C# - Prüfen ob eine Datei druckbar ist

using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;

namespace ctm.helpers
{
    /// <summary>
    /// Helperclass for Win32 shlwapi
    /// </summary>
    public class shlwapi
    {
        [DllImport("shlwapi.dll")]
        extern static int AssocCreate(ref Guid clsid,ref Guid riid,[MarshalAs(UnmanagedType.Interface)] out object ppv);

        [Flags]
        enum ASSOCF
        {
            INIT_NOREMAPCLSID = 0x00000001,
            INIT_BYEXENAME = 0x00000002,
            OPEN_BYEXENAME = 0x00000002,
            INIT_DEFAULTTOSTAR = 0x00000004,
            INIT_DEFAULTTOFOLDER = 0x00000008,
            NOUSERSETTINGS = 0x00000010,
            NOTRUNCATE = 0x00000020,
            VERIFY = 0x00000040,
            REMAPRUNDLL = 0x00000080,
            NOFIXUPS = 0x00000100,
            IGNOREBASECLASS = 0x00000200,
            INIT_IGNOREUNKNOWN = 0x00000400
        }

        enum ASSOCSTR
        {
            COMMAND = 1,
            EXECUTABLE,
            FRIENDLYDOCNAME,
            FRIENDLYAPPNAME,
            NOOPEN,
            SHELLNEWVALUE,
            DDECOMMAND,
            DDEIFEXEC,
            DDEAPPLICATION,
            DDETOPIC,
            INFOTIP,
            QUICKTIP,
            TILEINFO,
            CONTENTTYPE,
            DEFAULTICON,
            SHELLEXTENSION
        }

        enum ASSOCKEY
        {
            SHELLEXECCLASS = 1,
            APP,
            CLASS,
            BASECLASS
        }

        enum ASSOCDATA
        {
            MSIDESCRIPTOR = 1,
            NOACTIVATEHANDLER,
            QUERYCLASSSTORE,
            HASPERUSERASSOC,
            EDITFLAGS,
            VALUE
        }

        [Guid("c46ca590-3c3f-11d2-bee6-0000f805ca57"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
        interface IQueryAssociations
        {
            void Init(
              [In] ASSOCF flags,
              [In, MarshalAs(UnmanagedType.LPWStr)] string pszAssoc,
              [In] UIntPtr hkProgid,
              [In] IntPtr hwnd);

            void GetString(
              [In] ASSOCF flags,
              [In] ASSOCSTR str,
              [In, MarshalAs(UnmanagedType.LPWStr)] string pwszExtra,
              [Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder pwszOut,
              [In, Out] ref int pcchOut);

            void GetKey(
              [In] ASSOCF flags,
              [In] ASSOCKEY str,
              [In, MarshalAs(UnmanagedType.LPWStr)] string pwszExtra,
              [Out] out UIntPtr phkeyOut);

            void GetData(
              [In] ASSOCF flags,
              [In] ASSOCDATA data,
              [In, MarshalAs(UnmanagedType.LPWStr)] string pwszExtra,
              [Out, MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 4)] out byte[] pvOut,
              [In, Out] ref int pcbOut);

            void GetEnum(); // not used actually
        }

        static Guid CLSID_QueryAssociations = new Guid("a07034fd-6caa-4954-ac3f-97a27216f98a");
        static Guid IID_IQueryAssociations = new Guid("c46ca590-3c3f-11d2-bee6-0000f805ca57");

        /// <summary>
        /// Check if named File is a printable File
        /// </summary>
        /// <param name="aFileName">Full Name of File which must be checked.</param>
        /// <returns>Boolean value : true if printable, false if no Application is registered to print</returns>
        public Boolean IsPrintableFile(String aFileName)
        {
            if (aFileName == String.Empty)
            {
                return false;
            }
            try
            {
                object obj;
                AssocCreate(ref CLSID_QueryAssociations,ref IID_IQueryAssociations,out obj);
                IQueryAssociations qa = (IQueryAssociations)obj;
                qa.Init(ASSOCF.INIT_DEFAULTTOSTAR,Convert.ToString(Path.GetExtension(aFileName)),UIntPtr.Zero, IntPtr.Zero);

                int size = 0;
                qa.GetString(ASSOCF.NOTRUNCATE, ASSOCSTR.COMMAND,
                  "print", null, ref size);

                StringBuilder sb = new StringBuilder(size);
                qa.GetString(ASSOCF.NOTRUNCATE, ASSOCSTR.COMMAND,
                  "print", sb, ref size);

                return true;
            }
            catch (Exception e)
            {
                if ((uint)Marshal.GetHRForException(e) == 0x80070483)
                    return false;
                else
                    return false;
            }
        }
    }
}