1 /* 2 * Copyright 2018 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 "gm/gm.h" 9 #include "include/core/SkCanvas.h" 10 #include "include/core/SkColor.h" 11 #include "include/core/SkPaint.h" 12 #include "include/core/SkPath.h" 13 #include "include/core/SkPoint.h" 14 #include "include/core/SkScalar.h" 15 #include "include/core/SkSize.h" 16 #include "include/core/SkString.h" 17 #include "include/core/SkTypes.h" 18 #include "src/base/SkRandom.h" 19 #include "src/core/SkGeometry.h" 20 21 #include <math.h> 22 23 namespace skiagm { 24 25 // Slices paths into sliver-size contours shaped like ice cream cones. 26 class MandolineSlicer { 27 public: 28 inline static constexpr int kDefaultSubdivisions = 10; 29 MandolineSlicer(SkPoint anchorPt)30 MandolineSlicer(SkPoint anchorPt) { 31 fPath.setFillType(SkPathFillType::kEvenOdd); 32 fPath.setIsVolatile(true); 33 this->reset(anchorPt); 34 } 35 reset(SkPoint anchorPt)36 void reset(SkPoint anchorPt) { 37 fPath.reset(); 38 fLastPt = fAnchorPt = anchorPt; 39 } 40 sliceLine(SkPoint pt,int numSubdivisions=kDefaultSubdivisions)41 void sliceLine(SkPoint pt, int numSubdivisions = kDefaultSubdivisions) { 42 if (numSubdivisions <= 0) { 43 fPath.moveTo(fAnchorPt); 44 fPath.lineTo(fLastPt); 45 fPath.lineTo(pt); 46 fPath.close(); 47 fLastPt = pt; 48 return; 49 } 50 float T = this->chooseChopT(numSubdivisions); 51 if (0 == T) { 52 return; 53 } 54 SkPoint midpt = fLastPt * (1 - T) + pt * T; 55 this->sliceLine(midpt, numSubdivisions - 1); 56 this->sliceLine(pt, numSubdivisions - 1); 57 } 58 sliceQuadratic(SkPoint p1,SkPoint p2,int numSubdivisions=kDefaultSubdivisions)59 void sliceQuadratic(SkPoint p1, SkPoint p2, int numSubdivisions = kDefaultSubdivisions) { 60 if (numSubdivisions <= 0) { 61 fPath.moveTo(fAnchorPt); 62 fPath.lineTo(fLastPt); 63 fPath.quadTo(p1, p2); 64 fPath.close(); 65 fLastPt = p2; 66 return; 67 } 68 float T = this->chooseChopT(numSubdivisions); 69 if (0 == T) { 70 return; 71 } 72 SkPoint P[3] = {fLastPt, p1, p2}, PP[5]; 73 SkChopQuadAt(P, PP, T); 74 this->sliceQuadratic(PP[1], PP[2], numSubdivisions - 1); 75 this->sliceQuadratic(PP[3], PP[4], numSubdivisions - 1); 76 } 77 sliceCubic(SkPoint p1,SkPoint p2,SkPoint p3,int numSubdivisions=kDefaultSubdivisions)78 void sliceCubic(SkPoint p1, SkPoint p2, SkPoint p3, 79 int numSubdivisions = kDefaultSubdivisions) { 80 if (numSubdivisions <= 0) { 81 fPath.moveTo(fAnchorPt); 82 fPath.lineTo(fLastPt); 83 fPath.cubicTo(p1, p2, p3); 84 fPath.close(); 85 fLastPt = p3; 86 return; 87 } 88 float T = this->chooseChopT(numSubdivisions); 89 if (0 == T) { 90 return; 91 } 92 SkPoint P[4] = {fLastPt, p1, p2, p3}, PP[7]; 93 SkChopCubicAt(P, PP, T); 94 this->sliceCubic(PP[1], PP[2], PP[3], numSubdivisions - 1); 95 this->sliceCubic(PP[4], PP[5], PP[6], numSubdivisions - 1); 96 } 97 sliceConic(SkPoint p1,SkPoint p2,float w,int numSubdivisions=kDefaultSubdivisions)98 void sliceConic(SkPoint p1, SkPoint p2, float w, int numSubdivisions = kDefaultSubdivisions) { 99 if (numSubdivisions <= 0) { 100 fPath.moveTo(fAnchorPt); 101 fPath.lineTo(fLastPt); 102 