为什么getProjection（）在V3中不起作用 [英] Why getProjection() is not working in V3

问题描述

根据API ref，地图对象应该有一个getProjection
方法：

http://code.google.com/apis/maps/documentation/v3/reference.html#Map

According to the API ref, the map object should have a getProjection method:
http://code.google.com/apis/maps/documentation/v3/reference.html#Map

在这个例子中加载映射时，
应该提醒x，y点，但是
会将该值作为未定义值来引发。

While loading the map in this example should alert the x,y point, but instead throws the value as undefined. This is the below sample code called in onload.

function initialize() {
 var mapOptions = {
zoom: 8,
center: new google.maps.LatLng(-34.397, 150.644),
mapTypeId: google.maps.MapTypeId.ROADMAP
};
 map = new google.maps.Map(document.getElementById('map-canvas'),
  mapOptions);
alert("projection:"+map.getProjection());
}

推荐答案

地图完成初始化。您必须在访问它之前等待projection_changed事件。

It isn't available until the map is finished initializing. You have to wait on the "projection_changed" event before accessing it.

function initialize() {
 var mapOptions = {
   zoom: 8,
   center: new google.maps.LatLng(-34.397, 150.644),
   mapTypeId: google.maps.MapTypeId.ROADMAP
   };
 map = new google.maps.Map(document.getElementById('map-canvas'),
  mapOptions);
 google.maps.event.addListenerOnce(map,"projection_changed", function() {
   alert("projection:"+map.getProjection());
 });
}

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