     map.removeInteraction(drawTool);
            }
        
            //添加交互绘制功能控件
            addInteraction("Polygon");          
        }

        arrowStyle = function (feature) {
            var geometry = feature.getGeometry();
        
            var styles = [
                commonStyle
            ];
            if(geometry.getType()!=="LineString")
            return styles;
            geometry.forEachSegment(function (start, end) {
                var dx = end[0] - star