| OLD | NEW |
|---|
| (Empty) |
| 1 /* | |
| 2 * Copyright 2016 ARM Ltd. | |
| 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 "GrDistanceFieldGenFromVector.h" | |
| 9 #include "SkPoint.h" | |
| 10 #include "SkGeometry.h" | |
| 11 #include "SkPathOps.h" | |
| 12 #include "GrPathUtils.h" | |
| 13 #include "GrConfig.h" | |
| 14 | |
| 15 /** | |
| 16 * If a scanline (a row of texel) cross from the kRight_SegSide | |
| 17 * of a segment to the kLeft_SegSide, the winding score should | |
| 18 * add 1. | |
| 19 * And winding score should subtract 1 if the scanline cross | |
| 20 * from kLeft_SegSide to kRight_SegSide. | |
| 21 * Always return kNA_SegSide if the scanline does not cross over | |
| 22 * the segment. Winding score should be zero in this case. | |
| 23 * You can get the winding number for each texel of the scanline | |
| 24 * by adding the winding score from left to right. | |
| 25 * Assuming we always start from outside, so the winding number | |
| 26 * should always start from zero. | |
| 27 * ________ ________ | |
| 28 * | | | | | |
| 29 * ...R|L......L|R.....L|R......R|L..... <= Scanline & side of segment | |
| 30 * |+1 |-1 |-1 |+1 <= Winding score | |
| 31 * 0 | 1 ^ 0 ^ -1 |0 <= Winding number | |
| 32 * |________| |________| | |
| 33 * | |
| 34 * .......NA................NA.......... | |
| 35 * 0 0 | |
| 36 */ | |
| 37 enum SegSide { | |
| 38 kLeft_SegSide = -1, | |
| 39 kOn_SegSide = 0, | |
| 40 kRight_SegSide = 1, | |
| 41 kNA_SegSide = 2, | |
| 42 }; | |
| 43 | |
| 44 struct DFData { | |
| 45 float fDistSq; // distance squared to nearest (so far) edge | |
| 46 int fDeltaWindingScore; // +1 or -1 whenever a scanline cross over a segme
nt | |
| 47 }; | |
| 48 | |
| 49 /////////////////////////////////////////////////////////////////////////////// | |
| 50 | |
| 51 /* | |
| 52 * Type definition for double precision DPoint and DAffineMatrix | |
| 53 */ | |
| 54 | |
| 55 // Point with double precision | |
| 56 struct DPoint { | |
| 57 double fX, fY; | |
| 58 | |
| 59 static DPoint Make(double x, double y) { | |
| 60 DPoint pt; | |
| 61 pt.set(x, y); | |
| 62 return pt; | |
| 63 } | |
| 64 | |
| 65 double x() const { return fX; } | |
| 66 double y() const { return fY; } | |
| 67 | |
| 68 void set(double x, double y) { fX = x; fY = y; } | |
| 69 | |
| 70 /** Returns the euclidian distance from (0,0) to (x,y) | |
| 71 */ | |
| 72 static double Length(double x, double y) { | |
| 73 return sqrt(x * x + y * y); | |
| 74 } | |
| 75 | |
| 76 /** Returns the euclidian distance between a and b | |
| 77 */ | |
| 78 static double Distance(const DPoint& a, const DPoint& b) { | |
| 79 return Length(a.fX - b.fX, a.fY - b.fY); | |
| 80 } | |
| 81 | |
| 82 double distanceToSqd(const DPoint& pt) const { | |
| 83 double dx = fX - pt.fX; | |
| 84 double dy = fY - pt.fY; | |
| 85 return dx * dx + dy * dy; | |
| 86 } | |
| 87 }; | |
| 88 | |
| 89 // Matrix with double precision for affine transformation. | |
| 90 // We don't store row 3 because its always (0, 0, 1). | |
| 91 class DAffineMatrix { | |
| 92 public: | |
| 93 double operator[](int index) const { | |
| 94 SkASSERT((unsigned)index < 6); | |
| 95 return fMat[index]; | |
| 96 } | |
| 97 | |
| 98 double& operator[](int index) { | |
| 99 SkASSERT((unsigned)index < 6); | |
| 100 return fMat[index]; | |
| 101 } | |
| 102 | |
| 103 void setAffine(double m11, double m12, double m13, | |
| 104 double m21, double m22, double m23) { | |
| 105 fMat[0] = m11; | |
| 106 fMat[1] = m12; | |
| 107 fMat[2] = m13; | |
| 108 fMat[3] = m21; | |
| 109 fMat[4] = m22; | |
| 110 fMat[5] = m23; | |
| 111 } | |
| 112 | |
| 113 /** Set the matrix to identity | |
| 114 */ | |
| 115 void reset() { | |
| 116 fMat[0] = fMat[4] = 1.0; | |
| 117 fMat[1] = fMat[3] = | |
| 118 fMat[2] = fMat[5] = 0.0; | |
| 119 } | |
| 120 | |
| 121 // alias for reset() | |
| 122 void setIdentity() { this->reset(); } | |
| 123 | |
| 124 DPoint mapPoint(const SkPoint& src) const { | |
| 125 DPoint pt = DPoint::Make(src.x(), src.y()); | |
| 126 return this->mapPoint(pt); | |
| 127 } | |
| 128 | |
| 129 DPoint mapPoint(const DPoint& src) const { | |
