android 波形图

From:http://blog.youkuaiyun.com/jjdujiang/article/details/51811583

本周开发了Android画波形图，单击按钮，进入到新的activity，在新的activity中设置视图类setContentView(lineView)，lineView是继承View，重载函数onDraw就可以在画布上画波形图了。

附上主要代码

[java]  view plain  copy

1. // 背景  
2.         p.setStyle(Style.FILL);  
3.         p.setColor(Color.WHITE);  
4.         p.setStrokeWidth(1);  
5.         canvas.drawRect(0, 0, width, height, p);  
6.           
7.         // 图形区  
8.         p.setStyle(Style.STROKE);  
9.         p.setColor(Color.BLACK);  
10.         canvas.drawRect(rectRect, p);  
11.           
12.         // Y轴刻度  
13.         p.setStyle(Style.FILL);  
14.         for (int i = 0; i < strYScaleStrings.length; i++) {  
15.             Integer yInteger = rectRect.top + i * rectRect.height() / (strYScaleStrings.length - 1);  
16.             canvas.drawLine(rectRect.left, yInteger, rectRect.left - nInterInteger, yInteger, p);  
17.             canvas.drawText(strYScaleStrings[i], nInterInteger, yInteger, p);   
18.         }  
19.           
20.         // X轴刻度  
21.         for (int i = 0; i < strXScaleStrings.length; i++) {  
22.             Integer xInteger = rectRect.left + i * rectRect.width() / (strYScaleStrings.length - 1);  
23.             Integer xTextStartInteger = xInteger - rectXScaleWidthIntegers[i].width() / 2;  
24.             canvas.drawLine(xInteger, rectRect.bottom, xInteger, rectRect.bottom + nInterInteger, p);  
25.             canvas.drawText(strXScaleStrings[i], xTextStartInteger, height - rectXScaleWidthIntegers[i].height() / 2, p);   
26.         }  
27.           
28.         // X轴网格线  
29.         p.setColor(Color.LTGRAY);  
30.         p.setStrokeWidth(1);         
31.         p.setPathEffect(effects);  
32.         for (int i = 0; i < strXScaleStrings.length - 2; i++) {  
33.             Integer xInteger = rectRect.left + (i + 1) * rectRect.width() / (strYScaleStrings.length - 1);  
34.             canvas.drawLine(xInteger, rectRect.bottom, xInteger, rectRect.top, p);  
35.         }    
36.         // Y轴网格线  
37.         for (int i = 0; i < strYScaleStrings.length - 2; i++) {  
38.             Integer yInteger = rectRect.top + (i + 1) * rectRect.height() / (strYScaleStrings.length - 1);  
39.             canvas.drawLine(rectRect.left, yInteger, rectRect.right, yInteger, p);  
40.         }  
41.           
42.         // 画曲线  
43.         p.setStyle(Style.STROKE);  
44.         p.setPathEffect(null);  
45.         linePath.reset();  
46.         for (int i = 0; i < nPointDrawCountInteger; i++) {  
47.             double xValueDouble = (nPointStartInteger + i) / dbSampleFrequencyDouble;  
48.             double yValueDouble = app.ch1ValueArrayDoubles[i];  
49.               
50.             double dXInteger = rectRect.left +   
51.                     (xValueDouble - dbXMinDouble) * rectRect.width() / (dbXMaxDouble - dbXMinDouble);  
52.             int nXInteger = (int)(dXInteger + 0.5);  
53.             double dYIntegerDouble = rectRect.top +   
54.                     (yValueDouble - dbYMinDouble) * rectRect.height() / (dbYMaxDouble - dbYMinDouble);  
55.             int nYInteger = (int)(dYIntegerDouble + 0.5);  
56.             if (0 == i) {  
57.                 linePath.moveTo(nXInteger, nYInteger);  
58.             } else {  
59.                 linePath.lineTo(nXInteger, nYInteger);  
60.             }  
61.         }  
62.         p.setColor(Color.BLUE);  
63.         p.setStrokeWidth(3);    // 线条粗细  
64.         canvas.drawPath(linePath, p);