{Clrvwprt.PAS}
  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
  {Sample code for the ClearViewPort procedure.}

  uses Graph;

  var Gd, Gm: Integer;
  begin
    Gd := Detect;
    InitGraph(Gd, Gm, '');
    if GraphResult <> grOk then
      Halt(1);
    Rectangle(19, 19, GetMaxX - 19, GetMaxY - 19);
    SetViewPort(20, 20, GetMaxX - 20, GetMaxY - 20, ClipOn);
    OutTextXY(0, 0, '<ENTER> clears viewport:');
    Readln;
    ClearViewPort;
    OutTextXY(0, 0, '<ENTER> to quit:');
    Readln;  CloseGraph;
  end.