MVVM Windows Phone 8-将图钉集合添加到地图中

Question

这是XAML代码：

<maps:Map x:Name="NearbyMap" 
                  Center="{Binding MapCenter, Mode=TwoWay}"
                  ZoomLevel="{Binding ZoomLevel, Mode=TwoWay}"
              >
        <maptk:MapExtensions.Children>
            <maptk:MapItemsControl Name="StoresMapItemsControl" ItemsSource="{Binding Treks}">
                <maptk:MapItemsControl.ItemTemplate>
                    <DataTemplate>
                        <maptk:Pushpin x:Name="RouteDirectionsPushPin" GeoCoordinate="{Binding Location}" Visibility="Visible" Content="test"/>
                    </DataTemplate>
                </maptk:MapItemsControl.ItemTemplate>
            </maptk:MapItemsControl>
            <maptk:UserLocationMarker x:Name="UserLocationMarker" Visibility="Visible" GeoCoordinate="{Binding MyLocation}"/>
        </maptk:MapExtensions.Children>
    </maps:Map>
xmlns:maps="clr-namespace:Microsoft.Phone.Maps.Controls;assembly=Microsoft.Phone.Maps"
xmlns:maptk="clr-namespace:Microsoft.Phone.Maps.Toolkit;assembly=Microsoft.Phone.Controls.Toolkit"

PushPinModel有一个属性Location，它是一个GeoCoordinateTreks是一个ObservableCollection<PushPinModel>。我运行此代码，只显示UserLocationMarker，这是我的当前位置。

Answer 1

我最终通过使用依赖属性使其工作。我添加了一个新类：

public static class MapPushPinDependency
{
    public static readonly DependencyProperty ItemsSourceProperty =
            DependencyProperty.RegisterAttached(
             "ItemsSource", typeof(IEnumerable), typeof(MapPushPinDependency),
             new PropertyMetadata(OnPushPinPropertyChanged));
    private static void OnPushPinPropertyChanged(DependencyObject d,
            DependencyPropertyChangedEventArgs e)
    {
        UIElement uie = (UIElement)d;
        var pushpin = MapExtensions.GetChildren((Map)uie).OfType<MapItemsControl>().FirstOrDefault();
        pushpin.ItemsSource = (IEnumerable)e.NewValue;
    }

    #region Getters and Setters
    public static IEnumerable GetItemsSource(DependencyObject obj)
    {
        return (IEnumerable)obj.GetValue(ItemsSourceProperty);
    }
    public static void SetItemsSource(DependencyObject obj, IEnumerable value)
    {
        obj.SetValue(ItemsSourceProperty, value);
    }
    #endregion
}

在.xaml文件中，我添加了

xmlns:dp="clr-namespace:Treks.App.Util.DependencyProperties"

现在.xaml文件看起来是这样的：

<maps:Map x:Name="NearbyMap" 
                  Center="{Binding MapCenter, Mode=TwoWay}"
                  ZoomLevel="{Binding ZoomLevel, Mode=TwoWay}"
                  dp:MapPushPinDependency.ItemsSource="{Binding Path=Treks}"
              >
        <maptk:MapExtensions.Children>
            <maptk:MapItemsControl Name="StoresMapItemsControl">
                <maptk:MapItemsControl.ItemTemplate>
                    <DataTemplate>
                        <maptk:Pushpin x:Name="PushPins" GeoCoordinate="{Binding Location}" Visibility="Visible" Content="test"/>
                    </DataTemplate>
                </maptk:MapItemsControl.ItemTemplate>
            </maptk:MapItemsControl>
            <maptk:UserLocationMarker x:Name="UserLocationMarker" Visibility="Visible" GeoCoordinate="{Binding MyLocation}"/>
        </maptk:MapExtensions.Children>
    </maps:Map>

现在，所有图钉都已正确渲染。

Answer 2

MapItemsControl目前还不能绑定MVVM(据我所知(。所以最好的方法是在视图的代码后面设置它的ItemsSource。

不过，您仍然可以使用ViewModel中定义的集合！选项包括：

• 通过mvvm消息传递将集合从视图模型传递到视图的代码后面
• 使用视图的datacontext访问集合，如下所示：this.StoresMapItemsControl.ItemsSource = ServiceLocator.Current.GetInstance<MainViewModel>().Locations;