| 130 return DPoint::Make(fMat[0] * src.x() + fMat[1] * src.y() + fMat[2], | |
| 131 fMat[3] * src.x() + fMat[4] * src.y() + fMat[5]); | |
| 132 } | |
| 133 private: | |
| 134 double fMat[6]; | |
| 135 }; | |
| 136 | |
| 137 /////////////////////////////////////////////////////////////////////////////// | |
| 138 | |
| 139 static const double kClose = (SK_Scalar1 / 16.0); | |
| 140 static const double kCloseSqd = SkScalarMul(kClose, kClose); | |
| 141 static const double kNearlyZero = (SK_Scalar1 / (1 << 18)); | |
| 142 static const double kTangentTolerance = (SK_Scalar1 / (1 << 11)); | |
| 143 static const float kConicTolerance = 0.25f; | |
| 144 | |
| 145 static inline bool between_closed_open(double a, double b, double c, | |
| 146 double tolerance = 0.0, | |
| 147 bool xformToleranceToX = false) { | |
| 148 SkASSERT(tolerance >= 0.0); | |
| 149 double tolB = tolerance; | |
| 150 double tolC = tolerance; | |
| 151 | |
| 152 if (xformToleranceToX) { | |
| 153 // Canonical space is y = x^2 and the derivative of x^2 is 2x. | |
| 154 // So the slope of the tangent line at point (x, x^2) is 2x. | |
| 155 // | |
| 156 // /| | |
| 157 // sqrt(2x * 2x + 1 * 1) / | 2x | |
| 158 // /__| | |
| 159 // 1 | |
| 160 tolB = tolerance / sqrt(4.0 * b * b + 1.0); | |
| 161 tolC = tolerance / sqrt(4.0 * c * c + 1.0); | |
| 162 } | |
| 163 return b < c ? (a >= b - tolB && a < c - tolC) : | |
| 164 (a >= c - tolC && a < b - tolB); | |
| 165 } | |
| 166 | |
| 167 static inline bool between_closed(double a, double b, double c, | |
| 168 double tolerance = 0.0, | |
| 169 bool xformToleranceToX = false) { | |
| 170 SkASSERT(tolerance >= 0.0); | |
| 171 double tolB = tolerance; | |
| 172 double tolC = tolerance; | |
| 173 | |
| 174 if (xformToleranceToX) { | |
| 175 tolB = tolerance / sqrt(4.0 * b * b + 1.0); | |
| 176 tolC = tolerance / sqrt(4.0 * c * c + 1.0); | |
| 177 } | |
| 178 return b < c ? (a >= b - tolB && a <= c + tolC) : | |
| 179 (a >= c - tolC && a <= b + tolB); | |
| 180 } | |
| 181 | |
| 182 static inline bool nearly_zero(double x, double tolerance = kNearlyZero) { | |
| 183 SkASSERT(tolerance >= 0.0); | |
| 184 return fabs(x) <= tolerance; | |
| 185 } | |
| 186 | |
| 187 static inline bool nearly_equal(double x, double y, | |
| 188 double tolerance = kNearlyZero, | |
| 189 bool xformToleranceToX = false) { | |
| 190 SkASSERT(tolerance >= 0.0); | |
| 191 if (xformToleranceToX) { | |
| 192 tolerance = tolerance / sqrt(4.0 * y * y + 1.0); | |
| 193 } | |
| 194 return fabs(x - y) <= tolerance; | |
| 195 } | |
| 196 | |
| 197 static inline double sign_of(const double &val) { | |
| 198 return (val < 0.0) ? -1.0 : 1.0; | |
| 199 } | |
| 200 | |
| 201 static bool is_colinear(const SkPoint pts[3]) { | |
| 202 return nearly_zero((pts[1].y() - pts[0].y()) * (pts[1].x() - pts[2].x()) - | |
| 203 (pts[1].y() - pts[2].y()) * (pts[1].x() - pts[0].x()), kC
loseSqd); | |
| 204 } | |
| 205 | |
| 206 class PathSegment { | |
| 207 public: | |
| 208 enum { | |
| 209 // These enum values are assumed in member functions below. | |
| 210 kLine = 0, | |
| 211 kQuad = 1, | |
| 212 } fType; | |
| 213 | |
| 214 // line uses 2 pts, quad uses 3 pts | |
| 215 SkPoint fPts[3]; | |
| 216 | |
| 217 DPoint fP0T, fP2T; | |
| 218 DAffineMatrix fXformMatrix; | |
| 219 double fScalingFactor; | |
| 220 double fScalingFactorSqd; | |
| 221 double fNearlyZeroScaled; | |
| 222 double fTangentTolScaledSqd; | |
| 223 SkRect fBoundingBox; | |
| 224 | |
| 225 void init(); | |
| 226 | |
| 227 int countPoints() { | |
| 228 GR_STATIC_ASSERT(0 == kLine && 1 == kQuad); | |
| 229 return fType + 2; | |
| 230 } | |
| 231 | |
| 232 const SkPoint& endPt() const { | |
| 233 GR_STATIC_ASSERT(0 == kLine && 1 == kQuad); | |
| 234 return fPts[fType + 1]; | |
| 235 } | |
| 236 }; | |
| 237 | |
| 238 typedef SkTArray<PathSegment, true> PathSegmentArray; | |
| 239 | |
| 240 void PathSegment::init() { | |
| 241 const DPoint p0 = DPoint::Make(fPts[0].x(), fPts[0].y()); | |
| 242 const DPoint p2 = DPoint::Make(this->endPt().x(), this->endPt().y()); | |
| 243 const double p0x = p0.x(); | |
| 244 const double p0y = p0.y(); | |
