aboutsummaryrefslogtreecommitdiffhomepage
path: root/gm/strokedlines.cpp
blob: 7bcb3fb5789a656b2f529fd7915f437102922489 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
/*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "gm.h"
#include "SkBlurMaskFilter.h"
#include "SkDashPathEffect.h"
#include "SkGradientShader.h"
#include "SkPaint.h"
#include "SkPath.h"
#include "SkPoint3.h"

constexpr int kNumColumns = 6;
constexpr int kNumRows = 8;
constexpr int kRadius = 40;  // radius of the snowflake
constexpr int kPad = 5;      // padding on both sides of the snowflake
constexpr int kNumSpokes = 6;
constexpr SkScalar kStrokeWidth = 5.0f;

static void draw_fins(SkCanvas* canvas, const SkPoint& offset, float angle, const SkPaint& paint) {
    SkScalar cos, sin;

    // first fin
    sin = SkScalarSinCos(angle + (SK_ScalarPI/4), &cos);
    sin *= kRadius / 2.0f;
    cos *= kRadius / 2.0f;

    SkPath p;
    p.moveTo(offset.fX, offset.fY);
    p.lineTo(offset.fX + cos, offset.fY + sin);
    canvas->drawPath(p, paint);

    // second fin
    sin = SkScalarSinCos(angle - (SK_ScalarPI/4), &cos);
    sin *= kRadius / 2.0f;
    cos *= kRadius / 2.0f;

    p.reset();
    p.moveTo(offset.fX, offset.fY);
    p.lineTo(offset.fX + cos, offset.fY + sin);
    canvas->drawPath(p, paint);
}

// draw a snowflake centered at the origin
static void draw_snowflake(SkCanvas* canvas, const SkPaint& paint) {

    canvas->clipRect(SkRect::MakeLTRB(-kRadius-kPad, -kRadius-kPad, kRadius+kPad, kRadius+kPad));

    SkScalar sin, cos, angle = 0.0f;
    for (int i = 0; i < kNumSpokes/2; ++i, angle += SK_ScalarPI/(kNumSpokes/2)) {
        sin = SkScalarSinCos(angle, &cos);
        sin *= kRadius;
        cos *= kRadius;

        // main spoke
        SkPath p;
        p.moveTo(-cos, -sin);
        p.lineTo(cos, sin);
        canvas->drawPath(p, paint);

        // fins on positive side
        const SkPoint posOffset = SkPoint::Make(0.5f * cos, 0.5f * sin);
        draw_fins(canvas, posOffset, angle, paint);

        // fins on negative side
        const SkPoint negOffset = SkPoint::Make(-0.5f * cos, -0.5f * sin);
        draw_fins(canvas, negOffset, angle+SK_ScalarPI, paint);
    }
}

static void draw_row(SkCanvas* canvas, const SkPaint& paint, const SkMatrix& localMatrix) {
    canvas->translate(kRadius+kPad, 0.0f);

    for (auto cap : { SkPaint::kButt_Cap, SkPaint::kRound_Cap, SkPaint::kSquare_Cap }) {
        for (auto isAA : { true, false }) {
            SkPaint tmp(paint);
            tmp.setStrokeWidth(kStrokeWidth);
            tmp.setStyle(SkPaint::kStroke_Style);
            tmp.setStrokeCap(cap);
            tmp.setAntiAlias(isAA);

            int saveCount = canvas->save();
            canvas->concat(localMatrix);
            draw_snowflake(canvas, tmp);
            canvas->restoreToCount(saveCount);

            canvas->translate(2*(kRadius+kPad), 0.0f);
        }
    }
}

namespace skiagm {

// This GM exercises the special case of a stroked lines.
// Various shaders are applied to ensure the coordinate spaces work out right.
class StrokedLinesGM : public GM {
public:
    StrokedLinesGM() {
        this->setBGColor(sk_tool_utils::color_to_565(0xFF1A65D7));
    }

protected:
    SkString onShortName() override {
        return SkString("strokedlines");
    }

