如何在谷歌地图中计算所选区域的经度和纬度？

Question

I am using google map API integration.I need to get latitude and longitude from particular selected area in that map. In my script based on selected area in google map.

      function clearSelection() {
        if (selectedShape) {
          selectedShape.setEditable(false);
          selectedShape = null;
        }
      }

      function setSelection(shape) {
        clearSelection();
        selectedShape = shape;
        shape.setEditable(true);
        selectColor(shape.get('fillColor') || shape.get('strokeColor'));
      }

      function deleteSelectedShape() {
        if (selectedShape) {
          selectedShape.setMap(null);
        }
      }

      function selectColor(color) {
        selectedColor = color;
        for (var i = 0; i < colors.length; ++i) {
          var currColor = colors[i];
          colorButtons[currColor].style.border = currColor == color ? '2px solid #789' : '2px solid #fff';
        }

        // Retrieves the current options from the drawing manager and replaces the
        // stroke or fill color as appropriate.
        var polylineOptions = drawingManager.get('polylineOptions');
        polylineOptions.strokeColor = color;
        drawingManager.set('polylineOptions', polylineOptions);

        var rectangleOptions = drawingManager.get('rectangleOptions');
        rectangleOptions.fillColor = color;
        drawingManager.set('rectangleOptions', rectangleOptions);

        var circleOptions = drawingManager.get('circleOptions');
        circleOptions.fillColor = color;
        drawingManager.set('circleOptions', circleOptions);

        var polygonOptions = drawingManager.get('polygonOptions');
        polygonOptions.fillColor = color;
        drawingManager.set('polygonOptions', polygonOptions);
      }

      function setSelectedShapeColor(color) {
        if (selectedShape) {
          if (selectedShape.type == google.maps.drawing.OverlayType.POLYLINE) {
            selectedShape.set('strokeColor', color);
          } else {
            selectedShape.set('fillColor', color);
          }
        }
      }

      function makeColorButton(color) {
        var button = document.createElement('span');
        button.className = 'color-button';
        button.style.backgroundColor = color;
        google.maps.event.addDomListener(button, 'click', function() {
          selectColor(color);
          setSelectedShapeColor(color);
        });

        return button;
      }

       function buildColorPalette() {
         var colorPalette = document.getElementById('color-palette');
         for (var i = 0; i < colors.length; ++i) {
           var currColor = colors[i];
           var colorButton = makeColorButton(currColor);
           colorPalette.appendChild(colorButton);
           colorButtons[currColor] = colorButton;
         }
         selectColor(colors[0]);
       }

      function initialize() {
        var map = new google.maps.Map(document.getElementById('map'), {
          zoom: 10,
          center: new google.maps.LatLng(22.344, 114.048),
          mapTypeId: google.maps.MapTypeId.ROADMAP,
          disableDefaultUI: true,
          zoomControl: true
        });

        var polyOptions = {
          strokeWeight: 0,
          fillOpacity: 0.45,
          editable: true
        };
        // Creates a drawing manager attached to the map that allows the user to draw
        // markers, lines, and shapes.
        drawingManager = new google.maps.drawing.DrawingManager({
          drawingMode: google.maps.drawing.OverlayType.POLYGON,
          markerOptions: {
            draggable: true
          },
          polylineOptions: {
            editable: true
          },
          rectangleOptions: polyOptions,
          circleOptions: polyOptions,
          polygonOptions: polyOptions,
          map: map
        });

        google.maps.event.addListener(drawingManager, 'overlaycomplete', function(e) {
            if (e.type != google.maps.drawing.OverlayType.MARKER) {
            // Switch back to non-drawing mode after drawing a shape.
            drawingManager.setDrawingMode(null);

            // Add an event listener that selects the newly-drawn shape when the user
            // mouses down on it.
            var newShape = e.overlay;
            newShape.type = e.type;
            google.maps.event.addListener(newShape, 'click', function() {
              setSelection(newShape);
            });
            setSelection(newShape);
          }
        });

        // Clear the current selection when the drawing mode is changed, or when the
        // map is clicked.
        google.maps.event.addListener(drawingManager, 'drawingmode_changed', clearSelection);
        google.maps.event.addListener(map, 'click', clearSelection);
        google.maps.event.addDomListener(document.getElementById('delete-button'), 'click', deleteSelectedShape);

        buildColorPalette();
      }
      google.maps.event.addDomListener(window, 'load', initialize);
    </script>
<p> <div id="map" style="width:980px;height:480px;"></div></p>

In that script, i already create selected area in google map.but i need to get that particular selected area`s longitude and latitude.how to get selected area (cities and countries) value?

Answer 1

You can not get all the cities and countries inside an arbitrary polygon using the Google Maps API. You can get the city and country of a single point using the reverse geocoder using the Google Maps API v3 (or the web service), but an arbitrary polygon would be an infinite number of requests, and would tun into quota and rate limitations. If you have your own source of geographic data (say from geonames) in database that supports geographic queries, you can send the vertices of the polygon to your server and retrieve the locations in that polygon.