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1 /*
2  * Copyright 2011 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 "include/core/SkCanvas.h"
9 #include "include/core/SkColorPriv.h"
10 #include "include/core/SkFont.h"
11 #include "include/core/SkPaint.h"
12 #include "include/core/SkPath.h"
13 #include "include/utils/SkRandom.h"
14 #include "samplecode/Sample.h"
15 #include "src/core/SkClipOpPriv.h"
16 #include "src/core/SkPathPriv.h"
17 #include "tools/Resources.h"
18 
19 constexpr int W = 150;
20 constexpr int H = 200;
21 
show_text(SkCanvas * canvas,bool doAA)22 static void show_text(SkCanvas* canvas, bool doAA) {
23     SkRandom rand;
24     SkPaint paint;
25     SkFont font(nullptr, 20);
26     font.setEdging(doAA ? SkFont::Edging::kSubpixelAntiAlias : SkFont::Edging::kAlias);
27 
28     for (int i = 0; i < 200; ++i) {
29         paint.setColor((SK_A32_MASK << SK_A32_SHIFT) | rand.nextU());
30         canvas->drawString("Hamburgefons", rand.nextSScalar1() * W, rand.nextSScalar1() * H + 20,
31                            font, paint);
32     }
33 }
34 
show_fill(SkCanvas * canvas,bool doAA)35 static void show_fill(SkCanvas* canvas, bool doAA) {
36     SkRandom rand;
37     SkPaint paint;
38     paint.setAntiAlias(doAA);
39 
40     for (int i = 0; i < 50; ++i) {
41         SkRect r;
42         SkPath p;
43 
44         r.setXYWH(rand.nextSScalar1() * W, rand.nextSScalar1() * H,
45                   rand.nextUScalar1() * W, rand.nextUScalar1() * H);
46         paint.setColor(rand.nextU());
47         canvas->drawRect(r, paint);
48 
49         r.setXYWH(rand.nextSScalar1() * W, rand.nextSScalar1() * H,
50                   rand.nextUScalar1() * W, rand.nextUScalar1() * H);
51         paint.setColor(rand.nextU());
52         p.addOval(r);
53         canvas->drawPath(p, paint);
54     }
55 }
56 
randRange(SkRandom & rand,SkScalar min,SkScalar max)57 static SkScalar randRange(SkRandom& rand, SkScalar min, SkScalar max) {
58     SkASSERT(min <= max);
59     return min + rand.nextUScalar1() * (max - min);
60 }
61 
show_stroke(SkCanvas * canvas,bool doAA,SkScalar strokeWidth,int n)62 static void show_stroke(SkCanvas* canvas, bool doAA, SkScalar strokeWidth, int n) {
63     SkRandom rand;
64     SkPaint paint;
65     paint.setAntiAlias(doAA);
66     paint.setStyle(SkPaint::kStroke_Style);
67     paint.setStrokeWidth(strokeWidth);
68 
69     for (int i = 0; i < n; ++i) {
70         SkRect r;
71         SkPath p;
72 
73         r.setXYWH(rand.nextSScalar1() * W, rand.nextSScalar1() * H,
74                   rand.nextUScalar1() * W, rand.nextUScalar1() * H);
75         paint.setColor(rand.nextU());
76         canvas->drawRect(r, paint);
77 
78         r.setXYWH(rand.nextSScalar1() * W, rand.nextSScalar1() * H,
79                   rand.nextUScalar1() * W, rand.nextUScalar1() * H);
80         paint.setColor(rand.nextU());
81         p.addOval(r);
82         canvas->drawPath(p, paint);
83 
84         const SkScalar minx = -SkIntToScalar(W)/4;
85         const SkScalar maxx = 5*SkIntToScalar(W)/4;
86         const SkScalar miny = -SkIntToScalar(H)/4;
87         const SkScalar maxy = 5*SkIntToScalar(H)/4;
88         paint.setColor(rand.nextU());
89         canvas->drawLine(randRange(rand, minx, maxx), randRange(rand, miny, maxy),
90                          randRange(rand, minx, maxx), randRange(rand, miny, maxy),
91                          paint);
92     }
93 }
94 
show_hair(SkCanvas * canvas,bool doAA)95 static void show_hair(SkCanvas* canvas, bool doAA) {
96     show_stroke(canvas, doAA, 0, 150);
97 }
98 
show_thick(SkCanvas * canvas,bool doAA)99 static void show_thick(SkCanvas* canvas, bool doAA) {
100     show_stroke(canvas, doAA, SkIntToScalar(5), 50);
101 }
102 
103 typedef void (*CanvasProc)(SkCanvas*, bool);
104 
105 class ClipView : public Sample {
name()106     SkString name() override { return SkString("Clip"); }
107 
