samplecode/SampleQuadStroker.cpp - platform/external/skia - Gitiles

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "sk_tool_utils.h"
 #include "SampleCode.h"
 #include "SkView.h"
 #include "SkCanvas.h"
 #include "SkGeometry.h"
 #include "SkPathMeasure.h"
 #include "SkRandom.h"
 #include "SkRRect.h"
 #include "SkColorPriv.h"
 #include "SkStrokerPriv.h"
 #include "SkSurface.h"

 static bool hittest(const SkPoint& target, SkScalar x, SkScalar y) {
     const SkScalar TOL = 7;
     return SkPoint::Distance(target, SkPoint::Make(x, y)) <= TOL;
 }

 static int getOnCurvePoints(const SkPath& path, SkPoint storage[]) {
     SkPath::RawIter iter(path);
     SkPoint pts[4];
     SkPath::Verb verb;

     int count = 0;
     while ((verb = iter.next(pts)) != SkPath::kDone_Verb) {
         switch (verb) {
             case SkPath::kMove_Verb:
             case SkPath::kLine_Verb:
             case SkPath::kQuad_Verb:
             case SkPath::kConic_Verb:
             case SkPath::kCubic_Verb:
                 storage[count++] = pts[0];
                 break;
             default:
                 break;
         }
     }
     return count;
 }

 static void getContourCounts(const SkPath& path, SkTArray<int>* contourCounts) {
     SkPath::RawIter iter(path);
     SkPoint pts[4];
     SkPath::Verb verb;

     int count = 0;
     while ((verb = iter.next(pts)) != SkPath::kDone_Verb) {
         switch (verb) {
             case SkPath::kMove_Verb:
             case SkPath::kLine_Verb:
                 count += 1;
                 break;
             case SkPath::kQuad_Verb:
             case SkPath::kConic_Verb:
                 count += 2;
                 break;
             case SkPath::kCubic_Verb:
                 count += 3;
                 break;
             case SkPath::kClose_Verb:
                 contourCounts->push_back(count);
                 count = 0;
                 break;
             default:
                 break;
         }
     }
     if (count > 0) {
         contourCounts->push_back(count);
     }
 }

 static void erase(SkSurface* surface) {
     SkCanvas* canvas = surface->getCanvas();
     if (canvas) {
         canvas->clear(SK_ColorTRANSPARENT);
     }
 }

 struct StrokeTypeButton {
     SkRect fBounds;
     char fLabel;
     bool fEnabled;
 };

 struct CircleTypeButton : public StrokeTypeButton {
     bool fFill;
 };

 class QuadStrokerView : public SampleView {
     enum {
         SKELETON_COLOR = 0xFF0000FF,
         WIREFRAME_COLOR = 0x80FF0000
     };

     enum {
         kCount = 18
     };
     SkPoint fPts[kCount];
     SkRect fWeightControl;
     SkRect fRadiusControl;
     SkRect fErrorControl;
     SkRect fWidthControl;
     SkRect fBounds;
     SkMatrix fMatrix, fInverse;
     sk_sp<SkShader> fShader;
     SkAutoTUnref<SkSurface> fMinSurface;
     SkAutoTUnref<SkSurface> fMaxSurface;
     StrokeTypeButton fCubicButton;
     StrokeTypeButton fConicButton;
     StrokeTypeButton fQuadButton;
     StrokeTypeButton fArcButton;
     StrokeTypeButton fRRectButton;
     CircleTypeButton fCircleButton;
     StrokeTypeButton fTextButton;
     SkString fText;
     SkScalar fTextSize;
     SkScalar fWeight;
     SkScalar fRadius;
     SkScalar fWidth, fDWidth;
     SkScalar fWidthScale;
     int fW, fH, fZoom;
     bool fAnimate;
     bool fDrawRibs;
     bool fDrawTangents;
     bool fDrawTDivs;
 #ifdef SK_DEBUG
     #define kStrokerErrorMin 0.001f
     #define kStrokerErrorMax 5
 #endif
     #define kWidthMin 1
     #define kWidthMax 100
 public:
     QuadStrokerView() {
         this->setBGColor(SK_ColorLTGRAY);

         fPts[0].set(50, 200);  // cubic
         fPts[1].set(50, 100);
         fPts[2].set(150, 50);
         fPts[3].set(300, 50);

         fPts[4].set(350, 200);  // conic
         fPts[5].set(350, 100);
         fPts[6].set(450, 50);

         fPts[7].set(150, 300);  // quad
         fPts[8].set(150, 200);
         fPts[9].set(250, 150);

         fPts[10].set(250, 200);  // arc
         fPts[11].set(250, 300);
         fPts[12].set(150, 350);

         fPts[13].set(200, 200); // rrect
         fPts[14].set(400, 400);

         fPts[15].set(250, 250);  // oval
         fPts[16].set(450, 450);

         fText = "a";
         fTextSize = 12;
         fWidth = 50;
         fDWidth = 0.25f;
         fWeight = 1;
         fRadius = 150;

         fCubicButton.fLabel = 'C';
         fCubicButton.fEnabled = false;
         fConicButton.fLabel = 'K';
         fConicButton.fEnabled = false;
         fQuadButton.fLabel = 'Q';
         fQuadButton.fEnabled = false;
         fArcButton.fLabel = 'A';
         fArcButton.fEnabled = true;
         fRRectButton.fLabel = 'R';
         fRRectButton.fEnabled = false;
         fCircleButton.fLabel = 'O';
         fCircleButton.fEnabled = true;
         fCircleButton.fFill = true;
         fTextButton.fLabel = 'T';
         fTextButton.fEnabled = false;
         fAnimate = false;
         setAsNeeded();
     }

 protected:
     bool onQuery(SkEvent* evt) override {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, "QuadStroker");
             return true;
         }
         SkUnichar uni;
         if (fTextButton.fEnabled && SampleCode::CharQ(*evt, &uni)) {
             switch (uni) {
                 case ' ':
                     fText = "";
                     break;
                 case '-':
                     fTextSize = SkTMax(1.0f, fTextSize - 1);
                     break;
                 case '+':
                 case '=':
                     fTextSize += 1;
                     break;
                 default:
                     fText.appendUnichar(uni);
             }
             this->inval(nullptr);
             return true;
         }
         return this->INHERITED::onQuery(evt);
     }

     void onSizeChange() override {
         fRadiusControl.setXYWH(this->width() - 200, 30, 30, 400);
         fWeightControl.setXYWH(this->width() - 150, 30, 30, 400);
         fErrorControl.setXYWH(this->width() - 100, 30, 30, 400);
         fWidthControl.setXYWH(this->width() -  50, 30, 30, 400);
         int buttonOffset = 450;
         fCubicButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
         buttonOffset += 50;
         fConicButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
         buttonOffset += 50;
         fQuadButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
         buttonOffset += 50;
         fArcButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
         buttonOffset += 50;
         fRRectButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
         buttonOffset += 50;
         fCircleButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
         buttonOffset += 50;
         fTextButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
         this->INHERITED::onSizeChange();
     }

      void copyMinToMax() {
         erase(fMaxSurface);
         SkCanvas* canvas = fMaxSurface->getCanvas();
         canvas->save();
         canvas->concat(fMatrix);
         fMinSurface->draw(canvas, 0, 0, nullptr);
         canvas->restore();