| 245 const double p2x = p2.x(); | |
| 246 const double p2y = p2.y(); | |
| 247 | |
| 248 fBoundingBox.set(fPts[0], this->endPt()); | |
| 249 | |
| 250 if (fType == PathSegment::kLine) { | |
| 251 fScalingFactorSqd = fScalingFactor = 1.0; | |
| 252 double hypotenuse = DPoint::Distance(p0, p2); | |
| 253 | |
| 254 const double cosTheta = (p2x - p0x) / hypotenuse; | |
| 255 const double sinTheta = (p2y - p0y) / hypotenuse; | |
| 256 | |
| 257 fXformMatrix.setAffine( | |
| 258 cosTheta, sinTheta, -(cosTheta * p0x) - (sinTheta * p0y), | |
| 259 -sinTheta, cosTheta, (sinTheta * p0x) - (cosTheta * p0y) | |
| 260 ); | |
| 261 } else { | |
| 262 SkASSERT(fType == PathSegment::kQuad); | |
| 263 | |
| 264 // Calculate bounding box | |
| 265 const SkPoint _P1mP0 = fPts[1] - fPts[0]; | |
| 266 SkPoint t = _P1mP0 - fPts[2] + fPts[1]; | |
| 267 t.fX = _P1mP0.x() / t.x(); | |
| 268 t.fY = _P1mP0.y() / t.y(); | |
| 269 t.fX = SkScalarClampMax(t.x(), 1.0); | |
| 270 t.fY = SkScalarClampMax(t.y(), 1.0); | |
| 271 t.fX = _P1mP0.x() * t.x(); | |
| 272 t.fY = _P1mP0.y() * t.y(); | |
| 273 const SkPoint m = fPts[0] + t; | |
| 274 fBoundingBox.growToInclude(&m, 1); | |
| 275 | |
| 276 const double p1x = fPts[1].x(); | |
| 277 const double p1y = fPts[1].y(); | |
| 278 | |
| 279 const double p0xSqd = p0x * p0x; | |
| 280 const double p0ySqd = p0y * p0y; | |
| 281 const double p2xSqd = p2x * p2x; | |
| 282 const double p2ySqd = p2y * p2y; | |
| 283 const double p1xSqd = p1x * p1x; | |
| 284 const double p1ySqd = p1y * p1y; | |
| 285 | |
| 286 const double p01xProd = p0x * p1x; | |
| 287 const double p02xProd = p0x * p2x; | |
| 288 const double b12xProd = p1x * p2x; | |
| 289 const double p01yProd = p0y * p1y; | |
| 290 const double p02yProd = p0y * p2y; | |
| 291 const double b12yProd = p1y * p2y; | |
| 292 | |
| 293 const double sqrtA = p0y - (2.0 * p1y) + p2y; | |
| 294 const double a = sqrtA * sqrtA; | |
| 295 const double h = -1.0 * (p0y - (2.0 * p1y) + p2y) * (p0x - (2.0 * p1x) +
p2x); | |
| 296 const double sqrtB = p0x - (2.0 * p1x) + p2x; | |
| 297 const double b = sqrtB * sqrtB; | |
| 298 const double c = (p0xSqd * p2ySqd) - (4.0 * p01xProd * b12yProd) | |
| 299 - (2.0 * p02xProd * p02yProd) + (4.0 * p02xProd * p1ySqd) | |
| 300 + (4.0 * p1xSqd * p02yProd) - (4.0 * b12xProd * p01yProd) | |
| 301 + (p2xSqd * p0ySqd); | |
| 302 const double g = (p0x * p02yProd) - (2.0 * p0x * p1ySqd) | |
| 303 + (2.0 * p0x * b12yProd) - (p0x * p2ySqd) | |
| 304 + (2.0 * p1x * p01yProd) - (4.0 * p1x * p02yProd) | |
| 305 + (2.0 * p1x * b12yProd) - (p2x * p0ySqd) | |
| 306 + (2.0 * p2x * p01yProd) + (p2x * p02yProd) | |
| 307 - (2.0 * p2x * p1ySqd); | |
| 308 const double f = -((p0xSqd * p2y) - (2.0 * p01xProd * p1y) | |
| 309 - (2.0 * p01xProd * p2y) - (p02xProd * p0y) | |
| 310 + (4.0 * p02xProd * p1y) - (p02xProd * p2y) | |
| 311 + (2.0 * p1xSqd * p0y) + (2.0 * p1xSqd * p2y) | |
| 312 - (2.0 * b12xProd * p0y) - (2.0 * b12xProd * p1y) | |
| 313 + (p2xSqd * p0y)); | |
| 314 | |
| 315 const double cosTheta = sqrt(a / (a + b)); | |
| 316 const double sinTheta = -1.0 * sign_of((a + b) * h) * sqrt(b / (a + b)); | |
| 317 | |
| 318 const double gDef = cosTheta * g - sinTheta * f; | |
| 319 const double fDef = sinTheta * g + cosTheta * f; | |
| 320 | |
| 321 | |
| 322 const double x0 = gDef / (a + b); | |
| 323 const double y0 = (1.0 / (2.0 * fDef)) * (c - (gDef * gDef / (a + b))); | |
| 324 | |
| 325 | |
| 326 const double lambda = -1.0 * ((a + b) / (2.0 * fDef)); | |
| 327 fScalingFactor = fabs(1.0 / lambda); | |
| 328 fScalingFactorSqd = fScalingFactor * fScalingFactor; | |
| 329 | |
| 330 const double lambda_cosTheta = lambda * cosTheta; | |
| 331 const double lambda_sinTheta = lambda * sinTheta; | |
| 332 | |
| 333 fXformMatrix.setAffine( | |
| 334 lambda_cosTheta, -lambda_sinTheta, lambda * x0, | |
| 335 lambda_sinTheta, lambda_cosTheta, lambda * y0 | |
| 336 ); | |
| 337 } | |
| 338 | |
| 339 fNearlyZeroScaled = kNearlyZero / fScalingFactor; | |
| 340 fTangentTolScaledSqd = kTangentTolerance * kTangentTolerance / fScalingFacto
rSqd; | |
| 341 | |
