1 2 /* 3 * Copyright 2012 Google Inc. 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 #include "GrAAConvexPathRenderer.h" 10 11 #include "GrContext.h" 12 #include "GrDrawState.h" 13 #include "GrDrawTargetCaps.h" 14 #include "GrEffect.h" 15 #include "GrPathUtils.h" 16 #include "GrTBackendEffectFactory.h" 17 #include "SkString.h" 18 #include "SkStrokeRec.h" 19 #include "SkTrace.h" 20 21 #include "gl/GrGLEffect.h" 22 #include "gl/GrGLSL.h" 23 #include "gl/GrGLVertexEffect.h" 24 25 #include "effects/GrVertexEffect.h" 26 27 GrAAConvexPathRenderer::GrAAConvexPathRenderer() { 28 } 29 30 struct Segment { 31 enum { 32 // These enum values are assumed in member functions below. 33 kLine = 0, 34 kQuad = 1, 35 } fType; 36 37 // line uses one pt, quad uses 2 pts 38 GrPoint fPts[2]; 39 // normal to edge ending at each pt 40 GrVec fNorms[2]; 41 // is the corner where the previous segment meets this segment 42 // sharp. If so, fMid is a normalized bisector facing outward. 43 GrVec fMid; 44 45 int countPoints() { 46 GR_STATIC_ASSERT(0 == kLine && 1 == kQuad); 47 return fType + 1; 48 } 49 const SkPoint& endPt() const { 50 GR_STATIC_ASSERT(0 == kLine && 1 == kQuad); 51 return fPts[fType]; 52 }; 53 const SkPoint& endNorm() const { 54 GR_STATIC_ASSERT(0 == kLine && 1 == kQuad); 55 return fNorms[fType]; 56 }; 57 }; 58 59 typedef SkTArray<Segment, true> SegmentArray; 60 61 static void center_of_mass(const SegmentArray& segments, SkPoint* c) { 62 SkScalar area = 0; 63 SkPoint center = {0, 0}; 64 int count = segments.count(); 65 SkPoint p0 = {0, 0}; 66 if (count > 2) { 67 // We translate the polygon so that the first point is at the origin. 68 // This avoids some precision issues with small area polygons far away 69 // from the origin. 70 p0 = segments[0].endPt(); 71 SkPoint pi; 72 SkPoint pj; 73 // the first and last iteration of the below loop would compute 74 // zeros since the starting / ending point is (0,0). So instead we start 75 // at i=1 and make the last iteration i=count-2. 76 pj = segments[1].endPt() - p0; 77 for (int i = 1; i < count - 1; ++i) { 78 pi = pj; 79 const SkPoint pj = segments[i + 1].endPt() - p0; 80 81 SkScalar t = SkScalarMul(pi.fX, pj.fY) - SkScalarMul(pj.fX, pi.fY); 82 area += t; 83 center.fX += (pi.fX + pj.fX) * t; 84 center.fY += (pi.fY + pj.fY) * t; 85 86 } 87 } 88 // If the poly has no area then we instead return the average of 89 // its points. 90 if (SkScalarNearlyZero(area)) { 91 SkPoint avg; 92 avg.set(0, 0); 93 for (int i = 0; i < count; ++i) { 94 const SkPoint& pt = segments[i].endPt(); 95 avg.fX += pt.fX; 96 avg.fY += pt.fY; 97 } 98 SkScalar denom = SK_Scalar1 / count; 99 avg.scale(denom); 100 *c = avg; 101 } else { 102 area *= 3; 103 area = SkScalarDiv(SK_Scalar1, area); 104 center.fX = SkScalarMul(center.fX, area); 105 center.fY = SkScalarMul(center.fY, area); 106 // undo the translate of p0 to the origin. 