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