谷歌地图 v3 OverlayView.getProjection() [英] Google Maps v3 OverlayView.getProjection()

问题描述

我似乎无法弄清楚为什么 getProjection() 返回的对象未定义.这是我的代码:

I cannot seem to figure out why the object returned by getProjection() is undefined. Here is my code:

 // Handles the completion of the rectangle
  var ne = recBounds.getNorthEast();
  var sw = recBounds.getSouthWest();
  $("#map_tools_selat").attr( 'value', sw.lat() );
  $("#map_tools_nwlat").attr( 'value', ne.lat() );
  $("#map_tools_selng").attr( 'value', ne.lng() );
  $("#map_tools_nwlng").attr( 'value', sw.lng() );

  // Set Zoom Level
  $("#map_tools_zoomlevel").attr( 'value', HAR.map.getZoom()+1 );
  document.getElementById("map_tools_centerLat").value = HAR.map.getCenter().lat();
  document.getElementById("map_tools_centerLong").value = HAR.map.getCenter().lng(); 

  // All this junk below is for getting pixel coordinates for a lat/lng  =/
  MyOverlay.prototype = new google.maps.OverlayView();
  MyOverlay.prototype.onAdd = function() { }
  MyOverlay.prototype.onRemove = function() { }
  MyOverlay.prototype.draw = function() { }
  function MyOverlay(map) { this.setMap(map); }
  var overlay = new MyOverlay(HAR.map);
  var projection = overlay.getProjection();
  // END - all the junk
  var p = projection.fromLatLngToContainerPixel(recBounds.getCenter());
  alert(p.x+", "+p.y);

我的错误是:无法调用未定义的方法'fromLatLngToContainerPixel'

推荐答案

其实我之所以会出现这种情况，是因为在平移/缩放后地图空闲后创建了投影对象.因此，更好的解决方案是监听 google.maps.Map 对象的 idle 事件，并获取对那里的投影的引用:

Actually, i the reason why this happens is because the projection object is created after the map is idle after panning / zooming. So, a better solution is to listen on the idle event of the google.maps.Map object, and get a reference to the projection there:

// Create your map and overlay
var map;
MyOverlay.prototype = new google.maps.OverlayView();
MyOverlay.prototype.onAdd = function() { }
MyOverlay.prototype.onRemove = function() { }
MyOverlay.prototype.draw = function() { }
function MyOverlay(map) { this.setMap(map); }

var overlay = new MyOverlay(map);
var projection;

// Wait for idle map
google.maps.event.addListener(map, 'idle', function() {
   // Get projection
   projection = overlay.getProjection();
})

这篇关于谷歌地图 v3 OverlayView.getProjection()的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！