procedure TForm1.Button1Click(Sender: TObject); 
var 
 lb : TLogBrush; 
begin 
 lb.lbStyle := BS_SOLID; 
 lb.lbColor := RGB(255, 0, 0); 
 lb.lbHatch := 0; 
 Form1.Canvas.Pen.Handle := ExtCreatePen(PS_GEOMETRIC or PS_INSIDEFRAME or PS_ENDCAP_SQUARE or PS_JOIN_BEVEL, 20, lb, 0, nil); 
 BeginPath(Form1.Canvas.Handle); 
 Form1.Canvas.MoveTo(100, 30); 
 Form1.Canvas.LineTo(200, 100); 
 Form1.Canvas.LineTo(300, 30); 
 EndPath(Form1.Canvas.Handle); 
 StrokePath(Form1.Canvas.Handle); 
 Form1.Canvas.Pen.Width := 1; 
end;