107 *c = center + p0; 108 } 109 SkASSERT(!SkScalarIsNaN(c->fX) && !SkScalarIsNaN(c->fY)); 110 } 111 112 static void compute_vectors(SegmentArray* segments, 113 SkPoint* fanPt, 114 SkPath::Direction dir, 115 int* vCount, 116 int* iCount) { 117 center_of_mass(*segments, fanPt); 118 int count = segments->count(); 119 120 // Make the normals point towards the outside 121 GrPoint::Side normSide; 122 if (dir == SkPath::kCCW_Direction) { 123 normSide = GrPoint::kRight_Side; 124 } else { 125 normSide = GrPoint::kLeft_Side; 126 } 127 128 *vCount = 0; 129 *iCount = 0; 130 // compute normals at all points 131 for (int a = 0; a < count; ++a) { 132 Segment& sega = (*segments)[a]; 133 int b = (a + 1) % count; 134 Segment& segb = (*segments)[b]; 135 136 const GrPoint* prevPt = &sega.endPt(); 137 int n = segb.countPoints(); 138 for (int p = 0; p < n; ++p) { 139 segb.fNorms[p] = segb.fPts[p] - *prevPt; 140 segb.fNorms[p].normalize(); 141 segb.fNorms[p].setOrthog(segb.fNorms[p], normSide); 142 prevPt = &segb.fPts[p]; 143 } 144 if (Segment::kLine == segb.fType) { 145 *vCount += 5; 146 *iCount += 9; 147 } else { 148 *vCount += 6; 149 *iCount += 12; 150 } 151 } 152 153 // compute mid-vectors where segments meet. TODO: Detect shallow corners 154 // and leave out the wedges and close gaps by stitching segments together. 155 for (int a = 0; a < count; ++a) { 156 const Segment& sega = (*segments)[a]; 157 int b = (a + 1) % count; 158 Segment& segb = (*segments)[b]; 159 segb.fMid = segb.fNorms[0] + sega.endNorm(); 160 segb.fMid.normalize(); 161 // corner wedges 162 *vCount += 4; 163 *iCount += 6; 164 } 165 } 166 167 struct DegenerateTestData { 168 DegenerateTestData() { fStage = kInitial; } 169 bool isDegenerate() const { return kNonDegenerate != fStage; } 170 enum { 171 kInitial, 172 kPoint, 173 kLine, 174 kNonDegenerate 175 } fStage; 176 GrPoint fFirstPoint; 177 GrVec fLineNormal; 178 SkScalar fLineC; 179 }; 180 181 static const SkScalar kClose = (SK_Scalar1 / 16); 182 static const SkScalar kCloseSqd = SkScalarMul(kClose, kClose); 183 184 static void update_degenerate_test(DegenerateTestData* data, const GrPoint& pt) { 185 switch (data->fStage) { 186 case DegenerateTestData::kInitial: 187 data->fFirstPoint = pt; 188 data->fStage = DegenerateTestData::kPoint; 189 break; 190 case DegenerateTestData::kPoint: 191 if (pt.distanceToSqd(data->fFirstPoint) > kCloseSqd) { 192 data->fLineNormal = pt - data->fFirstPoint; 193 data->fLineNormal.normalize(); 194 data->fLineNormal.setOrthog(data->fLineNormal); 195 data->fLineC = -data->fLineNormal.dot(data->fFirstPoint); 196 data->fStage = DegenerateTestData::kLine; 197 } 198 break; 199 case DegenerateTestData::kLine: 200 if (SkScalarAbs(data->fLineNormal.dot(pt) + data->fLineC) > kClose) { 201 data->fStage = DegenerateTestData::kNonDegenerate; 202 } 203 case DegenerateTestData::kNonDegenerate: 204 break; 205 default: 206 GrCrash("Unexpected degenerate test stage."); 207 } 208 } 209 210 static inline bool get_direction(const SkPath& path, const SkMatrix& m, SkPath::Direction* dir) { 211 if (!path.cheapComputeDirection(dir)) { 212 return false; 213 } 214 // check whether m reverses the orientation 215 SkASSERT(!m.hasPerspective()); 216 SkScalar det2x2 = SkScalarMul(m.get(SkMatrix::kMScaleX), m.get(SkMatrix::kMScaleY)) - 217 SkScalarMul(m.get(SkMatrix::kMSkewX), m.get(SkMatrix::kMSkewY)); 218 if (det2x2 < 0) { 219 *dir = SkPath::OppositeDirection(*dir); 220 } 221 return true; 222 } 223 224 static inline void