c# - Bing Maps Ajax API v7 地理定位回调

Question

我使用 Bing Maps Ajax v7 API 从示例中获取用户位置 here

是否可以等到回调被执行，直到我得到用户位置的经度、纬度或者如果他/她不允许获取位置时出现错误？

    function test() {
          //Call GetMap() to get position
          GetMap();
          //Wait until callback is finished
         //Do something with user's location (result of the callback)

     }

     function GetMap()
     {

        // Set the map options
        var mapOptions = {credentials:"Bing Maps Key"};


        // Initialize the map
        var map = new Microsoft.Maps.Map(document.getElementById("mapDiv"), mapOptions);

        // Initialize the location provider
        var geoLocationProvider = new Microsoft.Maps.GeoLocationProvider(map);

        // Get the user's current location
        geoLocationProvider.getCurrentPosition({successCallback:displayCenter});

        //Execute some more code with user's location
     }

     function displayCenter(args)
     {
        // Display the user location when the geo location request returns
        alert("The user's location is " + args.center);
     }

Answer 1

在 JavaScript 中，我认为您不能显式暂停执行并等待回调完成，如下所示:jQuery: wait for function to complete to continue processing?如果您有一些依赖于获取位置回调结果的逻辑，为什么不将该逻辑作为回调的一部分调用呢？您不需要明确地等待它。关于您想完成的事情，您正在寻找这样的东西吗？

var map;
function test() {
      //Call GetMap() to get position
      GetMap();
      //Wait until callback is finished
     //Do something with user's location (result of the callback)

 }

 function GetMap()
 {

    // Set the map options
    var mapOptions = {credentials:"Bing Maps Key"};


    // Initialize the map
    map = new Microsoft.Maps.Map(document.getElementById("mapDiv"), mapOptions);

    // Initialize the location provider
    var geoLocationProvider = new Microsoft.Maps.GeoLocationProvider(map);

    // Get the user's current location
    geoLocationProvider.getCurrentPosition({successCallback:displayCenter},{errorCallback:onError});
 }

function onPositionReady(position) {
    // Execute some more code with user's location
    // For Example...
    // Apply the position to the map
    var location = new Microsoft.Maps.Location(position.coords.latitude,
        position.coords.longitude);
    map.setView({ zoom: 18, center: location });

    // Add a pushpin to the map representing the current location
    var pin = new Microsoft.Maps.Pushpin(location);
    map.entities.push(pin);
}

function onError(err) {
    switch (err.code) {
        case 0:
            alert("Unknown error");
            break;
        case 1:
            alert("The user said no!");
            break;
        case 2:
            alert("Location data unavailable");
            break;
        case 3:
            alert("Location request timed out");
            break;
    }
}

更新: 如果你想将参数传递到你的回调中，你可以使用函数绑定(bind)来覆盖回调中的 this 关键字并以这种方式传递参数:

例如，如果设置 myObject 来包含您的参数，您可以像这样传递它:

 geoLocationProvider.getCurrentPosition({ successCallback: onPositionReady.bind(myObject) }, { errorCallback: onError });

然后，您通过 this 关键字在回调中访问 myObject:

function onPositionReady(position) {
    var myProperty = this.yourProperty;  // this now refers to myObject
    // Execute some more code with user's location
    // For Example...
    // Apply the position to the map
    var location = new Microsoft.Maps.Location(position.coords.latitude,
        position.coords.longitude);
    map.setView({ zoom: 18, center: location });

    // Add a pushpin to the map representing the current location
    var pin = new Microsoft.Maps.Pushpin(location);
    map.entities.push(pin);
}