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 "include/utils/SkRandom.h" 19#include "src/core/SkGeometry.h" 20 21#include <math.h> 22 23namespace skiagm { 24 25// Slices paths into sliver-size contours shaped like ice cream cones. 26class MandolineSlicer { 27public: 28 inline static constexpr int kDefaultSubdivisions = 10; 29 30 MandolineSlicer(SkPoint anchorPt) { 31 fPath.setFillType(SkPathFillType::kEvenOdd); 32 fPath.setIsVolatile(true); 33 this->reset(anchorPt); 34 } 35 36 void reset(SkPoint anchorPt) { 37 fPath.reset(); 38 fLastPt = fAnchorPt = anchorPt; 39 } 40 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 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 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 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 } 118 119 const SkPath& path() const { return fPath; } 120 121private: 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 138class SliverPathsGM : public GM { 139public: 140 SliverPathsGM() { 141 this->setBGColor(SK_ColorBLACK); 142 } 143 144protected: 145 SkString onShortName() override { 146 return SkString("mandoline"); 147 } 148 149 SkISize onISize() override { 150 return SkISize::Make(560, 475); 151 } 152 153 void onDraw(SkCanvas* canvas) override { 154 SkPaint paint; 155 paint.setColor(SK_ColorWHITE); 156 paint.setAntiAlias(true); 157 158 MandolineSlicer mandoline({41, 43}); 159 mandoline.sliceCubic({5, 277}, {381, -74}, {243, 162}); 160 mandoline.sliceLine({41, 43}); 161 canvas->drawPath(mandoline.path(), paint); 162 163 mandoline.reset({357.049988f, 446.049988f}); 164 mandoline.sliceCubic({472.750000f, -71.950012f}, {639.750000f, 531.950012f}, 165 {309.049988f, 347.950012f}); 166 mandoline.sliceLine({309.049988f, 419}); 167 mandoline.sliceLine({357.049988f, 446.049988f}); 168 canvas->drawPath(mandoline.path(), paint); 169 170 canvas->save(); 171 canvas->translate(421, 105); 172 canvas->scale(100, 81); 173 mandoline.reset({-cosf(SkDegreesToRadians(-60)), sinf(SkDegreesToRadians(-60))}); 174 mandoline.sliceConic({-2, 0}, 175 {-cosf(SkDegreesToRadians(60)), sinf(SkDegreesToRadians(60))}, .5f); 176 mandoline.sliceConic({-cosf(SkDegreesToRadians(120))*2, sinf(SkDegreesToRadians(120))*2}, 177 {1, 0}, .5f); 178 mandoline.sliceLine({0, 0}); 179 mandoline.sliceLine({-cosf(SkDegreesToRadians(-60)), sinf(SkDegreesToRadians(-60))}); 180 canvas->drawPath(mandoline.path(), paint); 181 canvas->restore(); 182 183 canvas->save(); 184 canvas->translate(150, 300); 185 canvas->scale(75, 75); 186 mandoline.reset({1, 0}); 187 constexpr int nquads = 5; 188 for (int i = 0; i < nquads; ++i) { 189 float theta1 = 2*SK_ScalarPI/nquads * (i + .5f); 190 float theta2 = 2*SK_ScalarPI/nquads * (i + 1); 191 mandoline.sliceQuadratic({cosf(theta1)*2, sinf(theta1)*2}, 192 {cosf(theta2), sinf(theta2)}); 193 } 194 canvas->drawPath(mandoline.path(), paint); 195 canvas->restore(); 196 } 197}; 198 199DEF_GM(return new SliverPathsGM;) 200 201} // namespace skiagm 202