ASP.NET 上畫Pie chart和寫字

以下範例將教你怎麼在asp.net裡畫一個圓餅圖(Pie chart)並標上文字

步驟如下：

1. 新增default.aspx，加入一個按鈕和image
   

       <form id="form1" runat="server">
       <div>
       
           <asp:ScriptManager ID="ScriptManager1" runat="server">
           </asp:ScriptManager>
           <asp:UpdatePanel ID="UpdatePanel1" runat="server">
               <ContentTemplate>
                   <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />
                   <br />
                   <asp:Image ID="Image1" runat="server" />
               </ContentTemplate>
           </asp:UpdatePanel>
       
       </div>
       </form>

   
   



2. 並加入按鈕事件, 將pie chart產生
   
   
   
   

           protected void Button1_Click(object sender, EventArgs e)
           {
               Image1.ImageUrl = "Image.aspx";
           }
       

   
   



3. 另外再新增Image.aspx,並在Image.aspx.cs加入繪圖程式
   
   
   
   

          protected void Page_Load(object sender, EventArgs e)
           {
          // 設定回傳的 Type為Jpeg
   
           Response.ContentType = "image/jpeg";
   
           const int width = 200, height = 100;
           Bitmap objBitmap = new Bitmap(width, height);
   
           Graphics objGraphics = Graphics.FromImage(objBitmap);
   
           // 設定白色背景
           objGraphics.Clear(Color.White);
           // Create solid brush.建立固定刷子, 顏色:紅色
           SolidBrush redBrush = new SolidBrush(Color.Red);
   
   
           // Create rectangle for ellipse.建立圓的方形範圍, 
           //1,2位數字表左上角的座標(x,y) :(0,0)
           //3,4位數字表右上角的座標(x,y) :(200,100)
           Rectangle rect = new Rectangle(0, 0, width, height);
   
           //建立開始角度(以度為單位，依順時針方向測量之從 X 軸到派形區段的第一個邊的角度)
           float startAngle = 0.0F;
           //建立開扇角度(以度為單位，依順時針方向從 startAngle 參數到派形區段的第二個邊的角度)
           float sweepAngle = 360.0F;
   
           objGraphics.FillPie(redBrush, rect, startAngle, sweepAngle);
   
           //寫字
           Font myFont = new System.Drawing.Font("Helvetica", 10, FontStyle.Italic);
   
           Brush myBrush = new SolidBrush(System.Drawing.Color.Red);
           SolidBrush textBrush = new SolidBrush(Color.Black);
   
           objGraphics.DrawString("50%", myFont, textBrush, 10, 10);
   
   
           objBitmap.Save(Response.OutputStream, ImageFormat.Jpeg);
           
           // clean up...
   
           objGraphics.Dispose();
           objBitmap.Dispose();
   
           }

   
   

 

適用:

ASP.net 2.0以上

參考：

1. 3D Pie Chart in ASP.NET

2. Graphics.FillPie

3. Charts for Windows Application using C#

4. Drawing in ASP.NET 2.0 and C#

5. Drawing Graphics in C#