1// Copyright 2020 Google LLC.
2// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
3#include "tools/fiddle/examples.h"
4REG_FIDDLE(SkPath_cubicTo_example, 512, 512, false, 0) {
5/*
6        If the starting point is (x0, y0), then this curve is defined as the
7        paramentric curve as `t` goes from 0 to 1:
8          s := 1 - t
9          x := (s * s * s * x0) +
10               (3 * s * s * t * x1) +
11               (3 * s * t * t * x2) +
12               (t * t * t * x3)
13          y := (s * s * s * y0) +
14               (3 * s * s * t * y1) +
15               (3 * s * t * t * y2) +
16               (t * t * t * y3)
17
18*/
19void draw(SkCanvas* canvas) {
20    canvas->clear(SkColorSetARGB(255, 255, 255, 255));
21    SkFont font(nullptr, 32);
22
23    SkPaint paint;
24    paint.setAntiAlias(true);
25    paint.setStyle(SkPaint::kStroke_Style);
26    paint.setStrokeWidth(5);
27
28    SkPoint a{128, 64};
29    SkPoint b{448, 448};
30    SkPoint c{64, 448};
31    SkPoint d{384, 64};
32
33    SkPath threeSegments;
34    threeSegments.moveTo(a);
35    threeSegments.lineTo(b);
36    threeSegments.lineTo(c);
37    threeSegments.lineTo(d);
38
39    canvas->drawPath(threeSegments, paint);
40
41    paint.setColor(SkColorSetARGB(255, 0, 0, 255));
42    SkPath cubicCurve;
43    cubicCurve.moveTo(a);
44    cubicCurve.cubicTo(b, c, d);
45    canvas->drawPath(cubicCurve, paint);
46
47    SkPaint textPaint;
48    textPaint.setColor(SkColorSetARGB(255, 0, 255, 0));
49    textPaint.setAntiAlias(true);
50    canvas->drawString("a", a.x(), a.y(), font, textPaint);
51    canvas->drawString("b", b.x(), b.y(), font, textPaint);
52    canvas->drawString("c", c.x() - 20, c.y(), font, textPaint);
53    canvas->drawString("d", d.x(), d.y(), font, textPaint);
54}
55}  // END FIDDLE
56