用asp.net画饼图(可用于各种投票程序)

1@ Page Language="C#" 

 1<script language="c#" runat="server">   
 2public void page_load(Object obj,EventArgs e)   
 3{   
 4//把连接字串指定为一个常量   
 5const String strconn = "Provider=Microsoft.Jet.OLEDB.4.0;" +   
 6"Data Source=c:\\\mess.mdb";   
 7OleDbConnection conn=new OleDbConnection(strconn);   
 8conn.Open();   
 9string sql="select * from title";   
10OleDbCommand cmd=new OleDbCommand(sql,conn);   
11DataSet ds=new DataSet();   
12OleDbDataAdapter adapter1=new OleDbDataAdapter(cmd);   
13adapter1.Fill(ds);   
14conn.Close();   
15float total=0.0f,tmp;   
16int iloop;   
17for(iloop=0;iloop<ds.Tables[0].Rows.Count;iloop++)   
18{   
19tmp=Convert.ToSingle(ds.Tables[0].Rows[iloop]["point"]);//转换成单精度,投票不可能投半票。也可写成Convert.ToInt32   
20total+=tmp;   
21}   
22//Response.Write(Convert.ToString(total)); 
23
24Font fontlegend=new Font("verdana",9),fonttitle=new Font("verdana",10,FontStyle.Bold);//设置字体   
25//fonttitle为主标题的字体 
26
27int width=230;//白色背景宽   
28const int bufferspace=15;   
29int legendheight=fontlegend.Height*(ds.Tables[0].Rows.Count+1)+bufferspace;   
30int titleheight = fonttitle.Height + bufferspace;   
31int height = width + legendheight + titleheight + bufferspace;//白色背景高   
32int pieheight = width;   
33Rectangle pierect=new Rectangle(0,titleheight,width,pieheight); 
34
35//加上各种随机色   
36ArrayList colors = new ArrayList();   
37Random rnd = new Random();   
38for (iloop = 0; iloop < ds.Tables[0].Rows.Count; iloop++)   
39colors.Add(new SolidBrush(Color.FromArgb(rnd.Next(255), rnd.Next(255), rnd.Next(255)))); 
40
41Bitmap objbitmap=new Bitmap(width,height);//创建一个bitmap实例   
42//Bitmap objbitmap=new Bitmap(230,500);//创建一个bitmap实例   
43Graphics objgraphics=Graphics.FromImage(objbitmap); 
44
45objgraphics.FillRectangle(new SolidBrush(Color.White), 0, 0, width, height);//画一个白色背景   
46objgraphics.FillRectangle(new SolidBrush(Color.LightYellow), pierect);//画一个亮黄色背景   
47//以下为画饼图(有几行row画几个)   
48float currentdegree=0.0f;   
49for (iloop = 0; iloop < ds.Tables[0].Rows.Count; iloop++)   
50{   
51objgraphics.FillPie((SolidBrush) colors[iloop], pierect, currentdegree,   
52Convert.ToSingle(ds.Tables[0].Rows[iloop]["point"]) / total * 360);   
53currentdegree += Convert.ToSingle(ds.Tables[0].Rows[iloop]["point"]) / total * 360;   
54}   
55//---以下为生成主标题   
56SolidBrush blackbrush=new SolidBrush(Color.Black);   
57string title="本次《程序员大本营》推出了配套的专刊，您对专刊满意吗？";   
58StringFormat stringFormat = new StringFormat();   
59stringFormat.Alignment = StringAlignment.Center;   
60stringFormat.LineAlignment = StringAlignment.Center; 
61
62objgraphics.DrawString(title, fonttitle, blackbrush,   
63new Rectangle(0, 0, width, titleheight), stringFormat);   
64//列出各字段与得票数   
65objgraphics.DrawRectangle(new Pen(Color.Black, 2), 0, height - legendheight, width, legendheight);   
66for (iloop = 0; iloop < ds.Tables[0].Rows.Count; iloop++)   
67{   
68objgraphics.FillRectangle((SolidBrush) colors[iloop], 5, height - legendheight + fontlegend.Height * iloop + 5, 10, 10);   
69objgraphics.DrawString(((String) ds.Tables[0].Rows[iloop]["title"]) + " - " + Convert.ToString(ds.Tables[0].Rows[iloop]["point"]), fontlegend, blackbrush,   
7020, height - legendheight + fontlegend.Height * iloop + 1);   
71}   
72//   
73objgraphics.DrawString("总票数是:"+Convert.ToString(total),fontlegend,blackbrush, 5, height - fontlegend.Height );   
74//图像总的高度-一行字体的高度，即是最底行的一行字体高度(height - fontlegend.Height )   
75Response.ContentType="image/jpeg";   
76objbitmap.Save(Response.OutputStream,ImageFormat.Jpeg);   
77//objbitmap.Save("myyyyyyyyyyy.jpg", ImageFormat.Jpeg);//输出到文件 
78
79objgraphics.Dispose();   
80objbitmap.Dispose();   
81}   
82</script>