1
2/*
3 * Copyright 2011 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8#include "SampleCode.h"
9#include "SkView.h"
10#include "SkCanvas.h"
11#include "Sk64.h"
12#include "SkGradientShader.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, SkFloatToScalar(0.25f), SkFloatToScalar(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::CreateTwoPointRadial(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 = SkScalarFloor(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        SkRect rect;
70        SkScalar w = SK_Scalar1 * 500;
71        SkScalar h = SK_Scalar1 * 500;
72        SkScalar l = SK_Scalar1 * 100;
73        SkScalar t = SK_Scalar1 * 100;
74        draw_gradient2(canvas, SkRect::MakeXYWH(l, t, w, h), delta);
75        char txt[512];
76        sprintf(txt, "gap at \"tangent\" pt = %f", SkScalarToFloat(delta));
77        SkPaint paint;
78        paint.setAntiAlias(true);
79        paint.setColor(SK_ColorBLACK);
80        canvas->drawText(txt, strlen(txt), l + w/2 + w*DELTA_SCALE*delta, t + h + SK_Scalar1 * 10, paint);
81        this->inval(NULL);
82    }
83
84private:
85    SkScalar           fTime;
86    typedef SampleView INHERITED;
87};
88
89//////////////////////////////////////////////////////////////////////////////
90
91static SkView* MyFactory() { return new DegenerateTwoPtRadialsView; }
92static SkViewRegister reg(MyFactory);
93