         SkPaint paint;
         paint.setXfermodeMode(SkXfermode::kClear_Mode);
         for (int iy = 1; iy < fH; ++iy) {
             SkScalar y = SkIntToScalar(iy * fZoom);
             canvas->drawLine(0, y - SK_ScalarHalf, 999, y - SK_ScalarHalf, paint);
         }
         for (int ix = 1; ix < fW; ++ix) {
             SkScalar x = SkIntToScalar(ix * fZoom);
             canvas->drawLine(x - SK_ScalarHalf, 0, x - SK_ScalarHalf, 999, paint);
         }
     }

    void setWHZ(int width, int height, int zoom) {
         fZoom = zoom;
         fBounds.set(0, 0, SkIntToScalar(width * zoom), SkIntToScalar(height * zoom));
         fMatrix.setScale(SkIntToScalar(zoom), SkIntToScalar(zoom));
         fInverse.setScale(SK_Scalar1 / zoom, SK_Scalar1 / zoom);
         fShader = sk_tool_utils::create_checkerboard_shader(0xFFCCCCCC, 0xFFFFFFFF, zoom);

         SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
         fMinSurface.reset(SkSurface::NewRaster(info));
         info = info.makeWH(width * zoom, height * zoom);
         fMaxSurface.reset(SkSurface::NewRaster(info));
     }

     void draw_points(SkCanvas* canvas, const SkPath& path, SkColor color,
                      bool show_lines) {
         SkPaint paint;
         paint.setColor(color);
         paint.setAlpha(0x80);
         paint.setAntiAlias(true);
         int n = path.countPoints();
         SkAutoSTArray<32, SkPoint> pts(n);
         if (show_lines && fDrawTangents) {
             SkTArray<int> contourCounts;
             getContourCounts(path, &contourCounts);
             SkPoint* ptPtr = pts.get();
             for (int i = 0; i < contourCounts.count(); ++i) {
                 int count = contourCounts[i];
                 path.getPoints(ptPtr, count);
                 canvas->drawPoints(SkCanvas::kPolygon_PointMode, count, ptPtr, paint);
                 ptPtr += count;
             }
         } else {
             n = getOnCurvePoints(path, pts.get());
         }
         paint.setStrokeWidth(5);
         canvas->drawPoints(SkCanvas::kPoints_PointMode, n, pts.get(), paint);
     }

     void draw_ribs(SkCanvas* canvas, const SkPath& path, SkScalar width,
                    SkColor color) {
         const SkScalar radius = width / 2;

         SkPathMeasure meas(path, false);
         SkScalar total = meas.getLength();

         SkScalar delta = 8;
         SkPaint paint, labelP;
         paint.setColor(color);
         labelP.setColor(color & 0xff5f9f5f);
         SkPoint pos, tan;
         int index = 0;
         for (SkScalar dist = 0; dist <= total; dist += delta) {
             if (meas.getPosTan(dist, &pos, &tan)) {
                 tan.scale(radius);
                 tan.rotateCCW();
                 canvas->drawLine(pos.x() + tan.x(), pos.y() + tan.y(),
                                  pos.x() - tan.x(), pos.y() - tan.y(), paint);
                 if (0 == index % 10) {
                     SkString label;
                     label.appendS32(index);
                     SkRect dot = SkRect::MakeXYWH(pos.x() - 2, pos.y() - 2, 4, 4);
                     canvas->drawRect(dot, labelP);
                     canvas->drawText(label.c_str(), label.size(),
                         pos.x() - tan.x() * 1.25f, pos.y() - tan.y() * 1.25f, labelP);
                 }
             }
             ++index;
         }
     }

     void draw_t_divs(SkCanvas* canvas, const SkPath& path, SkScalar width, SkColor color) {
         const SkScalar radius = width / 2;
         SkPaint paint;
         paint.setColor(color);
         SkPathMeasure meas(path, false);
         SkScalar total = meas.getLength();
         SkScalar delta = 8;
         int ribs = 0;
         for (SkScalar dist = 0; dist <= total; dist += delta) {
             ++ribs;
         }
         SkPath::RawIter iter(path);
         SkPoint pts[4];
         if (SkPath::kMove_Verb != iter.next(pts)) {
             SkASSERT(0);
             return;
         }
         SkPath::Verb verb = iter.next(pts);
         SkASSERT(SkPath::kLine_Verb <= verb && verb <= SkPath::kCubic_Verb);
         SkPoint pos, tan;
         for (int index = 0; index < ribs; ++index) {
             SkScalar t = (SkScalar) index / ribs;
             switch (verb) {
                 case SkPath::kLine_Verb:
                     tan = pts[1] - pts[0];
                     pos = pts[0];
                     pos.fX += tan.fX * t;
                     pos.fY += tan.fY * t;
                     break;
                 case SkPath::kQuad_Verb:
                     pos = SkEvalQuadAt(pts, t);
                     tan = SkEvalQuadTangentAt(pts, t);
                     break;
                 case SkPath::kConic_Verb: {
                     SkConic conic(pts, iter.conicWeight());
                     pos = conic.evalAt(t);
                     tan = conic.evalTangentAt(t);
                     } break;
                 case SkPath::kCubic_Verb:
                     SkEvalCubicAt(pts, t, &pos, &tan, nullptr);
                     break;
                 default:
                     SkASSERT(0);
                     return;
             }
             tan.setLength(radius);
             tan.rotateCCW();
             canvas->drawLine(pos.x() + tan.x(), pos.y() + tan.y(),
                                 pos.x() - tan.x(), pos.y() - tan.y(), paint);
             if (0 == index % 10) {
                 SkString label;
                 label.appendS32(index);
                 canvas->drawText(label.c_str(), label.size(),
                     pos.x() + tan.x() * 1.25f, pos.y() + tan.y() * 1.25f, paint);
             }
         }
     }

     void draw_stroke(SkCanvas* canvas, const SkPath& path, SkScalar width, SkScalar scale,
             bool drawText) {
         if (path.isEmpty()) {
             return;
         }
         SkRect bounds = path.getBounds();
         this->setWHZ(SkScalarCeilToInt(bounds.right()), drawText
                 ? SkScalarRoundToInt(scale * 3 / 2) : SkScalarRoundToInt(scale),
                 SkScalarRoundToInt(950.0f / scale));
         erase(fMinSurface);
         SkPaint paint;
         paint.setColor(0x1f1f0f0f);
         paint.setStyle(SkPaint::kStroke_Style);
         paint.setStrokeWidth(width * scale * scale);
         paint.setColor(0x3f0f1f3f);
         if (drawText) {
             fMinSurface->getCanvas()->drawPath(path, paint);
             this->copyMinToMax();
             fMaxSurface->draw(canvas, 0, 0, nullptr);
         }
         paint.setAntiAlias(true);
         paint.setStyle(SkPaint::kStroke_Style);
         paint.setStrokeWidth(1);

         paint.setColor(SKELETON_COLOR);
         SkPath scaled;
         SkMatrix matrix;
         matrix.reset();
         matrix.setScale(950 / scale, 950 / scale);
         if (drawText) {
             path.transform(matrix, &scaled);
         } else {
             scaled = path;
         }
         canvas->drawPath(scaled, paint);
         draw_points(canvas, scaled, SKELETON_COLOR, true);

         if (fDrawRibs) {
             draw_ribs(canvas, scaled, width, 0xFF00FF00);
         }

         if (fDrawTDivs) {
             draw_t_divs(canvas, scaled, width, 0xFF3F3F00);
         }

