my @dim = $canvas->bbox("all");
    my $width = ($dim[2]-$dim[0]);
    my $height = ($dim[3]-$dim[1]); 
    
    my $ps = $canvas->
	postscript(  '-pagewidth'  => "8 i",
	 	     '-pageanchor' => "center",
		     '-width' => $width,
		     '-height' =>$height
                      );