop->fID, fBottom->fID, 381 other.fTop->fID, other.fBottom->fID); 382 if (fTop == other.fTop || fBottom == other.fBottom) { 383 return false; 384 } 385 double denom = fLine.fA * other.fLine.fB - fLine.fB * other.fLine.fA; 386 if (denom == 0.0) { 387 return false; 388 } 389 double dx = static_cast<double>(other.fTop->fPoint.fX) - fTop->fPoint.fX; 390 double dy = static_cast<double>(other.fTop->fPoint.fY) - fTop->fPoint.fY; 391 double sNumer = dy * other.fLine.fB + dx * other.fLine.fA; 392 double tNumer = dy * fLine.fB + dx * fLine.fA; 393 // If (sNumer / denom) or (tNumer / denom) is not in [0..1], exit early. 394 // This saves us doing the divide below unless absolutely necessary. 395 if (denom > 0.0 ? (sNumer < 0.0 || sNumer > denom || tNumer < 0.0 || tNumer > denom) 396 : (sNumer > 0.0 || sNumer < denom || tNumer > 0.0 || tNumer < denom)) { 397 return false; 398 } 399 double s = sNumer / denom; 400 SkASSERT(s >= 0.0 && s <= 1.0); 401 p->fX = SkDoubleToScalar(fTop->fPoint.fX - s * fLine.fB); 402 p->fY = SkDoubleToScalar(fTop->fPoint.fY + s * fLine.fA); 403 if (alpha) { 404 if (fType == Type::kConnector) { 405 *alpha = (1.0 - s) * fTop->fAlpha + s * fBottom->fAlpha; 406 } else if (other.fType == Type::kConnector) { 407 double t = tNumer / denom; 408 *alpha = (1.0 - t) * other.fTop->fAlpha + t * other.fBottom->fAlpha; 409 } else if (fType == Type::kOuter && other.fType == Type::kOuter) { 410 *alpha = 0; 411 } else { 412 *alpha = 255; 413 } 414 } 415 return true; 416 } 417}; 418 419struct EdgeList { 420 EdgeList() : fHead(nullptr), fTail(nullptr), fNext(nullptr) {} 421 Edge* fHead; 422 Edge* fTail; 423 EdgeList* fNext; 424 void insert(Edge* edge, Edge* prev, Edge* next) { 425 list_insert<Edge, &Edge::fLeft, &Edge::fRight>(edge, prev, next, &fHead, &fTail); 426 } 427 void append(Edge* e) { 428 insert(e, fTail, nullptr); 429 } 430 void remove(Edge* edge) { 431 list_remove<Edge, &Edge::fLeft, &Edge::fRight>(edge, &fHead, &fTail); 432 } 433 void close() { 434 if (fHead && fTail) { 435 fTail->fRight = fHead; 436 fHead->fLeft = fTail; 437 } 438 } 439 bool contains(Edge* edge) const { 440 return edge->fLeft || edge->fRight || fHead == edge; 441 } 442}; 443 444/***************************************************************************************/ 445 446struct Poly { 447 Poly(Vertex* v, int winding) 448 : fFirstVertex(v) 449 , fWinding(winding) 450 , fHead(nullptr) 451 , fTail(nullptr) 452 , fNext(nullptr) 453 , fPartner(nullptr) 454 , fCount(0) 455 { 456#if LOGGING_ENABLED 457 static int gID = 0; 458 fID = gID++; 459 LOG("*** created Poly %d\n", fID); 460#endif 461 } 462 typedef enum { kLeft_Side, kRight_Side } Side; 463 struct MonotonePoly { 464 MonotonePoly(Edge* edge, Side side) 465 : fSide(side) 466 , fFirstEdge(nullptr) 467 , fLastEdge(nullptr) 468 , fPrev(nullptr) 469 , fNext(nullptr) { 470 this->addEdge(edge); 471 } 472 Side fSide; 473 Edge* fFirstEdge; 474 Edge* fLastEdge; 475 MonotonePoly* fPrev; 476 MonotonePoly* fNext; 477 void addEdge(Edge* edge) { 478 if (fSide == kRight_Side) { 479 SkASSERT(!edge->fUsedInRightPoly); 480 list_insert<Edge, &Edge::fRightPolyPrev, &Edge::fRightPolyNext>( 481 edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); 482 edge->fUsedInRightPoly = true; 483 } else { 484 SkASSERT(!edge->fUsedInLeftPoly); 485 list_insert<Edge, &Edge::fLeftPolyPrev, &Edge::fLeftPolyNext>( 486 edge, fLastEdge, nullptr, &fFirstEdge, &fLastEdge); 487 edge->fUsedInLeftPoly = true; 488 } 489 } 490 491 void* emit(const AAParams* aaParams, void* data) { 492 Edge* e = fFirstEdge; 493 e->fTop->fPrev = e->fTop->fNext = nullptr; 494 VertexList vertices; 495 vertices.append(e->fTop); 496 while (e != nullptr) { 497 e->fBottom->fPrev = e->fBottom->fNext = nullptr; 498 if (kRight_Side == fSide) { 499 vertices.append(e->fBottom); 500 e = e->fRightPolyNext; 501 } else { 502 vertices.prepend(e->fBottom); 503 e = e->fLeftPolyNext; 504 } 505 } 506 Vertex* first = vertices.fHead; 507 Vertex* v = first->fNext; 508 while (v != vertices.fTail) { 509 SkASSERT(v && v->fPrev && v->fNext); 510 Vertex* prev = v->fPrev; 511 Vertex* curr = v; 512 Vertex* next = v->fNext; 513 double ax = static_cast<double>(curr->fPoint.fX) - prev->fPoint.fX; 514 double ay = static_cast<double>(curr->fPoint.fY) - prev->fPoint.fY; 515 double bx = static_cast<double>(next->fPoint.fX) - curr->fPoint.fX; 516 double by = static_cast<double>(next->fPoint.fY) - curr->fPoint.fY; 517 if (ax * by - ay * bx >= 0.0) { 518 data = emit_triangle(prev, curr, next, aaParams, data); 519 v->fPrev->fNext = v->fNext; 520 v->fNext->fPrev = v->fPrev; 521 if (v->fPrev == first) { 522 v = v->fNext; 523 } else { 524 v = v->fPrev; 525 } 526 } else { 527 v = v->fNext; 528 } 529 } 530 return data; 531 } 532 }; 533 Poly* addEdge(Edge* e, Side side, SkArenaAlloc& alloc) { 534 LOG("addEdge (%g -> %g) to poly %d, %s side\n", 535 e->fTop->fID, e->fBottom->fID, fID, side == kLeft_Side ? "left" : "right"); 536 Poly* partner = fPartner; 537 Poly* poly = this; 538 if (side == kRight_Side) { 539 if (e->fUsedInRightPoly) { 540 return this; 541 } 542 } else { 543 if (e->fUsedInLeftPoly) { 544 return this; 545 } 546 } 547 if (partner) { 548 fPartner = partner->fPartner = nullptr; 549 } 550 if (!fTail) { 551 fHead = fTail = alloc.make<MonotonePoly>(e, side); 552 fCount += 2; 553 } else if (e->fBottom == fTail->fLastEdge->fBottom) { 554 return poly; 555 } else if (side == fTail->fSide) { 556 fTail->addEdge(e); 557 fCount++; 558 } else { 559 e = alloc.make<Edge>(fTail->fLastEdge->fBottom, e->fBottom, 1, Edge::Type::kInner); 560 fTail->addEdge(e); 561 fCount++; 562 if (partner) { 563 partner->addEdge(e, side, alloc); 564 poly = partner; 565 } else { 566 MonotonePoly* m = alloc.make<MonotonePoly>(e, side); 567 m->fPrev = fTail; 568 fTail->fNext = m; 569 fTail = m; 570 } 571 } 572 return poly; 573 } 574 void* emit(const AAParams* aaParams, void *data) { 575 if (fCount < 3) { 576 return data; 577 } 578 LOG("emit() %d, size %d\n", fID, fCount); 579 for (MonotonePoly* m = fHead; m != nullptr; m = m->fNext) { 580 data = m->emit(aaParams, data); 581 } 582 return data; 