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interface
   :
   : 
function SHGetKnownFolderPath(rfid: TGUID; dwFlags: DWORD; hToken: THandle; var ppszPath: IntPtr): HRESULT;
function SHGetKnownFolderPathA(rfid: TGUID; dwFlags: DWORD; hToken: THandle; var ppszPath: IntPtr): HRESULT;
function SHGetKnownFolderPathW(rfid: TGUID; dwFlags: DWORD; hToken: THandle; var ppszPath: IntPtr): HRESULT;
   :
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implementation
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const
  Shell32Dll = 'Shell32.dll';

[SuppressUnmanagedCodeSecurity, DllImport(Shell32Dll, CharSet = CharSet.Auto, SetLastError = True, EntryPoint = 'SHGetKnownFolderPath')]
function SHGetKnownFolderPath; external;
[SuppressUnmanagedCodeSecurity, DllImport(Shell32Dll, CharSet = CharSet.Ansi, SetLastError = True, EntryPoint = 'SHGetKnownFolderPathA')]
function SHGetKnownFolderPathA; external;
[SuppressUnmanagedCodeSecurity, DllImport(Shell32Dll, CharSet = CharSet.Unicode, SetLastError = True, EntryPoint = 'SHGetKnownFolderPathW')]
function SHGetKnownFolderPathW; external;
     :
     :
function GetFolderPath(Folder: TGUID): String;
  var
    Buffer: IntPtr;
    Res: HRESULT;
begin
  Res := SHGetKnownFolderPath(Folder, 0, 0, Buffer);
  OleCheck(Res);
  Result := Marshal.PtrToStringAuto(Buffer);
  if Assigned(Buffer) then
    CoTaskMemFree(Buffer);
end;