{SetVwPrt.PAS}
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 {Sample code for the SetViewPort procedure.}

  uses Graph;

 var Gd, Gm: Integer;
 begin
   Gd := Detect;
   InitGraph(Gd, Gm, '');
   if GraphResult <> grOk then
     Halt(1);
   if (Gd = HercMono) or (Gd = EGA) or (Gd = EGA64) or (Gd = VGA) then
   begin
     SetVisualPage(0);
     SetActivePage(1);
     Rectangle(10, 20, 30, 40);
     SetVisualPage(1);
   end
   else
     OutText('No paging supported.');
   Readln;
   CloseGraph;
 end.