onDrawContent(SkCanvas * canvas)108     void onDrawContent(SkCanvas* canvas) override {
109         canvas->drawColor(SK_ColorWHITE);
110         canvas->translate(SkIntToScalar(20), SkIntToScalar(20));
111 
112         static const CanvasProc gProc[] = {
113             show_text, show_thick, show_hair, show_fill
114         };
115 
116         SkRect r = { 0, 0, SkIntToScalar(W), SkIntToScalar(H) };
117         SkPath clipPath;
118         r.inset(SK_Scalar1 / 4, SK_Scalar1 / 4);
119         clipPath.addRoundRect(r, SkIntToScalar(20), SkIntToScalar(20));
120 
121 //        clipPath.toggleInverseFillType();
122 
123         for (int aa = 0; aa <= 1; ++aa) {
124             canvas->save();
125             for (size_t i = 0; i < SK_ARRAY_COUNT(gProc); ++i) {
126                 canvas->save();
127                 canvas->clipPath(clipPath, kIntersect_SkClipOp, SkToBool(aa));
128 //                canvas->drawColor(SK_ColorWHITE);
129                 gProc[i](canvas, SkToBool(aa));
130                 canvas->restore();
131                 canvas->translate(W * SK_Scalar1 * 8 / 7, 0);
132             }
133             canvas->restore();
134             canvas->translate(0, H * SK_Scalar1 * 8 / 7);
135         }
136     }
137 };
138 
139 DEF_SAMPLE( return new ClipView(); )
140 
141 ///////////////////////////////////////////////////////////////////////////////
142 
143 struct SkHalfPlane {
144     SkScalar fA, fB, fC;
145 
evalSkHalfPlane146     SkScalar eval(SkScalar x, SkScalar y) const {
147         return fA * x + fB * y + fC;
148     }
operator ()SkHalfPlane149     SkScalar operator()(SkScalar x, SkScalar y) const { return this->eval(x, y); }
150 
twoPtsSkHalfPlane151     bool twoPts(SkPoint pts[2]) const {
152         // normalize plane to help with the perpendicular step, below
153         SkScalar len = SkScalarSqrt(fA*fA + fB*fB);
154         if (!len) {
155             return false;
156         }
157         SkScalar denom = SkScalarInvert(len);
158         SkScalar a = fA * denom;
159         SkScalar b = fB * denom;
160         SkScalar c = fC * denom;
161 
162         // We compute p0 on the half-plane by setting one of the components to 0
163         // We compute p1 by stepping from p0 along a perpendicular to the normal
164         if (b) {
165             pts[0] = { 0, -c / b };
166             pts[1] = { b, pts[0].fY - a};
167         } else if (a) {
168             pts[0] = { -c / a,        0 };
169             pts[1] = { pts[0].fX + b, -a };
170         } else {
171             return false;
172         }
173 
174         SkASSERT(SkScalarNearlyZero(this->operator()(pts[0].fX, pts[0].fY)));
175         SkASSERT(SkScalarNearlyZero(this->operator()(pts[1].fX, pts[1].fY)));
176         return true;
177     }
178 
179     enum Result {
180         kAllNegative,
181         kAllPositive,
182         kMixed
183     };
testSkHalfPlane184     Result test(const SkRect& bounds) const {
185         SkPoint diagMin, diagMax;
186         if (fA >= 0) {
187             diagMin.fX = bounds.fLeft;
188             diagMax.fX = bounds.fRight;
189         } else {
190             diagMin.fX = bounds.fRight;
191             diagMax.fX = bounds.fLeft;
192         }
193         if (fB >= 0) {
194             diagMin.fY = bounds.fTop;
195             diagMax.fY = bounds.fBottom;
196         } else {
197             diagMin.fY = bounds.fBottom;
198             diagMax.fY = bounds.fTop;
199         }
200         SkScalar test = this->eval(diagMin.fX, diagMin.fY);
201         SkScalar sign = test*this->eval(diagMax.fX, diagMin.fY);
202         if (sign > 0) {
203             // the path is either all on one side of the half-plane or the other
204             if (test < 0) {
205                 return kAllNegative;
206             } else {
207                 return kAllPositive;
208             }
209         }
210         return kMixed;
211     }
212 };
213 
214 #include "src/core/SkEdgeClipper.h"