add_line_to_segment(const SkPoint& pt, 225 SegmentArray* segments, 226 SkRect* devBounds) { 227 segments->push_back(); 228 segments->back().fType = Segment::kLine; 229 segments->back().fPts[0] = pt; 230 devBounds->growToInclude(pt.fX, pt.fY); 231 } 232 233 #ifdef SK_DEBUG 234 static inline bool contains_inclusive(const SkRect& rect, const SkPoint& p) { 235 return p.fX >= rect.fLeft && p.fX <= rect.fRight && p.fY >= rect.fTop && p.fY <= rect.fBottom; 236 } 237 #endif 238 239 static inline void add_quad_segment(const SkPoint pts[3], 240 SegmentArray* segments, 241 SkRect* devBounds) { 242 if (pts[0].distanceToSqd(pts[1]) < kCloseSqd || pts[1].distanceToSqd(pts[2]) < kCloseSqd) { 243 if (pts[0] != pts[2]) { 244 add_line_to_segment(pts[2], segments, devBounds); 245 } 246 } else { 247 segments->push_back(); 248 segments->back().fType = Segment::kQuad; 249 segments->back().fPts[0] = pts[1]; 250 segments->back().fPts[1] = pts[2]; 251 SkASSERT(contains_inclusive(*devBounds, pts[0])); 252 devBounds->growToInclude(pts + 1, 2); 253 } 254 } 255 256 static inline void add_cubic_segments(const SkPoint pts[4], 257 SkPath::Direction dir, 258 SegmentArray* segments, 259 SkRect* devBounds) { 260 SkSTArray<15, SkPoint, true> quads; 261 GrPathUtils::convertCubicToQuads(pts, SK_Scalar1, true, dir, &quads); 262 int count = quads.count(); 263 for (int q = 0; q < count; q += 3) { 264 add_quad_segment(&quads[q], segments, devBounds); 265 } 266 } 267 268 static bool get_segments(const SkPath& path, 269 const SkMatrix& m, 270 SegmentArray* segments, 271 SkPoint* fanPt, 272 int* vCount, 273 int* iCount, 274 SkRect* devBounds) { 275 SkPath::Iter iter(path, true); 276 // This renderer over-emphasizes very thin path regions. We use the distance 277 // to the path from the sample to compute coverage. Every pixel intersected 278 // by the path will be hit and the maximum distance is sqrt(2)/2. We don't 279 // notice that the sample may be close to a very thin area of the path and 280 // thus should be very light. This is particularly egregious for degenerate 281 // line paths. We detect paths that are very close to a line (zero area) and 282 // draw nothing. 283 DegenerateTestData degenerateData; 284 SkPath::Direction dir; 285 // get_direction can fail for some degenerate paths. 286 if (!get_direction(path, m, &dir)) { 287 return false; 288 } 289 290 for (;;) { 291 GrPoint pts[4]; 292 SkPath::Verb verb = iter.next(pts); 293 switch (verb) { 294 case SkPath::kMove_Verb: 295 m.mapPoints(pts, 1); 296 update_degenerate_test(°enerateData, pts[0]); 297 devBounds->set(pts->fX, pts->fY, pts->fX, pts->fY); 298 break; 299 case SkPath::kLine_Verb: { 300 m.mapPoints(&pts[1], 1); 301 update_degenerate_test(°enerateData, pts[1]); 302 add_line_to_segment(pts[1], segments, devBounds); 303 break; 304 } 305 case SkPath::kQuad_Verb: 306 m.mapPoints(pts, 3); 307 update_degenerate_test(°enerateData, pts[1]); 308 update_degenerate_test(°enerateData, pts[2]); 309 add_quad_segment(pts, segments, devBounds); 310 break; 311 case SkPath::kCubic_Verb: { 312 m.mapPoints(pts, 4); 313 update_degenerate_test(°enerateData, pts[1]); 314 update_degenerate_test(°enerateData, pts[2]); 315 