用asp.net畫餅圖(可用於各種投票程式)

//用asp.net畫餅圖(可用於各種投票程式)
//和asp相比asp.net擁有更強大的功能，使用gdi+可以輕易實現以前很多不能辦到的圖形功能。
//首先在c:\中建庫mess.mdb,並建表title.
//建二個欄位,title(char型),point(int型)
//非常滿意 281
//比較滿意 297
//還湊合 166
//不滿意 416
//我還寫了畫折線圖和橫條圖的部分,目前正在把它們全部寫進一個類中。需要的可以和我聯絡:mailto:ouyang76@263.net
<%@ Page Language="C#" %>
<%@import namespace="System.Data"%>
<%@import namespace="System.Data.OleDb"%>
<%@import namespace="System.Drawing"%>
<%@import namespace="System.Drawing.Imaging"%>
<script language="c#" runat="server">
public void page_load(Object obj,EventArgs e)
{
//把串連字串指定為一個常量
const String strconn = "Provider=Microsoft.Jet.OLEDB.4.0;" +
"Data Source=c:\\mess.mdb";
OleDbConnection conn=new OleDbConnection(strconn);
conn.Open();
string sql="select * from title";
OleDbCommand cmd=new OleDbCommand(sql,conn);
DataSet ds=new DataSet();
OleDbDataAdapter adapter1=new OleDbDataAdapter(cmd);
adapter1.Fill(ds);
conn.Close();
float total=0.0f,tmp;
int iloop;
for(iloop=0;iloop<ds.Tables[0].Rows.Count;iloop++)
{
tmp=Convert.ToSingle(ds.Tables[0].Rows[iloop]["point"]);//轉換成單精確度,投票不可能投半票。也可寫成Convert.ToInt32
total+=tmp;
}
//Response.Write(Convert.ToString(total));

Font fontlegend=new Font("verdana",9),fonttitle=new Font("verdana",10,FontStyle.Bold);//設定字型
//fonttitle為主標題的字型

int width=230;//白色背景寬
const int bufferspace=15;
int legendheight=fontlegend.Height*(ds.Tables[0].Rows.Count+1)+bufferspace;
int titleheight = fonttitle.Height + bufferspace;
int height = width + legendheight + titleheight + bufferspace;//白色背景高
int pieheight = width;
Rectangle pierect=new Rectangle(0,titleheight,width,pieheight);

//加上各種隨機色
ArrayList colors = new ArrayList();
Random rnd = new Random();
for (iloop = 0; iloop < ds.Tables[0].Rows.Count; iloop++)
colors.Add(new SolidBrush(Color.FromArgb(rnd.Next(255), rnd.Next(255), rnd.Next(255))));

Bitmap objbitmap=new Bitmap(width,height);//建立一個bitmap執行個體
//Bitmap objbitmap=new Bitmap(230,500);//建立一個bitmap執行個體
Graphics objgraphics=Graphics.FromImage(objbitmap);

objgraphics.FillRectangle(new SolidBrush(Color.White), 0, 0, width, height);//畫一個白色背景
objgraphics.FillRectangle(new SolidBrush(Color.LightYellow), pierect);//畫一個亮黃色背景
//以下為畫餅圖(有幾行row畫幾個)
float currentdegree=0.0f;
for (iloop = 0; iloop < ds.Tables[0].Rows.Count; iloop++)
{
objgraphics.FillPie((SolidBrush) colors[iloop], pierect, currentdegree,
Convert.ToSingle(ds.Tables[0].Rows[iloop]["point"]) / total * 360);
currentdegree += Convert.ToSingle(ds.Tables[0].Rows[iloop]["point"]) / total * 360;
}
//---以下為產生主標題
SolidBrush blackbrush=new SolidBrush(Color.Black);
string title="本次《程式員大本營》推出了配套的專刊，您對專刊滿意嗎？";
StringFormat stringFormat = new StringFormat();
stringFormat.Alignment = StringAlignment.Center;
stringFormat.LineAlignment = StringAlignment.Center;

objgraphics.DrawString(title, fonttitle, blackbrush,
new Rectangle(0, 0, width, titleheight), stringFormat);
//列出各欄位與得票數
objgraphics.DrawRectangle(new Pen(Color.Black, 2), 0, height - legendheight, width, legendheight);
for (iloop = 0; iloop < ds.Tables[0].Rows.Count; iloop++)
{
objgraphics.FillRectangle((SolidBrush) colors[iloop], 5, height - legendheight + fontlegend.Height * iloop + 5, 10, 10);
objgraphics.DrawString(((String) ds.Tables[0].Rows[iloop]["title"]) + " - " + Convert.ToString(ds.Tables[0].Rows[iloop]["point"]), fontlegend, blackbrush,
20, height - legendheight + fontlegend.Height * iloop + 1);
}
//
objgraphics.DrawString("總票數是:"+Convert.ToString(total),fontlegend,blackbrush, 5, height - fontlegend.Height );
//映像總的高度-一行字型的高度，即是最底行的一行字型高度(height - fontlegend.Height )
Response.ContentType="image/jpeg";
objbitmap.Save(Response.OutputStream,ImageFormat.Jpeg);
//objbitmap.Save("myyyyyyyyyyy.jpg", ImageFormat.Jpeg);//輸出到檔案

objgraphics.Dispose();
objbitmap.Dispose();
}
</script>