215 
clip(const SkPath & path,SkPoint p0,SkPoint p1,SkPath * clippedPath)216 static void clip(const SkPath& path, SkPoint p0, SkPoint p1, SkPath* clippedPath) {
217     SkMatrix mx, inv;
218     SkVector v = p1 - p0;
219     mx.setAll(v.fX, -v.fY, p0.fX,
220               v.fY,  v.fX, p0.fY,
221                  0,     0,     1);
222     SkAssertResult(mx.invert(&inv));
223 
224     SkPath rotated;
225     path.transform(inv, &rotated);
226 
227     SkScalar big = 1e28f;
228     SkRect clip = {-big, 0, big, big };
229 
230     struct Rec {
231         SkPath* fResult;
232         SkPoint fPrev;
233     } rec = { clippedPath, {0, 0} };
234 
235     SkEdgeClipper::ClipPath(rotated, clip, false,
236                             [](SkEdgeClipper* clipper, bool newCtr, void* ctx) {
237         Rec* rec = (Rec*)ctx;
238 
239         bool addLineTo = false;
240         SkPoint      pts[4];
241         SkPath::Verb verb;
242         while ((verb = clipper->next(pts)) != SkPath::kDone_Verb) {
243             if (newCtr) {
244                 rec->fResult->moveTo(pts[0]);
245                 rec->fPrev = pts[0];
246                 newCtr = false;
247             }
248 
249             if (addLineTo || pts[0] != rec->fPrev) {
250                 rec->fResult->lineTo(pts[0]);
251             }
252 
253             switch (verb) {
254                 case SkPath::kLine_Verb:
255                     rec->fResult->lineTo(pts[1]);
256                     rec->fPrev = pts[1];
257                     break;
258                 case SkPath::kQuad_Verb:
259                     rec->fResult->quadTo(pts[1], pts[2]);
260                     rec->fPrev = pts[2];
261                     break;
262                 case SkPath::kCubic_Verb:
263                     rec->fResult->cubicTo(pts[1], pts[2], pts[3]);
264                     rec->fPrev = pts[3];
265                     break;
266                 default: break;
267             }
268             addLineTo = true;
269         }
270     }, &rec);
271 
272     rec.fResult->transform(mx);
273 }
274 
draw_halfplane(SkCanvas * canvas,SkPoint p0,SkPoint p1,SkColor c)275 static void draw_halfplane(SkCanvas* canvas, SkPoint p0, SkPoint p1, SkColor c) {
276     SkVector v = p1 - p0;
277     p0 = p0 - v * 1000;
278     p1 = p1 + v * 1000;
279 
280     SkPaint paint;
281     paint.setColor(c);
282     canvas->drawLine(p0, p1, paint);
283 }
284 
make_path()285 static SkPath make_path() {
286     SkRandom rand;
287     auto rand_pt = [&rand]() {
288         auto x = rand.nextF();
289         auto y = rand.nextF();
290         return SkPoint{x * 400, y * 400};
291     };
292 
293     SkPath path;
294     for (int i = 0; i < 4; ++i) {
295         SkPoint pts[6];
296         for (auto& p : pts) {
297             p = rand_pt();
298         }
299         path.moveTo(pts[0]).quadTo(pts[1], pts[2]).quadTo(pts[3], pts[4]).lineTo(pts[5]);
300     }
301     return path;
302 }
303 
304 class HalfPlaneView : public Sample {
305     SkPoint fPts[2];
306     SkPath fPath;
307 
name()308     SkString name() override { return SkString("halfplane"); }
309 
onOnceBeforeDraw()310     void onOnceBeforeDraw() override {
311         fPts[0] = {0, 0};
312         fPts[1] = {3, 2};
313         fPath = make_path();
314     }
315 
onDrawContent(SkCanvas * canvas)316     void onDrawContent(SkCanvas* canvas) override {
317         SkPaint paint;
318 
319         paint.setColor({0.5f, 0.5f, 0.5f, 1.0f}, nullptr);
320         canvas->drawPath(fPath, paint);
321 
322         paint.setColor({0, 0, 0, 1}, nullptr);
323 
324         SkPath clippedPath;
325         clip(fPath, fPts[0], fPts[1], &clippedPath);
326         canvas->drawPath(clippedPath, paint);
327 
328         draw_halfplane(canvas, fPts[0], fPts[1], SK_ColorRED);
329     }
330 
onFindClickHandler(SkScalar x,SkScalar y,skui::ModifierKey modi)331     Click* onFindClickHandler(SkScalar x, SkScalar y, skui::ModifierKey modi) override {
