Xamarin Maps显示但不更新

Question

我正在尝试使用Xamarin表单制作Google地图，图钉会正确显示并放大到用户。 当页面开始时，它会显示初始地图，但是在移动或缩放地图时，地图不会发生变化；如果放大得足够大，它将变成网格。 我可以看到我的图钉在网格上以及所有东西上，但是我希望地图随图钉一起加载。

public partial class IssueMap2 : ContentPage
{
    public UIIssueVM Issue { get; set; }
    public GeoLocation Location { get; set; }

    public bool AllowPinMovment { get; set; }

    private ExtendedMap.ExtendedMap map;
    public Xamarin.Forms.Maps.Position OrgIssueLocation { get; set; }
    bool IsGettingLocation = false;




    bool bMapCtrlReady = false;
    IGeolocator Locator;

    public IssueMap2(UIIssueVM Issue, GeoLocation location)
    {
        AllowPinMovment = false;
        this.Issue = Issue;
        this.Location = location;
        Title = "Map";


        OrgIssueLocation = new Xamarin.Forms.Maps.Position(Issue.Latitude, Issue.Longitude);

        Locator = CrossGeolocator.Current;
        if (Locator.DesiredAccuracy != 100)
            Locator.DesiredAccuracy = 100;


        if (Device.RuntimePlatform != Device.WinPhone)
        {
            InitializeComponent();

            map = new ExtendedMap.ExtendedMap()
            {
                IsShowingUser = true,
                HeightRequest = 100,
                WidthRequest = 960,
                VerticalOptions = LayoutOptions.FillAndExpand
            };
            map.LongTap += OnMapLongTap;
            map.Ready += MapCtrlReady;
            slMap.Children.Add(map);
        }

    }

    public void MapCtrlReady(object sender, EventArgs args)
    {
        bMapCtrlReady = true;
    }

    public void OnMapLongTap(object sender, ExtendedMap.TapEventArgs args)
    {
        if (AllowPinMovment == false)
            return;

        if (Issue == null)
            return;

        var pos = args.Position;

        // Update Issue
        Issue.Latitude = pos.Latitude;
        Issue.Longitude = pos.Longitude;
        Issue.Changed = true;

        // Update Pin
        map.Pins.Clear();
        AddPin(pos, Issue.Title, Issue.Description);
    }

    protected void AddPin(Xamarin.Forms.Maps.Position pos, String Title, String Desc)
    {
        // MAP pin does not like it if labels are empty
        if (Title.Length == 0)
            Title = "-";

        if (Desc.Length == 0)
            Desc = "-";

        var pin = new Pin
        {
            Type = PinType.Place,
            Position = pos,
            Label = Title,
            Address = Desc
        };
        map.Pins.Add(pin);
    }
    protected override void OnAppearing()
    {
        if (Device.RuntimePlatform == Device.WinPhone)
        {
            aActIndicator.IsRunning = false;
            aActIndicator.IsVisible = false;

            if (Issue.IsNew == false)
            {
                var position = new Xamarin.Forms.Maps.Position(Issue.Latitude, Issue.Longitude);
                AddPin(position, Issue.Title, Issue.Description);
                MoveToPinLocation();
            }
            else // Issue is new
            {
                // Move to main location
                map.MoveToRegion(MapSpan.FromCenterAndRadius(new Xamarin.Forms.Maps.Position(Location.Latitude, Location.Longitude), Distance.FromMiles(1)));
                // Get current location for new item
                OnGetLocation();

            }
        }
    }


    protected override async void OnDisappearing()
    {
        if (Locator.IsListening)
        {
            await Locator.StopListeningAsync();
        }

        // Map controller crashes sometimes if we are to quick with exiting
        await Task.Delay(500);

        while (bMapCtrlReady == false)
        {
            await Task.Delay(500);
        }
    }

    void OnButtonCenter(object sender, EventArgs args)
    {
        MoveToPinLocation();
    }

    void MoveToPinLocation()
    {
        double KmDistace = 0.5;

        if (Issue != null)
        {
            map.MoveToRegion(MapSpan.FromCenterAndRadius(new Xamarin.Forms.Maps.Position(Issue.Latitude, Issue.Longitude), Distance.FromKilometers(KmDistace)));
        }
        else
            map.MoveToRegion(MapSpan.FromCenterAndRadius(new Xamarin.Forms.Maps.Position(Location.Latitude, Location.Longitude), Distance.FromKilometers(KmDistace)));

