c# - Shell Icon Overlay Interop Example? -

i trying set custom icon on top of files/directories in windows explorer. after researching on topic, found can achieved either creating desktop.ini files (directories only) or using windows api's shell icon overlay (both files , directories). i've seen c++ atl libraries on codeproject, tortoiseoverlay, , c# wrappers, working c# sample cannot found anywhere.

i've found following code sample:

public sealed class shellinterop {      private shellinterop()     {     }     [dllimport("shell32.dll")]     public static extern void shchangenotify(int eventid, uint flags, intptr item1, intptr item2);  }  [comvisible(false)] [comimport] [guid("0c6c4200-c589-11d0-999a-00c04fd655e1")] [interfacetype(cominterfacetype.interfaceisiunknown)] public interface ishelliconoverlayidentifier {      [preservesig]     int ismemberof([marshalas(unmanagedtype.lpwstr)]string path, uint attributes);      [preservesig]     int getoverlayinfo(         intptr iconfilebuffer,         int iconfilebuffersize,         out int iconindex,         out uint flags);      [preservesig]     int getpriority(out int priority); }  [comvisible(true)] [guid("b8fa9e43-38e6-4654-8a13-ff905ad22ce5")] public class myiconoverlay : ishelliconoverlayidentifier {      #region ishelliconoverlayidentifier members     public int ismemberof(string path, uint attributes)     {         //show icon overlay         return 0; // s_ok     }      public int getoverlayinfo(intptr iconfilebuffer, int     iconfilebuffersize,     out int iconindex, out uint flags)     {          system.diagnostics.debug.writeline(string.format("getoverlayinfo::{0}", iconfilebuffer));          system.diagnostics.debug.writeline(string.format("getoverlayinfo::{0}", iconfilebuffersize));         string fname = @"c:\normalicon.ico";          int bytescount = system.text.encoding.unicode.getbytecount(fname);          system.diagnostics.debug.writeline(string.format("getoverlayinfo::{0}", bytescount));          byte[] bytes = system.text.encoding.unicode.getbytes(fname);          if (bytes.length + 2 < iconfilebuffersize)         {             (int = 0; < bytes.length; i++)             {                 marshal.writebyte(iconfilebuffer, i, bytes[i]);             }             //write "\0\0"             marshal.writebyte(iconfilebuffer, bytes.length, 0);             marshal.writebyte(iconfilebuffer, bytes.length + 1, 0);         }          iconindex = 0;         flags = 1; // isioi_iconfile         return 0; // s_ok     }       public int getpriority(out int priority)     {         priority = 0; // 0-100 (0 highest priority)         return 0; // s_ok     }     #endregion      #region registry     [comregisterfunction]     public static void register(type t)     {         registrykey rk = registry.localmachine.createsubkey(@"software\microsoft\windows\currentversion\explorer\shelliconoverlayidentifiers\_"         + t.name);         rk.setvalue(string.empty, t.guid.tostring("b").toupper());         rk.close();         shellinterop.shchangenotify(0x08000000, 0, intptr.zero, intptr.zero);     }      [comunregisterfunction]     public static void unregister(type t)     {         registry.localmachine.deletesubkeytree(@"software\microsoft\windows\currentversion\explorer\shelliconoverlayidentifiers\_"         + t.name);         shellinterop.shchangenotify(0x08000000, 0, intptr.zero, intptr.zero);     }     #endregion } 

from understand, function "register" needs called first register app windows explorer, type parameter expects?

can explain in order need call these functions set icon "c:\overlay.ico" on top of "c:\test.txt"?

if provide example, appreciate it. let's assume console application main function entry point.

edit:

i got work in c++ atl. xearinox pointed out, shell extension code had in dll. after dll compiled has registered running regsvr32.exe command under administrator privileges. mistake thought ismemberof , getoverlayinfo functions had called main program - in fact called windows explorer. here link project on codeplex contains readme file explaining in more details - hope has same problem.