How to get system image list icon index of an IShellItem?

Question

Given a Windows Vista or newer IShellItem, how do i get the system image list icon index associated with that item?

For example (pseudo

Answer 1

In your great investigation you forget about IShellIcon interface. It available even in Windows XP.

function GetIconIndex(AFolder: IShellFolder; AChild: PItemIDList): Integer; overload;
var
  ShellIcon: IShellIcon;
  R: HRESULT;
begin
  OleCheck(AFolder.QueryInterface(IShellIcon, ShellIcon));
  try
    R := ShellIcon.GetIconOf(AChild, 0, Result);
    case R of
      S_OK:;
      S_FALSE:
        Result := -1; // icon can not be obtained for this object
    else
      OleCheck(R);
    end;
  finally
    ShellIcon := nil;
  end;
end;