composeshader.cpp revision edda70e020630103270c815b7499e8b02271875d 
1/*
2 * Copyright 2012 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 "gm.h"
9
10#include "SkCanvas.h"
11#include "SkComposeShader.h"
12#include "SkGradientShader.h"
13#include "SkGraphics.h"
14#include "SkShader.h"
15#include "SkString.h"
16#include "SkXfermode.h"
17
18static SkShader* make_shader(SkXfermode::Mode mode) {
19    SkPoint pts[2];
20    SkColor colors[2];
21
22    pts[0].set(0, 0);
23    pts[1].set(SkIntToScalar(100), 0);
24    colors[0] = SK_ColorRED;
25    colors[1] = SK_ColorBLUE;
26    SkAutoTUnref<SkShader> shaderA(SkGradientShader::CreateLinear(pts, colors, NULL, 2,
27                                                                  SkShader::kClamp_TileMode));
28
29    pts[0].set(0, 0);
30    pts[1].set(0, SkIntToScalar(100));
31    colors[0] = SK_ColorBLACK;
32    colors[1] = SkColorSetARGB(0x80, 0, 0, 0);
33    SkAutoTUnref<SkShader> shaderB(SkGradientShader::CreateLinear(pts, colors, NULL, 2,
34                                                                  SkShader::kClamp_TileMode));
35
36    SkAutoTUnref<SkXfermode> xfer(SkXfermode::Create(mode));
37
38    return SkNEW_ARGS(SkComposeShader, (shaderA, shaderB, xfer));
39}
40
41class ComposeShaderGM : public skiagm::GM {
42public:
43    ComposeShaderGM() {
44        fShader = make_shader(SkXfermode::kDstIn_Mode);
45    }
46
47    virtual ~ComposeShaderGM() {
48        SkSafeUnref(fShader);
49    }
50
51protected:
52    virtual uint32_t onGetFlags() const SK_OVERRIDE {
53        return kSkipTiled_Flag;
54    }
55
56    virtual SkString onShortName() SK_OVERRIDE {
57        return SkString("composeshader");
58    }
59
60    virtual SkISize onISize() SK_OVERRIDE {
61        return SkISize::Make(120, 120);
62    }
63
64    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
65
66        SkPaint paint;
67
68        paint.setColor(SK_ColorGREEN);
69        canvas->drawRectCoords(0, 0, SkIntToScalar(100), SkIntToScalar(100), paint);
70        paint.setShader(fShader);
71        canvas->drawRectCoords(0, 0, SkIntToScalar(100), SkIntToScalar(100), paint);
72    }
73
74protected:
75    SkShader*   fShader;
76
77private:
78    typedef GM INHERITED ;
79};
80
81class ComposeShaderAlphaGM : public skiagm::GM {
82public:
83    ComposeShaderAlphaGM() {}
84
85protected:
86    virtual SkString onShortName() SK_OVERRIDE {
87        return SkString("composeshader_alpha");
88    }
89
90    virtual SkISize onISize() SK_OVERRIDE {
91        return SkISize::Make(220, 750);
92    }
93
94    virtual uint32_t onGetFlags() const SK_OVERRIDE {
95        // we're only off by 1 bit per-component
96        return kSkipTiled_Flag;
97    }
98
99    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
100        SkAutoTUnref<SkShader> shader0(make_shader(SkXfermode::kDstIn_Mode));
101        SkAutoTUnref<SkShader> shader1(make_shader(SkXfermode::kSrcOver_Mode));
102        SkShader* shaders[] = { shader0.get(), shader1.get() };
103
104        SkPaint paint;
105        paint.setColor(SK_ColorGREEN);
106
107        const SkRect r = SkRect::MakeXYWH(5, 5, 100, 100);
108
109        for (size_t y = 0; y < SK_ARRAY_COUNT(shaders); ++y) {
110            SkShader* shader = shaders[y];
111            canvas->save();
112            for (int alpha = 0xFF; alpha > 0; alpha -= 0x28) {
113                paint.setAlpha(0xFF);
114                paint.setShader(NULL);
115                canvas->drawRect(r, paint);
116
117                paint.setAlpha(alpha);
118                paint.setShader(shader);
119                canvas->drawRect(r, paint);
120
121                canvas->translate(r.width() + 5, 0);
122            }
123            canvas->restore();
124            canvas->translate(0, r.height() + 5);
125        }
126    }
127};
128
129//////////////////////////////////////////////////////////////////////////////
130
131DEF_GM( return new ComposeShaderGM; )
132DEF_GM( return new ComposeShaderAlphaGM; )
133