Layer not getting removed - Google Maps

问题

I have Google Maps:

<!DOCTYPE html>
<html>
  <head>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no">
    <meta charset="utf-8">
    <title>Fusion Tables layers</title>
    <style>
      html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
      #map {
        height: 100%;
      }
    </style>
  </head>
  <body>
    <div id="map"></div>
    <script>
      function initMap() {
        var map = new google.maps.Map(document.getElementById('map'), {
          zoom: 4,
          center: {lat: 39.8282, lng: -98.5795}
        });

        google.maps.event.addListener(map, 'zoom_changed', function() {
         var zoom_level = map.getZoom();
         var layer;
         var layer1;

         //state level
         if(zoom_level >= 5 && zoom_level < 7) {
           layer = new google.maps.FusionTablesLayer({
            query: {
              select: '\'geometry\'',
              from: '17aT9Ud-YnGiXdXEJUyycH2ocUqreOeKGbzCkUw'
            },
            styles: [{
              polygonOptions: {
                fillColor: '#000000',
                fillOpacity: 0.001
              }
            }]


          });
          layer.setMap(map);
          }

         //county level
         if(zoom_level >= 7) {
          layer = null;
          layer.setMap(null);
           layer1 = new google.maps.FusionTablesLayer({
            query: {
              select: '\'geometry\'',
              from: '1xdysxZ94uUFIit9eXmnw1fYc6VcQiXhceFd_CVKa'
            },
            styles: [{
              polygonOptions: {
                fillColor: '#000000',
                fillOpacity: 0.001
              }
            }]

          });
          layer1.setMap(map);
          }
        });
      }
    </script>
    <script async defer
    src="https://maps.googleapis.com/maps/api/js?key=AIzaSyBMtoh9P3UkoxbXndKu_HOP7KsVwTRvxGU&callback=initMap">
    </script>
  </body>
</html>

When I zoom in to zoomlevel 7 and above, I still see state level (layer) and not layer1. How can I reset layer when zoom in?

回答1:

I would suggest that if you only ever want one layer at a time, only create one, hide it before creating a new version.

google.maps.event.addListener(map, 'zoom_changed', function() {
  var zoom_level = map.getZoom();
  if (layer) layer.setMap(null);
  //state level
  if (zoom_level >= 5 && zoom_level < 7) {
    layer = new google.maps.FusionTablesLayer({
      query: {
        select: '\'geometry\'',
        from: '17aT9Ud-YnGiXdXEJUyycH2ocUqreOeKGbzCkUw'
      },
      styles: [{
        polygonOptions: {
          fillColor: '#000000',
          fillOpacity: 0.001
        }
      }]
    });
    layer.setMap(map);
  }
  //county level
  if (zoom_level >= 7) {
    layer = new google.maps.FusionTablesLayer({
      query: {
        select: '\'geometry\'',
        from: '1xdysxZ94uUFIit9eXmnw1fYc6VcQiXhceFd_CVKa'
      },
      styles: [{
        polygonOptions: {
          fillColor: '#000000',
          fillOpacity: 0.001
        }
      }]
    });
    layer.setMap(map);
  }
});

proof of concept fiddle

code snippet:

var layer;
var layer1;
var map;

function initMap() {
  map = new google.maps.Map(document.getElementById('map'), {
    zoom: 4,
    center: {
      lat: 39.8282,
      lng: -98.5795
    }
  });

  google.maps.event.addListener(map, 'zoom_changed', function() {
    var zoom_level = map.getZoom();

    if (layer) layer.setMap(null);
    //state level
    if (zoom_level >= 5 && zoom_level < 7) {
      layer = new google.maps.FusionTablesLayer({
        query: {
          select: '\'geometry\'',
          from: '17aT9Ud-YnGiXdXEJUyycH2ocUqreOeKGbzCkUw'
        },
        styles: [{
          polygonOptions: {
            fillColor: '#000000',
            fillOpacity: 0.001
          }
        }]
      });
      layer.setMap(map);
    }
    //county level
    if (zoom_level >= 7) {
      layer = new google.maps.FusionTablesLayer({
        query: {
          select: '\'geometry\'',
          from: '1xdysxZ94uUFIit9eXmnw1fYc6VcQiXhceFd_CVKa'
        },
        styles: [{
          polygonOptions: {
            fillColor: '#000000',
            fillOpacity: 0.001
          }
        }]
      });
      layer.setMap(map);
    }
  });
}
google.maps.event.addDomListener(window, "load", initMap);

html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}
#map {
  height: 100%;
}

<script src="https://maps.googleapis.com/maps/api/js"></script>
<div id="map"></div>

来源：https://stackoverflow.com/questions/39979247/layer-not-getting-removed-google-maps

标签

google-maps-api-3