code: function(x1,y1,x2,y2){
  		if(this.range.x1 > x1){ this.range.x1 = x1;}
  		if(this.range.y1 > y1){ this.range.y1 = y1;}
  		if(this.range.x2 < x2){ this.range.x2 = x2;}
  		if(this.range.y2 < y2){ this.range.y2 = y2;}
  	}
docs: オーバーライド用