| 342 fP0T = fXformMatrix.mapPoint(p0); | |
| 343 fP2T = fXformMatrix.mapPoint(p2); | |
| 344 } | |
| 345 | |
| 346 static void init_distances(DFData* data, int size) { | |
| 347 DFData* currData = data; | |
| 348 | |
| 349 for (int i = 0; i < size; ++i) { | |
| 350 // init distance to "far away" | |
| 351 currData->fDistSq = SK_DistanceFieldMagnitude * SK_DistanceFieldMagnitud
e; | |
| 352 currData->fDeltaWindingScore = 0; | |
| 353 ++currData; | |
| 354 } | |
| 355 } | |
| 356 | |
| 357 static inline void add_line_to_segment(const SkPoint pts[2], | |
| 358 PathSegmentArray* segments) { | |
| 359 segments->push_back(); | |
| 360 segments->back().fType = PathSegment::kLine; | |
| 361 segments->back().fPts[0] = pts[0]; | |
| 362 segments->back().fPts[1] = pts[1]; | |
| 363 | |
| 364 segments->back().init(); | |
| 365 } | |
| 366 | |
| 367 static inline void add_quad_segment(const SkPoint pts[3], | |
| 368 PathSegmentArray* segments) { | |
| 369 if (pts[0].distanceToSqd(pts[1]) < kCloseSqd || | |
| 370 pts[1].distanceToSqd(pts[2]) < kCloseSqd || | |
| 371 is_colinear(pts)) { | |
| 372 if (pts[0] != pts[2]) { | |
| 373 SkPoint line_pts[2]; | |
| 374 line_pts[0] = pts[0]; | |
| 375 line_pts[1] = pts[2]; | |
| 376 add_line_to_segment(line_pts, segments); | |
| 377 } | |
| 378 } else { | |
| 379 segments->push_back(); | |
| 380 segments->back().fType = PathSegment::kQuad; | |
| 381 segments->back().fPts[0] = pts[0]; | |
| 382 segments->back().fPts[1] = pts[1]; | |
| 383 segments->back().fPts[2] = pts[2]; | |
| 384 | |
| 385 segments->back().init(); | |
| 386 } | |
| 387 } | |
| 388 | |
| 389 static inline void add_cubic_segments(const SkPoint pts[4], | |
| 390 PathSegmentArray* segments) { | |
| 391 SkSTArray<15, SkPoint, true> quads; | |
| 392 GrPathUtils::convertCubicToQuads(pts, SK_Scalar1, &quads); | |
| 393 int count = quads.count(); | |
| 394 for (int q = 0; q < count; q += 3) { | |
| 395 add_quad_segment(&quads[q], segments); | |
| 396 } | |
| 397 } | |
| 398 | |
| 399 static float calculate_nearest_point_for_quad( | |
| 400 const PathSegment& segment, | |
| 401 const DPoint &xFormPt) { | |
| 402 static const float kThird = 0.33333333333f; | |
| 403 static const float kTwentySeventh = 0.037037037f; | |
| 404 | |
| 405 const float a = 0.5f - (float)xFormPt.y(); | |
| 406 const float b = -0.5f * (float)xFormPt.x(); | |
| 407 | |
| 408 const float a3 = a * a * a; | |
| 409 const float b2 = b * b; | |
| 410 | |
| 411 const float c = (b2 * 0.25f) + (a3 * kTwentySeventh); | |
| 412 | |
| 413 if (c >= 0.f) { | |
| 414 const float sqrtC = sqrt(c); | |
| 415 const float result = (float)cbrt((-b * 0.5f) + sqrtC) + (float)cbrt((-b
* 0.5f) - sqrtC); | |
| 416 return result; | |
| 417 } else { | |
| 418 const float cosPhi = (float)sqrt((b2 * 0.25f) * (-27.f / a3)) * ((b > 0)
? -1.f : 1.f); | |
| 419 const float phi = (float)acos(cosPhi); | |
| 420 float result; | |
| 421 if (xFormPt.x() > 0.f) { | |
| 422 result = 2.f * (float)sqrt(-a * kThird) * (float)cos(phi * kThird); | |
| 423 if (!between_closed(result, segment.fP0T.x(), segment.fP2T.x())) { | |
| 424 result = 2.f * (float)sqrt(-a * kThird) * (float)cos((phi * kThi
rd) + (SK_ScalarPI * 2.f * kThird)); | |
| 425 } | |
| 426 } else { | |
| 427 result = 2.f * (float)sqrt(-a * kThird) * (float)cos((phi * kThird)
+ (SK_ScalarPI * 2.f * kThird)); | |
| 428 if (!between_closed(result, segment.fP0T.x(), segment.fP2T.x())) { | |
| 429 result = 2.f * (float)sqrt(-a * kThird) * (float)cos(phi * kThir
d); | |
| 430 } | |
| 431 } | |
| 432 return result; | |
| 433 } | |
| 434 } | |
| 435 | |
| 436 // This structure contains some intermediate values shared by the same row. | |
| 437 // It is used to calculate segment side of a quadratic bezier. | |
| 438 struct RowData { | |
| 439 // The intersection type of a scanline and y = x * x parabola in canonical s
pace. | |
| 440 enum IntersectionType { | |
| 441 kNoIntersection, | |
| 442 kVerticalLine, | |
| 443 kTangentLine, | |
| 444 kTwoPointsIntersect | |
| 445 } fIntersectionType; | |
| 446 | |
| 447 // The direction of the quadratic segment/scanline in the canonical space. | |