         SkPath fill;

         SkPaint p;
         p.setStyle(SkPaint::kStroke_Style);
         if (drawText) {
             p.setStrokeWidth(width * scale * scale);
         } else {
             p.setStrokeWidth(width);
         }
         p.getFillPath(path, &fill);
         SkPath scaledFill;
         if (drawText) {
             fill.transform(matrix, &scaledFill);
         } else {
             scaledFill = fill;
         }
         paint.setColor(WIREFRAME_COLOR);
         canvas->drawPath(scaledFill, paint);
         draw_points(canvas, scaledFill, WIREFRAME_COLOR, false);
     }

     void draw_fill(SkCanvas* canvas, const SkRect& rect, SkScalar width) {
         if (rect.isEmpty()) {
             return;
         }
         SkPaint paint;
         paint.setColor(0x1f1f0f0f);
         paint.setStyle(SkPaint::kStroke_Style);
         paint.setStrokeWidth(width);
         SkPath path;
         SkScalar maxSide = SkTMax(rect.width(), rect.height()) / 2;
         SkPoint center = { rect.fLeft + maxSide, rect.fTop + maxSide };
         path.addCircle(center.fX, center.fY, maxSide);
         canvas->drawPath(path, paint);
         paint.setStyle(SkPaint::kFill_Style);
         path.reset();
         path.addCircle(center.fX, center.fY, maxSide - width / 2);
         paint.setColor(0x3f0f1f3f);
         canvas->drawPath(path, paint);
         path.reset();
         path.setFillType(SkPath::kEvenOdd_FillType);
         path.addCircle(center.fX, center.fY, maxSide + width / 2);
         SkRect outside = SkRect::MakeXYWH(center.fX - maxSide - width, center.fY - maxSide - width,
                 (maxSide + width) * 2, (maxSide + width) * 2);
         path.addRect(outside);
         canvas->drawPath(path, paint);
     }

     void draw_button(SkCanvas* canvas, const StrokeTypeButton& button) {
         SkPaint paint;
         paint.setAntiAlias(true);
         paint.setStyle(SkPaint::kStroke_Style);
         paint.setColor(button.fEnabled ? 0xFF3F0000 : 0x6F3F0000);
         canvas->drawRect(button.fBounds, paint);
         paint.setTextSize(25.0f);
         paint.setColor(button.fEnabled ? 0xFF3F0000 : 0x6F3F0000);
         paint.setTextAlign(SkPaint::kCenter_Align);
         paint.setStyle(SkPaint::kFill_Style);
         canvas->drawText(&button.fLabel, 1, button.fBounds.centerX(), button.fBounds.fBottom - 5,
                 paint);
     }

     void draw_control(SkCanvas* canvas, const SkRect& bounds, SkScalar value,
             SkScalar min, SkScalar max, const char* name) {
         SkPaint paint;
         paint.setAntiAlias(true);
         paint.setStyle(SkPaint::kStroke_Style);
         canvas->drawRect(bounds, paint);
         SkScalar scale = max - min;
         SkScalar yPos = bounds.fTop + (value - min) * bounds.height() / scale;
         paint.setColor(0xFFFF0000);
         canvas->drawLine(bounds.fLeft - 5, yPos, bounds.fRight + 5, yPos, paint);
         SkString label;
         label.printf("%0.3g", value);
         paint.setColor(0xFF000000);
         paint.setTextSize(11.0f);
         paint.setStyle(SkPaint::kFill_Style);
         canvas->drawText(label.c_str(), label.size(), bounds.fLeft + 5, yPos - 5, paint);
         paint.setTextSize(13.0f);
         canvas->drawText(name, strlen(name), bounds.fLeft, bounds.bottom() + 11, paint);
     }

     void setForGeometry() {
         fDrawRibs = true;
         fDrawTangents = true;
         fDrawTDivs = false;
         fWidthScale = 1;
     }

     void setForText() {
         fDrawRibs = fDrawTangents = fDrawTDivs = false;
         fWidthScale = 0.002f;
     }

     void setForSingles() {
         setForGeometry();
         fDrawTDivs = true;
     }

     void setAsNeeded() {
         if (fConicButton.fEnabled || fCubicButton.fEnabled || fQuadButton.fEnabled) {
             setForSingles();
         } else if (fRRectButton.fEnabled || fCircleButton.fEnabled || fArcButton.fEnabled) {
             setForGeometry();
         } else {
             setForText();
         }
     }

     bool arcCenter(SkPoint* center) {
         SkPath path;
         path.moveTo(fPts[10]);
         path.arcTo(fPts[11], fPts[12], fRadius);
         SkPath::Iter iter(path, false);
         SkPoint pts[4];
         iter.next(pts);
         if (SkPath::kLine_Verb == iter.next(pts)) {
             iter.next(pts);
         }
         SkVector before = pts[0] - pts[1];
         SkVector after = pts[1] - pts[2];
         before.setLength(fRadius);
         after.setLength(fRadius);
         SkVector beforeCCW, afterCCW;
         before.rotateCCW(&beforeCCW);
         after.rotateCCW(&afterCCW);
         beforeCCW += pts[0];
         afterCCW += pts[2];
         *center = beforeCCW;
         if (SkScalarNearlyEqual(beforeCCW.fX, afterCCW.fX)
                 && SkScalarNearlyEqual(beforeCCW.fY, afterCCW.fY)) {
             return true;
         }
         SkVector beforeCW, afterCW;
         before.rotateCW(&beforeCW);
         after.rotateCW(&afterCW);
         beforeCW += pts[0];
         afterCW += pts[2];
         *center = beforeCW;
         return SkScalarNearlyEqual(beforeCW.fX, afterCW.fX)
                 && SkScalarNearlyEqual(beforeCCW.fY, afterCW.fY);
     }

     void onDrawContent(SkCanvas* canvas) override {
         SkPath path;
         SkScalar width = fWidth;

         if (fCubicButton.fEnabled) {
             path.moveTo(fPts[0]);
             path.cubicTo(fPts[1], fPts[2], fPts[3]);
             setForSingles();
             draw_stroke(canvas, path, width, 950, false);
         }

         if (fConicButton.fEnabled) {
             path.reset();
             path.moveTo(fPts[4]);
             path.conicTo(fPts[5], fPts[6], fWeight);
             setForSingles();
             draw_stroke(canvas, path, width, 950, false);
         }

         if (fQuadButton.fEnabled) {
             path.reset();
             path.moveTo(fPts[7]);
             path.quadTo(fPts[8], fPts[9]);
             setForSingles();
             draw_stroke(canvas, path, width, 950, false);
         }

         if (fArcButton.fEnabled) {
             path.reset();
             path.moveTo(fPts[10]);
             path.arcTo(fPts[11], fPts[12], fRadius);
             setForGeometry();
             draw_stroke(canvas, path, width, 950, false);
             SkPath pathPts;
             pathPts.moveTo(fPts[10]);
             pathPts.lineTo(fPts[11]);
             pathPts.lineTo(fPts[12]);
             draw_points(canvas, pathPts, SK_ColorDKGRAY, true);
         }

