如何在Android中用图标更改xamarin.forms.maps标记

Question

我想用图标改变xamarin.forms.maps上的当前标记。

在我的项目中，我使用以下代码创建了CustomMap.cs类和CustomPin.cs类：

using System;
using System.Collections.Generic;
using Xamarin.Forms.Maps;

namespace MaritsaTundzhaForecast
{
    public class CustomMap : Map
    {
        public List<CustomPin> CustomPins { get; set; }
    }
}

using System;
using Xamarin.Forms.Maps;

namespace MaritsaTundzhaForecast
{
    public class CustomPin : Pin
    {
        public string Name { get; set; }
        public string Url { get; set; }
    }
}

之后，我用以下代码在xaml页面上设置了映射：

 <Grid>
  <Label Text="Forecast Maritza-Tundzha"
         HorizontalOptions="CenterAndExpand"
         FontSize="Large"
         FontAttributes="Bold"/>
    <Grid Margin="0,30,0,10">
        <Grid.RowDefinitions>
            <RowDefinition Height="400" />
        </Grid.RowDefinitions>

      <local:CustomMap x:Name="customMap"
               MapType="Street" />
    </Grid>
</Grid>

在cs文件中的同一个xaml页面中，我用以下代码在地图上设置了标记：

 public MainPage()
    {
        InitializeComponent();

        CustomPin pin = new CustomPin
        {
            Type = PinType.Place,
            Position = new Position(37.79752, -122.40183),
            Label = "Xamarin San Francisco Office",
            Address = "394 Pacific Ave, San Francisco CA",
            Name = "Xamarin",
            Url = "http://xamarin.com/about/"
        };
        customMap.CustomPins = new List<CustomPin> { pin };
        customMap.Pins.Add(pin);
        customMap.MoveToRegion(MapSpan.FromCenterAndRadius(new Position(37.79752, -122.40183), Distance.FromMiles(1.0)));
    }

现在我读了这个示例，我不知道如何以我的方式使用这个示例中的代码：

    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));
    return marker;
}

因此，我在drawable文件夹中设置了图标。我可以从这段代码中更改什么来使用不同的图标，以及是否需要在另一个类中更改代码？

А会尝试用另一个图标替换标准图标，结果失败了。

Answer 1

正如杰森所说，在您提供的链接中有完整的示例应用程序。示例地图应用程序

您需要在android项目文件夹中创建一个自定义地图呈现器，如下所示。创建一个名为CustomMapRenderer的类

[assembly: ExportRenderer(typeof(CustomMap),typeof(CustomMapRenderer))]
    namespace CustomRenderer.Droid
    {
        public class CustomMapRenderer : MapRenderer, GoogleMap.IInfoWindowAdapter
        {
            List<CustomPin> customPins;
    
            public CustomMapRenderer(Context context) : base(context)
            {
            }
    
            protected override void OnElementChanged(Xamarin.Forms.Platform.Android.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));
                return marker;
            }
    
            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);
                }
            }
    
            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;
            }
    
            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;
            }
        }
    }

如您所见，您在此呈现中提到的代码部分。您可以在这里更改图标。

    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);

///<---- Change icon here--->
        marker.SetIcon(BitmapDescriptorFactory.FromResource(Resource.Drawable.pin));
        return marker;
    }