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/SkFont.h"
10 #include "include/core/SkString.h"
11 #include "include/effects/SkGradientShader.h"
12 #include "tools/fonts/FontToolUtils.h"
13 #include "tools/viewer/Slide.h"
14
draw_gradient2(SkCanvas * canvas,const SkRect & rect,SkScalar delta)15 static void draw_gradient2(SkCanvas* canvas, const SkRect& rect, SkScalar delta) {
16 SkColor colors[] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorMAGENTA };
17 SkScalar pos[] = { 0, 0.25f, 0.75f, SK_Scalar1 };
18
19 SkScalar l = rect.fLeft;
20 SkScalar t = rect.fTop;
21 SkScalar w = rect.width();
22 SkScalar h = rect.height();
23
24 SkASSERT(0 == SkScalarMod(w, SK_Scalar1 * 5));
25
26 SkPoint c0 = { l + 2 * w / 5 + delta, t + h / 2 };
27 SkPoint c1 = { l + 3 * w / 5, t + h / 2 };
28 SkScalar r0 = w / 5;
29 SkScalar r1 = 2 * w / 5;
30 SkPaint paint;
31 paint.setShader(SkGradientShader::MakeTwoPointConical(c0, r0, c1, r1, colors,
32 pos, std::size(pos),
33 SkTileMode::kClamp));
34 canvas->drawRect(rect, paint);
35 }
36
37
38 class DegenerateTwoPtRadialsSlide : public Slide {
39 public:
DegenerateTwoPtRadialsSlide()40 DegenerateTwoPtRadialsSlide() { fName = "DegenerateTwoPtRadials"; }
41
draw(SkCanvas * canvas)42 void draw(SkCanvas* canvas) override {
43 canvas->clear(0xFFDDDDDD);
44 SkScalar delta = fTime / 15.f;
45 int intPart = SkScalarFloorToInt(delta);
46 delta = delta - SK_Scalar1 * intPart;
47 if (intPart % 2) {
48 delta = SK_Scalar1 - delta;
49 }
50 delta -= SK_ScalarHalf;
51 static const int DELTA_SCALE = 500;
52 delta /= DELTA_SCALE;
53
54 SkScalar w = SK_Scalar1 * 500;
55 SkScalar h = SK_Scalar1 * 500;
56 SkScalar l = SK_Scalar1 * 100;
57 SkScalar t = SK_Scalar1 * 100;
58 draw_gradient2(canvas, SkRect::MakeXYWH(l, t, w, h), delta);
59 SkString txt;
60 txt.appendf("gap at \"tangent\" pt = %f", delta);
61 canvas->drawString(txt,
62 l + w / 2 + w * DELTA_SCALE * delta,
63 t + h + SK_Scalar1 * 10,
64 ToolUtils::DefaultFont(),
65 SkPaint());
66 }
67
animate(double nanos)68 bool animate(double nanos) override {
69 fTime = SkDoubleToScalar(1e-9 * nanos / 15);
70 return true;
71 }
72
73 private:
74 SkScalar fTime;
75 };
76
77 //////////////////////////////////////////////////////////////////////////////
78
79 DEF_SLIDE( return new DegenerateTwoPtRadialsSlide(); )
80