         if (fRRectButton.fEnabled) {
             SkScalar rad = 32;
             SkRect r;
             r.set(&fPts[13], 2);
             path.reset();
             SkRRect rr;
             rr.setRectXY(r, rad, rad);
             path.addRRect(rr);
             setForGeometry();
             draw_stroke(canvas, path, width, 950, false);

             path.reset();
             SkRRect rr2;
             rr.inset(width/2, width/2, &rr2);
             path.addRRect(rr2, SkPath::kCCW_Direction);
             rr.inset(-width/2, -width/2, &rr2);
             path.addRRect(rr2, SkPath::kCW_Direction);
             SkPaint paint;
             paint.setAntiAlias(true);
             paint.setColor(0x40FF8844);
             canvas->drawPath(path, paint);
         }

         if (fCircleButton.fEnabled) {
             path.reset();
             SkRect r;
             r.set(&fPts[15], 2);
             path.addOval(r);
             setForGeometry();
             if (fCircleButton.fFill) {
                 if (fArcButton.fEnabled) {
                     SkPoint center;
                     if (arcCenter(&center)) {
                         r.set(center.fX - fRadius, center.fY - fRadius, center.fX + fRadius,
                                 center.fY + fRadius);
                     }
                 }
                 draw_fill(canvas, r, width);
             } else {
                 draw_stroke(canvas, path, width, 950, false);
             }
         }

         if (fTextButton.fEnabled) {
             path.reset();
             SkPaint paint;
             paint.setAntiAlias(true);
             paint.setTextSize(fTextSize);
             paint.getTextPath(fText.c_str(), fText.size(), 0, fTextSize, &path);
             setForText();
             draw_stroke(canvas, path, width * fWidthScale / fTextSize, fTextSize, true);
         }

         if (fAnimate) {
             fWidth += fDWidth;
             if (fDWidth > 0 && fWidth > kWidthMax) {
                 fDWidth = -fDWidth;
             } else if (fDWidth < 0 && fWidth < kWidthMin) {
                 fDWidth = -fDWidth;
             }
         }
         setAsNeeded();
         if (fConicButton.fEnabled) {
             draw_control(canvas, fWeightControl, fWeight, 0, 5, "weight");
         }
         if (fArcButton.fEnabled) {
             draw_control(canvas, fRadiusControl, fRadius, 0, 500, "radius");
         }
 #ifdef SK_DEBUG
         draw_control(canvas, fErrorControl, gDebugStrokerError, kStrokerErrorMin, kStrokerErrorMax,
                 "error");
 #endif
         draw_control(canvas, fWidthControl, fWidth * fWidthScale, kWidthMin * fWidthScale,
                 kWidthMax * fWidthScale, "width");
         draw_button(canvas, fQuadButton);
         draw_button(canvas, fCubicButton);
         draw_button(canvas, fConicButton);
         draw_button(canvas, fArcButton);
         draw_button(canvas, fRRectButton);
         draw_button(canvas, fCircleButton);
         draw_button(canvas, fTextButton);
         this->inval(nullptr);
     }

     class MyClick : public Click {
     public:
         int fIndex;
         MyClick(SkView* target, int index) : Click(target), fIndex(index) {}
     };

     virtual SkView::Click* onFindClickHandler(SkScalar x, SkScalar y,
                                               unsigned modi) override {
         for (size_t i = 0; i < SK_ARRAY_COUNT(fPts); ++i) {
             if (hittest(fPts[i], x, y)) {
                 return new MyClick(this, (int)i);
             }
         }
         const SkRect& rectPt = SkRect::MakeXYWH(x, y, 1, 1);
         if (fWeightControl.contains(rectPt)) {
             return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 1);
         }
         if (fRadiusControl.contains(rectPt)) {
             return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 2);
         }
 #ifdef SK_DEBUG
         if (fErrorControl.contains(rectPt)) {
             return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 3);
         }
 #endif
         if (fWidthControl.contains(rectPt)) {
             return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 4);
         }
         if (fCubicButton.fBounds.contains(rectPt)) {
             fCubicButton.fEnabled ^= true;
             return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 5);
         }
         if (fConicButton.fBounds.contains(rectPt)) {
             fConicButton.fEnabled ^= true;
             return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 6);
         }
         if (fQuadButton.fBounds.contains(rectPt)) {
             fQuadButton.fEnabled ^= true;
             return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 7);
         }
         if (fArcButton.fBounds.contains(rectPt)) {
             fArcButton.fEnabled ^= true;
             return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 8);
         }
         if (fRRectButton.fBounds.contains(rectPt)) {
             fRRectButton.fEnabled ^= true;
             return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 9);
         }
         if (fCircleButton.fBounds.contains(rectPt)) {
             bool wasEnabled = fCircleButton.fEnabled;
             fCircleButton.fEnabled = !fCircleButton.fFill;
             fCircleButton.fFill = wasEnabled && !fCircleButton.fFill;
             return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 10);
         }
         if (fTextButton.fBounds.contains(rectPt)) {
             fTextButton.fEnabled ^= true;
             return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 11);
         }
         return this->INHERITED::onFindClickHandler(x, y, modi);
     }

     static SkScalar MapScreenYtoValue(int y, const SkRect& control, SkScalar min,
             SkScalar max) {
         return (SkIntToScalar(y) - control.fTop) / control.height() * (max - min) + min;
     }

     bool onClick(Click* click) override {
         int index = ((MyClick*)click)->fIndex;
         if (index < (int) SK_ARRAY_COUNT(fPts)) {
             fPts[index].offset(SkIntToScalar(click->fICurr.fX - click->fIPrev.fX),
                                SkIntToScalar(click->fICurr.fY - click->fIPrev.fY));
             this->inval(nullptr);
         } else if (index == (int) SK_ARRAY_COUNT(fPts) + 1) {
             fWeight = MapScreenYtoValue(click->fICurr.fY, fWeightControl, 0, 5);
         } else if (index == (int) SK_ARRAY_COUNT(fPts) + 2) {
             fRadius = MapScreenYtoValue(click->fICurr.fY, fRadiusControl, 0, 500);
         }
 #ifdef SK_DEBUG
         else if (index == (int) SK_ARRAY_COUNT(fPts) + 3) {
             gDebugStrokerError = SkTMax(FLT_EPSILON, MapScreenYtoValue(click->fICurr.fY,
                     fErrorControl, kStrokerErrorMin, kStrokerErrorMax));
             gDebugStrokerErrorSet = true;
         }
 #endif
         else if (index == (int) SK_ARRAY_COUNT(fPts) + 4) {
             fWidth = SkTMax(FLT_EPSILON, MapScreenYtoValue(click->fICurr.fY, fWidthControl,
                     kWidthMin, kWidthMax));
             fAnimate = fWidth <= kWidthMin;
         }
         return true;
     }

 private:
     typedef SkView INHERITED;
 };

