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"
4 REG_FIDDLE(Color_Wheel, 256, 256, false, 0) {
draw_color_wheel(SkCanvas * canvas,float scale)5 void draw_color_wheel(SkCanvas* canvas, float scale) {
6 const float stroke = scale * 3 / 64;
7 const float size = scale * 9 / 32;
8 SkAutoCanvasRestore autoCanvasRestore(canvas, true);
9 canvas->translate(0.5f * scale, 0.5f * scale);
10 canvas->clear(0);
11 canvas->drawCircle({0, 0}, (scale - stroke) * 0.5f, SkPaint(SkColors::kWhite));
12 {
13 SkPaint sweep;
14 const SkMatrix rotate = SkMatrix::MakeAll(0, -1, 0, 1, 0, 0, 0, 0, 1);
15 constexpr unsigned kColorCount = 7;
16 static const SkColor4f kColors[kColorCount] = {
17 SkColors::kRed, SkColors::kYellow, SkColors::kGreen, SkColors::kCyan,
18 SkColors::kBlue, SkColors::kMagenta, SkColors::kRed};
19 sweep.setShader(SkGradientShader::MakeSweep(0, 0, kColors, nullptr, nullptr,
20 kColorCount, 0, &rotate));
21 sweep.setStyle(SkPaint::kStroke_Style);
22 sweep.setStrokeWidth(stroke);
23 sweep.setAntiAlias(true);
24 canvas->drawCircle({0, 0}, (scale - stroke) * 0.5f, sweep);
25 }
26 sk_sp<SkFontMgr> fontMgr = SkFontMgr::RefDefault();
27 SkFont font(fontMgr->legacyMakeTypeface(nullptr, SkFontStyle::Bold()), size);
28 const struct { const char* str; float radius; float angle; SkColor4f color;} kLetters[] = {
29 {"K", 0, 0, SkColors::kBlack},
30 {"R", 1, 90, SkColors::kRed},
31 {"Y", 1, 150, SkColors::kYellow},
32 {"G", 1, 210, SkColors::kGreen},
33 {"C", 1, 270, SkColors::kCyan},
34 {"B", 1, 330, SkColors::kBlue},
35 {"M", 1, 30, SkColors::kMagenta},
36 };
37 for (const auto& v : kLetters) {
38 SkRect bnds;
39 font.measureText(v.str, strlen(v.str), SkTextEncoding::kUTF8, &bnds);
40 constexpr double pi_over_180 = 3.141592653589793 / 180;
41 float x = (float)(0.3 * scale * v.radius * cos(pi_over_180 * v.angle) - bnds.centerX());
42 float y = (float)(0.3 * scale * v.radius * sin(pi_over_180 * v.angle) - bnds.centerY());
43 canvas->drawString(v.str, x, y, font, SkPaint(v.color));
44 }
45 }
draw(SkCanvas * canvas)46 void draw(SkCanvas* canvas) { draw_color_wheel(canvas, 256); }
47 } // END FIDDLE
48