google-maps - 谷歌地图绘制多边形并删除前一个

Question

当用户选择多边形绘制按钮绘制新多边形时，我正在尝试删除现有多边形。
它与 drawingManager.setMap(null); 有关系但我不能让它在我的代码中工作。我已经尝试了很多东西，但无法弄清楚。

信息:
当页面加载时，绘图模式默认设置为多边形:drawingMode: google.maps.drawing.OverlayType.POLYGON
用户可以绘制一个多边形来标记一个区域。多边形完成后，DrawingMode 设置为 null:drawingManager.setDrawingMode(null);并将坐标放入输入字段中，以便稍后通过表单将它们保存在数据库中。

有人能帮帮我吗？到目前为止，这是我的代码:

var map;
var drawingManager;    

function initialize() {
var myLatlng = new google.maps.LatLng(51.51686166794058, 3.5945892333984375);
var mapOptions = {
    zoom: 9,
    center: myLatlng,
    mapTypeId: google.maps.MapTypeId.ROADMAP
}

//Getting map DOM element
var mapElement = document.getElementById('map_canvas');

map = new google.maps.Map(map_canvas, mapOptions);

drawingManager = new google.maps.drawing.DrawingManager({
    drawingMode: google.maps.drawing.OverlayType.POLYGON,
    drawingControl: true,
    drawingControlOptions: {
        position: google.maps.ControlPosition.TOP_CENTER,
        drawingModes: [google.maps.drawing.OverlayType.POLYGON]
    },
    polygonOptions: {
        editable: true,
        draggable: true
    }
});

drawingManager.setMap(map);

// Add a listener for creating new shape event.
google.maps.event.addListener(drawingManager, "overlaycomplete", function(event) {
    var newShape = event.overlay;
    newShape.type = event.type;
    if(drawingManager.getDrawingMode()) {
        drawingManager.setDrawingMode(null);
    }

});

// Add a listener for the "drag" event.
google.maps.event.addListener(drawingManager, "overlaycomplete", function(event){
    overlayDragListener(event.overlay);
    $('#vertices').val(event.overlay.getPath().getArray());
});
}    

function overlayDragListener(overlay) {
google.maps.event.addListener(overlay.getPath(), 'set_at', function(event){
    $('#vertices').val(overlay.getPath().getArray());
});
google.maps.event.addListener(overlay.getPath(), 'insert_at', function(event){
    $('#vertices').val(overlay.getPath().getArray());
});
}

google.maps.event.addDomListener(window, 'load', initialize);

Answer 1

两件事情:

添加一个全局数组(或变量)以允许访问形状

添加 drawingmode_changed事件处理程序，当绘图模式改回非空时，删除任何现有的多边形。

var shapes = [];

google.maps.event.addListener(drawingManager, "drawingmode_changed", function() {
    if (drawingManager.getDrawingMode() != null) {
      for (var i=0; i < shapes.length; i++) {
        shapes[i].setMap(null);
      }
      shapes = [];
    }
});

working fiddle

工作代码片段:

var map;
var drawingManager;
var shapes = [];

function initialize() {
  var myLatlng = new google.maps.LatLng(51.51686166794058, 3.5945892333984375);
  var mapOptions = {
    zoom: 9,
    center: myLatlng,
    mapTypeId: google.maps.MapTypeId.ROADMAP
  }

  //Getting map DOM element
  var mapElement = document.getElementById('map_canvas');

  map = new google.maps.Map(map_canvas, mapOptions);

  drawingManager = new google.maps.drawing.DrawingManager({
    drawingMode: google.maps.drawing.OverlayType.POLYGON,
    drawingControl: true,
    drawingControlOptions: {
      position: google.maps.ControlPosition.TOP_CENTER,
      drawingModes: [google.maps.drawing.OverlayType.POLYGON]
    },
    polygonOptions: {
      editable: true,
      draggable: true
    }
  });

  drawingManager.setMap(map);

  // Add a listener for creating new shape event.
  google.maps.event.addListener(drawingManager, "overlaycomplete", function(event) {
    var newShape = event.overlay;
    newShape.type = event.type;
    shapes.push(newShape);
    if (drawingManager.getDrawingMode()) {
      drawingManager.setDrawingMode(null);
    }

  });

  // add a listener for the drawing mode change event, delete any existing polygons
  google.maps.event.addListener(drawingManager, "drawingmode_changed", function() {
    if (drawingManager.getDrawingMode() != null) {
      for (var i = 0; i < shapes.length; i++) {
        shapes[i].setMap(null);
      }
      shapes = [];
    }
  });


  // Add a listener for the "drag" event.
  google.maps.event.addListener(drawingManager, "overlaycomplete", function(event) {
    overlayDragListener(event.overlay);
    $('#vertices').val(event.overlay.getPath().getArray());
  });
}

function overlayDragListener(overlay) {
  google.maps.event.addListener(overlay.getPath(), 'set_at', function(event) {
    $('#vertices').val(overlay.getPath().getArray());
  });
  google.maps.event.addListener(overlay.getPath(), 'insert_at', function(event) {
    $('#vertices').val(overlay.getPath().getArray());
  });
}

google.maps.event.addDomListener(window, 'load', initialize);

html,
body,
#map_canvas {
  height: 100%;
  width: 100%;
  margin: 0px;
  padding: 0px
}

<script src="https://maps.googleapis.com/maps/api/js?libraries=drawing&key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk"></script>
<div id="map_canvas" style="border: 2px solid #3872ac;"></div>