如何在 Android 中使用图标更改 xamarin.forms.maps 标记

Question

我想用图标更改xamarin.forms.maps 上的当前标记。

在我的项目中，我使用以下代码创建 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，我使用以下代码在 xaml 页面上设置地图：

 <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 文件的同一个 xaml 页面中，我使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)));
    }

现在我读到了这个example，但我不知道如何以我的方式使用示例中的这段代码：

    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;
}

所以我将图标设置在drawable 文件夹中。我可以从这段代码中更改什么以使用不同的图标以及是否需要更改另一个类中的代码？

我整天都在尝试用另一个图标替换标准图标但失败了。

Answer 1

就像 jason 所说，您提供的链接中有完整的示例应用程序。Sample map app

您需要像这样在您的 android 项目文件夹中创建自定义地图渲染器。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;
            }
        }
    }

您可以看到您在此渲染中提到的代码部分。您可以在此处更改图标

    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;
    }