update_degenerate_test(°enerateData, pts[3]); 316 add_cubic_segments(pts, dir, segments, devBounds); 317 break; 318 }; 319 case SkPath::kDone_Verb: 320 if (degenerateData.isDegenerate()) { 321 return false; 322 } else { 323 compute_vectors(segments, fanPt, dir, vCount, iCount); 324 return true; 325 } 326 default: 327 break; 328 } 329 } 330 } 331 332 struct QuadVertex { 333 GrPoint fPos; 334 GrPoint fUV; 335 SkScalar fD0; 336 SkScalar fD1; 337 }; 338 339 struct Draw { 340 Draw() : fVertexCnt(0), fIndexCnt(0) {} 341 int fVertexCnt; 342 int fIndexCnt; 343 }; 344 345 typedef SkTArray<Draw, true> DrawArray; 346 347 static void create_vertices(const SegmentArray& segments, 348 const SkPoint& fanPt, 349 DrawArray* draws, 350 QuadVertex* verts, 351 uint16_t* idxs) { 352 Draw* draw = &draws->push_back(); 353 // alias just to make vert/index assignments easier to read. 354 int* v = &draw->fVertexCnt; 355 int* i = &draw->fIndexCnt; 356 357 int count = segments.count(); 358 for (int a = 0; a < count; ++a) { 359 const Segment& sega = segments[a]; 360 int b = (a + 1) % count; 361 const Segment& segb = segments[b]; 362 363 // Check whether adding the verts for this segment to the current draw would cause index 364 // values to overflow. 365 int vCount = 4; 366 if (Segment::kLine == segb.fType) { 367 vCount += 5; 368 } else { 369 vCount += 6; 370 } 371 if (draw->fVertexCnt + vCount > (1 << 16)) { 372 verts += *v; 373 idxs += *i; 374 draw = &draws->push_back(); 375 v = &draw->fVertexCnt; 376 i = &draw->fIndexCnt; 377 } 378 379 // FIXME: These tris are inset in the 1 unit arc around the corner 380 verts[*v + 0].fPos = sega.endPt(); 381 verts[*v + 1].fPos = verts[*v + 0].fPos + sega.endNorm(); 382 verts[*v + 2].fPos = verts[*v + 0].fPos + segb.fMid; 383 verts[*v + 3].fPos = verts[*v + 0].fPos + segb.fNorms[0]; 384 verts[*v + 0].fUV.set(0,0); 385 verts[*v + 1].fUV.set(0,-SK_Scalar1); 386 verts[*v + 2].fUV.set(0,-SK_Scalar1); 387 verts[*v + 3].fUV.set(0,-SK_Scalar1); 388 verts[*v + 0].fD0 = verts[*v + 0].fD1 = -SK_Scalar1; 389 verts[*v + 1].fD0 = verts[*v + 1].fD1 = -SK_Scalar1; 390 verts[*v + 2].fD0 = verts[*v + 2].fD1 = -SK_Scalar1; 391 verts[*v + 3].fD0 = verts[*v + 3].fD1 = -SK_Scalar1; 392 393 idxs[*i + 0] = *v + 0; 394 idxs[*i + 1] = *v + 2; 395 idxs[*i + 2] = *v + 1; 396 idxs[*i + 3] = *v + 0; 397 idxs[*i + 4] = *v + 3; 398 idxs[*i + 5] = *v + 2; 399 400 *v += 4; 401 *i += 6; 402 403 if (Segment::kLine == segb.fType) { 404 verts[*v + 0].fPos = fanPt; 405 verts[*v + 1].fPos = sega.endPt(); 406 verts[*v + 2].fPos = segb.fPts[0]; 407 408 verts[*v + 3].fPos = verts[*v + 1].fPos + segb.fNorms[0]; 409 verts[*v + 4].fPos = verts[*v + 2].fPos + segb.fNorms[0]; 410 411 // we draw the line edge as a degenerate quad (u is 0, v is the 412 // signed distance to the edge) 413 SkScalar dist = fanPt.distanceToLineBetween(verts[*v + 1].fPos, 414 verts[*v + 2].fPos); 415 verts[*v + 0].fUV.set(0, dist); 416 verts[*v + 1].fUV.set(0, 0); 417 verts[*v + 2].fUV.set(0, 0); 418 verts[*v + 3].fUV.set(0, -SK_Scalar1); 419 verts[*v + 4].fUV.set(0, -SK_Scalar1); 420 421 verts[*v + 0].fD0 = verts[*v + 0].fD1 = -SK_Scalar1; 422 verts[*v + 1].fD0 = verts[*v + 1].fD1 = -SK_Scalar1; 