1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
package org.drrickorang.loopback;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.View;
/**
* Created by ninatai on 5/14/15.
*/
public class HistogramView extends View {
private Paint mHistPaint;
private Paint mTextPaint;
private Paint mLinePaint;
private Paint mXLabelPaint;
private static int[] mData;
private static int mMaxBufferPeriod = 0;
private static boolean mExceedRange = false;
private int mBase = 10; //base of logarithm
private int mNumberOfXLabel = 4;
private int mYLabelSize = 30;
private int mXLabelSize = 22;
private int mLineWidth = 3;
private int mHistogramInterval = 2; // separate each beam in the histogram by such amount
int mExtraYMargin = 5; // the extra margin between y labels and y-axis
public HistogramView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
// initiate once for optimization
private void init() {
mHistPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mHistPaint.setStyle(Paint.Style.FILL);
mHistPaint.setColor(Color.BLUE);
mTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mTextPaint.setColor(Color.RED);
mTextPaint.setTextSize(mYLabelSize);
mXLabelPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mXLabelPaint.setColor(Color.BLACK);
mXLabelPaint.setTextSize(mXLabelSize);
mLinePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mLinePaint.setColor(Color.BLACK);
mLinePaint.setStrokeWidth(mLineWidth);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawColor(Color.GRAY);
int arrayLength = mData.length;
if (mData == null || arrayLength == 0) {
return;
}
if (mMaxBufferPeriod != 0) {
// the range of latencies that's going to be displayed on histogram
int range;
if (mMaxBufferPeriod > arrayLength - 1) {
range = arrayLength;
mExceedRange = true;
} else {
range = mMaxBufferPeriod + 1;
mExceedRange = false;
}
if (range == 0) {
return;
}
// coordinate starts at (0,0), up to (right, bottom)
int right = this.getRight();
int bottom = this.getBottom();
// calculate the max frequency among all latencies
int maxBufferPeriodFreq = 0;
for (int i = 1; i < arrayLength; i++) {
if (mData[i] > maxBufferPeriodFreq) {
maxBufferPeriodFreq = mData[i];
}
}
if (maxBufferPeriodFreq == 0) {
return;
}
// find the closest order of "mBase" according to maxBufferPeriodFreq
int order = 0;
while (Math.pow(mBase, order) < maxBufferPeriodFreq) {
order += 1;
}
float height =( (float) (bottom - mXLabelSize - mLineWidth) / (order + 1)); // height for one decade
// y labels
String[] yLabels = new String[order+2]; // will store {"0", "1", "10", "100", ...} for base = 10
yLabels[0] = "0";
int yStartPoint = bottom - mXLabelSize - mLineWidth;
canvas.drawText(yLabels[0], 0, yStartPoint, mTextPaint);
int currentValue = 1;
for (int i = 1; i <= (order + 1); i++)
{
yLabels[i] = Integer.toString(currentValue);
// Label is displayed at a height that's lower than it should be by the amount of "mYLabelSize"
canvas.drawText(yLabels[i], 0, yStartPoint - (i * height) + mYLabelSize, mTextPaint);
currentValue *= mBase;
}
// draw x axis
canvas.drawLine(0, bottom - mXLabelSize, right, bottom - mXLabelSize, mLinePaint);
// draw y axis
int yMargin = getTextWidth(yLabels[order+1], mTextPaint);
canvas.drawLine(yMargin + mExtraYMargin, bottom, yMargin + mExtraYMargin, 0, mLinePaint);
// width of each beam in the histogram
float width = ((float) (right - yMargin - mExtraYMargin - mLineWidth - range * mHistogramInterval) / range);
// draw x labels
String[] xLabels = new String[mNumberOfXLabel];
int xLabelInterval = (range - 2) / mNumberOfXLabel;
xLabels[0] = "0"; // first label is for 0
canvas.drawText(xLabels[0], yMargin - getTextWidth(xLabels[0], mXLabelPaint), bottom, mXLabelPaint);
int xStartPoint = yMargin + mExtraYMargin + mLineWidth; // position where first beam is placed on x-axis
for (int i = 1; i < mNumberOfXLabel; i++) {
xLabels[i] = Integer.toString(i * xLabelInterval);
canvas.drawText(xLabels[i], xStartPoint + (xLabelInterval * i * (width + mHistogramInterval)), bottom, mXLabelPaint);
}
String lastXLabel; // last label is for the last beam
if (mExceedRange) {
lastXLabel = Integer.toString(range - 1) + "+";
} else {
lastXLabel = Integer.toString(range - 1);
}
canvas.drawText(lastXLabel, right - getTextWidth(lastXLabel, mXLabelPaint) - 1, bottom, mXLabelPaint);
// draw the histogram
float currentLeft = yMargin + mExtraYMargin + mLineWidth; // FIXME there's an extra 1 pixel split, not sure why
float currentTop;
float currentRight;
int currentBottom = bottom - mXLabelSize - mLineWidth;
for (int i = 0; i < range; i++) {
currentRight = currentLeft + width;
// calculate the height of the beam
if (mData[i] == 0) {
currentTop = currentBottom;
} else {
float units = (float) ((Math.log10((double) mData[i])) + 1.0); // FIXME change it to have "mBase" as the baset
currentTop = currentBottom - (height * units);
}
canvas.drawRect(currentLeft, currentTop, currentRight, currentBottom, mHistPaint);
currentLeft = currentRight + mHistogramInterval;
}
}
}
// get the width of a certain string, using a certain paint
public int getTextWidth(String text, Paint paint) {
Rect bounds = new Rect();
paint.getTextBounds(text, 0, text.length(), bounds);
int width = bounds.left + bounds.width();
return width;
}
void redraw() {
invalidate();
}
// Copy data into internal buffer
public static void setBufferPeriodArray(int[] pData) {
if (mData == null || pData.length != mData.length) {
mData = new int[pData.length];
}
System.arraycopy(pData, 0, mData, 0, pData.length);
// postInvalidate();
}
public static void setMaxBufferPeriod(int BufferPeriod) {
mMaxBufferPeriod = BufferPeriod;
}
}
|
