>
//用asp.net画饼图(可用于各种投票程序)
//和asp相比asp.net拥有更强大的功能,使用gdi+可以轻易实现以前很多不能办到的图形功能。
//首先在c:\中建库mess.mdb,并建表title.
//建二个字段,title(char型),point(int型)
//非常满意 281
//比较满意 297
//还凑合 166
//不满意 416
//我还写了画折线图和条形图的部分,目前正在把它们全部写进一个类中。需要的可以和我联系: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"%>
public void page_load(Object obj,EventArgs e)
{
//把连接字串指定为一个常量
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 { tmp=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 total+=tmp; } //Response.Write(Convert.ToString(total)); Font fontlegend=new Font("verdana",9),fonttitle=new Font("verdana",10,FontStyle.Bold);//设置字体 //fonttitle为主标题的字体 int width=230;//白色背景宽 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); //加上各种随机色 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);//创建一个bitmap实例 //Bitmap objbitmap=new Bitmap(230,500);//创建一个bitmap实例 Graphics objgraphics=Graphics.FromImage(objbitmap); objgraphics.FillRectangle(new SolidBrush(Color.White), 0, 0, width, height);//画一个白色背景 objgraphics.FillRectangle(new SolidBrush(Color.LightYellow), pierect);//画一个亮黄色背景 //以下为画饼图(有几行row画几个) 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; } //---以下为生成主标题 SolidBrush blackbrush=new SolidBrush(Color.Black); string title="本次《程序员大本营》推出了配套的专刊,您对专刊满意吗?"; StringFormat stringFormat = new StringFormat(); stringFormat.Alignment = StringAlignment.Center; stringFormat.LineAlignment = StringAlignment.Center;