| 448 // 1: The quadratic segment/scanline going from negative x-axis to positive
x-axis. | |
| 449 // 0: The scanline is a vertical line in the canonical space. | |
| 450 // -1: The quadratic segment/scanline going from positive x-axis to negative
x-axis. | |
| 451 int fQuadXDirection; | |
| 452 int fScanlineXDirection; | |
| 453 | |
| 454 // The y-value(equal to x*x) of intersection point for the kVerticalLine int
ersection type. | |
| 455 double fYAtIntersection; | |
| 456 | |
| 457 // The x-value for two intersection points. | |
| 458 double fXAtIntersection1; | |
| 459 double fXAtIntersection2; | |
| 460 }; | |
| 461 | |
| 462 void precomputation_for_row( | |
| 463 RowData *rowData, | |
| 464 const PathSegment& segment, | |
| 465 const SkPoint& pointLeft, | |
| 466 const SkPoint& pointRight | |
| 467 ) { | |
| 468 if (segment.fType != PathSegment::kQuad) { | |
| 469 return; | |
| 470 } | |
| 471 | |
| 472 const DPoint& xFormPtLeft = segment.fXformMatrix.mapPoint(pointLeft); | |
| 473 const DPoint& xFormPtRight = segment.fXformMatrix.mapPoint(pointRight);; | |
| 474 | |
| 475 rowData->fQuadXDirection = (int)sign_of(segment.fP2T.x() - segment.fP0T.x())
; | |
| 476 rowData->fScanlineXDirection = (int)sign_of(xFormPtRight.x() - xFormPtLeft.x
()); | |
| 477 | |
| 478 const double x1 = xFormPtLeft.x(); | |
| 479 const double y1 = xFormPtLeft.y(); | |
| 480 const double x2 = xFormPtRight.x(); | |
| 481 const double y2 = xFormPtRight.y(); | |
| 482 | |
| 483 if (nearly_equal(x1, x2, segment.fNearlyZeroScaled, true)) { | |
| 484 rowData->fIntersectionType = RowData::kVerticalLine; | |
| 485 rowData->fYAtIntersection = x1 * x1; | |
| 486 rowData->fScanlineXDirection = 0; | |
| 487 return; | |
| 488 } | |
| 489 | |
| 490 // Line y = mx + b | |
| 491 const double m = (y2 - y1) / (x2 - x1); | |
| 492 const double b = -m * x1 + y1; | |
| 493 | |
| 494 const double m2 = m * m; | |
| 495 const double c = m2 + 4.0 * b; | |
| 496 | |
| 497 const double tol = 4.0 * segment.fTangentTolScaledSqd / (m2 + 1.0); | |
| 498 | |
| 499 // Check if the scanline is the tangent line of the curve, | |
| 500 // and the curve start or end at the same y-coordinate of the scanline | |
| 501 if ((rowData->fScanlineXDirection == 1 && | |
| 502 (segment.fPts[0].y() == pointLeft.y() || | |
| 503 segment.fPts[2].y() == pointLeft.y())) && | |
| 504 nearly_zero(c, tol)) { | |
| 505 rowData->fIntersectionType = RowData::kTangentLine; | |
| 506 rowData->fXAtIntersection1 = m / 2.0; | |
| 507 rowData->fXAtIntersection2 = m / 2.0; | |
| 508 } else if (c <= 0.0) { | |
| 509 rowData->fIntersectionType = RowData::kNoIntersection; | |
| 510 return; | |
| 511 } else { | |
| 512 rowData->fIntersectionType = RowData::kTwoPointsIntersect; | |
| 513 const double d = sqrt(c); | |
| 514 rowData->fXAtIntersection1 = (m + d) / 2.0; | |
| 515 rowData->fXAtIntersection2 = (m - d) / 2.0; | |
| 516 } | |
| 517 } | |
| 518 | |
| 519 SegSide calculate_side_of_quad( | |
| 520 const PathSegment& segment, | |
| 521 const SkPoint& point, | |
| 522 const DPoint& xFormPt, | |
| 523 const RowData& rowData) { | |
| 524 SegSide side = kNA_SegSide; | |
| 525 | |
| 526 if (RowData::kVerticalLine == rowData.fIntersectionType) { | |
| 527 side = (SegSide)(int)(sign_of(xFormPt.y() - rowData.fYAtIntersection) *
rowData.fQuadXDirection); | |
| 528 } | |
| 529 else if (RowData::kTwoPointsIntersect == rowData.fIntersectionType) { | |
| 530 const double p1 = rowData.fXAtIntersection1; | |
| 531 const double p2 = rowData.fXAtIntersection2; | |
| 532 | |
| 533 int signP1 = (int)sign_of(p1 - xFormPt.x()); | |
| 534 bool includeP1 = true; | |
| 535 bool includeP2 = true; | |
| 536 | |
| 537 if (rowData.fScanlineXDirection == 1) { | |
| 538 if ((rowData.fQuadXDirection == -1 && segment.fPts[0].y() <= point.y
() && | |
| 539 nearly_equal(segment.fP0T.x(), p1, segment.fNearlyZeroScaled, t
rue)) || | |
| 540 (rowData.fQuadXDirection == 1 && segment.fPts[2].y() <= point.y
() && | |
| 541 nearly_equal(segment.fP2T.x(), p1, segment.fNearlyZeroScaled, t
rue))) { | |
| 542 includeP1 = false; | |
| 543 } | |