fPath.conicTo(p1, p2, w); 103 fPath.close(); 104 fLastPt = p2; 105 return; 106 } 107 float T = this->chooseChopT(numSubdivisions); 108 if (0 == T) { 109 return; 110 } 111 SkConic conic(fLastPt, p1, p2, w), halves[2]; 112 if (!conic.chopAt(T, halves)) { 113 SK_ABORT("SkConic::chopAt failed"); 114 } 115 this->sliceConic(halves[0].fPts[1], halves[0].fPts[2], halves[0].fW, numSubdivisions - 1); 116 this->sliceConic(halves[1].fPts[1], halves[1].fPts[2], halves[1].fW, numSubdivisions - 1); 117 } 118 path() const119 const SkPath& path() const { return fPath; } 120 121 private: chooseChopT(int numSubdivisions)122 float chooseChopT(int numSubdivisions) { 123 SkASSERT(numSubdivisions > 0); 124 if (numSubdivisions > 1) { 125 return .5f; 126 } 127 float T = (0 == fRand.nextU() % 10) ? 0 : scalbnf(1, -(int)fRand.nextRangeU(10, 149)); 128 SkASSERT(T >= 0 && T < 1); 129 return T; 130 } 131 132 SkRandom fRand; 133 SkPath fPath; 134 SkPoint fAnchorPt; 135 SkPoint fLastPt; 136 }; 137 138 class SliverPathsGM : public GM { 139 public: SliverPathsGM()140 SliverPathsGM() { 141 this->setBGColor(SK_ColorBLACK); 142 } 143 144 protected: getName() const145 SkString getName() const override { return SkString("mandoline"); } 146 getISize()147 SkISize getISize() override { return SkISize::Make(560, 475); } 148 onDraw(SkCanvas * canvas)149 void onDraw(SkCanvas* canvas) override { 150 SkPaint paint; 151 paint.setColor(SK_ColorWHITE); 152 paint.setAntiAlias(true); 153 154 MandolineSlicer mandoline({41, 43}); 155 mandoline.sliceCubic({5, 277}, {381, -74}, {243, 162}); 156 mandoline.sliceLine({41, 43}); 157 canvas->drawPath(mandoline.path(), paint); 158 159 mandoline.reset({357.049988f, 446.049988f}); 160 mandoline.sliceCubic({472.750000f, -71.950012f}, {639.750000f, 531.950012f}, 161 {309.049988f, 347.950012f}); 162 mandoline.sliceLine({309.049988f, 419}); 163 mandoline.sliceLine({357.049988f, 446.049988f}); 164 canvas->drawPath(mandoline.path(), paint); 165 166 canvas->save(); 167 canvas->translate(421, 105); 168 canvas->scale(100, 81); 169 mandoline.reset({-cosf(SkDegreesToRadians(-60)), sinf(SkDegreesToRadians(-60))}); 170 mandoline.sliceConic({-2, 0}, 171 {-cosf(SkDegreesToRadians(60)), sinf(SkDegreesToRadians(60))}, .5f); 172 mandoline.sliceConic({-cosf(SkDegreesToRadians(120))*2, sinf(SkDegreesToRadians(120))*2}, 173 {1, 0}, .5f); 174 mandoline.sliceLine({0, 0}); 175 mandoline.sliceLine({-cosf(SkDegreesToRadians(-60)), sinf(SkDegreesToRadians(-60))}); 176 canvas->drawPath(mandoline.path(), paint); 177 canvas->restore(); 178 179 canvas->save(); 180 canvas->translate(150, 300); 181 canvas->scale(75, 75); 182 mandoline.reset({1, 0}); 183 constexpr int nquads = 5; 184 for (int i = 0; i < nquads; ++i) { 185 float theta1 = 2*SK_ScalarPI/nquads * (i + .5f); 186 float theta2 = 2*SK_ScalarPI/nquads * (i + 1); 187 mandoline.sliceQuadratic({cosf(theta1)*2, sinf(theta1)*2}, 188 {cosf(theta2), sinf(theta2)}); 189 } 190 canvas->drawPath(mandoline.path(), paint); 191 canvas->restore(); 192 } 193 }; 194 195 DEF_GM(return new SliverPathsGM;) 196 197 } // namespace skiagm 198