Question

我正在尝试将图钉添加到Bing地图中。推针来自JSON提要。我想得到这样的东西： enter image description here 我的代码单独第一次不起作用，我不明白为什么。我的地图ViewModel是

public class MapViewModel : INotifyPropertyChanged
{
    public static ObservableCollection<PushpinModel> pushpins = new ObservableCollection<PushpinModel>();
    public static ObservableCollection<PushpinModel> Pushpins 
    {
            get { return pushpins; } 
        set { pushpins = value; } 
    }
}

Map xaml cs是：

//Map.xaml.cs
public partial class Map : PhoneApplicationPage
{
    #define DEBUG_AGENT
    private IGeoPositionWatcher<GeoCoordinate> watcher;
    private MapViewModel mapViewModel;

    public Map()
    {
        InitializeComponent();
        mapViewModel = new MapViewModel();
        this.DataContext = mapViewModel;
    }

    private void page_Loaded(object sender, RoutedEventArgs e)
    {
        if (watcher == null)
        {

    #if DEBUG_AGENT
            watcher = new Shoporific.My.FakeGPS();
    #else      
            watcher = new GeoCoordinateWatcher(GeoPositionAccuracy.Default);
    #endif
        }
        watcher.Start();

        mapViewModel.Center = watcher.Position.Location;
        PushpinModel myLocation = new PushpinModel() { Location = mapViewModel.Center, Content = "My Location" };
        MapViewModel.Pushpins.Add(myLocation);
        myLocation.RefreshNearbyDeals();
        watcher.Stop();
    }
}

最后，PushPinModelClass：

public class PushPinModel
{
    public void RefreshNearbyDeals()
    {
        System.Net.WebClient wc = new WebClient();
        wc.OpenReadCompleted += wc_OpenReadCompleted;
        wc.OpenReadAsync(" a valid uri");
    }

    void wc_OpenReadCompleted(object sender, System.Net.OpenReadCompletedEventArgs e)
    {
        var jsonStream = e.Result;
        DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(Deal[]));
        Deal[] deals = (ser.ReadObject(jsonStream) as Deal[]);

        if (deals.Any())
        {
                var currentLocation = MapViewModel.Pushpins.Where(pin => pin.Content == "My Location");
                MapViewModel.Pushpins = new ObservableCollection<PushpinModel>();
                foreach (var deal in deals)
                    MapViewModel.Pushpins.Add(new PushpinModel()
                    {
                        Content = deal.Store,
                        Location = new GeoCoordinate(deal.Location.Latitude, deal.Location.Longtitude),
                        Offers = deal.Offers,
                    });

        }
    }
}

我有点困惑，除了“我的位置”之外的Pushpins不会仅在第一次出现。它们第二次出现时是预期的（如果我向后导航然后再次移动到地图屏幕）。

Answer 1

在wc_OpenReadCompleted内，您正在重新实例化MapViewModel.Pushpins。

仅将构造函数调用ObservableCollection一次（在MainViewModel内）。再次调用它会弄乱我假设你在xaml页面中的绑定。

我相信你应该删除PushpinViewModel中的那一行，或者改为调用MainViewModel.Pushpins.Clear()（取决于你想要完成的事情）。

在Bing地图中添加PushPins

1 个答案: