How we can control the size of an Image with using FileInfo

Question

I am trying to control size of my picture to do not be more than 200 KB

how can I do this

Assume that I want to choose picture with FileUpload from my PC and before uploaded the Image check the size.

string stream = FileUpload1.FileName;
string sub = stream.Substring(stream.LastIndexOf(".") + 1);

FileInfo fileinfo = new FileInfo(Server.MapPath(stream.ToString()));
if (FileUpload1.HasFile)
{
    if (sub == "jpg" || sub == "jpeg" || sub == "png")
    {
        if ((fileinfo.Length / 1024) <= 200)
        {
            string path = Server.MapPath("~/Image/" + stream);
            Image1.ImageUrl = path;
            FileUpload1.SaveAs(path);

            //Image1.DataBind();
            Label1.Text = fileinfo.Length.ToString();
        }
        else
        {
            Label1.Text = "Please insert valid Image";
        }
    }
    else
    {
        Label1.Text = "Please insert valid Image";
    }
}

With this code I'm getting

error is the file not found

What is the code you are using for `FileUpload`, are you going to use `FileUpload` control provided by ASP.Net or `FormData` at client side ? in either place you can check the file size. — Habib, Apr 28 '15 at 15:44
@kamal - please try to provide exact error message (I've edited in your comment about error, but it is not exact error). — Alexei Levenkov, Apr 28 '15 at 15:59

score 1 · Answer 1 · answered Apr 28 '15 at 15:49

Using FileUpload, you can validate with something like this:

In page:

<asp:FileUpload ID="myFile" runat="server" />

<asp:CustomValidator ID="CustomValidator1" runat="server" ControlToValidate="myFile" ErrorMessage="File size should not be greater than 200 KB." OnServerValidate="CustomValidator1_ServerValidate"></asp:CustomValidator>

In code behind:

protected void CustomValidator1_ServerValidate(object source, ServerValidateEventArgs args)
{
    if (myFile.FileBytes.Length > 204800)
    {
        args.IsValid = false;
    }
    else
    {
        args.IsValid = true;       
    }
}

Side note: check the size of 204800, I think is right

score 0 · Answer 2 · edited May 23 '17 at 12:06

Nicer option for user is to check size client side before posting - see JavaScript file upload size validation

With your current code you are getting error because you trying to check file size on disk before actually creating disk file (FileInfo is just information about possible file location and does not mean on exists).

Fix:

use FileUpload.FileBytes to check length of the file before trying to save it
save file first and than check length if you want to use FileInfo.Length.

If 200K is max upload size on your site you can also restrict max request size in Web.Config, also you'll get very unfriendly error message and may need to do extra work to show something nicer. But it will protect your code from potential abuse by uploading huge files.

How we can control the size of an Image with using FileInfo

2 Answers2