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 "include/core/SkCanvas.h"
9#include "include/core/SkPaint.h"
10#include "include/core/SkPathBuilder.h"
11#include "include/utils/SkRandom.h"
12#include "samplecode/Sample.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 == nullptr.
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                      SkPathBuilder* plot, SkPathBuilder* fill) {
34    plot->incReserve(topData.count());
35    if (nullptr == bottomData) {
36        fill->incReserve(topData.count() + 2);
37    } else {
38        fill->incReserve(2 * topData.count());
39    }
40
41    leftShift %= topData.count();
42    SkScalar x = xLeft;
43
44    // Account for the leftShift using two loops
45    int shiftToEndCount = topData.count() - leftShift;
46    plot->moveTo(x, topData[leftShift]);
47    fill->moveTo(x, topData[leftShift]);
48
49    for (int i = 1; i < shiftToEndCount; ++i) {
50        plot->lineTo(x, topData[i + leftShift]);
51        fill->lineTo(x, topData[i + leftShift]);
52        x += xDelta;
53    }
54
55    for (int i = 0; i < leftShift; ++i) {
56        plot->lineTo(x, topData[i]);
57        fill->lineTo(x, topData[i]);
58        x += xDelta;
59    }
60
61    if (bottomData) {
62        SkASSERT(bottomData->count() == topData.count());
63        // iterate backwards over the previous graph's data to generate the bottom of the filled
64        // area (and account for leftShift).
65        for (int i = 0; i < leftShift; ++i) {
66            x -= xDelta;
67            fill->lineTo(x, (*bottomData)[leftShift - 1 - i]);
68        }
69        for (int i = 0; i < shiftToEndCount; ++i) {
70            x -= xDelta;
71            fill->lineTo(x, (*bottomData)[bottomData->count() - 1 - i]);
72        }
73    } else {
74        fill->lineTo(x - xDelta, yBase);
75        fill->lineTo(xLeft, yBase);
76    }
77}
78
79// A set of scrolling line plots with the area between each plot filled. Stresses out GPU path
80// filling
81class ChartView : public Sample {
82    inline static constexpr int kNumGraphs = 5;
83    inline static constexpr int kPixelsPerTick = 3;
84    inline static constexpr int kShiftPerFrame = 1;
85    int                 fShift = 0;
86    SkISize             fSize = {-1, -1};
87    SkTDArray<SkScalar> fData[kNumGraphs];
88
89    SkString name() override { return SkString("Chart"); }
90
91    void onDrawContent(SkCanvas* canvas) override {
92        bool sizeChanged = false;
93        if (canvas->getBaseLayerSize() != fSize) {
94            fSize = canvas->getBaseLayerSize();
95            sizeChanged = true;
96        }
97
98        SkScalar ySpread = SkIntToScalar(fSize.fHeight / 20);
99
100        SkScalar height = SkIntToScalar(fSize.fHeight);
101
102        if (sizeChanged) {
103            int dataPointCount = std::max(fSize.fWidth / kPixelsPerTick + 1, 2);
104
105            for (int i = 0; i < kNumGraphs; ++i) {
106                SkScalar y = (kNumGraphs - i) * (height - ySpread) / (kNumGraphs + 1);
107                fData[i].reset();
108                gen_data(y, ySpread, dataPointCount, fData + i);
109            }
110        }
111
112        canvas->clear(0xFFE0F0E0);
113
114        static SkRandom colorRand;
115        static SkColor gColors[kNumGraphs] = { 0x0 };
116        if (0 == gColors[0]) {
117            for (int i = 0; i < kNumGraphs; ++i) {
118                gColors[i] = colorRand.nextU() | 0xff000000;
119            }
120        }
121
122        static const SkScalar kStrokeWidth = SkIntToScalar(2);
123        SkPaint plotPaint;
124        SkPaint fillPaint;
125        plotPaint.setAntiAlias(true);
126        plotPaint.setStyle(SkPaint::kStroke_Style);
127        plotPaint.setStrokeWidth(kStrokeWidth);
128        plotPaint.setStrokeCap(SkPaint::kRound_Cap);
129        plotPaint.setStrokeJoin(SkPaint::kRound_Join);
130        fillPaint.setAntiAlias(true);
131        fillPaint.setStyle(SkPaint::kFill_Style);
132
133        SkPathBuilder plotPath, fillPath;
134        SkTDArray<SkScalar>* prevData = nullptr;
135
136        for (int i = 0; i < kNumGraphs; ++i) {
137            gen_paths(fData[i],
138                      prevData,
139                      height,
140                      0,
141                      SkIntToScalar(kPixelsPerTick),
142                      fShift,
143                      &plotPath,
144                      &fillPath);
145
146            // Make the fills partially transparent
147            fillPaint.setColor((gColors[i] & 0x00ffffff) | 0x80000000);
148            canvas->drawPath(fillPath.detach(), fillPaint);
149
150            plotPaint.setColor(gColors[i]);
151            canvas->drawPath(plotPath.detach(), plotPaint);
152
153            prevData = fData + i;
154        }
155
156        fShift += kShiftPerFrame;
157    }
158};
159
160DEF_SAMPLE( return new ChartView(); )
161