procedure ChangeOrientation(NewOrientation:DWORD);
var
  dm      : TDeviceMode;
  dwTemp  : DWORD;
  dmDisplayOrientation : DWORD;
begin
   ZeroMemory(@dm, sizeof(dm));
   dm.dmSize   := sizeof(dm);
   if EnumDisplaySettings(nil, DWORD(ENUM_CURRENT_SETTINGS), dm) then
   begin
      Move(dm.dmScale,dmDisplayOrientation,SizeOf(dmDisplayOrientation));
      // swap width and height
      if Odd(dmDisplayOrientation)<>Odd(NewOrientation) then
      begin
       dwTemp := dm.dmPelsHeight;
       dm.dmPelsHeight:= dm.dmPelsWidth;
       dm.dmPelsWidth := dwTemp;
      end;

      if dmDisplayOrientation<>NewOrientation then
      begin
        Move(NewOrientation,dm.dmScale,SizeOf(NewOrientation));
        if (ChangeDisplaySettings(dm, 0)<>DISP_CHANGE_SUCCESSFUL) then
         RaiseLastOSError;
      end;
   end;
end;