583 } 584 Vertex* lastVertex() const { return fTail ? fTail->fLastEdge->fBottom : fFirstVertex; } 585 Vertex* fFirstVertex; 586 int fWinding; 587 MonotonePoly* fHead; 588 MonotonePoly* fTail; 589 Poly* fNext; 590 Poly* fPartner; 591 int fCount; 592#if LOGGING_ENABLED 593 int fID; 594#endif 595}; 596 597/***************************************************************************************/ 598 599bool coincident(const SkPoint& a, const SkPoint& b) { 600 return a == b; 601} 602 603Poly* new_poly(Poly** head, Vertex* v, int winding, SkArenaAlloc& alloc) { 604 Poly* poly = alloc.make<Poly>(v, winding); 605 poly->fNext = *head; 606 *head = poly; 607 return poly; 608} 609 610EdgeList* new_contour(EdgeList** head, SkArenaAlloc& alloc) { 611 EdgeList* contour = alloc.make<EdgeList>(); 612 contour->fNext = *head; 613 *head = contour; 614 return contour; 615} 616 617Vertex* append_point_to_contour(const SkPoint& p, Vertex* prev, Vertex** head, 618 SkArenaAlloc& alloc) { 619 Vertex* v = alloc.make<Vertex>(p, 255); 620#if LOGGING_ENABLED 621 static float gID = 0.0f; 622 v->fID = gID++; 623#endif 624 if (prev) { 625 prev->fNext = v; 626 v->fPrev = prev; 627 } else { 628 *head = v; 629 } 630 return v; 631} 632 633Vertex* generate_quadratic_points(const SkPoint& p0, 634 const SkPoint& p1, 635 const SkPoint& p2, 636 SkScalar tolSqd, 637 Vertex* prev, 638 Vertex** head, 639 int pointsLeft, 640 SkArenaAlloc& alloc) { 641 SkScalar d = p1.distanceToLineSegmentBetweenSqd(p0, p2); 642 if (pointsLeft < 2 || d < tolSqd || !SkScalarIsFinite(d)) { 643 return append_point_to_contour(p2, prev, head, alloc); 644 } 645 646 const SkPoint q[] = { 647 { SkScalarAve(p0.fX, p1.fX), SkScalarAve(p0.fY, p1.fY) }, 648 { SkScalarAve(p1.fX, p2.fX), SkScalarAve(p1.fY, p2.fY) }, 649 }; 650 const SkPoint r = { SkScalarAve(q[0].fX, q[1].fX), SkScalarAve(q[0].fY, q[1].fY) }; 651 652 pointsLeft >>= 1; 653 prev = generate_quadratic_points(p0, q[0], r, tolSqd, prev, head, pointsLeft, alloc); 654 prev = generate_quadratic_points(r, q[1], p2, tolSqd, prev, head, pointsLeft, alloc); 655 return prev; 656} 657 658Vertex* generate_cubic_points(const SkPoint& p0, 659 const SkPoint& p1, 660 const SkPoint& p2, 661 const SkPoint& p3, 662 SkScalar tolSqd, 663 Vertex* prev, 664 Vertex** head, 665 int pointsLeft, 666 SkArenaAlloc& alloc) { 667 SkScalar d1 = p1.distanceToLineSegmentBetweenSqd(p0, p3); 668 SkScalar d2 = p2.distanceToLineSegmentBetweenSqd(p0, p3); 669 if (pointsLeft < 2 || (d1 < tolSqd && d2 < tolSqd) || 670 !SkScalarIsFinite(d1) || !SkScalarIsFinite(d2)) { 671 return append_point_to_contour(p3, prev, head, alloc); 672 } 673 const SkPoint q[] = { 674 { SkScalarAve(p0.fX, p1.fX), SkScalarAve(p0.fY, p1.fY) }, 675 { SkScalarAve(p1.fX, p2.fX), SkScalarAve(p1.fY, p2.fY) }, 676 { SkScalarAve(p2.fX, p3.fX), SkScalarAve(p2.fY, p3.fY) } 677 }; 678 const SkPoint r[] = { 679 { SkScalarAve(q[0].fX, q[1].fX), SkScalarAve(q[0].fY, q[1].fY) }, 680 { SkScalarAve(q[1].fX, q[2].fX), SkScalarAve(q[1].fY, q[2].fY) } 681 }; 682 const SkPoint s = { SkScalarAve(r[0].fX, r[1].fX), SkScalarAve(r[0].fY, r[1].fY) }; 683 pointsLeft >>= 1; 684 prev = generate_cubic_points(p0, q[0], r[0], s, tolSqd, prev, head, pointsLeft, alloc); 685 prev = generate_cubic_points(s, r[1], q[2], p3, tolSqd, prev, head, pointsLeft, alloc); 686 return prev; 687} 688 689// Stage 1: convert the input path to a set of linear contours (linked list of Vertices). 690 691void path_to_contours(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 692 Vertex** contours, SkArenaAlloc& alloc, bool *isLinear) { 693 SkScalar toleranceSqd = tolerance * tolerance; 694 695 SkPoint pts[4]; 696 bool done = false; 697 *isLinear = true; 698 SkPath::Iter iter(path, false); 699 Vertex* prev = nullptr; 700 Vertex* head = nullptr; 701 if (path.isInverseFillType()) { 702 SkPoint quad[4]; 703 clipBounds.toQuad(quad); 704 for (int i = 3; i >= 0; i--) { 705 prev = append_point_to_contour(quad[i], prev, &head, alloc); 706 } 707 head->fPrev = prev; 708 prev->fNext = head; 709 *contours++ = head; 710 head = prev = nullptr; 711 } 712 SkAutoConicToQuads converter; 713 while (!done) { 714 SkPath::Verb verb = iter.next(pts); 715 switch (verb) { 716 case SkPath::kConic_Verb: { 717 SkScalar weight = iter.conicWeight(); 718 const SkPoint* quadPts = converter.computeQuads(pts, weight, toleranceSqd); 719 for (int i = 0; i < converter.countQuads(); ++i) { 720 int pointsLeft = GrPathUtils::quadraticPointCount(quadPts, tolerance); 721 prev = generate_quadratic_points(quadPts[0], quadPts[1], quadPts[2], 722 toleranceSqd, prev, &head, pointsLeft, alloc); 723 quadPts += 2; 724 } 725 *isLinear = false; 726 break; 727 } 728 case SkPath::kMove_Verb: 729 if (head) { 730 head->fPrev = prev; 731 prev->fNext = head; 732 *contours++ = head; 733 } 734 head = prev = nullptr; 735 prev = append_point_to_contour(pts[0], prev, &head, alloc); 736 break; 737 case SkPath::kLine_Verb: { 738 prev = append_point_to_contour(pts[1], prev, &head, alloc); 739 break; 740 } 741 case SkPath::kQuad_Verb: { 742 int pointsLeft = GrPathUtils::quadraticPointCount(pts, tolerance); 743 prev = generate_quadratic_points(pts[0], pts[1], pts[2], toleranceSqd, prev, 744 &head, pointsLeft, alloc); 745 *isLinear = false; 746 break; 747 } 748 case SkPath::kCubic_Verb: { 749 int pointsLeft = GrPathUtils::cubicPointCount(pts, tolerance); 750 prev = generate_cubic_points(pts[0], pts[1], pts[2], pts[3], 751 toleranceSqd, prev, &head, pointsLeft, alloc); 752 *isLinear = false; 753 break; 754 } 755 case SkPath::kClose_Verb: 756 if (head) { 757 head->fPrev = prev; 758 prev->fNext = head; 759 *contours++ = head; 760 } 761 head = prev = nullptr; 762 break; 763 case SkPath::kDone_Verb: 764 if (head) { 765 head->fPrev = prev; 766 prev->fNext = head; 767 *contours++ = head; 768 } 769 done = true; 770 break; 771 } 772 } 773} 774 775inline bool apply_fill_type(SkPath::FillType fillType, int winding) { 776 switch (fillType) { 777 case SkPath::kWinding_FillType: 778 return winding != 0; 779 case SkPath::kEvenOdd_FillType: 780 return (winding & 1) != 0; 781 case SkPath::kInverseWinding_FillType: 782 return winding == 1; 783 case SkPath::kInverseEvenOdd_FillType: 784 return (winding & 1) == 1; 785 default: 786 SkASSERT(false); 787 return false; 788 } 789} 790 791inline bool apply_fill_type(SkPath::FillType fillType, Poly* poly) { 792 return poly && apply_fill_type(fillType, poly->fWinding); 793} 794 795Edge* new_edge(Vertex* prev, Vertex* next, Edge::Type type, Comparator& c, SkArenaAlloc& alloc) { 796 int winding = c.sweep_lt(prev->fPoint, next->fPoint) ? 