 ///////////////////////////////////////////////////////////////////////////////

 static SkView* F2() { return new QuadStrokerView; }
 static SkViewRegister gR2(F2);
	/*
	* Copyright 2012 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "sk_tool_utils.h"
	#include "SampleCode.h"
	#include "SkView.h"
	#include "SkCanvas.h"
	#include "SkGeometry.h"
	#include "SkPathMeasure.h"
	#include "SkRandom.h"
	#include "SkRRect.h"
	#include "SkColorPriv.h"
	#include "SkStrokerPriv.h"
	#include "SkSurface.h"

	static bool hittest(const SkPoint& target, SkScalar x, SkScalar y) {
	const SkScalar TOL = 7;
	return SkPoint::Distance(target, SkPoint::Make(x, y)) <= TOL;
	}

	static int getOnCurvePoints(const SkPath& path, SkPoint storage[]) {
	SkPath::RawIter iter(path);
	SkPoint pts[4];
	SkPath::Verb verb;

	int count = 0;
	while ((verb = iter.next(pts)) != SkPath::kDone_Verb) {
	switch (verb) {
	case SkPath::kMove_Verb:
	case SkPath::kLine_Verb:
	case SkPath::kQuad_Verb:
	case SkPath::kConic_Verb:
	case SkPath::kCubic_Verb:
	storage[count++] = pts[0];
	break;
	default:
	break;
	}
	}
	return count;
	}

	static void getContourCounts(const SkPath& path, SkTArray<int>* contourCounts) {
	SkPath::RawIter iter(path);
	SkPoint pts[4];
	SkPath::Verb verb;

	int count = 0;
	while ((verb = iter.next(pts)) != SkPath::kDone_Verb) {
	switch (verb) {
	case SkPath::kMove_Verb:
	case SkPath::kLine_Verb:
	count += 1;
	break;
	case SkPath::kQuad_Verb:
	case SkPath::kConic_Verb:
	count += 2;
	break;
	case SkPath::kCubic_Verb:
	count += 3;
	break;
	case SkPath::kClose_Verb:
	contourCounts->push_back(count);
	count = 0;
	break;
	default:
	break;
	}
	}
	if (count > 0) {
	contourCounts->push_back(count);
	}
	}

	static void erase(SkSurface* surface) {
	SkCanvas* canvas = surface->getCanvas();
	if (canvas) {
	canvas->clear(SK_ColorTRANSPARENT);
	}
	}

	struct StrokeTypeButton {
	SkRect fBounds;
	char fLabel;
	bool fEnabled;
	};

	struct CircleTypeButton : public StrokeTypeButton {
	bool fFill;
	};

	class QuadStrokerView : public SampleView {
	enum {
	SKELETON_COLOR = 0xFF0000FF,
	WIREFRAME_COLOR = 0x80FF0000
	};

	enum {
	kCount = 18
	};
	SkPoint fPts[kCount];
	SkRect fWeightControl;
	SkRect fRadiusControl;
	SkRect fErrorControl;
	SkRect fWidthControl;
	SkRect fBounds;
	SkMatrix fMatrix, fInverse;
	sk_sp<SkShader> fShader;
	SkAutoTUnref<SkSurface> fMinSurface;
	SkAutoTUnref<SkSurface> fMaxSurface;
	StrokeTypeButton fCubicButton;
	StrokeTypeButton fConicButton;
	StrokeTypeButton fQuadButton;
	StrokeTypeButton fArcButton;
	StrokeTypeButton fRRectButton;
	CircleTypeButton fCircleButton;
	StrokeTypeButton fTextButton;
	SkString fText;
	SkScalar fTextSize;
	SkScalar fWeight;
	SkScalar fRadius;
	SkScalar fWidth, fDWidth;
	SkScalar fWidthScale;
	int fW, fH, fZoom;
	bool fAnimate;
	bool fDrawRibs;
	bool fDrawTangents;
	bool fDrawTDivs;
	#ifdef SK_DEBUG
	#define kStrokerErrorMin 0.001f
	#define kStrokerErrorMax 5
	#endif
	#define kWidthMin 1
	#define kWidthMax 100
	public:
	QuadStrokerView() {
	this->setBGColor(SK_ColorLTGRAY);

	fPts[0].set(50, 200); // cubic
	fPts[1].set(50, 100);
	fPts[2].set(150, 50);
	fPts[3].set(300, 50);

	fPts[4].set(350, 200); // conic
	fPts[5].set(350, 100);
	fPts[6].set(450, 50);

	fPts[7].set(150, 300); // quad
	fPts[8].set(150, 200);
	fPts[9].set(250, 150);

	fPts[10].set(250, 200); // arc
	fPts[11].set(250, 300);
	fPts[12].set(150, 350);

	fPts[13].set(200, 200); // rrect
	fPts[14].set(400, 400);

	fPts[15].set(250, 250); // oval
	fPts[16].set(450, 450);

	fText = "a";
	fTextSize = 12;
	fWidth = 50;
	fDWidth = 0.25f;
	fWeight = 1;
	fRadius = 150;

	fCubicButton.fLabel = 'C';
	fCubicButton.fEnabled = false;
	fConicButton.fLabel = 'K';
	fConicButton.fEnabled = false;
	fQuadButton.fLabel = 'Q';
	fQuadButton.fEnabled = false;
	fArcButton.fLabel = 'A';
	fArcButton.fEnabled = true;
	fRRectButton.fLabel = 'R';
	fRRectButton.fEnabled = false;
	fCircleButton.fLabel = 'O';
	fCircleButton.fEnabled = true;
	fCircleButton.fFill = true;
	fTextButton.fLabel = 'T';
	fTextButton.fEnabled = false;
	fAnimate = false;
	setAsNeeded();
	}

	protected:
	bool onQuery(SkEvent* evt) override {
	if (SampleCode::TitleQ(*evt)) {
	SampleCode::TitleR(evt, "QuadStroker");
	return true;
	}
	SkUnichar uni;
	if (fTextButton.fEnabled && SampleCode::CharQ(*evt, &uni)) {
	switch (uni) {
	case ' ':
	fText = "";
	break;
	case '-':
	fTextSize = SkTMax(1.0f, fTextSize - 1);
	break;
	case '+':
	case '=':
	fTextSize += 1;
	break;
	default:
	fText.appendUnichar(uni);
	}
	this->inval(nullptr);
	return true;
	}
	return this->INHERITED::onQuery(evt);
	}

	void onSizeChange() override {
	fRadiusControl.setXYWH(this->width() - 200, 30, 30, 400);
	fWeightControl.setXYWH(this->width() - 150, 30, 30, 400);
	fErrorControl.setXYWH(this->width() - 100, 30, 30, 400);
	fWidthControl.setXYWH(this->width() - 50, 30, 30, 400);
	int buttonOffset = 450;
	fCubicButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
	buttonOffset += 50;
	fConicButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
	buttonOffset += 50;
	fQuadButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
	buttonOffset += 50;
	fArcButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
	buttonOffset += 50;
	fRRectButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
	buttonOffset += 50;
	fCircleButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
	buttonOffset += 50;
	fTextButton.fBounds.setXYWH(this->width() - 50, SkIntToScalar(buttonOffset), 30, 30);
	this->INHERITED::onSizeChange();
	}

	void copyMinToMax() {
	erase(fMaxSurface);
	SkCanvas* canvas = fMaxSurface->getCanvas();
	canvas->save();
	canvas->concat(fMatrix);
	fMinSurface->draw(canvas, 0, 0, nullptr);
	canvas->restore();

