| // Copyright 2020 Google LLC. |
| // Use of this source code is governed by a BSD-style license that can be found in the LICENSE file. |
| #include "tools/fiddle/examples.h" |
| REG_FIDDLE(SkPath_arcto_conic_parametric, 512, 512, false, 0) { |
| SkPoint conic(SkPoint p0, SkPoint p1, SkPoint p2, float w, float t) { |
| float s = 1 - t; |
| return {((s * s * p0.x()) + (2 * s * t * w * p1.x()) + (t * t * p2.x())) / |
| ((s * s) + (w * 2 * s * t) + (t * t)), |
| ((s * s * p0.y()) + (2 * s * t * w * p1.y()) + (t * t * p2.y())) / |
| ((s * s) + (w * 2 * s * t) + (t * t))}; |
| } |
| |
| void draw(SkCanvas* canvas) { |
| canvas->clear(SkColorSetARGB(255, 255, 255, 255)); |
| |
| SkPaint paint; |
| paint.setAntiAlias(true); |
| paint.setStyle(SkPaint::kStroke_Style); |
| paint.setStrokeWidth(2.5); |
| |
| SkPoint center = {256, 256}; |
| float r = 192; |
| SkRect oval = {center.x() - r, center.y() - r, center.x() + r, center.y() + r}; |
| canvas->drawOval(oval, paint); |
| float startAngle = 0; |
| float sweepAngle = 179; |
| |
| SkPath arc; |
| arc.arcTo(oval, startAngle, sweepAngle, false); |
| |
| paint.setStrokeWidth(5); |
| paint.setColor(SkColorSetARGB(255, 0, 0, 255)); |
| canvas->drawPath(arc, paint); |
| |
| SkPaint pointPaint; |
| pointPaint.setAntiAlias(true); |
| pointPaint.setStrokeWidth(8); |
| pointPaint.setStrokeCap(SkPaint::kRound_Cap); |
| pointPaint.setColor(SkColorSetARGB(255, 0, 255, 0)); |
| |
| float finalAngle = startAngle + sweepAngle; |
| float middleAngle = startAngle + 0.5f * sweepAngle; |
| float weight = cos(SkDegreesToRadians(sweepAngle) / 2); |
| SkPoint p0 = {r * SkScalarCos(SkDegreesToRadians(startAngle)), |
| r * SkScalarSin(SkDegreesToRadians(startAngle))}; |
| float d = r / weight; |
| SkPoint p1 = {d * SkScalarCos(SkDegreesToRadians(middleAngle)), |
| d * SkScalarSin(SkDegreesToRadians(middleAngle))}; |
| SkPoint p2 = {r * SkScalarCos(SkDegreesToRadians(finalAngle)), |
| r * SkScalarSin(SkDegreesToRadians(finalAngle))}; |
| p0 += center; |
| p1 += center; |
| p2 += center; |
| |
| const int N = 8; |
| for (int i = 0; i <= N; ++i) { |
| SkPoint p = conic(p0, p1, p2, weight, (float)i / N); |
| canvas->drawPoint(p.x(), p.y(), pointPaint); |
| } |
| pointPaint.setColor(SkColorSetARGB(255, 255, 0, 0)); |
| canvas->drawPoint(p0.x(), p0.y(), pointPaint); |
| canvas->drawPoint(p1.x(), p1.y(), pointPaint); |
| canvas->drawPoint(p2.x(), p2.y(), pointPaint); |
| |
| SkPath weightedQuadratic; |
| weightedQuadratic.moveTo(p0); |
| weightedQuadratic.conicTo(p1, p2, weight); |
| paint.setColor(SK_ColorCYAN); |
| paint.setStrokeWidth(1); |
| canvas->drawPath(weightedQuadratic, paint); |
| } |
| } // END FIDDLE |