| 544 if ((rowData.fQuadXDirection == -1 && segment.fPts[2].y() <= point.y
() && | |
| 545 nearly_equal(segment.fP2T.x(), p2, segment.fNearlyZeroScaled, t
rue)) || | |
| 546 (rowData.fQuadXDirection == 1 && segment.fPts[0].y() <= point.y
() && | |
| 547 nearly_equal(segment.fP0T.x(), p2, segment.fNearlyZeroScaled, t
rue))) { | |
| 548 includeP2 = false; | |
| 549 } | |
| 550 } | |
| 551 | |
| 552 if (includeP1 && between_closed(p1, segment.fP0T.x(), segment.fP2T.x(), | |
| 553 segment.fNearlyZeroScaled, true)) { | |
| 554 side = (SegSide)(signP1 * rowData.fQuadXDirection); | |
| 555 } | |
| 556 if (includeP2 && between_closed(p2, segment.fP0T.x(), segment.fP2T.x(), | |
| 557 segment.fNearlyZeroScaled, true)) { | |
| 558 int signP2 = (int)sign_of(p2 - xFormPt.x()); | |
| 559 if (side == kNA_SegSide || signP2 == 1) { | |
| 560 side = (SegSide)(-signP2 * rowData.fQuadXDirection); | |
| 561 } | |
| 562 } | |
| 563 } else if (RowData::kTangentLine == rowData.fIntersectionType) { | |
| 564 // The scanline is the tangent line of current quadratic segment. | |
| 565 | |
| 566 const double p = rowData.fXAtIntersection1; | |
| 567 int signP = (int)sign_of(p - xFormPt.x()); | |
| 568 if (rowData.fScanlineXDirection == 1) { | |
| 569 // The path start or end at the tangent point. | |
| 570 if (segment.fPts[0].y() == point.y()) { | |
| 571 side = (SegSide)(signP); | |
| 572 } else if (segment.fPts[2].y() == point.y()) { | |
| 573 side = (SegSide)(-signP); | |
| 574 } | |
| 575 } | |
| 576 } | |
| 577 | |
| 578 return side; | |
| 579 } | |
| 580 | |
| 581 static float distance_to_segment(const SkPoint& point, | |
| 582 const PathSegment& segment, | |
| 583 const RowData& rowData, | |
| 584 SegSide* side) { | |
| 585 SkASSERT(side); | |
| 586 | |
| 587 const DPoint xformPt = segment.fXformMatrix.mapPoint(point); | |
| 588 | |
| 589 if (segment.fType == PathSegment::kLine) { | |
| 590 float result = SK_DistanceFieldPad * SK_DistanceFieldPad; | |
| 591 | |
| 592 if (between_closed(xformPt.x(), segment.fP0T.x(), segment.fP2T.x())) { | |
| 593 result = (float)(xformPt.y() * xformPt.y()); | |
| 594 } else if (xformPt.x() < segment.fP0T.x()) { | |
| 595 result = (float)(xformPt.x() * xformPt.x() + xformPt.y() * xformPt.y
()); | |
| 596 } else { | |
| 597 result = (float)((xformPt.x() - segment.fP2T.x()) * (xformPt.x() - s
egment.fP2T.x()) | |
| 598 + xformPt.y() * xformPt.y()); | |
| 599 } | |
| 600 | |
| 601 if (between_closed_open(point.y(), segment.fBoundingBox.top(), | |
| 602 segment.fBoundingBox.bottom())) { | |
| 603 *side = (SegSide)(int)sign_of(xformPt.y()); | |
| 604 } else { | |
| 605 *side = kNA_SegSide; | |
| 606 } | |
| 607 return result; | |
| 608 } else { | |
| 609 SkASSERT(segment.fType == PathSegment::kQuad); | |
| 610 | |
| 611 const float nearestPoint = calculate_nearest_point_for_quad(segment, xfo
rmPt); | |
| 612 | |
| 613 float dist; | |
| 614 | |
| 615 if (between_closed(nearestPoint, segment.fP0T.x(), segment.fP2T.x())) { | |
| 616 DPoint x = DPoint::Make(nearestPoint, nearestPoint * nearestPoint); | |
| 617 dist = (float)xformPt.distanceToSqd(x); | |
| 618 } else { | |
| 619 const float distToB0T = (float)xformPt.distanceToSqd(segment.fP0T); | |
| 620 const float distToB2T = (float)xformPt.distanceToSqd(segment.fP2T); | |
| 621 | |
| 622 if (distToB0T < distToB2T) { | |
| 623 dist = distToB0T; | |
| 624 } else { | |
| 625 dist = distToB2T; | |
| 626 } | |
| 627 } | |
| 628 | |
| 629 if (between_closed_open(point.y(), segment.fBoundingBox.top(), | |
| 630 segment.fBoundingBox.bottom())) { | |
| 631 *side = calculate_side_of_quad(segment, point, xformPt, rowData); | |
| 632 } else { | |
| 633 *side = kNA_SegSide; | |
| 634 } | |
| 635 | |
| 636 return (float)(dist * segment.fScalingFactorSqd); | |
| 637 } | |
| 638 } | |
| 639 | |
| 640 static void calculate_distance_field_data(PathSegmentArray* segments, | |
| 641 DFData* dataPtr, | |
| 642 int width, int height) { | |
| 643 int count = segments->count(); | |
| 644 for (int a = 0; a < count; ++a) { | |
| 645 PathSegment& segment = (*segments)[a]; | |
| 646 const SkRect& segBB = segment.fBoundingBox.makeOutset( | |
