How Can I Check That A File Is A Valid XPS File With C#?

Question

I have a WinForms application that processes XPS files. How can I check that the file the user has selected in the open dialog is a valid XPS file using C#?

There WILL be files present with the .XPS extension that are not really XPS files.

Since XPS files are really in the PKZIP format, I could check for the PKZIP byte signature but that would give false positives on ZIP archives.

dup? http://stackoverflow.com/questions/3785784/how-to-validate-an-xps-document — kenny, Apr 13 '12 at 17:11
@harold - Yes, that's what I want to do. Do you have a code sample? Do I check for a specific exception after some operation? — DaveB, Apr 13 '12 at 17:21
http://msdn.microsoft.com/en-us/library/windows/desktop/dd316976(v=vs.85).aspx — kenny, Apr 13 '12 at 17:26
@DaveB well, msdn doesn't want me to know about the exceptions, so I can't really go into detail.. — harold, Apr 13 '12 at 17:30

score 2 · Accepted Answer · answered Apr 14 '12 at 07:03

The following will distinguish XPS files from other ZIP archives and non-ZIP files. It won't determine whether the file is fully-valid XPS - for that you would need to load each page.

using System;
using System.IO;
using System.Windows.Xps.Packaging;

class Tester
{
    public static bool IsXps(string filename)
    {
        try
        {
            XpsDocument x = new XpsDocument(filename, FileAccess.Read);

            IXpsFixedDocumentSequenceReader fdsr = x.FixedDocumentSequenceReader;

            // Needed to actually try to find the FixedDocumentSequence
            Uri uri = fdsr.Uri;

            return true;
        }
        catch (Exception)
        {
        }

        return false;
    }
}

Thanks so much. Works great. Took about 33 seconds to check a 621 MB test file on a network share from my workstation. Didn't give any false positives in my testing. — DaveB, Apr 17 '12 at 16:24

score -2 · Answer 2 · answered Apr 13 '12 at 17:14

-2

You can check for the content Type of the file instead of the file extension.

answered Apr 13 '12 at 17:14

Nudier Mena

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And how do you check that "content Type" ? – H H Apr 13 '12 at 17:17
HttpPostedFile.ContentType check PostedFile.ContentType.ToLower() = whaterver mime type you are looking for. I would check on both extension and content type sorry just saw that this is winforms not web – Brian Apr 13 '12 at 17:19
take a glance at this article, http://msdn.microsoft.com/en-us/library/ms775147(v=vs.85).aspx#introduction – Nudier Mena Apr 13 '12 at 17:20
This is a WinForms app. There is no ContentType to check. There is no uploaded file. – DaveB Apr 13 '12 at 17:23
I found this article, but I have not test it yet, http://www.codeproject.com/Articles/6871/Get-a-File-ContentType-from-a-Windows-Forms-App – Nudier Mena Apr 13 '12 at 17:28

How Can I Check That A File Is A Valid XPS File With C#?

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