    SkISize onISize() override {
        return SkISize::Make(kNumColumns * (2*kRadius+2*kPad), kNumRows * (2*kRadius+2*kPad));
    }

    void onOnceBeforeDraw() override {
        // paints
        {
            // basic white
            SkPaint p;
            p.setColor(SK_ColorWHITE);
            fPaints.push_back(p);
        }
        {
            // gradient
            SkColor colors[] = { SK_ColorRED, SK_ColorGREEN };
            SkPoint pts[] = { {-kRadius-kPad, -kRadius-kPad }, { kRadius+kPad, kRadius+kPad } };

            SkPaint p;
            p.setShader(SkGradientShader::MakeLinear(pts, colors, nullptr, 2,
                                                     SkShader::kClamp_TileMode, 0, nullptr));

            fPaints.push_back(p);
        }
        {
            // dashing
            SkScalar intervals[] = { kStrokeWidth, kStrokeWidth };
            int intervalCount = (int) SK_ARRAY_COUNT(intervals);
            SkPaint p;
            p.setColor(SK_ColorWHITE);
            p.setPathEffect(SkDashPathEffect::Make(intervals, intervalCount, kStrokeWidth));

            fPaints.push_back(p);
        }
        {
            // Bitmap shader
            SkBitmap bm;
            bm.allocN32Pixels(2, 2);
            *bm.getAddr32(0, 0) = *bm.getAddr32(1, 1) = 0xFFFFFFFF;
            *bm.getAddr32(1, 0) = *bm.getAddr32(0, 1) = 0x0;

            SkMatrix m;
            m.setRotate(12.0f);
            m.preScale(3.0f, 3.0f);;

            SkPaint p;
            p.setShader(SkShader::MakeBitmapShader(bm,
                                                   SkShader::kRepeat_TileMode,
                                                   SkShader::kRepeat_TileMode,
                                                   &m));
            fPaints.push_back(p);
        }
        {
            // blur
            SkPaint p;
            p.setColor(SK_ColorWHITE);
            p.setMaskFilter(SkBlurMaskFilter::Make(kOuter_SkBlurStyle, 3.0f,
                                                   SkBlurMaskFilter::kHighQuality_BlurFlag));
            fPaints.push_back(p);
        }

        // matrices
        {
            // rotation
            SkMatrix m;
            m.setRotate(12.0f);

            fMatrices.push_back(m);
        }
        {
            // skew
            SkMatrix m;
            m.setSkew(0.3f, 0.5f);

            fMatrices.push_back(m);
        }
        {
            // perspective
            SkMatrix m;
            m.reset();
            m.setPerspX(-SK_Scalar1 / 300);
            m.setPerspY(SK_Scalar1 / 300);

            fMatrices.push_back(m);
        }

        SkASSERT(kNumRows == fPaints.count() + fMatrices.count());
    }

    void onDraw(SkCanvas* canvas) override {
        canvas->translate(0, kRadius+kPad);

        for (int i = 0; i < fPaints.count(); ++i) {
            int saveCount = canvas->save();
            draw_row(canvas, fPaints[i], SkMatrix::I());
            canvas->restoreToCount(saveCount);

            canvas->translate(0, 2*(kRadius+kPad));
        }

        for (int i = 0; i < fMatrices.count(); ++i) {
            int saveCount = canvas->save();
            draw_row(canvas, fPaints[0], fMatrices[i]);
            canvas->restoreToCount(saveCount);

            canvas->translate(0, 2*(kRadius+kPad));
        }
    }

private:
    SkTArray<SkPaint> fPaints;
    SkTArray<SkMatrix> fMatrices;

    typedef GM INHERITED;
};

//////////////////////////////////////////////////////////////////////////////

DEF_GM(return new StrokedLinesGM;)
}