当注释的位置在自定义地图上可见时调用方法 Xamarin.Android

Question

这个post是这个的延续我需要为 Android 的 CustomMapRenderer 找到等效方法 Xamarin.Forms.Maps.iOS.MapRenderer.GetViewForAnnotation。对于此 documentation，当注释的位置在地图上可见时，将调用 iOS 的 GetViewForAnnotation 方法，并用于在显示之前自定义注释。我需要找到等效项，因为我想在我的地图上显示带有已展开 window 消息的图钉（无需单击它们）。

Answer 1

您可以在从自定义图钉中获取标记后直接显示信息窗口。

重写 CreateMarker 方法时添加以下代码。

NativeMap.AddMarker(marker).ShowInfoWindow();

Android 的全部自定义渲染器：

  public class CustomMapRenderer : MapRenderer, GoogleMap.IInfoWindowAdapter
{
    List<CustomPin> customPins;


    public CustomMapRenderer(Context context) : base(context)
    {
    }
    protected override void OnElementChanged(ElementChangedEventArgs<Map> e)
    {
        base.OnElementChanged(e);
        if (e.OldElement != null)
        {
            NativeMap.InfoWindowClick -= OnInfoWindowClick;
        }

        if (e.NewElement != null)
        {
            var formsMap = (CustomMap)e.NewElement;
            customPins = formsMap.CustomPins;
        }
    }


    protected override void OnMapReady(GoogleMap map)
    {
        base.OnMapReady(map);


        NativeMap.InfoWindowClick += OnInfoWindowClick;
        NativeMap.SetInfoWindowAdapter(this);

    }
    protected override MarkerOptions CreateMarker(Pin pin)
    {
        var marker = new MarkerOptions();
        marker.SetPosition(new LatLng(pin.Position.Latitude, pin.Position.Longitude));
        marker.SetTitle(pin.Label);
        marker.SetSnippet(pin.Address);
        marker.SetIcon(BitmapDescriptorFactory.FromResource(Resource.Drawable.pin));

        NativeMap.AddMarker(marker).ShowInfoWindow();

        return marker;
    }


    private void OnInfoWindowClick(object sender, GoogleMap.InfoWindowClickEventArgs e)
    {
        var customPin = GetCustomPin(e.Marker);
        if (customPin == null)
        {
            throw new Exception("Custom pin not found");
        }

        if (!string.IsNullOrWhiteSpace(customPin.Url))
        {
            var url = Android.Net.Uri.Parse(customPin.Url);
            var intent = new Intent(Intent.ActionView, url);
            intent.AddFlags(ActivityFlags.NewTask);
            Android.App.Application.Context.StartActivity(intent);
        }
    }

    CustomPin GetCustomPin(Marker annotation)
    {
        var position = new Position(annotation.Position.Latitude, annotation.Position.Longitude);
        foreach (var pin in customPins)
        {
            if (pin.Position == position)
            {
                return pin;
            }
        }
        return null;
    }

    public Android.Views.View GetInfoContents(Marker marker)
    {
        var inflater = Android.App.Application.Context.GetSystemService(Context.LayoutInflaterService) as Android.Views.LayoutInflater;
        if (inflater != null)
        {
            Android.Views.View view;

            var customPin = GetCustomPin(marker);
            if (customPin == null)
            {
                throw new Exception("Custom pin not found");
            }

            if (customPin.Name.Equals("Xamarin"))
            {
                view = inflater.Inflate(Resource.Layout.XamarinMapInfoWindow, null);
            }
            else
            {
                view = inflater.Inflate(Resource.Layout.MapInfoWindow, null);
            }

            var infoTitle = view.FindViewById<TextView>(Resource.Id.InfoWindowTitle);
            var infoSubtitle = view.FindViewById<TextView>(Resource.Id.InfoWindowSubtitle);

            if (infoTitle != null)
            {
                infoTitle.Text = marker.Title;
            }
            if (infoSubtitle != null)
            {
                infoSubtitle.Text = marker.Snippet;
            }

            return view;
        }
        return null;
    }

    public Android.Views.View GetInfoWindow(Marker marker)
    {

        return null;
    }
}

更多细节，您可以参考MS文档。 https://docs.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/custom-renderer/map-pin

当注释的位置在自定义地图上可见时调用方法 Xamarin.Android

Call method when the location of the annotation becomes visible on the custom map Xamarin.Android

xamarin

xamarin.android

xamarin.forms.maps