xref: /third_party/skia/gm/polygons.cpp (revision cb93a386)
1/*
2 * Copyright 2013 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/gm.h"
9#include "include/core/SkCanvas.h"
10#include "include/core/SkColor.h"
11#include "include/core/SkPaint.h"
12#include "include/core/SkPathBuilder.h"
13#include "include/core/SkPoint.h"
14#include "include/core/SkScalar.h"
15#include "include/core/SkSize.h"
16#include "include/core/SkString.h"
17#include "include/core/SkTypes.h"
18#include "include/private/SkTArray.h"
19#include "include/utils/SkRandom.h"
20
21namespace skiagm {
22
23// This GM tests a grab-bag of convex and concave polygons. They are triangles,
24// trapezoid, diamond, polygons with lots of edges, several concave polygons...
25// But rectangles are excluded.
26class PolygonsGM: public GM {
27public:
28    PolygonsGM() {}
29
30protected:
31
32    SkString onShortName() override {
33        return SkString("polygons");
34    }
35
36    SkISize onISize() override {
37        int width = kNumPolygons * kCellSize + 40;
38        int height = (kNumJoins * kNumStrokeWidths + kNumExtraStyles) * kCellSize + 40;
39        return SkISize::Make(width, height);
40    }
41
42    // Construct all polygons
43    void onOnceBeforeDraw() override {
44        SkPoint p0[] = {{0, 0}, {60, 0}, {90, 40}};  // triangle
45        SkPoint p1[] = {{0, 0}, {0, 40}, {60, 40}, {40, 0}};  // trapezoid
46        SkPoint p2[] = {{0, 0}, {40, 40}, {80, 40}, {40, 0}};  // diamond
47        SkPoint p3[] = {{10, 0}, {50, 0}, {60, 10}, {60, 30}, {50, 40},
48                        {10, 40}, {0, 30}, {0, 10}};  // octagon
49        SkPoint p4[32];  // circle-like polygons with 32-edges.
50        SkPoint p5[] = {{0, 0}, {20, 20}, {0, 40}, {60, 20}};  // concave polygon with 4 edges
51        SkPoint p6[] = {{0, 40}, {0, 30}, {15, 30}, {15, 20}, {30, 20},
52                        {30, 10}, {45, 10}, {45, 0}, {60, 0}, {60, 40}};  // stairs-like polygon
53        SkPoint p7[] = {{0, 20}, {20, 20}, {30, 0}, {40, 20}, {60, 20},
54                        {45, 30}, {55, 50}, {30, 40}, {5, 50}, {15, 30}};  // five-point stars
55
56        for (size_t i = 0; i < SK_ARRAY_COUNT(p4); ++i) {
57            SkScalar angle = 2 * SK_ScalarPI * i / SK_ARRAY_COUNT(p4);
58            p4[i].set(20 * SkScalarCos(angle) + 20, 20 * SkScalarSin(angle) + 20);
59        }
60
61        struct Polygons {
62            SkPoint* fPoints;
63            size_t fPointNum;
64        } pgs[] = {
65            { p0, SK_ARRAY_COUNT(p0) },
66            { p1, SK_ARRAY_COUNT(p1) },
67            { p2, SK_ARRAY_COUNT(p2) },
68            { p3, SK_ARRAY_COUNT(p3) },
69            { p4, SK_ARRAY_COUNT(p4) },
70            { p5, SK_ARRAY_COUNT(p5) },
71            { p6, SK_ARRAY_COUNT(p6) },
72            { p7, SK_ARRAY_COUNT(p7) }
73        };
74
75        SkASSERT(SK_ARRAY_COUNT(pgs) == kNumPolygons);
76        for (size_t pgIndex = 0; pgIndex < SK_ARRAY_COUNT(pgs); ++pgIndex) {
77            SkPathBuilder b;
78            b.moveTo(pgs[pgIndex].fPoints[0].fX,
79                     pgs[pgIndex].fPoints[0].fY);
80            for (size_t ptIndex = 1; ptIndex < pgs[pgIndex].fPointNum; ++ptIndex) {
81                b.lineTo(pgs[pgIndex].fPoints[ptIndex].fX,
82                         pgs[pgIndex].fPoints[ptIndex].fY);
83            }
84            b.close();
85            fPolygons.push_back(b.detach());
86        }
87    }
88
89    // Set the location for the current test on the canvas
90    static void SetLocation(SkCanvas* canvas, int counter, int lineNum) {
91        SkScalar x = SK_Scalar1 * kCellSize * (counter % lineNum) + 30 + SK_Scalar1 / 4;
92        SkScalar y = SK_Scalar1 * kCellSize * (counter / lineNum) + 30 + 3 * SK_Scalar1 / 4;