423 verts[*v + 2].fD0 = verts[*v + 2].fD1 = -SK_Scalar1; 424 verts[*v + 3].fD0 = verts[*v + 3].fD1 = -SK_Scalar1; 425 verts[*v + 4].fD0 = verts[*v + 4].fD1 = -SK_Scalar1; 426 427 idxs[*i + 0] = *v + 0; 428 idxs[*i + 1] = *v + 2; 429 idxs[*i + 2] = *v + 1; 430 431 idxs[*i + 3] = *v + 3; 432 idxs[*i + 4] = *v + 1; 433 idxs[*i + 5] = *v + 2; 434 435 idxs[*i + 6] = *v + 4; 436 idxs[*i + 7] = *v + 3; 437 idxs[*i + 8] = *v + 2; 438 439 *v += 5; 440 *i += 9; 441 } else { 442 GrPoint qpts[] = {sega.endPt(), segb.fPts[0], segb.fPts[1]}; 443 444 GrVec midVec = segb.fNorms[0] + segb.fNorms[1]; 445 midVec.normalize(); 446 447 verts[*v + 0].fPos = fanPt; 448 verts[*v + 1].fPos = qpts[0]; 449 verts[*v + 2].fPos = qpts[2]; 450 verts[*v + 3].fPos = qpts[0] + segb.fNorms[0]; 451 verts[*v + 4].fPos = qpts[2] + segb.fNorms[1]; 452 verts[*v + 5].fPos = qpts[1] + midVec; 453 454 SkScalar c = segb.fNorms[0].dot(qpts[0]); 455 verts[*v + 0].fD0 = -segb.fNorms[0].dot(fanPt) + c; 456 verts[*v + 1].fD0 = 0.f; 457 verts[*v + 2].fD0 = -segb.fNorms[0].dot(qpts[2]) + c; 458 verts[*v + 3].fD0 = -SK_ScalarMax/100; 459 verts[*v + 4].fD0 = -SK_ScalarMax/100; 460 verts[*v + 5].fD0 = -SK_ScalarMax/100; 461 462 c = segb.fNorms[1].dot(qpts[2]); 463 verts[*v + 0].fD1 = -segb.fNorms[1].dot(fanPt) + c; 464 verts[*v + 1].fD1 = -segb.fNorms[1].dot(qpts[0]) + c; 465 verts[*v + 2].fD1 = 0.f; 466 verts[*v + 3].fD1 = -SK_ScalarMax/100; 467 verts[*v + 4].fD1 = -SK_ScalarMax/100; 468 verts[*v + 5].fD1 = -SK_ScalarMax/100; 469 470 GrPathUtils::QuadUVMatrix toUV(qpts); 471 toUV.apply<6, sizeof(QuadVertex), sizeof(GrPoint)>(verts + *v); 472 473 idxs[*i + 0] = *v + 3; 474 idxs[*i + 1] = *v + 1; 475 idxs[*i + 2] = *v + 2; 476 idxs[*i + 3] = *v + 4; 477 idxs[*i + 4] = *v + 3; 478 idxs[*i + 5] = *v + 2; 479 480 idxs[*i + 6] = *v + 5; 481 idxs[*i + 7] = *v + 3; 482 idxs[*i + 8] = *v + 4; 483 484 idxs[*i + 9] = *v + 0; 485 idxs[*i + 10] = *v + 2; 486 idxs[*i + 11] = *v + 1; 487 488 *v += 6; 489 *i += 12; 490 } 491 } 492 } 493 494 /////////////////////////////////////////////////////////////////////////////// 495 496 /* 497 * Quadratic specified by 0=u^2-v canonical coords. u and v are the first 498 * two components of the vertex attribute. Coverage is based on signed 499 * distance with negative being inside, positive outside. The edge is specified in 500 * window space (y-down). If either the third or fourth component of the interpolated 501 * vertex coord is > 0 then the pixel is considered outside the edge. This is used to 502 * attempt to trim to a portion of the infinite quad. 503 * Requires shader derivative instruction support. 504 */ 505 506 class QuadEdgeEffect : public GrVertexEffect { 507 public: 508 509 static GrEffectRef* Create() { 510 GR_CREATE_STATIC_EFFECT(gQuadEdgeEffect, QuadEdgeEffect, ()); 511 gQuadEdgeEffect->ref(); 512 return gQuadEdgeEffect; 513 } 514 515 virtual ~QuadEdgeEffect() {} 516 517 static const char* Name() { return "QuadEdge"; } 518 519 virtual void getConstantColorComponents(GrColor* color, 520 uint32_t* validFlags) const SK_OVERRIDE { 521 *validFlags = 0; 522 } 523 524 virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE { 525 return