	SkPaint paint;
	paint.setXfermodeMode(SkXfermode::kClear_Mode);
	for (int iy = 1; iy < fH; ++iy) {
	SkScalar y = SkIntToScalar(iy * fZoom);
	canvas->drawLine(0, y - SK_ScalarHalf, 999, y - SK_ScalarHalf, paint);
	}
	for (int ix = 1; ix < fW; ++ix) {
	SkScalar x = SkIntToScalar(ix * fZoom);
	canvas->drawLine(x - SK_ScalarHalf, 0, x - SK_ScalarHalf, 999, paint);
	}
	}

	void setWHZ(int width, int height, int zoom) {
	fZoom = zoom;
	fBounds.set(0, 0, SkIntToScalar(width * zoom), SkIntToScalar(height * zoom));
	fMatrix.setScale(SkIntToScalar(zoom), SkIntToScalar(zoom));
	fInverse.setScale(SK_Scalar1 / zoom, SK_Scalar1 / zoom);
	fShader = sk_tool_utils::create_checkerboard_shader(0xFFCCCCCC, 0xFFFFFFFF, zoom);

	SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
	fMinSurface.reset(SkSurface::NewRaster(info));
	info = info.makeWH(width * zoom, height * zoom);
	fMaxSurface.reset(SkSurface::NewRaster(info));
	}

	void draw_points(SkCanvas* canvas, const SkPath& path, SkColor color,
	bool show_lines) {
	SkPaint paint;
	paint.setColor(color);
	paint.setAlpha(0x80);
	paint.setAntiAlias(true);
	int n = path.countPoints();
	SkAutoSTArray<32, SkPoint> pts(n);
	if (show_lines && fDrawTangents) {
	SkTArray<int> contourCounts;
	getContourCounts(path, &contourCounts);
	SkPoint* ptPtr = pts.get();
	for (int i = 0; i < contourCounts.count(); ++i) {
	int count = contourCounts[i];
	path.getPoints(ptPtr, count);
	canvas->drawPoints(SkCanvas::kPolygon_PointMode, count, ptPtr, paint);
	ptPtr += count;
	}
	} else {
	n = getOnCurvePoints(path, pts.get());
	}
	paint.setStrokeWidth(5);
	canvas->drawPoints(SkCanvas::kPoints_PointMode, n, pts.get(), paint);
	}

	void draw_ribs(SkCanvas* canvas, const SkPath& path, SkScalar width,
	SkColor color) {
	const SkScalar radius = width / 2;

	SkPathMeasure meas(path, false);
	SkScalar total = meas.getLength();

	SkScalar delta = 8;
	SkPaint paint, labelP;
	paint.setColor(color);
	labelP.setColor(color & 0xff5f9f5f);
	SkPoint pos, tan;
	int index = 0;
	for (SkScalar dist = 0; dist <= total; dist += delta) {
	if (meas.getPosTan(dist, &pos, &tan)) {
	tan.scale(radius);
	tan.rotateCCW();
	canvas->drawLine(pos.x() + tan.x(), pos.y() + tan.y(),
	pos.x() - tan.x(), pos.y() - tan.y(), paint);
	if (0 == index % 10) {
	SkString label;
	label.appendS32(index);
	SkRect dot = SkRect::MakeXYWH(pos.x() - 2, pos.y() - 2, 4, 4);
	canvas->drawRect(dot, labelP);
	canvas->drawText(label.c_str(), label.size(),
	pos.x() - tan.x() * 1.25f, pos.y() - tan.y() * 1.25f, labelP);
	}
	}
	++index;
	}
	}

	void draw_t_divs(SkCanvas* canvas, const SkPath& path, SkScalar width, SkColor color) {
	const SkScalar radius = width / 2;
	SkPaint paint;
	paint.setColor(color);
	SkPathMeasure meas(path, false);
	SkScalar total = meas.getLength();
	SkScalar delta = 8;
	int ribs = 0;
	for (SkScalar dist = 0; dist <= total; dist += delta) {
	++ribs;
	}
	SkPath::RawIter iter(path);
	SkPoint pts[4];
	if (SkPath::kMove_Verb != iter.next(pts)) {
	SkASSERT(0);
	return;
	}
	SkPath::Verb verb = iter.next(pts);
	SkASSERT(SkPath::kLine_Verb <= verb && verb <= SkPath::kCubic_Verb);
	SkPoint pos, tan;
	for (int index = 0; index < ribs; ++index) {
	SkScalar t = (SkScalar) index / ribs;
	switch (verb) {
	case SkPath::kLine_Verb:
	tan = pts[1] - pts[0];
	pos = pts[0];
	pos.fX += tan.fX * t;
	pos.fY += tan.fY * t;
	break;
	case SkPath::kQuad_Verb:
	pos = SkEvalQuadAt(pts, t);
	tan = SkEvalQuadTangentAt(pts, t);
	break;
	case SkPath::kConic_Verb: {
	SkConic conic(pts, iter.conicWeight());
	pos = conic.evalAt(t);
	tan = conic.evalTangentAt(t);
	} break;
	case SkPath::kCubic_Verb:
	SkEvalCubicAt(pts, t, &pos, &tan, nullptr);
	break;
	default:
	SkASSERT(0);
	return;
	}
	tan.setLength(radius);
	tan.rotateCCW();
	canvas->drawLine(pos.x() + tan.x(), pos.y() + tan.y(),
	pos.x() - tan.x(), pos.y() - tan.y(), paint);
	if (0 == index % 10) {
	SkString label;
	label.appendS32(index);
	canvas->drawText(label.c_str(), label.size(),
	pos.x() + tan.x() * 1.25f, pos.y() + tan.y() * 1.25f, paint);
	}
	}
	}

	void draw_stroke(SkCanvas* canvas, const SkPath& path, SkScalar width, SkScalar scale,
	bool drawText) {
	if (path.isEmpty()) {
	return;
	}
	SkRect bounds = path.getBounds();
	this->setWHZ(SkScalarCeilToInt(bounds.right()), drawText
	? SkScalarRoundToInt(scale * 3 / 2) : SkScalarRoundToInt(scale),
	SkScalarRoundToInt(950.0f / scale));
	erase(fMinSurface);
	SkPaint paint;
	paint.setColor(0x1f1f0f0f);
	paint.setStyle(SkPaint::kStroke_Style);
	paint.setStrokeWidth(width * scale * scale);
	paint.setColor(0x3f0f1f3f);
	if (drawText) {
	fMinSurface->getCanvas()->drawPath(path, paint);
	this->copyMinToMax();
	fMaxSurface->draw(canvas, 0, 0, nullptr);
	}
	paint.setAntiAlias(true);
	paint.setStyle(SkPaint::kStroke_Style);
	paint.setStrokeWidth(1);

	paint.setColor(SKELETON_COLOR);
	SkPath scaled;
	SkMatrix matrix;
	matrix.reset();
	matrix.setScale(950 / scale, 950 / scale);
	if (drawText) {
	path.transform(matrix, &scaled);
	} else {
	scaled = path;
	}
	canvas->drawPath(scaled, paint);
	draw_points(canvas, scaled, SKELETON_COLOR, true);

	if (fDrawRibs) {
	draw_ribs(canvas, scaled, width, 0xFF00FF00);
	}

	if (fDrawTDivs) {
	draw_t_divs(canvas, scaled, width, 0xFF3F3F00);
	}

	SkPath fill;

