//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'%>
<script language='c#' runat='server'>
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<ds.Tables[0].Rows.Count;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;
objgraphics.DrawString(title, fonttitle, blackbrush,
new Rectangle(0, 0, width, titleheight), stringFormat);
//列出各字段与得票数
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('总票数是:'+Convert.ToString(total),fontlegend,blackbrush, 5, height - fontlegend.Height );
//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 )
Response.ContentType='image/jpeg';
objbitmap.Save(Response.OutputStream,ImageFormat.Jpeg);
//objbitmap.Save('myyyyyyyyyyy.jpg', ImageFormat.Jpeg);//输出到文件
objgraphics.Dispose();
objbitmap.Dispose();
}
</script>