| 647 SK_DistanceFieldPad, SK_DistanceFieldPad); | |
| 648 int startColumn = (int)segBB.left(); | |
| 649 int endColumn = SkScalarCeilToInt(segBB.right()); | |
| 650 | |
| 651 int startRow = (int)segBB.top(); | |
| 652 int endRow = SkScalarCeilToInt(segBB.bottom()); | |
| 653 | |
| 654 SkASSERT((startColumn >= 0) && "StartColumn < 0!"); | |
| 655 SkASSERT((endColumn <= width) && "endColumn > width!"); | |
| 656 SkASSERT((startRow >= 0) && "StartRow < 0!"); | |
| 657 SkASSERT((endRow <= height) && "EndRow > height!"); | |
| 658 | |
| 659 for (int row = startRow; row < endRow; ++row) { | |
| 660 SegSide prevSide = kNA_SegSide; | |
| 661 const float pY = row + 0.5f; | |
| 662 RowData rowData; | |
| 663 | |
| 664 const SkPoint pointLeft = SkPoint::Make((SkScalar)startColumn, pY); | |
| 665 const SkPoint pointRight = SkPoint::Make((SkScalar)endColumn, pY); | |
| 666 | |
| 667 if (between_closed_open(pY, segment.fBoundingBox.top(), | |
| 668 segment.fBoundingBox.bottom())) { | |
| 669 precomputation_for_row(&rowData, segment, pointLeft, pointRight)
; | |
| 670 } | |
| 671 | |
| 672 for (int col = startColumn; col < endColumn; ++col) { | |
| 673 int idx = (row * width) + col; | |
| 674 | |
| 675 const float pX = col + 0.5f; | |
| 676 const SkPoint point = SkPoint::Make(pX, pY); | |
| 677 | |
| 678 const float distSq = dataPtr[idx].fDistSq; | |
| 679 int dilation = distSq < 1.5 * 1.5 ? 1 : | |
| 680 distSq < 2.5 * 2.5 ? 2 : | |
| 681 distSq < 3.5 * 3.5 ? 3 : SK_DistanceFieldPad; | |
| 682 if (dilation > SK_DistanceFieldPad) { | |
| 683 dilation = SK_DistanceFieldPad; | |
| 684 } | |
| 685 | |
| 686 // Optimisation for not calculating some points. | |
| 687 if (dilation != SK_DistanceFieldPad && !segment.fBoundingBox.rou
ndOut() | |
| 688 .makeOutset(dilation, dilation).contains(col, row)) { | |
| 689 continue; | |
| 690 } | |
| 691 | |
| 692 SegSide side = kNA_SegSide; | |
| 693 int deltaWindingScore = 0; | |
| 694 float currDistSq = distance_to_segment(point, segment, rowData
, &side); | |
| 695 if (prevSide == kLeft_SegSide && side == kRight_SegSide) { | |
| 696 deltaWindingScore = -1; | |
| 697 } else if (prevSide == kRight_SegSide && side == kLeft_SegSide)
{ | |
| 698 deltaWindingScore = 1; | |
| 699 } | |
| 700 | |
| 701 prevSide = side; | |
| 702 | |
| 703 if (currDistSq < distSq) { | |
| 704 dataPtr[idx].fDistSq = currDistSq; | |
| 705 } | |
| 706 | |
| 707 dataPtr[idx].fDeltaWindingScore += deltaWindingScore; | |
| 708 } | |
| 709 } | |
| 710 } | |
| 711 } | |
| 712 | |
| 713 template <int distanceMagnitude> | |
| 714 static unsigned char pack_distance_field_val(float dist) { | |
| 715 // The distance field is constructed as unsigned char values, so that the ze
ro value is at 128, | |
| 716 // Beside 128, we have 128 values in range [0, 128), but only 127 values in
range (128, 255]. | |
| 717 // So we multiply distanceMagnitude by 127/128 at the latter range to avoid
overflow. | |
| 718 dist = SkScalarPin(-dist, -distanceMagnitude, distanceMagnitude * 127.0f / 1
28.0f); | |
| 719 | |
| 720 // Scale into the positive range for unsigned distance. | |
| 721 dist += distanceMagnitude; | |
| 722 | |
| 723 // Scale into unsigned char range. | |
| 724 // Round to place negative and positive values as equally as possible around
128 | |
| 725 // (which represents zero). | |
| 726 return (unsigned char)SkScalarRoundToInt(dist / (2 * distanceMagnitude) * 25
6.0f); | |
| 727 } | |
| 728 | |
| 729 bool GrGenerateDistanceFieldFromPath(unsigned char* distanceField, | |
| 730 const SkPath& path, const SkMatrix& drawMat
rix, | |
| 731 int width, int height, size_t rowBytes) { | |
| 732 SkASSERT(distanceField); | |
| 733 | |
| 734 SkPath simplifiedPath; | |
| 735 SkPath workingPath; | |
| 736 if (Simplify(path, &simplifiedPath)) { | |
| 737 workingPath = simplifiedPath; | |
| 738 } else { | |
| 739 workingPath = path; | |
| 740 } | |
| 741 | |
| 742 if (!IsDistanceFieldSupportedFillType(workingPath.getFillType())) { | |
| 743 return false; | |
| 744 } | |
| 745 | |
| 746 workingPath.transform(drawMatrix); | |
| 747 | |
| 748 // translate path to offset (SK_DistanceFieldPad, SK_DistanceFieldPad) | |