	SkPaint p;
	p.setStyle(SkPaint::kStroke_Style);
	if (drawText) {
	p.setStrokeWidth(width * scale * scale);
	} else {
	p.setStrokeWidth(width);
	}
	p.getFillPath(path, &fill);
	SkPath scaledFill;
	if (drawText) {
	fill.transform(matrix, &scaledFill);
	} else {
	scaledFill = fill;
	}
	paint.setColor(WIREFRAME_COLOR);
	canvas->drawPath(scaledFill, paint);
	draw_points(canvas, scaledFill, WIREFRAME_COLOR, false);
	}

	void draw_fill(SkCanvas* canvas, const SkRect& rect, SkScalar width) {
	if (rect.isEmpty()) {
	return;
	}
	SkPaint paint;
	paint.setColor(0x1f1f0f0f);
	paint.setStyle(SkPaint::kStroke_Style);
	paint.setStrokeWidth(width);
	SkPath path;
	SkScalar maxSide = SkTMax(rect.width(), rect.height()) / 2;
	SkPoint center = { rect.fLeft + maxSide, rect.fTop + maxSide };
	path.addCircle(center.fX, center.fY, maxSide);
	canvas->drawPath(path, paint);
	paint.setStyle(SkPaint::kFill_Style);
	path.reset();
	path.addCircle(center.fX, center.fY, maxSide - width / 2);
	paint.setColor(0x3f0f1f3f);
	canvas->drawPath(path, paint);
	path.reset();
	path.setFillType(SkPath::kEvenOdd_FillType);
	path.addCircle(center.fX, center.fY, maxSide + width / 2);
	SkRect outside = SkRect::MakeXYWH(center.fX - maxSide - width, center.fY - maxSide - width,
	(maxSide + width) * 2, (maxSide + width) * 2);
	path.addRect(outside);
	canvas->drawPath(path, paint);
	}

	void draw_button(SkCanvas* canvas, const StrokeTypeButton& button) {
	SkPaint paint;
	paint.setAntiAlias(true);
	paint.setStyle(SkPaint::kStroke_Style);
	paint.setColor(button.fEnabled ? 0xFF3F0000 : 0x6F3F0000);
	canvas->drawRect(button.fBounds, paint);
	paint.setTextSize(25.0f);
	paint.setColor(button.fEnabled ? 0xFF3F0000 : 0x6F3F0000);
	paint.setTextAlign(SkPaint::kCenter_Align);
	paint.setStyle(SkPaint::kFill_Style);
	canvas->drawText(&button.fLabel, 1, button.fBounds.centerX(), button.fBounds.fBottom - 5,
	paint);
	}

	void draw_control(SkCanvas* canvas, const SkRect& bounds, SkScalar value,
	SkScalar min, SkScalar max, const char* name) {
	SkPaint paint;
	paint.setAntiAlias(true);
	paint.setStyle(SkPaint::kStroke_Style);
	canvas->drawRect(bounds, paint);
	SkScalar scale = max - min;
	SkScalar yPos = bounds.fTop + (value - min) * bounds.height() / scale;
	paint.setColor(0xFFFF0000);
	canvas->drawLine(bounds.fLeft - 5, yPos, bounds.fRight + 5, yPos, paint);
	SkString label;
	label.printf("%0.3g", value);
	paint.setColor(0xFF000000);
	paint.setTextSize(11.0f);
	paint.setStyle(SkPaint::kFill_Style);
	canvas->drawText(label.c_str(), label.size(), bounds.fLeft + 5, yPos - 5, paint);
	paint.setTextSize(13.0f);
	canvas->drawText(name, strlen(name), bounds.fLeft, bounds.bottom() + 11, paint);
	}

	void setForGeometry() {
	fDrawRibs = true;
	fDrawTangents = true;
	fDrawTDivs = false;
	fWidthScale = 1;
	}

	void setForText() {
	fDrawRibs = fDrawTangents = fDrawTDivs = false;
	fWidthScale = 0.002f;
	}

	void setForSingles() {
	setForGeometry();
	fDrawTDivs = true;
	}

	void setAsNeeded() {
	if (fConicButton.fEnabled \|\| fCubicButton.fEnabled \|\| fQuadButton.fEnabled) {
	setForSingles();
	} else if (fRRectButton.fEnabled \|\| fCircleButton.fEnabled \|\| fArcButton.fEnabled) {
	setForGeometry();
	} else {
	setForText();
	}
	}

	bool arcCenter(SkPoint* center) {
	SkPath path;
	path.moveTo(fPts[10]);
	path.arcTo(fPts[11], fPts[12], fRadius);
	SkPath::Iter iter(path, false);
	SkPoint pts[4];
	iter.next(pts);
	if (SkPath::kLine_Verb == iter.next(pts)) {
	iter.next(pts);
	}
	SkVector before = pts[0] - pts[1];
	SkVector after = pts[1] - pts[2];
	before.setLength(fRadius);
	after.setLength(fRadius);
	SkVector beforeCCW, afterCCW;
	before.rotateCCW(&beforeCCW);
	after.rotateCCW(&afterCCW);
	beforeCCW += pts[0];
	afterCCW += pts[2];
	*center = beforeCCW;
	if (SkScalarNearlyEqual(beforeCCW.fX, afterCCW.fX)
	&& SkScalarNearlyEqual(beforeCCW.fY, afterCCW.fY)) {
	return true;
	}
	SkVector beforeCW, afterCW;
	before.rotateCW(&beforeCW);
	after.rotateCW(&afterCW);
	beforeCW += pts[0];
	afterCW += pts[2];
	*center = beforeCW;
	return SkScalarNearlyEqual(beforeCW.fX, afterCW.fX)
	&& SkScalarNearlyEqual(beforeCCW.fY, afterCW.fY);
	}

	void onDrawContent(SkCanvas* canvas) override {
	SkPath path;
	SkScalar width = fWidth;

	if (fCubicButton.fEnabled) {
	path.moveTo(fPts[0]);
	path.cubicTo(fPts[1], fPts[2], fPts[3]);
	setForSingles();
	draw_stroke(canvas, path, width, 950, false);
	}

	if (fConicButton.fEnabled) {
	path.reset();
	path.moveTo(fPts[4]);
	path.conicTo(fPts[5], fPts[6], fWeight);
	setForSingles();
	draw_stroke(canvas, path, width, 950, false);
	}

	if (fQuadButton.fEnabled) {
	path.reset();
	path.moveTo(fPts[7]);
	path.quadTo(fPts[8], fPts[9]);
	setForSingles();
	draw_stroke(canvas, path, width, 950, false);
	}

	if (fArcButton.fEnabled) {
	path.reset();
	path.moveTo(fPts[10]);
	path.arcTo(fPts[11], fPts[12], fRadius);
	setForGeometry();
	draw_stroke(canvas, path, width, 950, false);
	SkPath pathPts;
	pathPts.moveTo(fPts[10]);
	pathPts.lineTo(fPts[11]);
	pathPts.lineTo(fPts[12]);
	draw_points(canvas, pathPts, SK_ColorDKGRAY, true);
	}