1 : -1; 797 Vertex* top = winding < 0 ? next : prev; 798 Vertex* bottom = winding < 0 ? prev : next; 799 return alloc.make<Edge>(top, bottom, winding, type); 800} 801 802void remove_edge(Edge* edge, EdgeList* edges) { 803 LOG("removing edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); 804 SkASSERT(edges->contains(edge)); 805 edges->remove(edge); 806} 807 808void insert_edge(Edge* edge, Edge* prev, EdgeList* edges) { 809 LOG("inserting edge %g -> %g\n", edge->fTop->fID, edge->fBottom->fID); 810 SkASSERT(!edges->contains(edge)); 811 Edge* next = prev ? prev->fRight : edges->fHead; 812 edges->insert(edge, prev, next); 813} 814 815void find_enclosing_edges(Vertex* v, EdgeList* edges, Edge** left, Edge** right) { 816 if (v->fFirstEdgeAbove) { 817 *left = v->fFirstEdgeAbove->fLeft; 818 *right = v->fLastEdgeAbove->fRight; 819 return; 820 } 821 Edge* next = nullptr; 822 Edge* prev; 823 for (prev = edges->fTail; prev != nullptr; prev = prev->fLeft) { 824 if (prev->isLeftOf(v)) { 825 break; 826 } 827 next = prev; 828 } 829 *left = prev; 830 *right = next; 831} 832 833void find_enclosing_edges(Edge* edge, EdgeList* edges, Comparator& c, Edge** left, Edge** right) { 834 Edge* prev = nullptr; 835 Edge* next; 836 for (next = edges->fHead; next != nullptr; next = next->fRight) { 837 if ((c.sweep_gt(edge->fTop->fPoint, next->fTop->fPoint) && next->isRightOf(edge->fTop)) || 838 (c.sweep_gt(next->fTop->fPoint, edge->fTop->fPoint) && edge->isLeftOf(next->fTop)) || 839 (c.sweep_lt(edge->fBottom->fPoint, next->fBottom->fPoint) && 840 next->isRightOf(edge->fBottom)) || 841 (c.sweep_lt(next->fBottom->fPoint, edge->fBottom->fPoint) && 842 edge->isLeftOf(next->fBottom))) { 843 break; 844 } 845 prev = next; 846 } 847 *left = prev; 848 *right = next; 849} 850 851void fix_active_state(Edge* edge, EdgeList* activeEdges, Comparator& c) { 852 if (!activeEdges) { 853 return; 854 } 855 if (activeEdges->contains(edge)) { 856 if (edge->fBottom->fProcessed || !edge->fTop->fProcessed) { 857 remove_edge(edge, activeEdges); 858 } 859 } else if (edge->fTop->fProcessed && !edge->fBottom->fProcessed) { 860 Edge* left; 861 Edge* right; 862 find_enclosing_edges(edge, activeEdges, c, &left, &right); 863 insert_edge(edge, left, activeEdges); 864 } 865} 866 867void insert_edge_above(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) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); 873 Edge* prev = nullptr; 874 Edge* next; 875 for (next = v->fFirstEdgeAbove; next; next = next->fNextEdgeAbove) { 876 if (next->isRightOf(edge->fTop)) { 877 break; 878 } 879 prev = next; 880 } 881 list_insert<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( 882 edge, prev, next, &v->fFirstEdgeAbove, &v->fLastEdgeAbove); 883} 884 885void insert_edge_below(Edge* edge, Vertex* v, Comparator& c) { 886 if (edge->fTop->fPoint == edge->fBottom->fPoint || 887 c.sweep_gt(edge->fTop->fPoint, edge->fBottom->fPoint)) { 888 return; 889 } 890 LOG("insert edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, v->fID); 891 Edge* prev = nullptr; 892 Edge* next; 893 for (next = v->fFirstEdgeBelow; next; next = next->fNextEdgeBelow) { 894 if (next->isRightOf(edge->fBottom)) { 895 break; 896 } 897 prev = next; 898 } 899 list_insert<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( 900 edge, prev, next, &v->fFirstEdgeBelow, &v->fLastEdgeBelow); 901} 902 903void remove_edge_above(Edge* edge) { 904 LOG("removing edge (%g -> %g) above vertex %g\n", edge->fTop->fID, edge->fBottom->fID, 905 edge->fBottom->fID); 906 list_remove<Edge, &Edge::fPrevEdgeAbove, &Edge::fNextEdgeAbove>( 907 edge, &edge->fBottom->fFirstEdgeAbove, &edge->fBottom->fLastEdgeAbove); 908} 909 910void remove_edge_below(Edge* edge) { 911 LOG("removing edge (%g -> %g) below vertex %g\n", edge->fTop->fID, edge->fBottom->fID, 912 edge->fTop->fID); 913 list_remove<Edge, &Edge::fPrevEdgeBelow, &Edge::fNextEdgeBelow>( 914 edge, &edge->fTop->fFirstEdgeBelow, &edge->fTop->fLastEdgeBelow); 915} 916 917void disconnect(Edge* edge) 918{ 919 remove_edge_above(edge); 920 remove_edge_below(edge); 921} 922 923void erase_edge(Edge* edge, EdgeList* edges) { 924 LOG("erasing edge (%g -> %g)\n", edge->fTop->fID, edge->fBottom->fID); 925 disconnect(edge); 926 if (edges && edges->contains(edge)) { 927 remove_edge(edge, edges); 928 } 929} 930 931void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Comparator& c); 932 933void set_top(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c) { 934 remove_edge_below(edge); 935 edge->fTop = v; 936 edge->recompute(); 937 insert_edge_below(edge, v, c); 938 fix_active_state(edge, activeEdges, c); 939 merge_collinear_edges(edge, activeEdges, c); 940} 941 942void set_bottom(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c) { 943 remove_edge_above(edge); 944 edge->fBottom = v; 945 edge->recompute(); 946 insert_edge_above(edge, v, c); 947 fix_active_state(edge, activeEdges, c); 948 merge_collinear_edges(edge, activeEdges, c); 949} 950 951void merge_edges_above(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c) { 952 if (coincident(edge->fTop->fPoint, other->fTop->fPoint)) { 953 LOG("merging coincident above 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(edge, activeEdges); 958 } else if (c.sweep_lt(edge->fTop->fPoint, other->fTop->fPoint)) { 959 other->fWinding += edge->fWinding; 960 set_bottom(edge, other->fTop, activeEdges, c); 961 } else { 962 edge->fWinding += other->fWinding; 963 set_bottom(other, edge->fTop, activeEdges, c); 964 } 965} 966 967void merge_edges_below(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c) { 968 if (coincident(edge->fBottom->fPoint, other->fBottom->fPoint)) { 969 LOG("merging coincident below edges (%g, %g) -> (%g, %g)\n", 970 edge->fTop->fPoint.fX, edge->fTop->fPoint.fY, 971 edge->fBottom->fPoint.fX, edge->fBottom->fPoint.fY); 972 other->fWinding += edge->fWinding; 973 erase_edge(edge, activeEdges); 974 } else if (c.sweep_lt(edge->fBottom->fPoint, other->fBottom->fPoint)) { 975 edge->fWinding += other->fWinding; 976 set_top(other, edge->fBottom, activeEdges, c); 977 } else { 978 other->fWinding += edge->fWinding; 979 set_top(edge, other->fBottom, activeEdges, c); 980 } 981} 982 983void merge_collinear_edges(Edge* edge, EdgeList* activeEdges, Comparator& c) { 984 if (edge->fPrevEdgeAbove && (edge->fTop == edge->fPrevEdgeAbove->fTop || 985 !edge->fPrevEdgeAbove->isLeftOf(edge->fTop))) { 986 merge_edges_above(edge, edge->fPrevEdgeAbove, activeEdges, c); 987 } else if (edge->fNextEdgeAbove && (edge->fTop == edge->fNextEdgeAbove->fTop || 988 !edge->isLeftOf(edge->fNextEdgeAbove->fTop))) { 989 merge_edges_above(edge, edge->fNextEdgeAbove, activeEdges, c); 990 } 991 if (edge->fPrevEdgeBelow && (edge->fBottom == edge->fPrevEdgeBelow->fBottom || 992 !edge->fPrevEdgeBelow->isLeftOf(edge->fBottom))) { 993 merge_edges_below(edge, edge->fPrevEdgeBelow, activeEdges, c); 994 } else if (edge->fNextEdgeBelow && (edge->fBottom == edge->fNextEdgeBelow->fBottom || 995 !edge->isLeftOf(edge->fNextEdgeBelow->fBottom))) { 996 merge_edges_below(edge, edge->fNextEdgeBelow, activeEdges, c); 997 } 998} 999 1000void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, SkArenaAlloc& alloc); 1001 1002void cleanup_active_edges(Edge* edge, EdgeList* activeEdges, Comparator& c, SkArenaAlloc& alloc) { 1003 Vertex* top = edge->fTop; 1004 Vertex* bottom = edge->fBottom; 1005 if (edge->fLeft) { 1006 Vertex* leftTop = edge->fLeft->fTop; 1007 Vertex* leftBottom = edge->fLeft->fBottom; 1008 if (c.sweep_gt(top->fPoint, leftTop->fPoint) && !edge->fLeft->isLeftOf(top)) { 1009 split_edge(edge->fLeft, edge->fTop, activeEdges, c, alloc); 1010 } else if (c.sweep_gt(leftTop->fPoint, top->fPoint) && !edge->isRightOf(leftTop)) { 1011 split_edge(edge, leftTop, activeEdges, c, alloc); 1012 } else if (c.sweep_lt(bottom->fPoint, leftBottom->fPoint) && 1013 !edge->fLeft->isLeftOf(bottom)) { 1014 split_edge(edge->fLeft, bottom, activeEdges, c, alloc); 1015 } else if (c.sweep_lt(leftBottom->fPoint, bottom->fPoint) && !edge->isRightOf(leftBottom)) { 1016 split_edge(edge, leftBottom, activeEdges, c, alloc); 1017 } 1018 } 1019 if (edge->fRight) { 1020 Vertex* rightTop = edge->fRight->fTop; 1021 Vertex* rightBottom = edge->fRight->fBottom; 1022 if (c.sweep_gt(top->fPoint, rightTop->fPoint) && !edge->fRight->isRightOf(top)) { 1023 split_edge(edge->fRight, top, activeEdges, c, alloc); 1024 } else if (c.sweep_gt(rightTop->fPoint, top->fPoint) && !edge->isLeftOf(rightTop)) { 1025 split_edge(edge, rightTop, activeEdges, c, alloc); 1026 } else if (c.sweep_lt(bottom->fPoint, rightBottom->fPoint) && 1027 !edge->fRight->isRightOf(bottom)) { 1028 split_edge(edge->fRight, bottom, activeEdges, c, alloc); 1029 } else if (c.sweep_lt(rightBottom->fPoint, bottom->fPoint) && 1030 !edge->isLeftOf(rightBottom)) { 1031 split_edge(edge, rightBottom, activeEdges, c, alloc); 1032 } 1033 } 1034} 1035 1036void split_edge(Edge* edge, Vertex* v, EdgeList* activeEdges, Comparator& c, SkArenaAlloc& alloc) { 1037 LOG("splitting edge (%g -> %g) at vertex %g (%g, %g)\n", 1038 edge->fTop->fID, edge->fBottom->fID, 1039 v->fID, v->fPoint.fX, v->fPoint.fY); 1040 if (c.sweep_lt(v->fPoint, edge->fTop->fPoint)) { 1041 set_top(edge, v, activeEdges, c); 1042 } else if (c.sweep_gt(v->fPoint, edge->fBottom->fPoint)) { 1043 set_bottom(edge, v, activeEdges, c); 1044 } else { 1045 Edge* newEdge = alloc.make<Edge>(v, edge->fBottom, edge->fWinding, edge->fType); 1046 insert_edge_below(newEdge, v, c); 1047 insert_edge_above(newEdge, edge->fBottom, c); 1048 set_bottom(edge, v, activeEdges, c); 1049 cleanup_active_edges(edge, activeEdges, c, alloc); 1050 fix_active_state(newEdge, activeEdges, c); 1051 merge_collinear_edges(newEdge, activeEdges, c); 1052 } 1053} 1054 1055Edge* connect(Vertex* prev, Vertex* next, Edge::Type type, Comparator& c, SkArenaAlloc& alloc, 1056 int winding_scale = 1) { 1057 Edge* edge = new_edge(prev, next, type, c, alloc); 1058 insert_edge_below(edge, edge->fTop, c); 1059 insert_edge_above(edge, edge->fBottom, c); 1060 edge->fWinding *= winding_scale; 1061 merge_collinear_edges(edge, nullptr, c); 1062 return edge; 1063} 1064 1065void merge_vertices(Vertex* src, Vertex* dst, VertexList* mesh, Comparator& c, 1066 SkArenaAlloc& alloc) { 1067 LOG("found coincident verts at %g, %g; merging %g into %g\n", src->fPoint.fX, src->fPoint.fY, 1068 src->fID, dst->fID); 1069 dst->fAlpha = SkTMax(src->fAlpha, dst->fAlpha); 1070 for (Edge* edge = src->fFirstEdgeAbove; edge;) { 1071 Edge* next = edge->fNextEdgeAbove; 1072 set_bottom(edge, dst, nullptr, c); 1073 edge = next; 1074 } 1075 for (Edge* edge = src->fFirstEdgeBelow; edge;) { 1076 Edge* next = edge->fNextEdgeBelow; 1077 set_top(edge, dst, nullptr, c); 1078 edge = next; 1079 } 1080 mesh->remove(src); 1081} 1082 1083uint8_t max_edge_alpha(Edge* a, Edge* b) { 1084 if (a->fType == Edge::Type::kInner || b->fType == Edge::Type::kInner) { 1085 return 255; 1086 } else if (a->fType == Edge::Type::kOuter && b->fType == Edge::Type::kOuter) { 1087 return 0; 1088 } else { 1089 return SkTMax(SkTMax(a->fTop->fAlpha, a->fBottom->fAlpha), 1090 SkTMax(b->fTop->fAlpha, b->fBottom->fAlpha)); 1091 } 1092} 1093 1094Vertex* check_for_intersection(Edge* edge, Edge* other, EdgeList* activeEdges, Comparator& c, 1095 SkArenaAlloc& alloc) { 1096 if (!edge || !other) { 1097 return nullptr; 1098 } 1099 SkPoint p; 1100 uint8_t alpha; 1101 if (edge->intersect(*other, &p, &alpha)) { 1102 Vertex* v; 1103 LOG("found intersection, pt is %g, %g\n", p.fX, p.fY); 1104 if (p == edge->fTop->fPoint || c.sweep_lt(p, edge->fTop->fPoint)) { 1105 split_edge(other, edge->fTop, activeEdges, c, alloc); 1106 v = edge->fTop; 1107 } else if (p == edge->fBottom->fPoint || c.sweep_gt(p, edge->fBottom->fPoint)) { 