332         return new Click;
333     }
334 
onClick(Click * click)335     bool onClick(Click* click) override {
336         fPts[0] = click->fCurr;
337         fPts[1] = fPts[0] + SkPoint{3, 2};
338         return true;
339     }
340 };
DEF_SAMPLE(return new HalfPlaneView ();)341 DEF_SAMPLE( return new HalfPlaneView(); )
342 
343 static void draw_halfplane(SkCanvas* canvas, const SkHalfPlane& p, SkColor c) {
344     SkPoint pts[2];
345     p.twoPts(pts);
346     draw_halfplane(canvas, pts[0], pts[1], c);
347 }
348 
compute_half_planes(const SkMatrix & mx,SkScalar W,SkScalar H,SkHalfPlane planes[4])349 static void compute_half_planes(const SkMatrix& mx, SkScalar W, SkScalar H,
350                                 SkHalfPlane planes[4]) {
351     SkScalar a = mx[0], b = mx[1], c = mx[2],
352              d = mx[3], e = mx[4], f = mx[5],
353              g = mx[6], h = mx[7], i = mx[8];
354 
355     planes[0] = { 2*g - 2*a/W,  2*h - 2*b/W,  2*i - 2*c/W };
356     planes[1] = { 2*a/W,        2*b/W,        2*c/W };
357     planes[2] = { 2*g - 2*d/H,  2*h - 2*e/H,  2*i - 2*f/H };
358     planes[3] = { 2*d/H,        2*e/H,        2*f/H };
359 }
360 
361 class HalfPlaneView2 : public Sample {
362     SkPoint fPts[4];
363     SkPath fPath;
364 
name()365     SkString name() override { return SkString("halfplane2"); }
366 
onOnceBeforeDraw()367     void onOnceBeforeDraw() override {
368         fPath = make_path();
369         SkRect r = fPath.getBounds();
370         r.toQuad(fPts);
371     }
372 
onDrawContent(SkCanvas * canvas)373     void onDrawContent(SkCanvas* canvas) override {
374         SkMatrix mx;
375         {
376             SkRect r = fPath.getBounds();
377             SkPoint src[4];
378             r.toQuad(src);
379             mx.setPolyToPoly(src, fPts, 4);
380         }
381 
382         SkPaint paint;
383         canvas->drawPath(fPath, paint);
384 
385         canvas->save();
386         canvas->concat(mx);
387         paint.setColor(0x40FF0000);
388         canvas->drawPath(fPath, paint);
389         canvas->restore();
390 
391         // draw the frame
392         paint.setStrokeWidth(10);
393         paint.setColor(SK_ColorGREEN);
394         canvas->drawPoints(SkCanvas::kPoints_PointMode, 4, fPts, paint);
395 
396         // draw the half-planes
397         SkHalfPlane planes[4];
398         compute_half_planes(mx, 400, 400, planes);
399         for (auto& p : planes) {
400             draw_halfplane(canvas, p, SK_ColorRED);
401         }
402     }
403 
onFindClickHandler(SkScalar x,SkScalar y,skui::ModifierKey modi)404     Click* onFindClickHandler(SkScalar x, SkScalar y, skui::ModifierKey modi) override {
405         SkScalar r = 8;
406         SkRect rect = SkRect::MakeXYWH(x - r, y - r, 2*r, 2*r);
407         for (int i = 0; i < 4; ++i) {
408             if (rect.contains(fPts[i].fX, fPts[i].fY)) {
409                 Click* c = new Click;
410                 c->fMeta.setS32("index", i);
411                 return c;
412             }
413         }
414         return nullptr;
415     }
416 
onClick(Click * click)417     bool onClick(Click* click) override {
418         int32_t index;
419         SkAssertResult(click->fMeta.findS32("index", &index));
420         SkASSERT(index >= 0 && index < 4);
421         fPts[index] = click->fCurr;
422         return true;
423     }
424 };
DEF_SAMPLE(return new HalfPlaneView2 ();)425 DEF_SAMPLE( return new HalfPlaneView2(); )
426 
427 static SkM44 inv(const SkM44& m) {
428     SkM44 inverse;
429     SkAssertResult(m.invert(&inverse));
430     return inverse;
431 }
432 
half_plane_w0(const SkMatrix & m)433 static SkHalfPlane half_plane_w0(const SkMatrix& m) {
434     return { m[SkMatrix::kMPersp0], m[SkMatrix::kMPersp1], m[SkMatrix::kMPersp2] - 0.05f };
435 }
436 
437 class SampleCameraView : public Sample {
438     float   fNear = 0.05f;
439     float   fFar = 4;
