Get the MIME type of a file.

Public Shared Function GetMimeType(ByVal file As String) As String
            Dim mime As String = Nothing
            Dim MaxContent As Integer = CInt(New FileInfo(file).Length)
            If MaxContent > 4096 Then
                MaxContent = 4096
            End If
 
            Dim fs As New FileStream(file, FileMode.Open)
 
            Dim buf(MaxContent) As Byte
            fs.Read(buf, 0, MaxContent)
            fs.Close()
            Dim result As Integer = FindMimeFromData(IntPtr.Zero, file, buf, MaxContent, Nothing, 0, mime, 0)
 
            Return mime
        End Function
 
        <DllImport("urlmon.dll", CharSet:=CharSet.Auto)> _
        Private Shared Function FindMimeFromData( _
            ByVal pBC As IntPtr, _
            <MarshalAs(UnmanagedType.LPWStr)> _
            ByVal pwzUrl As String, _
            <MarshalAs(UnmanagedType.LPArray, ArraySubType:=UnmanagedType.I1, SizeParamIndex:=3)> ByVal _
            pBuffer As Byte(), _
            ByVal cbSize As Integer, _
            <MarshalAs(UnmanagedType.LPWStr)> _
            ByVal pwzMimeProposed As String, _
            ByVal dwMimeFlags As Integer, _
            <MarshalAs(UnmanagedType.LPWStr)> _
            ByRef ppwzMimeOut As String, _
            ByVal dwReserved As Integer) As Integer
        End Function