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/*
* Copyright 2018 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "gm.h"
#include "sk_tool_utils.h"
#include "SkPaint.h"
#include "SkPath.h"
#include "SkPoint.h"
#include "SkGeometry.h"
#include <math.h>
namespace skiagm {
// Slices paths into sliver-size contours shaped like ice cream cones.
class MandolineSlicer {
public:
static constexpr int kDefaultSubdivisions = 10;
MandolineSlicer(SkPoint anchorPt) {
fPath.setFillType(SkPath::kEvenOdd_FillType);
fPath.setIsVolatile(true);
this->reset(anchorPt);
}
void reset(SkPoint anchorPt) {
fPath.reset();
fLastPt = fAnchorPt = anchorPt;
}
void sliceLine(SkPoint pt, int numSubdivisions = kDefaultSubdivisions) {
if (numSubdivisions <= 0) {
fPath.moveTo(fAnchorPt);
fPath.lineTo(fLastPt);
fPath.lineTo(pt);
fPath.close();
fLastPt = pt;
return;
}
float T = this->chooseChopT(numSubdivisions);
if (0 == T) {
fPath.lineTo(fLastPt);
this->sliceLine(pt, numSubdivisions - 1);
return;
}
SkPoint midpt = fLastPt * (1 - T) + pt * T;
this->sliceLine(midpt, numSubdivisions - 1);
this->sliceLine(pt, numSubdivisions - 1);
}
void sliceQuadratic(SkPoint p1, SkPoint p2, int numSubdivisions = kDefaultSubdivisions) {
if (numSubdivisions <= 0) {
fPath.moveTo(fAnchorPt);
fPath.lineTo(fLastPt);
fPath.quadTo(p1, p2);
fPath.close();
fLastPt = p2;
return;
}
float T = this->chooseChopT(numSubdivisions);
if (0 == T) {
fPath.quadTo(fLastPt, fLastPt);
this->sliceQuadratic(p1, p2, numSubdivisions - 1);
return;
}
SkPoint P[3] = {fLastPt, p1, p2}, PP[5];
SkChopQuadAt(P, PP, T);
this->sliceQuadratic(PP[1], PP[2], numSubdivisions - 1);
this->sliceQuadratic(PP[3], PP[4], numSubdivisions - 1);
}
void sliceCubic(SkPoint p1, SkPoint p2, SkPoint p3,
int numSubdivisions = kDefaultSubdivisions) {
if (numSubdivisions <= 0) {
fPath.moveTo(fAnchorPt);
fPath.lineTo(fLastPt);
fPath.cubicTo(p1, p2, p3);
fPath.close();
fLastPt = p3;
return;
}
float T = this->chooseChopT(numSubdivisions);
if (0 == T) {
fPath.cubicTo(fLastPt, fLastPt, fLastPt);
this->sliceCubic(p1, p2, p3, numSubdivisions - 1);
return;
}
SkPoint P[4] = {fLastPt, p1, p2, p3}, PP[7];
SkChopCubicAt(P, PP, T);
this->sliceCubic(PP[1], PP[2], PP[3], numSubdivisions - 1);
this->sliceCubic(PP[4], PP[5], PP[6], numSubdivisions - 1);
}
void sliceConic(SkPoint p1, SkPoint p2, float w, int numSubdivisions = kDefaultSubdivisions) {
if (numSubdivisions <= 0) {
fPath.moveTo(fAnchorPt);
fPath.lineTo(fLastPt);
fPath.conicTo(p1, p2, w);
fPath.close();
fLastPt = p2;
return;
}
float T = this->chooseChopT(numSubdivisions);
if (0 == T) {
fPath.conicTo(fLastPt, fLastPt, w);
this->sliceConic(p1, p2, w, numSubdivisions - 1);
return;
}
SkConic conic(fLastPt, p1, p2, w), halves[2];
if (!conic.chopAt(T, halves)) {
SK_ABORT("SkConic::chopAt failed");
}
this->sliceConic(halves[0].fPts[1], halves[0].fPts[2], halves[0].fW, numSubdivisions - 1);
this->sliceConic(halves[1].fPts[1], halves[1].fPts[2], halves[1].fW, numSubdivisions - 1);
}
const SkPath& path() const { return fPath; }
private:
float chooseChopT(int numSubdivisions) {
SkASSERT(numSubdivisions > 0);
if (numSubdivisions > 1) {
return .5f;
}
float T = (0 == fRand.nextU() % 10) ? 0 : scalbnf(1, -(int)fRand.nextRangeU(10, 149));
SkASSERT(T >= 0 && T < 1);
return T;
}
SkRandom fRand;
SkPath fPath;
SkPoint fAnchorPt;
SkPoint fLastPt;
};
class SliverPathsGM : public GM {
public:
SliverPathsGM() {
this->setBGColor(sk_tool_utils::color_to_565(SK_ColorBLACK));
}
protected:
SkString onShortName() override {
return SkString("mandoline");
}
SkISize onISize() override {
return SkISize::Make(560, 475);
}
void onDraw(SkCanvas* canvas) override {
SkPaint paint;
paint.setColor(SK_ColorWHITE);
paint.setAntiAlias(true);
MandolineSlicer mandoline({41, 43});
mandoline.sliceCubic({5, 277}, {381, -74}, {243, 162});
mandoline.sliceLine({41, 43});
canvas->drawPath(mandoline.path(), paint);
mandoline.reset({357.049988f, 446.049988f});
mandoline.sliceCubic({472.750000f, -71.950012f}, {639.750000f, 531.950012f},
{309.049988f, 347.950012f});
mandoline.sliceLine({309.049988f, 419});
mandoline.sliceLine({357.049988f, 446.049988f});
canvas->drawPath(mandoline.path(), paint);
canvas->save();
canvas->translate(421, 105);
canvas->scale(100, 81);
mandoline.reset({-cosf(SkDegreesToRadians(-60)), sinf(SkDegreesToRadians(-60))});
mandoline.sliceConic({-2, 0},
{-cosf(SkDegreesToRadians(60)), sinf(SkDegreesToRadians(60))}, .5f);
mandoline.sliceConic({-cosf(SkDegreesToRadians(120))*2, sinf(SkDegreesToRadians(120))*2},
{1, 0}, .5f);
mandoline.sliceLine({0, 0});
mandoline.sliceLine({-cosf(SkDegreesToRadians(-60)), sinf(SkDegreesToRadians(-60))});
canvas->drawPath(mandoline.path(), paint);
canvas->restore();
canvas->save();
canvas->translate(150, 300);
canvas->scale(75, 75);
mandoline.reset({1, 0});
constexpr int nquads = 5;
for (int i = 0; i < nquads; ++i) {
float theta1 = 2*SK_ScalarPI/nquads * (i + .5f);
float theta2 = 2*SK_ScalarPI/nquads * (i + 1);
mandoline.sliceQuadratic({cosf(theta1)*2, sinf(theta1)*2},
{cosf(theta2), sinf(theta2)});
}
canvas->drawPath(mandoline.path(), paint);
canvas->restore();
}
};
DEF_GM(return new SliverPathsGM;)
}
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