1108 split_edge(other, edge->fBottom, activeEdges, c, alloc); 1109 v = edge->fBottom; 1110 } else if (p == other->fTop->fPoint || c.sweep_lt(p, other->fTop->fPoint)) { 1111 split_edge(edge, other->fTop, activeEdges, c, alloc); 1112 v = other->fTop; 1113 } else if (p == other->fBottom->fPoint || c.sweep_gt(p, other->fBottom->fPoint)) { 1114 split_edge(edge, other->fBottom, activeEdges, c, alloc); 1115 v = other->fBottom; 1116 } else { 1117 Vertex* nextV = edge->fTop; 1118 while (c.sweep_lt(p, nextV->fPoint)) { 1119 nextV = nextV->fPrev; 1120 } 1121 while (c.sweep_lt(nextV->fPoint, p)) { 1122 nextV = nextV->fNext; 1123 } 1124 Vertex* prevV = nextV->fPrev; 1125 if (coincident(prevV->fPoint, p)) { 1126 v = prevV; 1127 } else if (coincident(nextV->fPoint, p)) { 1128 v = nextV; 1129 } else { 1130 v = alloc.make<Vertex>(p, alpha); 1131 LOG("inserting between %g (%g, %g) and %g (%g, %g)\n", 1132 prevV->fID, prevV->fPoint.fX, prevV->fPoint.fY, 1133 nextV->fID, nextV->fPoint.fX, nextV->fPoint.fY); 1134#if LOGGING_ENABLED 1135 v->fID = (nextV->fID + prevV->fID) * 0.5f; 1136#endif 1137 v->fPrev = prevV; 1138 v->fNext = nextV; 1139 prevV->fNext = v; 1140 nextV->fPrev = v; 1141 } 1142 split_edge(edge, v, activeEdges, c, alloc); 1143 split_edge(other, v, activeEdges, c, alloc); 1144 } 1145 v->fAlpha = SkTMax(v->fAlpha, alpha); 1146 return v; 1147 } 1148 return nullptr; 1149} 1150 1151void sanitize_contours(Vertex** contours, int contourCnt, bool approximate) { 1152 for (int i = 0; i < contourCnt; ++i) { 1153 SkASSERT(contours[i]); 1154 if (approximate) { 1155 round(&contours[i]->fPrev->fPoint); 1156 } 1157 for (Vertex* v = contours[i];;) { 1158 if (approximate) { 1159 round(&v->fPoint); 1160 } 1161 if (coincident(v->fPrev->fPoint, v->fPoint)) { 1162 LOG("vertex %g,%g coincident; removing\n", v->fPoint.fX, v->fPoint.fY); 1163 if (v->fPrev == v) { 1164 contours[i] = nullptr; 1165 break; 1166 } 1167 v->fPrev->fNext = v->fNext; 1168 v->fNext->fPrev = v->fPrev; 1169 if (contours[i] == v) { 1170 contours[i] = v->fPrev; 1171 } 1172 v = v->fPrev; 1173 } else { 1174 v = v->fNext; 1175 if (v == contours[i]) break; 1176 } 1177 } 1178 } 1179} 1180 1181void merge_coincident_vertices(VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1182 for (Vertex* v = mesh->fHead->fNext; v != nullptr; v = v->fNext) { 1183 if (c.sweep_lt(v->fPoint, v->fPrev->fPoint)) { 1184 v->fPoint = v->fPrev->fPoint; 1185 } 1186 if (coincident(v->fPrev->fPoint, v->fPoint)) { 1187 merge_vertices(v->fPrev, v, mesh, c, alloc); 1188 } 1189 } 1190} 1191 1192// Stage 2: convert the contours to a mesh of edges connecting the vertices. 1193 1194void build_edges(Vertex** contours, int contourCnt, VertexList* mesh, Comparator& c, 1195 SkArenaAlloc& alloc) { 1196 Vertex* prev = nullptr; 1197 for (int i = 0; i < contourCnt; ++i) { 1198 for (Vertex* v = contours[i]; v != nullptr;) { 1199 Vertex* vNext = v->fNext; 1200 connect(v->fPrev, v, Edge::Type::kInner, c, alloc); 1201 if (prev) { 1202 prev->fNext = v; 1203 v->fPrev = prev; 1204 } else { 1205 mesh->fHead = v; 1206 } 1207 prev = v; 1208 v = vNext; 1209 if (v == contours[i]) break; 1210 } 1211 } 1212 if (prev) { 1213 prev->fNext = mesh->fHead->fPrev = nullptr; 1214 } 1215 mesh->fTail = prev; 1216} 1217 1218// Stage 3: sort the vertices by increasing sweep direction. 1219 1220template <CompareFunc sweep_lt> 1221void merge_sort(VertexList* vertices) { 1222 Vertex* slow = vertices->fHead; 1223 if (!slow) { 1224 return; 1225 } 1226 Vertex* fast = slow->fNext; 1227 if (!fast) { 1228 return; 1229 } 1230 do { 1231 fast = fast->fNext; 1232 if (fast) { 1233 fast = fast->fNext; 1234 slow = slow->fNext; 1235 } 1236 } while (fast); 1237 VertexList front(vertices->fHead, slow); 1238 VertexList back(slow->fNext, vertices->fTail); 1239 front.fTail->fNext = back.fHead->fPrev = nullptr; 1240 1241 merge_sort<sweep_lt>(&front); 1242 merge_sort<sweep_lt>(&back); 1243 1244 vertices->fHead = vertices->fTail = nullptr; 1245 Vertex* a = front.fHead; 1246 Vertex* b = back.fHead; 1247 while (a && b) { 1248 if (sweep_lt(a->fPoint, b->fPoint)) { 1249 Vertex* next = a->fNext; 1250 vertices->append(a); 1251 a = next; 1252 } else { 1253 Vertex* next = b->fNext; 1254 vertices->append(b); 1255 b = next; 1256 } 1257 } 1258 if (a) { 1259 vertices->insert(a, vertices->fTail, a->fNext); 1260 } 1261 if (b) { 1262 vertices->insert(b, vertices->fTail, b->fNext); 1263 } 1264} 1265 1266// Stage 4: Simplify the mesh by inserting new vertices at intersecting edges. 1267 1268void simplify(const VertexList& vertices, Comparator& c, SkArenaAlloc& alloc) { 1269 LOG("simplifying complex polygons\n"); 1270 EdgeList activeEdges; 1271 for (Vertex* v = vertices.fHead; v != nullptr; v = v->fNext) { 1272 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1273 continue; 1274 } 1275#if LOGGING_ENABLED 1276 LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); 1277#endif 1278 Edge* leftEnclosingEdge; 1279 Edge* rightEnclosingEdge; 1280 bool restartChecks; 1281 do { 1282 restartChecks = false; 1283 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1284 if (v->fFirstEdgeBelow) { 1285 for (Edge* edge = v->fFirstEdgeBelow; edge; edge = edge->fNextEdgeBelow) { 1286 if (check_for_intersection(edge, leftEnclosingEdge, &activeEdges, c, alloc)) { 1287 restartChecks = true; 1288 break; 1289 } 1290 if (check_for_intersection(edge, rightEnclosingEdge, &activeEdges, c, alloc)) { 1291 restartChecks = true; 1292 break; 1293 } 1294 } 1295 } else { 1296 if (Vertex* pv = check_for_intersection(leftEnclosingEdge, rightEnclosingEdge, 1297 &activeEdges, c, alloc)) { 1298 if (c.sweep_lt(pv->fPoint, v->fPoint)) { 1299 v = pv; 1300 } 1301 restartChecks = true; 1302 } 1303 1304 } 1305 } while (restartChecks); 1306 if (v->fAlpha == 0) { 1307 if ((leftEnclosingEdge && leftEnclosingEdge->fWinding < 0) && 1308 (rightEnclosingEdge && rightEnclosingEdge->fWinding > 0)) { 1309 v->fAlpha = max_edge_alpha(leftEnclosingEdge, rightEnclosingEdge); 1310 } 1311 } 1312 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 1313 remove_edge(e, &activeEdges); 1314 } 1315 Edge* leftEdge = leftEnclosingEdge; 1316 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1317 insert_edge(e, leftEdge, &activeEdges); 1318 leftEdge = e; 1319 } 1320 v->fProcessed = true; 1321 } 1322} 1323 1324// Stage 5: Tessellate the simplified mesh into monotone polygons. 