GrTBackendEffectFactory<QuadEdgeEffect>::getInstance(); 526 } 527 528 class GLEffect : public GrGLVertexEffect { 529 public: 530 GLEffect(const GrBackendEffectFactory& factory, const GrDrawEffect&) 531 : INHERITED (factory) {} 532 533 virtual void emitCode(GrGLFullShaderBuilder* builder, 534 const GrDrawEffect& drawEffect, 535 EffectKey key, 536 const char* outputColor, 537 const char* inputColor, 538 const TransformedCoordsArray&, 539 const TextureSamplerArray& samplers) SK_OVERRIDE { 540 const char *vsName, *fsName; 541 const SkString* attrName = 542 builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0]); 543 builder->fsCodeAppendf("\t\tfloat edgeAlpha;\n"); 544 545 SkAssertResult(builder->enableFeature( 546 GrGLShaderBuilder::kStandardDerivatives_GLSLFeature)); 547 builder->addVarying(kVec4f_GrSLType, "QuadEdge", &vsName, &fsName); 548 549 // keep the derivative instructions outside the conditional 550 builder->fsCodeAppendf("\t\tvec2 duvdx = dFdx(%s.xy);\n", fsName); 551 builder->fsCodeAppendf("\t\tvec2 duvdy = dFdy(%s.xy);\n", fsName); 552 builder->fsCodeAppendf("\t\tif (%s.z > 0.0 && %s.w > 0.0) {\n", fsName, fsName); 553 // today we know z and w are in device space. We could use derivatives 554 builder->fsCodeAppendf("\t\t\tedgeAlpha = min(min(%s.z, %s.w) + 0.5, 1.0);\n", fsName, 555 fsName); 556 builder->fsCodeAppendf ("\t\t} else {\n"); 557 builder->fsCodeAppendf("\t\t\tvec2 gF = vec2(2.0*%s.x*duvdx.x - duvdx.y,\n" 558 "\t\t\t 2.0*%s.x*duvdy.x - duvdy.y);\n", 559 fsName, fsName); 560 builder->fsCodeAppendf("\t\t\tedgeAlpha = (%s.x*%s.x - %s.y);\n", fsName, fsName, 561 fsName); 562 builder->fsCodeAppendf("\t\t\tedgeAlpha = " 563 "clamp(0.5 - edgeAlpha / length(gF), 0.0, 1.0);\n\t\t}\n"); 564 565 566 builder->fsCodeAppendf("\t%s = %s;\n", outputColor, 567 (GrGLSLExpr4(inputColor) * GrGLSLExpr1("edgeAlpha")).c_str()); 568 569 builder->vsCodeAppendf("\t%s = %s;\n", vsName, attrName->c_str()); 570 } 571 572 static inline EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) { 573 return 0x0; 574 } 575 576 virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE {} 577 578 private: 579 typedef GrGLVertexEffect INHERITED; 580 }; 581 582 private: 583 QuadEdgeEffect() { 584 this->addVertexAttrib(kVec4f_GrSLType); 585 } 586 587 virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE { 588 return true; 589 } 590 591 GR_DECLARE_EFFECT_TEST; 592 593 typedef GrVertexEffect INHERITED; 594 }; 595 596 GR_DEFINE_EFFECT_TEST(QuadEdgeEffect); 597 598 GrEffectRef* QuadEdgeEffect::TestCreate(SkRandom* random, 599 GrContext*, 600 const GrDrawTargetCaps& caps, 601 GrTexture*[]) { 602 // Doesn't work without derivative instructions. 603 return caps.shaderDerivativeSupport() ? QuadEdgeEffect::Create() : NULL; 604 } 605 606 /////////////////////////////////////////////////////////////////////////////// 607 608 bool GrAAConvexPathRenderer::canDrawPath(const SkPath& path, 609 const SkStrokeRec& stroke, 610 const GrDrawTarget* target, 611 bool antiAlias) const { 612 return (target->caps()->shaderDerivativeSupport() && antiAlias && 613 stroke.isFillStyle() && !path.isInverseFillType() && path.isConvex()); 614 } 615 616 namespace { 