ImageServices2

出自ProgWiki

目錄 1 用途 2 程式碼 3 使用範例 3.1 Default.aspx 3.2 Default.aspx.cs

用途

• Web-Server端，動態圖檔顯示。（透過GDI+做Jpeg轉檔）

• 模式 "Paste" 與 "Temp"

• 自硬碟裡動態取出 QueryString["Filename"] 所指定的圖檔。

• 模式 "Register"

• 顯示出 Session["RegisterCode"] 的內容。

程式碼

<%@ WebHandler Language="C#" Class="ImageServices2" %>
 
using System;
using System.Web;
using System.Web.SessionState;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
 
 
public class ImageServices2 : IHttpHandler, IRequiresSessionState
{
 
    public void ProcessRequest (HttpContext context)
    {
        Bitmap Bmp = null; 
        string strMode = context.Request.QueryString["Mode"];
        switch( strMode )
        {
            case "Paste":
            case "Temp":
                {
                    System.Text.StringBuilder sbFile = new System.Text.StringBuilder(100);
                    sbFile.Append("C:\\").Append(context.Request.QueryString["Mode"]).Append("\\");
                    sbFile.Append(context.Request.QueryString["Filename"].Replace("-", "\\"));
 
                    //判斷檔案是否存在
                    if (File.Exists(sbFile.ToString()))
                    {
                        Bmp = new Bitmap(sbFile.ToString());
                    }
                    else
                    {
                        context.Response.Write("Not Exists");
                        context.Response.End();
                    }
                }
                break;
            case "Register":
                {
                    if (context.Session["RegisterCode"] != "") 
                    {
                        //宣告 Bmp 圖形物件，建立動態字串圖示
                        Bmp = new Bitmap(240, 60, PixelFormat.Format16bppRgb565);
 
                        //定義繪圖元件、字形、筆刷
                        using (Graphics formGraphics = Graphics.FromImage(Bmp))
                        {
                            using (Font drawFont = new Font("Lucida Console", 32, FontStyle.Strikeout))
                            {
                                using (SolidBrush drawBrush = new SolidBrush(Color.Yellow))
                                {
                                    StringFormat drawFormat = new StringFormat();
 
                                    //繪製文字
                                    string strDraw = context.Session["RegisterCode"] as string;
                                    formGraphics.DrawString(    strDraw,
                                                                drawFont,
                                                                drawBrush,
                                                                20.0f, 6.0f, drawFormat);
 
                                }
                            }
                        }
                    }
                    else
                    {
                        context.Response.Write("RegisterCode Is Nothing");
                        context.Response.End();
                    }
                }
                break;
           default:
                {
                    context.Response.Write("Else");
                    context.Response.End();
                }
                break;
        }
 
        //設定輸出類型
        context.Response.ContentType = "image/Jpeg";
 
        //處理圖形品質
        ImageCodecInfo[] codecs  = ImageCodecInfo.GetImageEncoders();
        ImageCodecInfo ici = null;
 
        //'找出 Encoder
        foreach(ImageCodecInfo codec in codecs)
        {
            if (codec.MimeType == "image/jpeg")
                ici = codec;
        }
 
 
        //參數 - 高品質圖檔
        EncoderParameters ep = new EncoderParameters();
        int nQuality = 100;
        ep.Param[0] = new EncoderParameter(Encoder.Quality, nQuality);
 
        if ((ici == null) || (ep == null))
        {
            //儲存 - 低品質
            Bmp.Save(context.Response.OutputStream, ImageFormat.Jpeg);
        }
        else
        {
            //儲存 - 高品質
            Bmp.Save(context.Response.OutputStream, ici, ep);
        }
 
 
        //釋放
        Bmp.Dispose();
        context.Response.End();
    }
 
    public bool IsReusable {
        get {
            return false;
        }
    }
}

使用範例

Default.aspx

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>
 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>未命名頁面</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <img src="ImageServices.ashx?Mode=Register" alt=""/><br/>
    </div>
    </form>
</body>
</html>

Default.aspx.cs

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
 
public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
		Session["RegisterCode"] = "xyz";
    }
}