1325 1326Poly* tessellate(const VertexList& vertices, SkArenaAlloc& alloc) { 1327 LOG("tessellating simple polygons\n"); 1328 EdgeList activeEdges; 1329 Poly* polys = nullptr; 1330 for (Vertex* v = vertices.fHead; v != nullptr; v = v->fNext) { 1331 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1332 continue; 1333 } 1334#if LOGGING_ENABLED 1335 LOG("\nvertex %g: (%g,%g), alpha %d\n", v->fID, v->fPoint.fX, v->fPoint.fY, v->fAlpha); 1336#endif 1337 Edge* leftEnclosingEdge; 1338 Edge* rightEnclosingEdge; 1339 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1340 Poly* leftPoly; 1341 Poly* rightPoly; 1342 if (v->fFirstEdgeAbove) { 1343 leftPoly = v->fFirstEdgeAbove->fLeftPoly; 1344 rightPoly = v->fLastEdgeAbove->fRightPoly; 1345 } else { 1346 leftPoly = leftEnclosingEdge ? leftEnclosingEdge->fRightPoly : nullptr; 1347 rightPoly = rightEnclosingEdge ? rightEnclosingEdge->fLeftPoly : nullptr; 1348 } 1349#if LOGGING_ENABLED 1350 LOG("edges above:\n"); 1351 for (Edge* e = v->fFirstEdgeAbove; e; e = e->fNextEdgeAbove) { 1352 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1353 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1354 } 1355 LOG("edges below:\n"); 1356 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1357 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1358 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1359 } 1360#endif 1361 if (v->fFirstEdgeAbove) { 1362 if (leftPoly) { 1363 leftPoly = leftPoly->addEdge(v->fFirstEdgeAbove, Poly::kRight_Side, alloc); 1364 } 1365 if (rightPoly) { 1366 rightPoly = rightPoly->addEdge(v->fLastEdgeAbove, Poly::kLeft_Side, alloc); 1367 } 1368 for (Edge* e = v->fFirstEdgeAbove; e != v->fLastEdgeAbove; e = e->fNextEdgeAbove) { 1369 Edge* rightEdge = e->fNextEdgeAbove; 1370 SkASSERT(rightEdge->isRightOf(e->fTop)); 1371 remove_edge(e, &activeEdges); 1372 if (e->fRightPoly) { 1373 e->fRightPoly->addEdge(e, Poly::kLeft_Side, alloc); 1374 } 1375 if (rightEdge->fLeftPoly && rightEdge->fLeftPoly != e->fRightPoly) { 1376 rightEdge->fLeftPoly->addEdge(e, Poly::kRight_Side, alloc); 1377 } 1378 } 1379 remove_edge(v->fLastEdgeAbove, &activeEdges); 1380 if (!v->fFirstEdgeBelow) { 1381 if (leftPoly && rightPoly && leftPoly != rightPoly) { 1382 SkASSERT(leftPoly->fPartner == nullptr && rightPoly->fPartner == nullptr); 1383 rightPoly->fPartner = leftPoly; 1384 leftPoly->fPartner = rightPoly; 1385 } 1386 } 1387 } 1388 if (v->fFirstEdgeBelow) { 1389 if (!v->fFirstEdgeAbove) { 1390 if (leftPoly && rightPoly) { 1391 if (leftPoly == rightPoly) { 1392 if (leftPoly->fTail && leftPoly->fTail->fSide == Poly::kLeft_Side) { 1393 leftPoly = new_poly(&polys, leftPoly->lastVertex(), 1394 leftPoly->fWinding, alloc); 1395 leftEnclosingEdge->fRightPoly = leftPoly; 1396 } else { 1397 rightPoly = new_poly(&polys, rightPoly->lastVertex(), 1398 rightPoly->fWinding, alloc); 1399 rightEnclosingEdge->fLeftPoly = rightPoly; 1400 } 1401 } 1402 Edge* join = alloc.make<Edge>(leftPoly->lastVertex(), v, 1, Edge::Type::kInner); 1403 leftPoly = leftPoly->addEdge(join, Poly::kRight_Side, alloc); 1404 rightPoly = rightPoly->addEdge(join, Poly::kLeft_Side, alloc); 1405 } 1406 } 1407 Edge* leftEdge = v->fFirstEdgeBelow; 1408 leftEdge->fLeftPoly = leftPoly; 1409 insert_edge(leftEdge, leftEnclosingEdge, &activeEdges); 1410 for (Edge* rightEdge = leftEdge->fNextEdgeBelow; rightEdge; 1411 rightEdge = rightEdge->fNextEdgeBelow) { 1412 insert_edge(rightEdge, leftEdge, &activeEdges); 1413 int winding = leftEdge->fLeftPoly ? leftEdge->fLeftPoly->fWinding : 0; 1414 winding += leftEdge->fWinding; 1415 if (winding != 0) { 1416 Poly* poly = new_poly(&polys, v, winding, alloc); 1417 leftEdge->fRightPoly = rightEdge->fLeftPoly = poly; 1418 } 1419 leftEdge = rightEdge; 1420 } 1421 v->fLastEdgeBelow->fRightPoly = rightPoly; 1422 } 1423#if LOGGING_ENABLED 1424 LOG("\nactive edges:\n"); 1425 for (Edge* e = activeEdges.fHead; e != nullptr; e = e->fRight) { 1426 LOG("%g -> %g, lpoly %d, rpoly %d\n", e->fTop->fID, e->fBottom->fID, 1427 e->fLeftPoly ? e->fLeftPoly->fID : -1, e->fRightPoly ? e->fRightPoly->fID : -1); 1428 } 1429#endif 1430 } 1431 return polys; 1432} 1433 1434void remove_non_boundary_edges(const VertexList& mesh, SkPath::FillType fillType, 1435 SkArenaAlloc& alloc) { 1436 LOG("removing non-boundary edges\n"); 1437 EdgeList activeEdges; 1438 for (Vertex* v = mesh.fHead; v != nullptr; v = v->fNext) { 1439 if (!v->fFirstEdgeAbove && !v->fFirstEdgeBelow) { 1440 continue; 1441 } 1442 Edge* leftEnclosingEdge; 1443 Edge* rightEnclosingEdge; 1444 find_enclosing_edges(v, &activeEdges, &leftEnclosingEdge, &rightEnclosingEdge); 1445 bool prevFilled = leftEnclosingEdge && 1446 apply_fill_type(fillType, leftEnclosingEdge->fWinding); 1447 for (Edge* e = v->fFirstEdgeAbove; e;) { 1448 Edge* next = e->fNextEdgeAbove; 1449 remove_edge(e, &activeEdges); 1450 bool filled = apply_fill_type(fillType, e->fWinding); 1451 if (filled == prevFilled) { 1452 disconnect(e); 1453 } 1454 prevFilled = filled; 1455 e = next; 1456 } 1457 Edge* prev = leftEnclosingEdge; 1458 for (Edge* e = v->fFirstEdgeBelow; e; e = e->fNextEdgeBelow) { 1459 if (prev) { 1460 e->fWinding += prev->fWinding; 1461 } 1462 insert_edge(e, prev, &activeEdges); 1463 prev = e; 1464 } 1465 } 1466} 1467 1468void get_edge_normal(const Edge* e, SkVector* normal) { 1469 normal->setNormalize(SkDoubleToScalar(e->fLine.fA) * e->fWinding, 1470 SkDoubleToScalar(e->fLine.fB) * e->fWinding); 1471} 1472 1473// Stage 5c: detect and remove "pointy" vertices whose edge normals point in opposite directions 1474// and whose adjacent vertices are less than a quarter pixel from an edge. These are guaranteed to 1475// invert on stroking. 