93        canvas->translate(x, y);
94    }
95
96    static void SetColorAndAlpha(SkPaint* paint, SkRandom* rand) {
97        SkColor color = rand->nextU();
98        color |= 0xff000000;
99        paint->setColor(color);
100        if (40 == paint->getStrokeWidth()) {
101            paint->setAlpha(0xA0);
102        }
103    }
104
105    void onDraw(SkCanvas* canvas) override {
106        // Stroke widths are:
107        // 0(may use hairline rendering), 10(common case for stroke-style)
108        // 40(>= geometry width/height, make the contour filled in fact)
109        constexpr int kStrokeWidths[] = {0, 10, 40};
110        SkASSERT(kNumStrokeWidths == SK_ARRAY_COUNT(kStrokeWidths));
111
112        constexpr SkPaint::Join kJoins[] = {
113            SkPaint::kMiter_Join, SkPaint::kRound_Join, SkPaint::kBevel_Join
114        };
115        SkASSERT(kNumJoins == SK_ARRAY_COUNT(kJoins));
116
117        int counter = 0;
118        SkPaint paint;
119        paint.setAntiAlias(true);
120
121        SkRandom rand;
122        // For stroke style painter
123        paint.setStyle(SkPaint::kStroke_Style);
124        for (int join = 0; join < kNumJoins; ++join) {
125            for (int width = 0; width < kNumStrokeWidths; ++width) {
126                for (int i = 0; i < fPolygons.count(); ++i) {
127                    canvas->save();
128                    SetLocation(canvas, counter, fPolygons.count());
129
130                    SetColorAndAlpha(&paint, &rand);
131                    paint.setStrokeJoin(kJoins[join]);
132                    paint.setStrokeWidth(SkIntToScalar(kStrokeWidths[width]));
133
134                    canvas->drawPath(fPolygons[i], paint);
135                    canvas->restore();
136                    ++counter;
137                }
138            }
139        }
140
141        // For stroke-and-fill style painter and fill style painter
142        constexpr SkPaint::Style kStyles[] = {
143            SkPaint::kStrokeAndFill_Style, SkPaint::kFill_Style
144        };
145        SkASSERT(kNumExtraStyles == SK_ARRAY_COUNT(kStyles));
146
147        paint.setStrokeJoin(SkPaint::kMiter_Join);
148        paint.setStrokeWidth(SkIntToScalar(20));
149        for (int style = 0; style < kNumExtraStyles; ++style) {
150            paint.setStyle(kStyles[style]);
151            for (int i = 0; i < fPolygons.count(); ++i) {
152                canvas->save();
153                SetLocation(canvas, counter, fPolygons.count());
154                SetColorAndAlpha(&paint, &rand);
155                canvas->drawPath(fPolygons[i], paint);
156                canvas->restore();
157                ++counter;
158            }
159        }
160    }
161
162private:
163    inline static constexpr int kNumPolygons = 8;
164    inline static constexpr int kCellSize = 100;
165    inline static constexpr int kNumExtraStyles = 2;
166    inline static constexpr int kNumStrokeWidths = 3;
167    inline static constexpr int kNumJoins = 3;
168
169    SkTArray<SkPath> fPolygons;
170    using INHERITED = GM;
171};
172
173//////////////////////////////////////////////////////////////////////////////
174
175DEF_GM(return new PolygonsGM;)
176
177// see crbug.com/1197461
178DEF_SIMPLE_GM(conjoined_polygons, canvas, 400, 400) {
179    SkPathBuilder b;
180    b.moveTo(0.f, 120.f);
181    b.lineTo(0.f, 0.f);
182    b.lineTo(50.f, 330.f);
183    b.lineTo(90.f, 0.f);
184    b.lineTo(340.f, 0.f);
185    b.lineTo(90.f, 330.f);
186    b.lineTo(50.f, 330.f);
187    b.close();
188
189    SkPaint paint;
190    paint.setAntiAlias(true);
191    canvas->drawPath(b.detach(), paint);
192}
193
194}  // namespace skiagm
195