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 "SampleCode.h"
9 #include "SkAnimTimer.h"
10 #include "SkView.h"
11 #include "SkCanvas.h"
12 #include "SkGradientShader.h"
13 #include "SkString.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 SkShader* s = SkGradientShader::CreateTwoPointConical(c0, r0, c1, r1, colors,
31 pos, SK_ARRAY_COUNT(pos),
32 SkShader::kClamp_TileMode);
33 SkPaint paint;
34 paint.setShader(s)->unref();
35
36 canvas->drawRect(rect, paint);
37 }
38
39
40 class DegenerateTwoPtRadialsView : public SampleView {
41 public:
DegenerateTwoPtRadialsView()42 DegenerateTwoPtRadialsView() {
43 fTime = 0;
44 this->setBGColor(0xFFDDDDDD);
45 }
46
47 protected:
onQuery(SkEvent * evt)48 bool onQuery(SkEvent* evt) override {
49 if (SampleCode::TitleQ(*evt)) {
50 SampleCode::TitleR(evt, "DegenerateTwoPtRadials");
51 return true;
52 }
53 return this->INHERITED::onQuery(evt);
54 }
55
onDrawContent(SkCanvas * canvas)56 void onDrawContent(SkCanvas* canvas) override {
57 SkScalar delta = fTime / 15.f;
58 int intPart = SkScalarFloorToInt(delta);
59 delta = delta - SK_Scalar1 * intPart;
60 if (intPart % 2) {
61 delta = SK_Scalar1 - delta;
62 }
63 delta -= SK_ScalarHalf;
64 static const int DELTA_SCALE = 500;
65 delta /= DELTA_SCALE;
66
67 SkScalar w = SK_Scalar1 * 500;
68 SkScalar h = SK_Scalar1 * 500;
69 SkScalar l = SK_Scalar1 * 100;
70 SkScalar t = SK_Scalar1 * 100;
71 draw_gradient2(canvas, SkRect::MakeXYWH(l, t, w, h), delta);
72 SkString txt;
73 txt.appendf("gap at \"tangent\" pt = %f", SkScalarToFloat(delta));
74 SkPaint paint;
75 paint.setAntiAlias(true);
76 paint.setColor(SK_ColorBLACK);
77 canvas->drawText(txt.c_str(), txt.size(), l + w/2 + w*DELTA_SCALE*delta, t + h + SK_Scalar1 * 10, paint);
78 }
79
onAnimate(const SkAnimTimer & timer)80 bool onAnimate(const SkAnimTimer& timer) override {
81 fTime = SkDoubleToScalar(timer.secs() / 15);
82 return true;
83 }
84
85 private:
86 SkScalar fTime;
87 typedef SampleView INHERITED;
88 };
89
90 //////////////////////////////////////////////////////////////////////////////
91
MyFactory()92 static SkView* MyFactory() { return new DegenerateTwoPtRadialsView; }
93 static SkViewRegister reg(MyFactory);
94