440     float   fAngle = SK_ScalarPI / 4;
441 
442     SkV3    fEye { 0, 0, 1.0f/tan(fAngle/2) - 1 };
443     SkV3    fCOA { 0, 0, 0 };
444     SkV3    fUp  { 0, 1, 0 };
445 
446     SkM44  fRot;
447     SkV3   fTrans;
448 
rotate(float x,float y,float z)449     void rotate(float x, float y, float z) {
450         SkM44 r;
451         if (x) {
452             r.setRotateUnit({1, 0, 0}, x);
453         } else if (y) {
454             r.setRotateUnit({0, 1, 0}, y);
455         } else {
456             r.setRotateUnit({0, 0, 1}, z);
457         }
458         fRot = r * fRot;
459     }
460 
461 public:
get44(const SkRect & r) const462     SkM44 get44(const SkRect& r) const {
463         SkScalar w = r.width();
464         SkScalar h = r.height();
465 
466         SkM44 camera = Sk3LookAt(fEye, fCOA, fUp),
467               perspective = Sk3Perspective(fNear, fFar, fAngle),
468               translate = SkM44::Translate(fTrans.x, fTrans.y, fTrans.z),
469               viewport = SkM44::Translate(r.centerX(), r.centerY(), 0) *
470                          SkM44::Scale(w*0.5f, h*0.5f, 1);
471 
472         return viewport * perspective * camera * translate * fRot * inv(viewport);
473     }
474 
onChar(SkUnichar uni)475     bool onChar(SkUnichar uni) override {
476         float delta = SK_ScalarPI / 30;
477         switch (uni) {
478             case '8': this->rotate( delta, 0, 0); return true;
479             case '2': this->rotate(-delta, 0, 0); return true;
480             case '4': this->rotate(0,  delta, 0); return true;
481             case '6': this->rotate(0, -delta, 0); return true;
482             case '-': this->rotate(0, 0,  delta); return true;
483             case '+': this->rotate(0, 0, -delta); return true;
484 
485             case 'i': fTrans.z += 0.1f; SkDebugf("z %g\n", fTrans.z); return true;
486             case 'k': fTrans.z -= 0.1f; SkDebugf("z %g\n", fTrans.z); return true;
487 
488             case 'n': fNear += 0.1f; SkDebugf("near %g\n", fNear); return true;
489             case 'N': fNear -= 0.1f; SkDebugf("near %g\n", fNear); return true;
490             case 'f': fFar  += 0.1f; SkDebugf("far  %g\n", fFar); return true;
491             case 'F': fFar  -= 0.1f; SkDebugf("far  %g\n", fFar); return true;
492             default: break;
493         }
494         return false;
495     }
496 };
497 
498 class HalfPlaneView3 : public SampleCameraView {
499     SkPath fPath;
500     sk_sp<SkShader> fShader;
501     bool fShowUnclipped = false;
502 
name()503     SkString name() override { return SkString("halfplane3"); }
504 
onOnceBeforeDraw()505     void onOnceBeforeDraw() override {
506         fPath = make_path();
507         fShader = GetResourceAsImage("images/mandrill_128.png")
508                         ->makeShader(SkMatrix::MakeScale(3, 3));
509     }
510 
onChar(SkUnichar uni)511     bool onChar(SkUnichar uni) override {
512         switch (uni) {
513             case 'u': fShowUnclipped = !fShowUnclipped; return true;
514             default: break;
515         }
516         return this->SampleCameraView::onChar(uni);
517     }
518 
onDrawContent(SkCanvas * canvas)519     void onDrawContent(SkCanvas* canvas) override {
520         SkM44 mx = this->get44({0, 0, 400, 400});
521 
522         SkPaint paint;
523         paint.setColor({0.75, 0.75, 0.75, 1});
524         canvas->drawPath(fPath, paint);
525 
526         paint.setShader(fShader);
527 
528         if (fShowUnclipped) {
529             canvas->save();
530             canvas->concat44(mx);
531             paint.setAlphaf(0.33f);
532             canvas->drawPath(fPath, paint);
533             paint.setAlphaf(1.f);
534             canvas->restore();
535         }
536 
537 
538         SkColor planeColor = SK_ColorBLUE;
539         SkPath clippedPath, *path = &fPath;
540         if (SkPathPriv::PerspectiveClip(fPath, mx.asM33(), &clippedPath)) {
541             path = &clippedPath;
