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 "gm.h"
9#include "SkCanvas.h"
10#include "SkColorPriv.h"
11#include "SkShader.h"
12
13#include "SkArithmeticMode.h"
14#include "SkGradientShader.h"
15#define WW  100
16#define HH  32
17
18static SkBitmap make_bm() {
19    SkBitmap bm;
20    bm.allocN32Pixels(WW, HH);
21    bm.eraseColor(SK_ColorTRANSPARENT);
22    return bm;
23}
24
25static SkBitmap make_src() {
26    SkBitmap bm = make_bm();
27    SkCanvas canvas(bm);
28    SkPaint paint;
29    SkPoint pts[] = { {0, 0}, {SkIntToScalar(WW), SkIntToScalar(HH)} };
30    SkColor colors[] = {
31        SK_ColorTRANSPARENT, SK_ColorGREEN, SK_ColorCYAN,
32        SK_ColorRED, SK_ColorMAGENTA, SK_ColorWHITE,
33    };
34    SkShader* s = SkGradientShader::CreateLinear(pts, colors, NULL, SK_ARRAY_COUNT(colors),
35                                                 SkShader::kClamp_TileMode);
36    paint.setShader(s)->unref();
37    canvas.drawPaint(paint);
38    return bm;
39}
40
41static SkBitmap make_dst() {
42    SkBitmap bm = make_bm();
43    SkCanvas canvas(bm);
44    SkPaint paint;
45    SkPoint pts[] = { {0, SkIntToScalar(HH)}, {SkIntToScalar(WW), 0} };
46    SkColor colors[] = {
47        SK_ColorBLUE, SK_ColorYELLOW, SK_ColorBLACK, SK_ColorGREEN, SK_ColorGRAY
48    };
49    SkShader* s = SkGradientShader::CreateLinear(pts, colors, NULL, SK_ARRAY_COUNT(colors),
50                                                 SkShader::kClamp_TileMode);
51    paint.setShader(s)->unref();
52    canvas.drawPaint(paint);
53    return bm;
54}
55
56static void show_k_text(SkCanvas* canvas, SkScalar x, SkScalar y, const SkScalar k[]) {
57    SkPaint paint;
58    paint.setTextSize(SkIntToScalar(24));
59    paint.setAntiAlias(true);
60    for (int i = 0; i < 4; ++i) {
61        SkString str;
62        str.appendScalar(k[i]);
63        SkScalar width = paint.measureText(str.c_str(), str.size());
64        canvas->drawText(str.c_str(), str.size(), x, y + paint.getTextSize(), paint);
65        x += width + SkIntToScalar(10);
66    }
67}
68
69class ArithmodeGM : public skiagm::GM {
70public:
71    ArithmodeGM () {}
72
73protected:
74
75    virtual SkString onShortName() {
76        return SkString("arithmode");
77    }
78
79    virtual SkISize onISize() { return SkISize::Make(640, 480); }
80
81    virtual void onDraw(SkCanvas* canvas) {
82        SkBitmap src = make_src();
83        SkBitmap dst = make_dst();
84
85        const SkScalar one = SK_Scalar1;
86        static const SkScalar K[] = {
87            0, 0, 0, 0,
88            0, 0, 0, one,
89            0, one, 0, 0,
90            0, 0, one, 0,
91            0, one, one, 0,
92            0, one, -one, 0,
93            0, one/2, one/2, 0,
94            0, one/2, one/2, one/4,
95            0, one/2, one/2, -one/4,
96            one/4, one/2, one/2, 0,
97            -one/4, one/2, one/2, 0,
98        };
99
100        const SkScalar* k = K;
101        const SkScalar* stop = k + SK_ARRAY_COUNT(K);
102        SkScalar y = 0;
103        SkScalar gap = SkIntToScalar(src.width() + 20);
104        while (k < stop) {
105            SkScalar x = 0;
106            canvas->drawBitmap(src, x, y, NULL);
107            x += gap;
108            canvas->drawBitmap(dst, x, y, NULL);
109            x += gap;
110            SkRect rect = SkRect::MakeXYWH(x, y, SkIntToScalar(WW), SkIntToScalar(HH));
111            canvas->saveLayer(&rect, NULL);
112            canvas->drawBitmap(dst, x, y, NULL);
113            SkXfermode* xfer = SkArithmeticMode::Create(k[0], k[1], k[2], k[3]);
114            SkPaint paint;
115            paint.setXfermode(xfer)->unref();
116            canvas->drawBitmap(src, x, y, &paint);
117            canvas->restore();
118            x += gap;
119            show_k_text(canvas, x, y, k);
120            k += 4;
121            y += SkIntToScalar(src.height() + 12);
122        }
123    }
124
125private:
126    typedef GM INHERITED;
127};
128
129///////////////////////////////////////////////////////////////////////////////
130
131static skiagm::GM* MyFactory(void*) { return new ArithmodeGM; }
132static skiagm::GMRegistry reg(MyFactory);
133