我使用MVVMCross用GoogleMaps开发了简单的Xamarin.Forms应用程序。我的目标是在启动 map 时将 map 的位置居中到用户的当前位置。不幸的是,我不知道如何将这些值绑定(bind)到GoogleMaps的构造函数。现在它只是静态值,但我想从CurrentLocation对象(具有这些属性)传递纬度和经度值。
看法:
<ContentPage.Content>
<maps:Map MapType="Street" IsShowingUser="True" HasZoomEnabled="True">
<x:Arguments>
<maps:MapSpan>
<x:Arguments>
<maps:Position>
<x:Arguments>
<x:Double>56.368533</x:Double>
<x:Double>3.258646</x:Double>
</x:Arguments>
</maps:Position>
<x:Double>0.01</x:Double>
<x:Double>0.01</x:Double>
</x:Arguments>
</maps:MapSpan>
</x:Arguments>
</maps:Map>
</ContentPage.Content>
这是我的ViewModel的一部分:
public class NearbyBollardsMapViewModel : MvxViewModel
{
private Location _currentLocation;
public Location CurrentLocation
{
get => _currentLocation;
set
{
_currentLocation = value;
RaisePropertyChanged(() => CurrentLocation);
}
}
public NearbyBollardsMapViewModel(ILocationService locationService)
{
this._locationService = locationService;
CurrentLocation = _locationService.GetCurrentUsersLocation().Result;
}
}
最佳答案
您需要创建一个从Maps扩展的PCL类,并向其中添加BlindableProperty。
1º-创建一个类,并从Xamarin.Forms.Maps.Map进行扩展
(我包括了Bindable属性的代码,您可以阅读更多Here)
public class BindableMap : Xamarin.Forms.Maps.Map
{
public BindableMap()
{
}
public MapSpan MapSpan
{
get { return (MapSpan)GetValue(MapSpanProperty); }
set { SetValue(MapSpanProperty, value); }
}
public static readonly BindableProperty MapSpanProperty = BindableProperty.Create(
propertyName: "MapSpan",
returnType: typeof(MapSpan),
declaringType: typeof(BindableProspectDetailMap),
defaultValue: null,
defaultBindingMode: BindingMode.TwoWay,
validateValue: null,
propertyChanged: MapSpanPropertyChanged);
private static void MapSpanPropertyChanged(BindableObject bindable, object oldValue, object newValue)
{
try
{
var thisInstance = bindable as BindableProspectDetailMap;
var newMapSpan = newValue as MapSpan;
thisInstance?.MoveToRegion(newMapSpan);
}
catch (Exception ex)
{
}
}
}
2º-在ViewModel中添加将用于绑定(bind)MapSpan的属性
private MapSpan _mapSpanView;
public MapSpan MapSpanView
{
get { return _mapSpanView; }
set { SetProperty(ref _mapSpanView, value); }
}
...
Position position = new Position((double)Latitude, (double)Longitude);
MapSpanView = MapSpan.FromCenterAndRadius(
prospectPosition,
Distance.FromMeters(2500)
);
3º-然后将其绑定(bind)到xaml中
xmlns:map="clr-namespace:YourNameSpace.Mobile.TheFolderWhereTheClassIs"
...
<StackLayout x:Name="mapHolder">
<map:BindableMap
x:Name="map"
MapSpan="{Binding MapSpanView}"
MapType="Street" IsShowingUser="True" HasZoomEnabled="True"/>
</StackLayout>
关于c# - 将构造函数参数绑定(bind)到Xamarin.Forms的GoogleMaps,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/60515196/