ASP.NET上传图片并生成水印--缩略图

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Drawing.Imaging;

namespace WebApplication2
{
 /// <summary>
 /// WebForm14 的摘要说明。
 /// </summary>
 public class WebForm14 : System.Web.UI.Page
 {
  protected System.Web.UI.HtmlControls.HtmlInputFile File1;
  protected System.Web.UI.WebControls.Button Button1;
 
  private void Page_Load(object sender, System.EventArgs e)
  {
   // 在此处放置用户代码以初始化页面
  }

  #region Web 窗体设计器生成的代码
  override protected void OnInit(EventArgs e)
  {
   //
   // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
   //
   InitializeComponent();
   base.OnInit(e);
  }
  
  /// <summary>
  /// 设计器支持所需的方法 - 不要使用代码编辑器修改
  /// 此方法的内容。
  /// </summary>
  private void InitializeComponent()
  {   
   this.Button1.Click += new System.EventHandler(this.Button1_Click);
   this.Load += new System.EventHandler(this.Page_Load);

  }
  #endregion

  private void Button1_Click(object sender, System.EventArgs e)
  {
   string filePath = System.Web.HttpContext.Current.Server.MapPath("2.jpg");
   Response.Write(filePath);
   //数据库路径，GDI处理的图片， 不属于Asp.net的东西一般都要应用物理路径
   //WinForm中Application.startPath, 在asp.net中System.Web.HttpContext.Current.Request.ApplicationPath
   //它们都可以应用webConfig的方式 System.Configuration.ConfigurationSettings.AppSettings["BbsUrl"];
   //相对路径在web中应得很多，对于不属于内部对像中一般都要应用物理路径
   MakeSLT(ApplicationPath +@"/2.jpg",ApplicationPath + @"/s2.jpg");
  }

  public string UploadImage(System.Web.HttpPostedFile postFile)
  {
   try
   {
    if(postFile.ContentLength==0)
    {
     throw(new Exception("NotExistedPostFile"));
    }
    else
     if(postFile.ContentLength>Convert.ToInt32(System.Configuration.ConfigurationSettings.AppSettings["MaxImageSize"]))
    {
     throw(new Exception("TooLargePostFile"));
    }
    String strExt=System.IO.Path.GetExtension(postFile.FileName);
    if(System.Configuration.ConfigurationSettings.AppSettings["ImageExtension"].IndexOf(";"+strExt+";")>-1)
    {
     throw(new Exception("ErrorImageExtension"));
    }

    String strFileName=@"/uploads/images/"+DateTime.Now.ToString("yyyyMMddHHmmssffff")+".jpg";
    String strAbsoluteFileName=System.Web.HttpContext.Current.Server.MapPath(strFileName);
    String Copyright=System.Configuration.ConfigurationSettings.AppSettings["CopyRight"];

    System.Drawing.Image imgPhoto=System.Drawing.Image.FromStream(postFile.InputStream,true);
    //取高和宽
    int phWidth = imgPhoto.Width;
    int phHeight =imgPhoto.Height;
    //建新图,指定格式为每像素 24 位；红色、绿色和蓝色分量各使用 8 位。
    Bitmap bmPhoto = new Bitmap(phWidth, phHeight,PixelFormat.Format24bppRgb);
    //设置分辨率
    bmPhoto.SetResolution(imgPhoto.HorizontalResolution,imgPhoto.VerticalResolution);
    //准备Graphics
    Graphics grPhoto = Graphics.FromImage(bmPhoto);
    try
    {
     //指定消除锯齿的呈现。
     grPhoto.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
     //拷贝原图到做图区
     grPhoto.DrawImage(
      imgPhoto,                              
      new Rectangle(0, 0, phWidth, phHeight),
      0,                                     
      0,                                      
      phWidth,                               
      phHeight,                              
      GraphicsUnit.Pixel);
     //用指定Sizes绘制图片时，测量用指定的字串宽度
     //取可能的最大宽度
     int[] sizes = new int[]{64,48,32,16,8,6,4};
     Font crFont = null;
     SizeF crSize = new SizeF();
     for (int i=0 ;i<7; i++)
     {
      crFont = new Font("Verdana", sizes[i],
       FontStyle.Bold);
      crSize = grPhoto.MeasureString(Copyright,
       crFont);
      if((ushort)crSize.Width < (ushort)phWidth)
       break;
     }
     //指定做图点
     int yPixlesFromBottom = (int)(phHeight *.05);
     float yPosFromBottom = ((phHeight -
      yPixlesFromBottom)-(crSize.Height/2));
     float xCenterOfImg = (phWidth/2);
     StringFormat StrFormat = new StringFormat();
     StrFormat.Alignment = StringAlignment.Center;
     //绘制copyright
     SolidBrush semiTransBrush2 =
      new SolidBrush(Color.FromArgb(100, 0, 0,0));
     grPhoto.DrawString(Copyright,                   
      crFont,                                     
      semiTransBrush2,                            
      new PointF(xCenterOfImg+1,yPosFromBottom+1),
      StrFormat);
     SolidBrush semiTransBrush = new SolidBrush(
      Color.FromArgb(100, 255, 255, 255));
     grPhoto.DrawString(Copyright,                
      crFont,                                  
      semiTransBrush,                          
      new PointF(xCenterOfImg,yPosFromBottom), 
      StrFormat);
     bmPhoto.Save(strAbsoluteFileName,ImageFormat.Jpeg);
    }
    finally
    {
     grPhoto.Dispose();
     bmPhoto.Dispose();
     imgPhoto.Dispose();
    }
    return strFileName;
   }
   catch(Exception excep)
   {
    throw(excep);
   }
  }

  private void MakeSLT(string oldImagePath,string newImagePath)
  {
   //oldImagePath -原图地址 newImagePath 生成缩略图地址
   int width = 150;//缩略图的宽度
   int height = 112;// 缩略图的高度
   int level = 80; //缩略图的质量 1-100的范围

   System.Drawing.Image oldimage = System.Drawing.Image.FromFile(oldImagePath);
   //System.Drawing.Image thumbnailImage = oldimage.GetThumbnailImage(width, height,new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback), IntPtr.Zero);
   System.Drawing.Image thumbnailImage = oldimage.GetThumbnailImage(width, height,null, IntPtr.Zero);

   Bitmap bm=new Bitmap(thumbnailImage);

   //处理JPG质量的函数
   ImageCodecInfo[] codecs=ImageCodecInfo.GetImageEncoders();
   ImageCodecInfo ici=null;
   foreach(ImageCodecInfo codec in codecs)
   {
    if(codec.MimeType=="image/jpeg")
     ici=codec;
   }
   EncoderParameters ep=new EncoderParameters();
   ep.Param[0]=new EncoderParameter(Encoder.Quality,(long)level);

   bm.Save(newImagePath,ici,ep);
  }
 }
}