1476 1477void simplify_boundary(EdgeList* boundary, Comparator& c, SkArenaAlloc& alloc) { 1478 Edge* prevEdge = boundary->fTail; 1479 SkVector prevNormal; 1480 get_edge_normal(prevEdge, &prevNormal); 1481 for (Edge* e = boundary->fHead; e != nullptr;) { 1482 Vertex* prev = prevEdge->fWinding == 1 ? prevEdge->fTop : prevEdge->fBottom; 1483 Vertex* next = e->fWinding == 1 ? e->fBottom : e->fTop; 1484 double dist = e->dist(prev->fPoint); 1485 SkVector normal; 1486 get_edge_normal(e, &normal); 1487 float denom = 0.0625f * static_cast<float>(e->fLine.magSq()); 1488 if (prevNormal.dot(normal) < 0.0 && (dist * dist) <= denom) { 1489 Edge* join = new_edge(prev, next, Edge::Type::kInner, c, alloc); 1490 insert_edge(join, e, boundary); 1491 remove_edge(prevEdge, boundary); 1492 remove_edge(e, boundary); 1493 if (join->fLeft && join->fRight) { 1494 prevEdge = join->fLeft; 1495 e = join; 1496 } else { 1497 prevEdge = boundary->fTail; 1498 e = boundary->fHead; // join->fLeft ? join->fLeft : join; 1499 } 1500 get_edge_normal(prevEdge, &prevNormal); 1501 } else { 1502 prevEdge = e; 1503 prevNormal = normal; 1504 e = e->fRight; 1505 } 1506 } 1507} 1508 1509void fix_inversions(Vertex* prev, Vertex* next, Edge* prevBisector, Edge* nextBisector, 1510 Edge* prevEdge, Comparator& c) { 1511 if (!prev || !next) { 1512 return; 1513 } 1514 int winding = c.sweep_lt(prev->fPoint, next->fPoint) ? 1 : -1; 1515 SkPoint p; 1516 uint8_t alpha; 1517 if (winding != prevEdge->fWinding && prevBisector->intersect(*nextBisector, &p, &alpha)) { 1518 prev->fPoint = next->fPoint = p; 1519 prev->fAlpha = next->fAlpha = alpha; 1520 } 1521} 1522 1523// Stage 5d: Displace edges by half a pixel inward and outward along their normals. Intersect to 1524// find new vertices, and set zero alpha on the exterior and one alpha on the interior. Build a 1525// new antialiased mesh from those vertices. 1526 1527void boundary_to_aa_mesh(EdgeList* boundary, VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1528 // A boundary with fewer than 3 edges is degenerate. 1529 if (!boundary->fHead || !boundary->fHead->fRight || !boundary->fHead->fRight->fRight) { 1530 return; 1531 } 1532 Edge* prevEdge = boundary->fTail; 1533 float radius = 0.5f; 1534 double offset = radius * sqrt(prevEdge->fLine.magSq()) * prevEdge->fWinding; 1535 Line prevInner(prevEdge->fTop, prevEdge->fBottom); 1536 prevInner.fC -= offset; 1537 Line prevOuter(prevEdge->fTop, prevEdge->fBottom); 1538 prevOuter.fC += offset; 1539 VertexList innerVertices; 1540 VertexList outerVertices; 1541 Edge* prevBisector = nullptr; 1542 for (Edge* e = boundary->fHead; e != nullptr; e = e->fRight) { 1543 double offset = radius * sqrt(e->fLine.magSq()) * e->fWinding; 1544 Line inner(e->fTop, e->fBottom); 1545 inner.fC -= offset; 1546 Line outer(e->fTop, e->fBottom); 1547 outer.fC += offset; 1548 SkPoint innerPoint, outerPoint; 1549 if (prevInner.intersect(inner, &innerPoint) && 1550 prevOuter.intersect(outer, &outerPoint)) { 1551 Vertex* innerVertex = alloc.make<Vertex>(innerPoint, 255); 1552 Vertex* outerVertex = alloc.make<Vertex>(outerPoint, 0); 1553 Edge* bisector = new_edge(outerVertex, innerVertex, Edge::Type::kConnector, c, alloc); 1554 fix_inversions(innerVertices.fTail, innerVertex, prevBisector, bisector, prevEdge, c); 1555 fix_inversions(outerVertices.fTail, outerVertex, prevBisector, bisector, prevEdge, c); 1556 innerVertices.append(innerVertex); 1557 outerVertices.append(outerVertex); 1558 prevBisector = bisector; 1559 } 1560 prevInner = inner; 1561 prevOuter = outer; 1562 prevEdge = e; 1563 } 1564 innerVertices.close(); 1565 outerVertices.close(); 1566 1567 Vertex* innerVertex = innerVertices.fHead; 1568 Vertex* outerVertex = outerVertices.fHead; 1569 if (!innerVertex || !outerVertex) { 1570 return; 1571 } 1572 Edge* bisector = new_edge(outerVertices.fHead, innerVertices.fHead, Edge::Type::kConnector, c, 1573 alloc); 1574 fix_inversions(innerVertices.fTail, innerVertices.fHead, prevBisector, bisector, prevEdge, c); 1575 fix_inversions(outerVertices.fTail, outerVertices.fHead, prevBisector, bisector, prevEdge, c); 1576 do { 1577 // Connect vertices into a quad mesh. Outer edges get default (1) winding. 1578 // Inner edges get -2 winding. This ensures that the interior is always filled 1579 // (-1 winding number for normal cases, 3 for thin features where the interior inverts). 1580 // Connector edges get zero winding, since they're only structural (i.e., to ensure 1581 // no 0-0-0 alpha triangles are produced), and shouldn't affect the poly winding number. 1582 connect(outerVertex->fPrev, outerVertex, Edge::Type::kOuter, c, alloc); 1583 connect(innerVertex->fPrev, innerVertex, Edge::Type::kInner, c, alloc, -2); 1584 connect(outerVertex, innerVertex, Edge::Type::kConnector, c, alloc, 0); 1585 Vertex* innerNext = innerVertex->fNext; 1586 Vertex* outerNext = outerVertex->fNext; 1587 mesh->append(innerVertex); 1588 mesh->append(outerVertex); 1589 innerVertex = innerNext; 1590 outerVertex = outerNext; 1591 } while (innerVertex != innerVertices.fHead && outerVertex != outerVertices.fHead); 1592} 1593 1594void extract_boundary(EdgeList* boundary, Edge* e, SkPath::FillType fillType, SkArenaAlloc& alloc) { 1595 bool down = apply_fill_type(fillType, e->fWinding); 1596 while (e) { 1597 e->fWinding = down ? 1 : -1; 1598 Edge* next; 1599 boundary->append(e); 1600 if (down) { 1601 // Find outgoing edge, in clockwise order. 1602 if ((next = e->fNextEdgeAbove)) { 1603 down = false; 1604 } else if ((next = e->fBottom->fLastEdgeBelow)) { 1605 down = true; 1606 } else if ((next = e->fPrevEdgeAbove)) { 1607 down = false; 1608 } 1609 } else { 1610 // Find outgoing edge, in counter-clockwise order. 1611 if ((next = e->fPrevEdgeBelow)) { 1612 down = true; 1613 } else if ((next = e->fTop->fFirstEdgeAbove)) { 1614 down = false; 1615 } else if ((next = e->fNextEdgeBelow)) { 1616 down = true; 1617 } 1618 } 1619 disconnect(e); 1620 e = next; 1621 } 1622} 1623 1624// Stage 5b: Extract boundary edges. 