請問Google Map api中
已將google.maps.DirectionsRenderer之中設定draggable為true
但要如何去獲取路線上新增的點的座標or位置訊息
想將新增的點存入資料庫
以下為現有程式碼

        var directionsService;
		var directionsDisplay;
		var myWayPoints;
		var waypts = [];

		function initMap() {
			var map = new google.maps.Map(document.getElementById('map'), {
				zoom : 11,
				center : {
					lat : 25.0019497,
					lng : 121.1481835
				}
			});

			directionsService = new google.maps.DirectionsService;
			directionsDisplay = new google.maps.DirectionsRenderer({
				draggable : true,
				map : map,
			});

			directionsDisplay.addListener('directions_changed', function() {
				computeTotalDistance(directionsDisplay.getDirections());
			});
			var start = document.getElementById('start').value;
			var end = document.getElementById('end').value;
			displayRoute(start, end, directionsService, directionsDisplay);
			directionsDisplay.setMap(map);
		}

		function displayRoute(start, end, service, display) {
			service.route({
				origin : start+",TW",
				destination : end+",TW",
				waypoints:waypts,
				travelMode : 'WALKING',
				provideRouteAlternatives : true,
				avoidHighways : true,
				avoidTolls : true,
			}, function(response, status) {
				if (status === 'OK') {
					display.setDirections(response);
				} else {
					alert('錯誤訊息: ' + status);
				}
			});
		}
        function computeTotalDistance(result) {
			var total = 0;
			var myroute = result.routes[0];
			for (var i = 0; i < myroute.legs.length; i++) {
				total += myroute.legs[i].distance.value;
			}
			total = total / 1000;
			document.getElementById('pathlength').value=total;
		}