问使用谷歌地图API呈现一张地图的多种旅行模式

EN

var goo = google.maps,
    map = new goo.Map(document.getElementById('map-canvas'), {
      center: new goo.LatLng(52.52, 13.40),
      zoom: 10
    }),
    App = {
      map: map,
      bounds: new goo.LatLngBounds(),
      directionsService: new goo.DirectionsService(),
      directionsDisplay1: new goo.DirectionsRenderer({
        map: map,
        preserveViewport: true,
        polylineOptions: {
          strokeColor: 'red'
        }
      }),
      directionsDisplay2: new goo.DirectionsRenderer({
        map: map,
        preserveViewport: true,
        polylineOptions: {
          strokeColor: 'blue'
        }
      }),
      directionsDisplay3: new goo.DirectionsRenderer({
        map: map,
        preserveViewport: true,
        polylineOptions: {
          strokeColor: 'yellow'
        }
      })

    },
    startLeg = {
      origin: 'Rome',
      destination: 'Paris',
      travelMode: goo.TravelMode.DRIVING
    },
    middleLeg = {
      origin: 'Paris',
      destination: 'Berlin',
      travelMode: goo.TravelMode.TRANSIT
    },
    endLeg = {
      origin: 'Berlin',
      destination: 'Buxtehude',
      travelMode: goo.TravelMode.BICYCLING
    };

  App.directionsService.route(startLeg, function (result, status) {
    if (status == google.maps.DirectionsStatus.OK) {
      App.directionsDisplay1.setDirections(result);
      App.map.fitBounds(App.bounds.union(result.routes[0].bounds));
    }
  });

  App.directionsService.route(middleLeg, function (result, status) {
    if (status == google.maps.DirectionsStatus.OK) {
      App.directionsDisplay2.setDirections(result);
      App.map.fitBounds(App.bounds.union(result.routes[0].bounds));
    }
  });

  App.directionsService.route(endLeg, function (result, status) {
    if (status == google.maps.DirectionsStatus.OK) {
      App.directionsDisplay3.setDirections(result);
      App.map.fitBounds(App.bounds.union(result.routes[0].bounds));
    }
  });