1625 1626EdgeList* extract_boundaries(const VertexList& mesh, SkPath::FillType fillType, 1627 SkArenaAlloc& alloc) { 1628 LOG("extracting boundaries\n"); 1629 remove_non_boundary_edges(mesh, fillType, alloc); 1630 EdgeList* boundaries = nullptr; 1631 for (Vertex* v = mesh.fHead; v != nullptr; v = v->fNext) { 1632 while (v->fFirstEdgeBelow) { 1633 EdgeList* boundary = new_contour(&boundaries, alloc); 1634 extract_boundary(boundary, v->fFirstEdgeBelow, fillType, alloc); 1635 } 1636 } 1637 return boundaries; 1638} 1639 1640// This is a driver function which calls stages 2-5 in turn. 1641 1642void contours_to_mesh(Vertex** contours, int contourCnt, bool antialias, 1643 VertexList* mesh, Comparator& c, SkArenaAlloc& alloc) { 1644#if LOGGING_ENABLED 1645 for (int i = 0; i < contourCnt; ++i) { 1646 Vertex* v = contours[i]; 1647 SkASSERT(v); 1648 LOG("path.moveTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); 1649 for (v = v->fNext; v != contours[i]; v = v->fNext) { 1650 LOG("path.lineTo(%20.20g, %20.20g);\n", v->fPoint.fX, v->fPoint.fY); 1651 } 1652 } 1653#endif 1654 sanitize_contours(contours, contourCnt, antialias); 1655 build_edges(contours, contourCnt, mesh, c, alloc); 1656} 1657 1658void sort_and_simplify(VertexList* vertices, Comparator& c, SkArenaAlloc& alloc) { 1659 if (!vertices || !vertices->fHead) { 1660 return; 1661 } 1662 1663 // Sort vertices in Y (secondarily in X). 1664 if (c.fDirection == Comparator::Direction::kHorizontal) { 1665 merge_sort<sweep_lt_horiz>(vertices); 1666 } else { 1667 merge_sort<sweep_lt_vert>(vertices); 1668 } 1669 merge_coincident_vertices(vertices, c, alloc); 1670#if LOGGING_ENABLED 1671 for (Vertex* v = vertices->fHead; v != nullptr; v = v->fNext) { 1672 static float gID = 0.0f; 1673 v->fID = gID++; 1674 } 1675#endif 1676 simplify(*vertices, c, alloc); 1677} 1678 1679Poly* contours_to_polys(Vertex** contours, int contourCnt, SkPath::FillType fillType, 1680 const SkRect& pathBounds, bool antialias, 1681 SkArenaAlloc& alloc) { 1682 Comparator c(pathBounds.width() > pathBounds.height() ? Comparator::Direction::kHorizontal 1683 : Comparator::Direction::kVertical); 1684 VertexList mesh; 1685 contours_to_mesh(contours, contourCnt, antialias, &mesh, c, alloc); 1686 sort_and_simplify(&mesh, c, alloc); 1687 if (antialias) { 1688 EdgeList* boundaries = extract_boundaries(mesh, fillType, alloc); 1689 VertexList aaMesh; 1690 for (EdgeList* boundary = boundaries; boundary != nullptr; boundary = boundary->fNext) { 1691 simplify_boundary(boundary, c, alloc); 1692 boundary_to_aa_mesh(boundary, &aaMesh, c, alloc); 1693 } 1694 sort_and_simplify(&aaMesh, c, alloc); 1695 return tessellate(aaMesh, alloc); 1696 } else { 1697 return tessellate(mesh, alloc); 1698 } 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, SkArenaAlloc& 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 1725int get_contour_count(const SkPath& path, SkScalar tolerance) { 1726 int contourCnt; 1727 int maxPts = GrPathUtils::worstCasePointCount(path, &contourCnt, tolerance); 1728 if (maxPts <= 0) { 1729 return 0; 1730 } 1731 if (maxPts > ((int)SK_MaxU16 + 1)) { 1732 SkDebugf("Path not rendered, too many verts (%d)\n", maxPts); 1733 return 0; 1734 } 1735 return contourCnt; 1736} 1737 1738int count_points(Poly* polys, SkPath::FillType fillType) { 1739 int count = 0; 1740 for (Poly* poly = polys; poly; poly = poly->fNext) { 1741 if (apply_fill_type(fillType, poly) && poly->fCount >= 3) { 1742 count += (poly->fCount - 2) * (TESSELLATOR_WIREFRAME ? 6 : 3); 1743 } 1744 } 1745 return count; 1746} 1747 1748} // namespace 1749 1750namespace GrTessellator { 1751 1752// Stage 6: Triangulate the monotone polygons into a vertex buffer. 1753 1754int PathToTriangles(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 1755 VertexAllocator* vertexAllocator, bool antialias, const GrColor& color, 1756 bool canTweakAlphaForCoverage, bool* isLinear) { 1757 int contourCnt = get_contour_count(path, tolerance); 1758 if (contourCnt <= 0) { 1759 *isLinear = true; 1760 return 0; 1761 } 1762 SkArenaAlloc alloc(kArenaChunkSize); 1763 Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, antialias, 1764 isLinear); 1765 SkPath::FillType fillType = antialias ? SkPath::kWinding_FillType : path.getFillType(); 1766 int count = count_points(polys, fillType); 1767 if (0 == count) { 1768 return 0; 1769 } 1770 1771 void* verts = vertexAllocator->lock(count); 1772 if (!verts) { 1773 SkDebugf("Could not allocate vertices\n"); 1774 return 0; 1775 } 1776 1777 LOG("emitting %d verts\n", count); 1778 AAParams aaParams; 1779 aaParams.fTweakAlpha = canTweakAlphaForCoverage; 1780 aaParams.fColor = color; 1781 1782 void* end = polys_to_triangles(polys, fillType, antialias ? &aaParams : nullptr, verts); 1783 int actualCount = static_cast<int>((static_cast<uint8_t*>(end) - static_cast<uint8_t*>(verts)) 1784 / vertexAllocator->stride()); 1785 SkASSERT(actualCount <= count); 1786 vertexAllocator->unlock(actualCount); 1787 return actualCount; 1788} 1789 1790int PathToVertices(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 1791 GrTessellator::WindingVertex** verts) { 1792 int contourCnt = get_contour_count(path, tolerance); 1793 if (contourCnt <= 0) { 1794 return 0; 1795 } 1796 SkArenaAlloc alloc(kArenaChunkSize); 1797 bool isLinear; 1798 Poly* polys = path_to_polys(path, tolerance, clipBounds, contourCnt, alloc, false, &isLinear); 1799 SkPath::FillType fillType = path.getFillType(); 1800 int count = count_points(polys, fillType); 1801 if (0 == count) { 1802 *verts = nullptr; 1803 return 0; 1804 } 1805 1806 *verts = new GrTessellator::WindingVertex[count]; 1807 GrTessellator::WindingVertex* vertsEnd = *verts; 1808 SkPoint* points = new SkPoint[count]; 1809 SkPoint* pointsEnd = points; 1810 for (Poly* poly = polys; poly; poly = poly->fNext) { 1811 if (apply_fill_type(fillType, poly)) { 1812 SkPoint* start = pointsEnd; 1813 pointsEnd = static_cast<SkPoint*>(poly->emit(nullptr, pointsEnd)); 1814 while (start != pointsEnd) { 1815 vertsEnd->fPos = *start; 1816 vertsEnd->fWinding = poly->fWinding; 1817 ++start; 1818 ++vertsEnd; 1819 } 1820 } 1821 } 1822 int actualCount = static_cast<int>(vertsEnd - *verts); 1823 SkASSERT(actualCount <= count); 1824 SkASSERT(pointsEnd - points == actualCount); 1825 delete[] points; 1826 return actualCount; 1827} 1828 1829} // namespace 1830