上传控件的问题，如何限定图片大小？

Question

   一个html上传控件   <input type="file" runat="server" id="fileuploadid" style="width: 439px" />
   
后台： if (fileuploadid.PostedFile.FileName != "")
        {
            savePath = "";  // DateTime.Now.ToString("yyyyMM")+"/";   //指定上传附件保存的目录,根据年月生成 如200804/
            Exception excp = InitUploadSaveDirectory(savePath);
            //如果返回异常则退出程序
            if (excp != null)                               
            {
                Response.Write(excp.ToString());
                return;
            }
            filePath = fileuploadid.PostedFile.FileName;
            fileName = Path.GetFileName(filePath);                           //原始附件名称
            fileSize = fileuploadid.PostedFile.ContentLength;               //附件大小
            tt = fileName.LastIndexOf(".");
            fileType = fileName.Substring(tt).ToLower();                   //附件格式,小写
            //获取服务端附件保存根目录,如D:\上传\upfiles\200804/
            sAbsoluteSavePath = Path.Combine(Request.MapPath(UploadSavePath), savePath);
            //指定附件保存在服务器上的名称(根本上传时间生成,重名处理)
            sFileSaveName = DateTime.Now.ToString("MMdd") + DateTime.Now.ToString("hhmmss") + fileType;            if (fileSize > 0 && fileType.Length > 0 && ("|" + UploadFileTypes + "|").IndexOf("|" + fileType + "|") > -1)
            {
              try
              {
                  string sqlInsert;
                  fileuploadid.PostedFile.SaveAs(Path.Combine(sAbsoluteSavePath, sFileSaveName));
                  SqlConnection sqlcon = new SqlConnection(strConn);
                  sqlInsert = "insert into UploadFiles(FileName,OrigialName,SavePath,FileSize,Uptime) values('" + sFileSaveName + "','" + fileName + "','" + sAbsoluteSavePath + "','" + fileSize + "','" + DateTime.Now.ToString("yyyy - MM - dd") + "')";
                  SqlCommand sqlcom = new SqlCommand(sqlInsert,sqlcon);
                  sqlcon.Open();
                  sqlcom.ExecuteNonQuery();                  
                  Response.Write("<script>alert('上传成功!');</script>");              }
              catch (Exception ex)
              {
                  Response.Write("错误：" +ex.Message);
              }
            }
        }
        else
        {           
            Response.Write("<script>alert('空的不能传的!');</script>");
        }
我现在的要求是：将所有上传的图片都搞成一样的大小，有就是长啊，宽都限定！怎么来处理这个： fileSize = fileuploadid.PostedFile.ContentLength;               //附件大小    呵呵 小弟在线等

Answer 1

img = Image.FromFile(上传文件);
bmp = new Bitmap(width, height);
g = Graphics.FromImage(bmp);
g.DrawImage(img, new Rectangle(0, 0, width, height), new Rectangle(0, 0, img.Width, img.Height), GraphicsUnit.Pixel);
bmp.Save(...);
大概就这样吧，应该能满足你的要求

Answer 2

    #region 上传图片时尺寸过大就提示
    private bool GetPicWidth(HtmlInputFile Pic)
    {
        Helper helper = new Helper();
        HttpPostedFile UpFile = Pic.PostedFile;
        Byte[] FileByteArray = new byte[UpFile.ContentLength];
        Stream StreamObject = UpFile.InputStream;
        StreamObject.Read(FileByteArray, 0, UpFile.ContentLength);
        string Base64String = ByteToBase64(FileByteArray, 0, FileByteArray.Length);        System.Drawing.Image myImage = System.Drawing.Image.FromStream(StreamObject);        bool CheckImageResult = CheckImage(Convert.ToInt32(myImage.Width), Convert.ToInt32(myImage.Height));
        if (CheckImageResult == false)
        {
            helper.Alert("图片尺寸过大!请上传宽小于600的图片", Page);
            return false;
        }
        else
        {
            return true;
        }    }
    private bool CheckImage(int Width, int Height)
    {
        bool Result = true;
        int width = 600, height = 10;
        if (Width > width)
        {
            Result = false;
        }
        return Result;
    }
    //这里是进行二进制到Base64的转换
    private string ByteToBase64(byte[] ByteArry, int Start, int Length)
    {
        string Result;
        Result = System.Convert.ToBase64String(ByteArry, Start, Length);
        return Result;
    }
    #endregion

Answer 3

////使用說明
////直接引用
//文件大於4M將不能上載
function CheckFileSize(obj)
{
if(obj==null)
obj=window.event.srcElement;
var id=obj.id;
    var maxLength=4096000;//4M
    var fso = new ActiveXObject('Scripting.FileSystemObject');
    if(obj.value.trim()=="")
return;
    if(fso.FileExists(obj.value))
    {
        var file = fso.GetFile(obj.value);
        if(file.Size>maxLength)
        {
            alert('The size of attachment exceed 4Mb.');
            obj.outerHTML=obj.outerHTML;
            document.getElementById(id).attachEvent("onkeydown",function() {CheckKeyDown(document.getElementById(id));});
document.getElementById(id).attachEvent("onchange",function() {CheckFileSize(document.getElementById(id));});
        }
    }
    else
    {
alert('File does not exist.');
obj.outerHTML=obj.outerHTML;
document.getElementById(id).attachEvent("onkeydown",function() {CheckKeyDown(document.getElementById(id));});
document.getElementById(id).attachEvent("onchange",function() {CheckFileSize(document.getElementById(id));});
    }
}//Backspace & Delete鍵有效,並且將FileField內容清空
function CheckKeyDown(obj)
{
if(obj==null)
obj=window.event.srcElement;
var id=obj.id;
if(window.event.keyCode!=8&&window.event.keyCode!=46)
{
window.event.returnValue=false;
}
else
{
window.event.returnValue=false;
obj.outerHTML=obj.outerHTML;
        document.getElementById(id).attachEvent("onkeydown",function() {CheckKeyDown(document.getElementById(id));});
document.getElementById(id).attachEvent("onchange",function() {CheckFileSize(document.getElementById(id));});
}
}if (document.all)
{
window.attachEvent("onload",function(){AddEvent();})
}
else
{
window.addEventListener("load",function(){AddEvent();},false);
}function AddEvent()
{ 
var input_file=document.getElementsByTagName("INPUT");
for (var i=0; i<input_file.length; i++)
{ 
if (input_file[i].type=="file") 
{
input_file[i].attachEvent("onkeydown",function() {CheckKeyDown(null);});
input_file[i].attachEvent("onchange",function() {CheckFileSize(null);});
} 
}
}String.prototype.trim= function()  
{  
return this.replace(/(^\s*)|(\s*$)/g, "");  
}

Answer 4

等比例缩放图片
 /// 生成缩略图
  public  void MakeThumbnail(string originalImagePath,string thumbnailPath, int width, int height, string mode)
  {
       System.Drawing.Image originalImage =System.Drawing.Image.FromFile(originalImagePath);
               
       int towidth = width;
       int toheight = height;
           
       int x = 0;
       int y = 0;
       int ow = originalImage.Width;
       int oh = originalImage.Height;               switch (mode)
       {        
            case "HW":               
             break;
            case "W":                  
             toheight = originalImage.Height * width/originalImage.Width;
             break;
            case "H":
             towidth = originalImage.Width * height/originalImage.Height;             
             break;
            case "A":
                if (originalImage.Width / originalImage.Height >= width / height)
                {
                    if (originalImage.Width > width)
                    {
                        towidth = width;
                        toheight = (originalImage.Height * width) / originalImage.Width;
                    }
                    else
                    {
                        towidth = originalImage.Width;
                        toheight = originalImage.Height;
                    }
                }
                else
                {
                    if (originalImage.Height > height)
                    {
                        toheight = height;
                        towidth = (originalImage.Width * height) / originalImage.Height;
                    }
                    else
                    {
                        towidth = originalImage.Width;
                        toheight = originalImage.Height;
                    }
                }
                break;
            case "Cut":               
             if((double)originalImage.Width/(double)originalImage.Height > (double)towidth/(double)toheight)
             {
              oh = originalImage.Height;
              ow = originalImage.Height*towidth/toheight;
              y = 0;
              x = (originalImage.Width - ow)/2;
             }
             else
             {
              ow = originalImage.Width;
              oh = originalImage.Width*height/towidth;
              x = 0;
              y = (originalImage.Height - oh)/2;
             }
             break;                    
            default :
             break;
       }    
               
       System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth,toheight);
       Graphics g = System.Drawing.Graphics.FromImage(bitmap);
       g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.Half;
       g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;       g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;       g.Clear(Color.Transparent);       g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
        new Rectangle(x, y, ow,oh),
        GraphicsUnit.Pixel);       try
       {            
        bitmap.Save(Server.MapPath("file/" + DateTime.Now.ToString("yyyyMMddHHmmssffff") + ".jpg"), System.Drawing.Imaging.ImageFormat.Jpeg); 
       }
       catch(System.Exception e)
       {
        throw e;
       }
       finally
       {
        originalImage.Dispose();
        bitmap.Dispose();                        
        g.Dispose();
       }参考