一个很实用的操作上传图片的函数（C#)

 

一个可以使得上传的图片大小按照指定的宽度，高度自动按比例进行缩放

，生成的JPG还可以指定其图片的压缩比。很实用。

  public string upimgscalesave(HttpPostedFile UpFile,string id,int imgw,string bcwz)

//UpFile HtmlInputFile控件类

//id 上传后保存的文件名

//改变的图片宽度，高度吗，当然是自动计算拉！

//bcwz上传后要存服务器那里啊！

  {
   int FileLength;
   int imgh=0;
   FileLength = UpFile.ContentLength; //记录文件长度
 
   if (FileLength == 0)
   { //文件长度为零时
    return "null";
   }
   else
   {
    Byte[] FileByteArray = new Byte[FileLength]; //图象文件临时储存Byte数组
    Stream StreamObject = UpFile.InputStream; //建立数据流对像
    StreamObject.Read(FileByteArray,0,FileLength);
    System.Drawing.Image orimg=System.Drawing.Image.FromStream(StreamObject);
    
    
    string mimeType ="image/jpeg";
    ImageCodecInfo[] encoders;
    encoders = ImageCodecInfo.GetImageEncoders();
    for(int j = 0; j < encoders.Length; ++j)
    {
      if(encoders[j].MimeType == mimeType)
      myImageCodecInfo=encoders[j];
    }

    System.Drawing.Imaging.Encoder myEncoder = System.Drawing.Imaging.Encoder.Quality;
    myEncoderParameters = new EncoderParameters(1);
    myEncoderParameter = new EncoderParameter(myEncoder, 80L);

 

 

//80L压缩比拉

 

    myEncoderParameters.Param[0] = myEncoderParameter;
    
    
    if(imgw==0&&imgh==0)
    { 
     
     
     
     orimg.Save(bcwz+"\\"+id+".jpg",myImageCodecInfo,myEncoderParameters);
    
     
     
     //orimg.Save(bcwz+"\\"+id+".jpg",ImageFormat.Jpeg);
     orimg.Dispose();
     
    }
    else
    {
     double bl=0.0F;
     bl=imgw/Convert.ToDouble(orimg.Width);
     imgh=Convert.ToInt32(orimg.Height*bl);
     b = new Bitmap(imgw,imgh);
     g = Graphics.FromImage(b);  
     Rectangle destRect1 = new Rectangle( 0, 0, imgw, imgh);
     //GraphicsUnit units = GraphicsUnit.Pixel;
     g.DrawImage(orimg,destRect1);
     b.Save(bcwz+"\\"+id+".jpg",myImageCodecInfo,myEncoderParameters);
     b.Dispose();
     g.Dispose();
     orimg.Dispose();

    }
    return bcwz;
   }
  }