在加载时显示点标签

Question

I want make something like this image我正在使用 Xamarin.Forms.GoogleMaps 插件。
我想默认显示我的 pin 标签，而不点击地图中的 pin。这可能吗？

Answer 1

你好像要默认打开 Pin 的信息窗口。

您可以使用 自定义渲染器 。并在特定平台上实现。

在共享项目中

创建自定义地图并固定

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

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

  
using Xamarin.Forms.Maps;

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

在 iOS 中

using MapKit;

namespace xxx.iOS
{
    public class CustomMKAnnotationView : MKAnnotationView
    {
        public string Name { get; set; }

        public string Url { get; set; }

        public CustomMKAnnotationView(IMKAnnotation annotation, string id)
            : base(annotation, id)
        {
        }
    }
}

using System;
using System.Collections.Generic;
using CoreGraphics;
using xxx;
using xxx.iOS;
using MapKit;
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Maps;
using Xamarin.Forms.Maps.iOS;
using Xamarin.Forms.Platform.iOS;

[assembly: ExportRenderer(typeof(CustomMap), typeof(CustomMapRenderer))]
namespace xxx.iOS
{
    public class CustomMapRenderer : MapRenderer
    {
        UIView customPinView;
        List<CustomPin> customPins;

        protected override void OnElementChanged(ElementChangedEventArgs<View> e)
        {
            base.OnElementChanged(e);

            if (e.NewElement != null)
            {
                var formsMap = (CustomMap)e.NewElement;
                var nativeMap = Control as MKMapView;
                customPins = formsMap.CustomPins;

               
                //add MapLoaded  Event
                nativeMap.MapLoaded += NativeMap_MapLoaded;
            }
        }

        private void NativeMap_MapLoaded(object sender, EventArgs e)
        {
            annotationView.SetSelected(true,true);
        }

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

在安卓中

using System;
using System.Collections.Generic;
using Android.Content;
using Android.Gms.Maps;
using Android.Gms.Maps.Model;
using Android.Widget;
using xxx;
using xxx.Droid;
using Xamarin.Forms;
using Xamarin.Forms.Maps;
using Xamarin.Forms.Maps.Android;

[assembly: ExportRenderer(typeof(CustomMap), typeof(CustomMapRenderer))]
namespace xxx.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.ShowInfoWindow(); 
            marker.SetIcon(BitmapDescriptorFactory.FromResource(Resource.Drawable.pin));
            return marker;
        }

        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;
        }
    }
}

这里有一个sample关于自定义pin，你可以了解更多关于如何自定义信息窗口的外观。