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 "SampleCode.h"
9#include "SkCanvas.h"
10#include "SkPaint.h"
11#include "SkPath.h"
12#include "SkRandom.h"
13#include "SkView.h"
14
15// Generates y values for the chart plots.
16static void gen_data(SkScalar yAvg, SkScalar ySpread, int count, SkTDArray<SkScalar>* dataPts) {
17    dataPts->setCount(count);
18    static SkRandom gRandom;
19    for (int i = 0; i < count; ++i) {
20        (*dataPts)[i] = gRandom.nextRangeScalar(yAvg - SkScalarHalf(ySpread),
21                                                yAvg + SkScalarHalf(ySpread));
22    }
23}
24
25// Generates a path to stroke along the top of each plot and a fill path for the area below each
26// plot. The fill path is bounded below by the bottomData plot points or a horizontal line at
27// yBase if bottomData == nullptr.
28// The plots are animated by rotating the data points by leftShift.
29static void gen_paths(const SkTDArray<SkScalar>& topData,
30                      const SkTDArray<SkScalar>* bottomData,
31                      SkScalar yBase,
32                      SkScalar xLeft, SkScalar xDelta,
33                      int leftShift,
34                      SkPath* plot, SkPath* fill) {
35    plot->rewind();
36    fill->rewind();
37    plot->incReserve(topData.count());
38    if (nullptr == bottomData) {
39        fill->incReserve(topData.count() + 2);
40    } else {
41        fill->incReserve(2 * topData.count());
42    }
43
44    leftShift %= topData.count();
45    SkScalar x = xLeft;
46
47    // Account for the leftShift using two loops
48    int shiftToEndCount = topData.count() - leftShift;
49    plot->moveTo(x, topData[leftShift]);
50    fill->moveTo(x, topData[leftShift]);
51
52    for (int i = 1; i < shiftToEndCount; ++i) {
53        plot->lineTo(x, topData[i + leftShift]);
54        fill->lineTo(x, topData[i + leftShift]);
55        x += xDelta;
56    }
57
58    for (int i = 0; i < leftShift; ++i) {
59        plot->lineTo(x, topData[i]);
60        fill->lineTo(x, topData[i]);
61        x += xDelta;
62    }
63
64    if (bottomData) {
65        SkASSERT(bottomData->count() == topData.count());
66        // iterate backwards over the previous graph's data to generate the bottom of the filled
67        // area (and account for leftShift).
68        for (int i = 0; i < leftShift; ++i) {
69            x -= xDelta;
70            fill->lineTo(x, (*bottomData)[leftShift - 1 - i]);
71        }
72        for (int i = 0; i < shiftToEndCount; ++i) {
73            x -= xDelta;
74            fill->lineTo(x, (*bottomData)[bottomData->count() - 1 - i]);
75        }
76    } else {
77        fill->lineTo(x - xDelta, yBase);
78        fill->lineTo(xLeft, yBase);
79    }
80}
81
82// A set of scrolling line plots with the area between each plot filled. Stresses out GPU path
83// filling
84class ChartView : public SampleView {
85public:
86    ChartView() {
87        fShift = 0;
88        fSize.set(-1, -1);
89    }
90
91protected:
92    bool onQuery(SkEvent* evt) override {
93        if (SampleCode::TitleQ(*evt)) {
94            SampleCode::TitleR(evt, "Chart");
95            return true;
96        }
97        return this->INHERITED::onQuery(evt);
98    }
99
100    void onDrawContent(SkCanvas* canvas) override {
101        bool sizeChanged = false;
102        if (canvas->getBaseLayerSize() != fSize) {
103            fSize = canvas->getBaseLayerSize();
104            sizeChanged = true;
105        }
106
107        SkScalar ySpread = SkIntToScalar(fSize.fHeight / 20);
108
109        SkScalar height = SkIntToScalar(fSize.fHeight);
110
111        if (sizeChanged) {
112            int dataPointCount = SkMax32(fSize.fWidth / kPixelsPerTick + 1, 2);
113
114            for (int i = 0; i < kNumGraphs; ++i) {
115                SkScalar y = (kNumGraphs - i) * (height - ySpread) / (kNumGraphs + 1);
116                fData[i].reset();
117                gen_data(y, ySpread, dataPointCount, fData + i);
118            }
119        }
120
121        canvas->clear(0xFFE0F0E0);
122
123        static SkRandom colorRand;
124        static SkColor gColors[kNumGraphs] = { 0x0 };
125        if (0 == gColors[0]) {
126            for (int i = 0; i < kNumGraphs; ++i) {
127                gColors[i] = colorRand.nextU() | 0xff000000;
128            }
129        }
130
131        SkPath plotPath;
132        SkPath fillPath;
133
134        static const SkScalar kStrokeWidth = SkIntToScalar(2);
135        SkPaint plotPaint;
136        SkPaint fillPaint;
137        plotPaint.setAntiAlias(true);
138        plotPaint.setStyle(SkPaint::kStroke_Style);
139        plotPaint.setStrokeWidth(kStrokeWidth);
140        plotPaint.setStrokeCap(SkPaint::kRound_Cap);
141        plotPaint.setStrokeJoin(SkPaint::kRound_Join);
142        fillPaint.setAntiAlias(true);
143        fillPaint.setStyle(SkPaint::kFill_Style);
144
145        SkTDArray<SkScalar>* prevData = nullptr;
146        for (int i = 0; i < kNumGraphs; ++i) {
147            gen_paths(fData[i],
148                      prevData,
149                      height,
150                      0,
151                      SkIntToScalar(kPixelsPerTick),
152                      fShift,
153                      &plotPath,
154                      &fillPath);
155
156            // Make the fills partially transparent
157            fillPaint.setColor((gColors[i] & 0x00ffffff) | 0x80000000);
158            canvas->drawPath(fillPath, fillPaint);
159
160            plotPaint.setColor(gColors[i]);
161            canvas->drawPath(plotPath, plotPaint);
162
163            prevData = fData + i;
164        }
165
166        fShift += kShiftPerFrame;
167    }
168
169private:
170    enum {
171        kNumGraphs = 5,
172        kPixelsPerTick = 3,
173        kShiftPerFrame = 1,
174    };
175    int                 fShift;
176    SkISize             fSize;
177    SkTDArray<SkScalar> fData[kNumGraphs];
178    typedef SampleView INHERITED;
179};
180
181//////////////////////////////////////////////////////////////////////////////
182
183static SkView* MyFactory() { return new ChartView; }
184static SkViewRegister reg(MyFactory);
185