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 "SkView.h"
10#include "SkCanvas.h"
11#include "SkGradientShader.h"
12#include "SkString.h"
13
14static void draw_gradient2(SkCanvas* canvas, const SkRect& rect, SkScalar delta) {
15    SkColor colors[] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorMAGENTA };
16    SkScalar pos[] = { 0, 0.25f, 0.75f, SK_Scalar1 };
17
18    SkScalar l = rect.fLeft;
19    SkScalar t = rect.fTop;
20    SkScalar w = rect.width();
21    SkScalar h = rect.height();
22
23    SkASSERT(0 == SkScalarMod(w, SK_Scalar1 * 5));
24
25    SkPoint c0 = { l + 2 * w / 5 + delta, t + h / 2 };
26    SkPoint c1 = { l + 3 * w / 5, t + h / 2 };
27    SkScalar r0 = w / 5;
28    SkScalar r1 = 2 * w / 5;
29    SkShader* s = SkGradientShader::CreateTwoPointConical(c0, r0, c1, r1, colors,
30                                                         pos, SK_ARRAY_COUNT(pos),
31                                                         SkShader::kClamp_TileMode);
32    SkPaint paint;
33    paint.setShader(s)->unref();
34
35    canvas->drawRect(rect, paint);
36}
37
38
39class DegenerateTwoPtRadialsView : public SampleView {
40
41public:
42    DegenerateTwoPtRadialsView() {
43        fTime = 0;
44        this->setBGColor(0xFFDDDDDD);
45    }
46
47protected:
48    // overrides from SkEventSink
49    virtual bool onQuery(SkEvent* evt) {
50        if (SampleCode::TitleQ(*evt)) {
51            SampleCode::TitleR(evt, "DegenerateTwoPtRadials");
52            return true;
53        }
54        return this->INHERITED::onQuery(evt);
55    }
56
57    virtual void onDrawContent(SkCanvas* canvas) {
58        fTime += SampleCode::GetAnimSecondsDelta();
59        SkScalar delta = fTime / 15.f;
60        int intPart = SkScalarFloorToInt(delta);
61        delta = delta - SK_Scalar1 * intPart;
62        if (intPart % 2) {
63            delta = SK_Scalar1 - delta;
64        }
65        delta -= SK_ScalarHalf;
66        static const int DELTA_SCALE = 500;
67        delta /= DELTA_SCALE;
68
69        SkScalar w = SK_Scalar1 * 500;
70        SkScalar h = SK_Scalar1 * 500;
71        SkScalar l = SK_Scalar1 * 100;
72        SkScalar t = SK_Scalar1 * 100;
73        draw_gradient2(canvas, SkRect::MakeXYWH(l, t, w, h), delta);
74        SkString txt;
75        txt.appendf("gap at \"tangent\" pt = %f", SkScalarToFloat(delta));
76        SkPaint paint;
77        paint.setAntiAlias(true);
78        paint.setColor(SK_ColorBLACK);
79        canvas->drawText(txt.c_str(), txt.size(), l + w/2 + w*DELTA_SCALE*delta, t + h + SK_Scalar1 * 10, paint);
80        this->inval(NULL);
81    }
82
83private:
84    SkScalar           fTime;
85    typedef SampleView INHERITED;
86};
87
88//////////////////////////////////////////////////////////////////////////////
89
90static SkView* MyFactory() { return new DegenerateTwoPtRadialsView; }
91static SkViewRegister reg(MyFactory);
92