uses Graph,crt;
{----------------------------SetGraph_BEGIN---------------------------------}
type
SetGraph=object
{Procedure Hide(x1,y1,x2,y2: integer);}
Procedure Show(x1,y1,x2,y2,rec_color: integer);
end;


(*
Procedure SetGraph.Hide;
begin
setwritemode(xorput);
Setcolor(rec_color);
Rectangle(x1,y1,x2,y2);
setwritemode(copyput);
end;
*)

Procedure SetGraph.Show;
begin
setwritemode(xorput);
SetColor(rec_color);
Rectangle(x1,y1,x2,y2);
setwritemode(copyput);
end;


{----------------------------SetGraph_END-----------------------------------}

var d,r,px1,px2,py1,py2,pcolor: integer;
rect: setgraph;
Procedure Move(a,b,c,d: integer);
begin
(*
rect.hide(px1,py1,px2,py2);
*)
rect.show(px1,py1,px2,py2,pcolor);
inc(px1,a);
inc(pY1,b);
inc(px2,c);
inc(py2,d);
rect.show(px1,py1,px2,py2,pcolor);
end;


begin
d:=detect;
initgraph(d,r,'');
px1:=(GetMaxX div 2)-30;
py1:=(GetMaxY div 2)-30;
px2:=(GetMaxX div 2)+30;
py2:=(GetMaxY div 2)+30;
pcolor:=3;


SetColor(white);
Rectangle(0,0,GetMaxX,GetMaxY);
Line(0,0,GetMaxX,GetMaxY);
line(getmaxX,0,0,getmaxY);

{move(0,0,0,0);}
rect.show(px1,py1,px2,py2,pcolor);

repeat begin
if keypressed then begin
case readkey of
#77: move(1,0,1,0);
#75: move(-1,0,-1,0);
#80: move(0,1,0,1);
#72: move(0,-1,0,-1);
end
end
end until readkey=#27;
closegraph;
end.