542             planeColor = SK_ColorRED;
543         }
544         canvas->save();
545         canvas->concat44(mx);
546         canvas->drawPath(*path, paint);
547         canvas->restore();
548 
549         SkHalfPlane hpw = half_plane_w0(mx.asM33());
550         draw_halfplane(canvas, hpw, planeColor);
551     }
552 };
553 DEF_SAMPLE( return new HalfPlaneView3(); )
554 
555 class HalfPlaneCoons : public SampleCameraView {
556     SkPoint fPatch[12];
557     SkColor fColors[4] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorBLACK };
558     SkPoint fTex[4]    = {{0, 0}, {256, 0}, {256, 256}, {0, 256}};
559     sk_sp<SkShader> fShader;
560 
561     bool fShowHandles = false;
562     bool fShowSkeleton = false;
563     bool fShowTex = false;
564 
name()565     SkString name() override { return SkString("halfplane-coons"); }
566 
onOnceBeforeDraw()567     void onOnceBeforeDraw() override {
568         fPatch[0] = {   0, 0 };
569         fPatch[1] = { 100, 0 };
570         fPatch[2] = { 200, 0 };
571         fPatch[3] = { 300, 0 };
572         fPatch[4] = { 300, 100 };
573         fPatch[5] = { 300, 200 };
574         fPatch[6] = { 300, 300 };
575         fPatch[7] = { 200, 300 };
576         fPatch[8] = { 100, 300 };
577         fPatch[9] = {   0, 300 };
578         fPatch[10] = {  0, 200 };
579         fPatch[11] = {  0, 100 };
580 
581         fShader = GetResourceAsImage("images/mandrill_256.png")->makeShader();
582     }
583 
onDrawContent(SkCanvas * canvas)584     void onDrawContent(SkCanvas* canvas) override {
585         SkPaint paint;
586 
587         canvas->save();
588         canvas->concat44(this->get44({0, 0, 300, 300}));
589 
590         const SkPoint* tex = nullptr;
591         const SkColor* col = nullptr;
592         if (!fShowSkeleton) {
593             if (fShowTex) {
594                 paint.setShader(fShader);
595                 tex = fTex;
596             } else {
597                 col = fColors;
598             }
599         }
600         canvas->drawPatch(fPatch, col, tex, SkBlendMode::kSrc, paint);
601         paint.setShader(nullptr);
602 
603         if (fShowHandles) {
604             paint.setAntiAlias(true);
605             paint.setStrokeCap(SkPaint::kRound_Cap);
606             paint.setStrokeWidth(8);
607             canvas->drawPoints(SkCanvas::kPoints_PointMode, 12, fPatch, paint);
608             paint.setColor(SK_ColorWHITE);
609             paint.setStrokeWidth(6);
610             canvas->drawPoints(SkCanvas::kPoints_PointMode, 12, fPatch, paint);
611         }
612 
613         canvas->restore();
614     }
615 
onFindClickHandler(SkScalar x,SkScalar y,skui::ModifierKey modi)616     Click* onFindClickHandler(SkScalar x, SkScalar y, skui::ModifierKey modi) override {
617         auto dist = [](SkPoint a, SkPoint b) { return (b - a).length(); };
618 
619         const float tol = 15;
620         for (int i = 0; i < 12; ++i) {
621             if (dist({x,y}, fPatch[i]) <= tol) {
622                 Click* c = new Click;
623                 c->fMeta.setS32("index", i);
624                 return c;
625             }
626         }
627         return nullptr;
628     }
629 
onClick(Click * click)630     bool onClick(Click* click) override {
631         int32_t index;
632         SkAssertResult(click->fMeta.findS32("index", &index));
633         SkASSERT(index >= 0 && index < 12);
634         fPatch[index] = click->fCurr;
635         return true;
636     }
637 
onChar(SkUnichar uni)638     bool onChar(SkUnichar uni) override {
639         switch (uni) {
640             case 'h': fShowHandles = !fShowHandles; return true;
641             case 'k': fShowSkeleton = !fShowSkeleton; return true;
642             case 't': fShowTex = !fShowTex; return true;
643             default: break;
644         }
645         return this->SampleCameraView::onChar(uni);
646     }
647 
648 };
649 DEF_SAMPLE( return new HalfPlaneCoons(); )
650