| 749 SkMatrix dfMatrix; | |
| 750 dfMatrix.setTranslate(SK_DistanceFieldPad, SK_DistanceFieldPad); | |
| 751 workingPath.transform(dfMatrix); | |
| 752 | |
| 753 // create temp data | |
| 754 size_t dataSize = width * height * sizeof(DFData); | |
| 755 SkAutoSMalloc<1024> dfStorage(dataSize); | |
| 756 DFData* dataPtr = (DFData*) dfStorage.get(); | |
| 757 | |
| 758 // create initial distance data | |
| 759 init_distances(dataPtr, width * height); | |
| 760 | |
| 761 SkPath::Iter iter(workingPath, true); | |
| 762 SkSTArray<15, PathSegment, true> segments; | |
| 763 | |
| 764 for (;;) { | |
| 765 SkPoint pts[4]; | |
| 766 SkPath::Verb verb = iter.next(pts); | |
| 767 switch (verb) { | |
| 768 case SkPath::kMove_Verb: | |
| 769 break; | |
| 770 case SkPath::kLine_Verb: { | |
| 771 add_line_to_segment(pts, &segments); | |
| 772 break; | |
| 773 } | |
| 774 case SkPath::kQuad_Verb: | |
| 775 add_quad_segment(pts, &segments); | |
| 776 break; | |
| 777 case SkPath::kConic_Verb: { | |
| 778 SkScalar weight = iter.conicWeight(); | |
| 779 SkAutoConicToQuads converter; | |
| 780 const SkPoint* quadPts = converter.computeQuads(pts, weight, kCo
nicTolerance); | |
| 781 for (int i = 0; i < converter.countQuads(); ++i) { | |
| 782 add_quad_segment(quadPts + 2*i, &segments); | |
| 783 } | |
| 784 break; | |
| 785 } | |
| 786 case SkPath::kCubic_Verb: { | |
| 787 add_cubic_segments(pts, &segments); | |
| 788 break; | |
| 789 }; | |
| 790 default: | |
| 791 break; | |
| 792 } | |
| 793 if (verb == SkPath::kDone_Verb) { | |
| 794 break; | |
| 795 } | |
| 796 } | |
| 797 | |
| 798 calculate_distance_field_data(&segments, dataPtr, width, height); | |
| 799 | |
| 800 for (int row = 0; row < height; ++row) { | |
| 801 int windingNumber = 0; // Winding number start from zero for each scanli
ne | |
| 802 for (int col = 0; col < width; ++col) { | |
| 803 int idx = (row * width) + col; | |
| 804 windingNumber += dataPtr[idx].fDeltaWindingScore; | |
| 805 | |
| 806 enum DFSign { | |
| 807 kInside = -1, | |
| 808 kOutside = 1 | |
| 809 } dfSign; | |
| 810 | |
| 811 if (workingPath.getFillType() == SkPath::kWinding_FillType) { | |
| 812 dfSign = windingNumber ? kInside : kOutside; | |
| 813 } else if (workingPath.getFillType() == SkPath::kInverseWinding_Fill
Type) { | |
| 814 dfSign = windingNumber ? kOutside : kInside; | |
| 815 } else if (workingPath.getFillType() == SkPath::kEvenOdd_FillType) { | |
| 816 dfSign = (windingNumber % 2) ? kInside : kOutside; | |
| 817 } else { | |
| 818 SkASSERT(workingPath.getFillType() == SkPath::kInverseEvenOdd_Fi
llType); | |
| 819 dfSign = (windingNumber % 2) ? kOutside : kInside; | |
| 820 } | |
| 821 | |
| 822 // The winding number at the end of a scanline should be zero. | |
| 823 // SkASSERT(((col != width - 1) || (windingNumber == 0)) && | |
| 824 // "Winding number should be zero at the end of a scan line.
"); | |
| 825 // Fallback to use SkPath::contains to determine the sign of pixel i
nstead of assertion. | |
| 826 if (col == width - 1 && windingNumber != 0) { | |
| 827 for (int col = 0; col < width; ++col) { | |
| 828 int idx = (row * width) + col; | |
| 829 dfSign = workingPath.contains(col + 0.5, row + 0.5) ? kInsid
e : kOutside; | |
| 830 const float miniDist = sqrt(dataPtr[idx].fDistSq); | |
| 831 const float dist = dfSign * miniDist; | |
| 832 | |
| 833 unsigned char pixelVal = pack_distance_field_val<SK_Distance
FieldMagnitude>(dist); | |
| 834 | |
| 835 distanceField[(row * rowBytes) + col] = pixelVal; | |
| 836 } | |
| 837 continue; | |
| 838 } | |
| 839 | |
| 840 const float miniDist = sqrt(dataPtr[idx].fDistSq); | |
| 841 const float dist = dfSign * miniDist; | |
| 842 | |
| 843 unsigned char pixelVal = pack_distance_field_val<SK_DistanceFieldMag
nitude>(dist); | |
| 844 | |
| 845 distanceField[(row * rowBytes) + col] = pixelVal; | |
| 846 } | |
| 847 } | |
| 848 return true; | |
| 849 } | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 2580373002:
Revert of Generate Signed Distance Field directly from vector path (Closed)
Base URL: https://skia.googlesource.com/skia.git@master