var
  TL, M: TDoublePoint;
  BR, N: TDoublePoint;
begin
  TL.X := GetLLon;
  TL.Y := GetTLat;
  BR.X := GetRLon;
  BR.Y := GetBLat;

  if Assigned(DefProjConverter) then begin
    M := DefProjConverter.LonLat2XY(TL);
    N := DefProjConverter.LonLat2XY(BR);
    ResultURL := GetURLBase + RoundEx(M.X, 9) + ',' + RoundEx(N.Y, 9) + ',' + RoundEx(N.X, 9) + ',' + RoundEx(M.Y, 9);
  end else begin
    ResultURL := 'invalid_url';
  end;
end.