	if (fRRectButton.fEnabled) {
	SkScalar rad = 32;
	SkRect r;
	r.set(&fPts[13], 2);
	path.reset();
	SkRRect rr;
	rr.setRectXY(r, rad, rad);
	path.addRRect(rr);
	setForGeometry();
	draw_stroke(canvas, path, width, 950, false);

	path.reset();
	SkRRect rr2;
	rr.inset(width/2, width/2, &rr2);
	path.addRRect(rr2, SkPath::kCCW_Direction);
	rr.inset(-width/2, -width/2, &rr2);
	path.addRRect(rr2, SkPath::kCW_Direction);
	SkPaint paint;
	paint.setAntiAlias(true);
	paint.setColor(0x40FF8844);
	canvas->drawPath(path, paint);
	}

	if (fCircleButton.fEnabled) {
	path.reset();
	SkRect r;
	r.set(&fPts[15], 2);
	path.addOval(r);
	setForGeometry();
	if (fCircleButton.fFill) {
	if (fArcButton.fEnabled) {
	SkPoint center;
	if (arcCenter(&center)) {
	r.set(center.fX - fRadius, center.fY - fRadius, center.fX + fRadius,
	center.fY + fRadius);
	}
	}
	draw_fill(canvas, r, width);
	} else {
	draw_stroke(canvas, path, width, 950, false);
	}
	}

	if (fTextButton.fEnabled) {
	path.reset();
	SkPaint paint;
	paint.setAntiAlias(true);
	paint.setTextSize(fTextSize);
	paint.getTextPath(fText.c_str(), fText.size(), 0, fTextSize, &path);
	setForText();
	draw_stroke(canvas, path, width * fWidthScale / fTextSize, fTextSize, true);
	}

	if (fAnimate) {
	fWidth += fDWidth;
	if (fDWidth > 0 && fWidth > kWidthMax) {
	fDWidth = -fDWidth;
	} else if (fDWidth < 0 && fWidth < kWidthMin) {
	fDWidth = -fDWidth;
	}
	}
	setAsNeeded();
	if (fConicButton.fEnabled) {
	draw_control(canvas, fWeightControl, fWeight, 0, 5, "weight");
	}
	if (fArcButton.fEnabled) {
	draw_control(canvas, fRadiusControl, fRadius, 0, 500, "radius");
	}
	#ifdef SK_DEBUG
	draw_control(canvas, fErrorControl, gDebugStrokerError, kStrokerErrorMin, kStrokerErrorMax,
	"error");
	#endif
	draw_control(canvas, fWidthControl, fWidth * fWidthScale, kWidthMin * fWidthScale,
	kWidthMax * fWidthScale, "width");
	draw_button(canvas, fQuadButton);
	draw_button(canvas, fCubicButton);
	draw_button(canvas, fConicButton);
	draw_button(canvas, fArcButton);
	draw_button(canvas, fRRectButton);
	draw_button(canvas, fCircleButton);
	draw_button(canvas, fTextButton);
	this->inval(nullptr);
	}

	class MyClick : public Click {
	public:
	int fIndex;
	MyClick(SkView* target, int index) : Click(target), fIndex(index) {}
	};

	virtual SkView::Click* onFindClickHandler(SkScalar x, SkScalar y,
	unsigned modi) override {
	for (size_t i = 0; i < SK_ARRAY_COUNT(fPts); ++i) {
	if (hittest(fPts[i], x, y)) {
	return new MyClick(this, (int)i);
	}
	}
	const SkRect& rectPt = SkRect::MakeXYWH(x, y, 1, 1);
	if (fWeightControl.contains(rectPt)) {
	return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 1);
	}
	if (fRadiusControl.contains(rectPt)) {
	return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 2);
	}
	#ifdef SK_DEBUG
	if (fErrorControl.contains(rectPt)) {
	return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 3);
	}
	#endif
	if (fWidthControl.contains(rectPt)) {
	return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 4);
	}
	if (fCubicButton.fBounds.contains(rectPt)) {
	fCubicButton.fEnabled ^= true;
	return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 5);
	}
	if (fConicButton.fBounds.contains(rectPt)) {
	fConicButton.fEnabled ^= true;
	return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 6);
	}
	if (fQuadButton.fBounds.contains(rectPt)) {
	fQuadButton.fEnabled ^= true;
	return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 7);
	}
	if (fArcButton.fBounds.contains(rectPt)) {
	fArcButton.fEnabled ^= true;
	return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 8);
	}
	if (fRRectButton.fBounds.contains(rectPt)) {
	fRRectButton.fEnabled ^= true;
	return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 9);
	}
	if (fCircleButton.fBounds.contains(rectPt)) {
	bool wasEnabled = fCircleButton.fEnabled;
	fCircleButton.fEnabled = !fCircleButton.fFill;
	fCircleButton.fFill = wasEnabled && !fCircleButton.fFill;
	return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 10);
	}
	if (fTextButton.fBounds.contains(rectPt)) {
	fTextButton.fEnabled ^= true;
	return new MyClick(this, (int) SK_ARRAY_COUNT(fPts) + 11);
	}
	return this->INHERITED::onFindClickHandler(x, y, modi);
	}

	static SkScalar MapScreenYtoValue(int y, const SkRect& control, SkScalar min,
	SkScalar max) {
	return (SkIntToScalar(y) - control.fTop) / control.height() * (max - min) + min;
	}

	bool onClick(Click* click) override {
	int index = ((MyClick*)click)->fIndex;
	if (index < (int) SK_ARRAY_COUNT(fPts)) {
	fPts[index].offset(SkIntToScalar(click->fICurr.fX - click->fIPrev.fX),
	SkIntToScalar(click->fICurr.fY - click->fIPrev.fY));
	this->inval(nullptr);
	} else if (index == (int) SK_ARRAY_COUNT(fPts) + 1) {
	fWeight = MapScreenYtoValue(click->fICurr.fY, fWeightControl, 0, 5);
	} else if (index == (int) SK_ARRAY_COUNT(fPts) + 2) {
	fRadius = MapScreenYtoValue(click->fICurr.fY, fRadiusControl, 0, 500);
	}
	#ifdef SK_DEBUG
	else if (index == (int) SK_ARRAY_COUNT(fPts) + 3) {
	gDebugStrokerError = SkTMax(FLT_EPSILON, MapScreenYtoValue(click->fICurr.fY,
	fErrorControl, kStrokerErrorMin, kStrokerErrorMax));
	gDebugStrokerErrorSet = true;
	}
	#endif
	else if (index == (int) SK_ARRAY_COUNT(fPts) + 4) {
	fWidth = SkTMax(FLT_EPSILON, MapScreenYtoValue(click->fICurr.fY, fWidthControl,
	kWidthMin, kWidthMax));
	fAnimate = fWidth <= kWidthMin;
	}
	return true;
	}

	private:
	typedef SkView INHERITED;
	};

	///////////////////////////////////////////////////////////////////////////////

	static SkView* F2() { return new QuadStrokerView; }
	static SkViewRegister gR2(F2);