上传图片并生成缩略图

                int maxwidth=120;
                int maxheight=120;
                string fcolor=colors.SelectedItem.Value;

                if(myfile.PostedFile!=null)
                {
                    if(typeid!=null &&  typeid.ToString()!="")
                    {
                        HttpPostedFile mfile=myfile.PostedFile;
                        if(mfile.ContentLength<0)
                        {
                            error.InnerHtml="<img src=img/error.gif>　请输入正确的路径！";
                            return;
                        }
                        if(mfile.ContentLength>size)
                        {
                            error.InnerHtml="<img src=img/error.gif>　文件太大！请不要超过"+(size/1024).ToString()+"K";
                            return;
                        }
                        int myfilesize=mfile.ContentLength;
                        int filesizes=mfile.ContentLength;
                        string[] typef=ftype.Split(new char[]{','});
                        string dot=mfile.FileName.Substring(mfile.FileName.Length-3).ToLower().Replace(",",",");

                        bool iffile=false;
                        for(int i=0;i<typef.Length;i++)
                        {
                            if(typef.GetValue(i).ToString().ToLower()==dot)
                            {
                                iffile=true;
                            }
                        }
                        if(iffile==false)
                        {
                            error.InnerHtml="<img src=img/error.gif>　文件类型不正确！";
                            return;
                        }
                        if(dot=="peg")
                        {
                            dot="jpeg";
                        }
    
                        string titles=Server.HtmlEncode(title.Text);
         
                
                        string now=DateTime.Now.ToString().Replace(":","-").Replace(" ","-");
                        Random dom=new Random();
                        string mydon=dom.Next(1000).ToString();
                        string bigpath="File/"+uid.ToString()+"/bigimg/"+typeid+"-"+now+mydon+"."+dot;
                    
                        byte[] mFileByte = new Byte[filesizes];
                        mfile.InputStream.Read(mFileByte,0,filesizes);
                        System.IO.FileStream saveFile = new System.IO.FileStream(Server.MapPath(bigpath),System.IO.FileMode.Create);
                        saveFile.Write(mFileByte,0,mFileByte.Length);
                        saveFile.Close();

                        string   strFilename;
                        strFilename = Server.MapPath(bigpath)  ; 
                        string smallpath="File/"+uid.ToString()+"/smallimg/"+typeid+"-"+now+mydon+".jpg";
                        System.Drawing.Image img = System.Drawing.Image.FromFile(Server.MapPath(bigpath));

                        int w=img.Width;
                        int h=img.Height;
                        Double sw=img.Width;
                        Double sh=img.Height;
                        if(w>h)
                        {
                            if(w>maxwidth)
                            {
                                sw=maxwidth;
                                sh=Convert.ToDouble(h*maxwidth/w);

                            }
                        }
                        else   
                        {
                            if(h>maxheight)
                            {
                                sh=maxheight;
                                sw=Convert.ToDouble(w*maxheight/h);

                            }
                        }
                     
             
                    
                     
                 


                        //生成缩略图
                        string file=bigpath; 
                        string newfile=smallpath; 
                        string strAdd=fonts.Text; 
                        int left=Convert.ToInt32(lefts.Text);
                        int right=Convert.ToInt32(rights.Text);
                        System.Drawing.Image oldimage = System.Drawing.Image.FromFile(Server.MapPath(file)); 
                        System.Drawing.Image thumbnailImage = 
                            oldimage.GetThumbnailImage(Convert.ToInt32(sw),Convert.ToInt32(sh),new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback), IntPtr.Zero); 
                        Response.Clear(); 
                        Bitmap output=new Bitmap(thumbnailImage); 
                        Graphics g=Graphics.FromImage(output); 
                        if(fcolor=="Green")
                        {
                            g.DrawString(strAdd,new Font("Arial", 10),new SolidBrush(Color.Green),left,right); 
                        }
                        else if(fcolor=="Blue")
                        {
                            g.DrawString(strAdd,new Font("Arial", 10),new SolidBrush(Color.Blue),left,right); 
                        }
                        else if(fcolor=="Red")
                        {
                            g.DrawString(strAdd,new Font("Arial", 10),new SolidBrush(Color.Red),left,right); 
                        }
                        else if(fcolor=="Yellow")
                        {
                            g.DrawString(strAdd,new Font("Arial", 10),new SolidBrush(Color.Yellow),left,right); 
                        }
                        output.Save(Server.MapPath(newfile),System.Drawing.Imaging.ImageFormat.Jpeg); 

                        //