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.
gen_data(SkScalar yAvg,SkScalar ySpread,int count,SkTDArray<SkScalar> * dataPts)15 static 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.
gen_paths(const SkTDArray<SkScalar> & topData,const SkTDArray<SkScalar> * bottomData,SkScalar yBase,SkScalar xLeft,SkScalar xDelta,int leftShift,SkPathBuilder * plot,SkPathBuilder * fill)28 static 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
81 class ChartView : public Sample {
82 static constexpr int kNumGraphs = 5;
83 static constexpr int kPixelsPerTick = 3;
84 static constexpr int kShiftPerFrame = 1;
85 int fShift = 0;
86 SkISize fSize = {-1, -1};
87 SkTDArray<SkScalar> fData[kNumGraphs];
88
name()89 SkString name() override { return SkString("Chart"); }
90
onDrawContent(SkCanvas * canvas)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
160 DEF_SAMPLE( return new ChartView(); )
161