617 618 // position + edge 619 extern const GrVertexAttrib gPathAttribs[] = { 620 {kVec2f_GrVertexAttribType, 0, kPosition_GrVertexAttribBinding}, 621 {kVec4f_GrVertexAttribType, sizeof(GrPoint), kEffect_GrVertexAttribBinding} 622 }; 623 624 }; 625 626 bool GrAAConvexPathRenderer::onDrawPath(const SkPath& origPath, 627 const SkStrokeRec&, 628 GrDrawTarget* target, 629 bool antiAlias) { 630 631 const SkPath* path = &origPath; 632 if (path->isEmpty()) { 633 return true; 634 } 635 636 SkMatrix viewMatrix = target->getDrawState().getViewMatrix(); 637 GrDrawTarget::AutoStateRestore asr; 638 if (!asr.setIdentity(target, GrDrawTarget::kPreserve_ASRInit)) { 639 return false; 640 } 641 GrDrawState* drawState = target->drawState(); 642 643 // We use the fact that SkPath::transform path does subdivision based on 644 // perspective. Otherwise, we apply the view matrix when copying to the 645 // segment representation. 646 SkPath tmpPath; 647 if (viewMatrix.hasPerspective()) { 648 origPath.transform(viewMatrix, &tmpPath); 649 path = &tmpPath; 650 viewMatrix = SkMatrix::I(); 651 } 652 653 QuadVertex *verts; 654 uint16_t* idxs; 655 656 int vCount; 657 int iCount; 658 enum { 659 kPreallocSegmentCnt = 512 / sizeof(Segment), 660 kPreallocDrawCnt = 4, 661 }; 662 SkSTArray<kPreallocSegmentCnt, Segment, true> segments; 663 SkPoint fanPt; 664 665 // We can't simply use the path bounds because we may degenerate cubics to quads which produces 666 // new control points outside the original convex hull. 667 SkRect devBounds; 668 if (!get_segments(*path, viewMatrix, &segments, &fanPt, &vCount, &iCount, &devBounds)) { 669 return false; 670 } 671 672 // Our computed verts should all be within one pixel of the segment control points. 673 devBounds.outset(SK_Scalar1, SK_Scalar1); 674 675 drawState->setVertexAttribs<gPathAttribs>(SK_ARRAY_COUNT(gPathAttribs)); 676 677 static const int kEdgeAttrIndex = 1; 678 GrEffectRef* quadEffect = QuadEdgeEffect::Create(); 679 drawState->addCoverageEffect(quadEffect, kEdgeAttrIndex)->unref(); 680 681 GrDrawTarget::AutoReleaseGeometry arg(target, vCount, iCount); 682 if (!arg.succeeded()) { 683 return false; 684 } 685 SkASSERT(sizeof(QuadVertex) == drawState->getVertexSize()); 686 verts = reinterpret_cast<QuadVertex*>(arg.vertices()); 687 idxs = reinterpret_cast<uint16_t*>(arg.indices()); 688 689 SkSTArray<kPreallocDrawCnt, Draw, true> draws; 690 create_vertices(segments, fanPt, &draws, verts, idxs); 691 692 // Check devBounds 693 #ifdef SK_DEBUG 694 SkRect tolDevBounds = devBounds; 695 tolDevBounds.outset(SK_Scalar1 / 10000, SK_Scalar1 / 10000); 696 SkRect actualBounds; 697 actualBounds.set(verts[0].fPos, verts[1].fPos); 698 for (int i = 2; i < vCount; ++i) { 699 actualBounds.growToInclude(verts[i].fPos.fX, verts[i].fPos.fY); 700 } 701 SkASSERT(tolDevBounds.contains(actualBounds)); 702 #endif 703 704 int vOffset = 0; 705 for (int i = 0; i < draws.count(); ++i) { 706 const Draw& draw = draws[i]; 707 target->drawIndexed(kTriangles_GrPrimitiveType, 708 vOffset, // start vertex 709 0, // start index 710 draw.fVertexCnt, 711 draw.fIndexCnt, 712 &devBounds); 713 vOffset += draw.fVertexCnt; 714 } 715 716 return true; 717 } 718