    }

    void OnButtonMainLocation(object sender, EventArgs args)
    {
        double KmDistace = 0.5;
        map.MoveToRegion(MapSpan.FromCenterAndRadius(new Xamarin.Forms.Maps.Position(Location.Latitude, Location.Longitude), Distance.FromKilometers(KmDistace)));
    }

    void OnButtonGetLocation(object sender, EventArgs args)
    {
        OnGetLocation();
    }

    async void OnGetLocation()
    {
        if (IsGettingLocation == true)
            return; // already getting location

        try
        {
            if (Locator.IsListening == true)
            {
                await Locator.StopListeningAsync();
            }

            if (Locator.IsGeolocationAvailable == false)
            {
                lbPosText.Text = "GeoLocation is not available.";
                this.ForceLayout();
                return;
            }

            if (Locator.IsGeolocationEnabled == false)
            {
                lbPosText.Text = "GeoLocation is not enabled.";
                this.ForceLayout();
                return;
            }

            IsGettingLocation = true;

            IsBusy = true;
            slCommands.IsVisible = false;
            aActIndicator.IsVisible = true;
            aActIndicator.IsRunning = true;
            lbPosText.Text = "Searching for GPS location...";
            this.ForceLayout();

            TimeSpan timeSpan = TimeSpan.FromTicks(120 * 1000);
            var position = await Locator.GetPositionAsync(timeSpan);

            // Update Issue Position
            Issue.Latitude = position.Latitude;
            Issue.Longitude = position.Longitude;
            Issue.Changed = true;


            // Update Pin Postion
            var pos = new Xamarin.Forms.Maps.Position(Issue.Latitude, Issue.Longitude);
            map.Pins.Clear();
            AddPin(pos, Issue.Title, Issue.Description);

            UpdateGPSLocationText();

            aActIndicator.IsRunning = false;
            aActIndicator.IsVisible = false;
            IsGettingLocation = false;
            IsBusy = false;
            slCommands.IsVisible = true;
            this.ForceLayout();
            // Center map around pin
            MoveToPinLocation();
        }
        catch (Exception /*ex*/)
        {
            aActIndicator.IsRunning = false;
            aActIndicator.IsVisible = false;
            IsGettingLocation = false;
            IsBusy = false;
            slCommands.IsVisible = true;
            lbPosText.Text = "Unable to find position!";
            lbPosText.IsVisible = true;
            this.ForceLayout();
        }
    }

    void UpdateGPSLocationText()
    {
        String text = String.Format("{0} x {1}", Issue.Longitude, Issue.Latitude);
        lbPosText.Text = text;
    }



}

}

Android扩展地图渲染器

[assembly: ExportRenderer(typeof(ExtendedMap.ExtendedMap), typeof(ExtendedMapRenderer))]
namespace ExtendedMap.Android
{
    public class ExtendedMapRenderer : MapRenderer, IOnMapReadyCallback
    {
        private GoogleMap _map;

        public ExtendedMapRenderer()
        {
        }

        public ExtendedMapRenderer(IntPtr javaReference, JniHandleOwnership jniHandleOwnership)
        {

            int x = 0;
            x++;
        }

        private void InvokeOnMapReadyBaseClassHack(GoogleMap googleMap)
        {
            System.Reflection.MethodInfo onMapReadyMethodInfo = null;

            Type baseType = typeof(MapRenderer);
            foreach (var currentMethod in baseType.GetMethods(System.Reflection.BindingFlags.NonPublic |
                                                             System.Reflection.BindingFlags.Instance |
                                                              System.Reflection.BindingFlags.DeclaredOnly))
            {

                if (currentMethod.IsFinal && currentMethod.IsPrivate)
                {
                    if (string.Equals(currentMethod.Name, "OnMapReady", StringComparison.Ordinal))
                    {
                        onMapReadyMethodInfo = currentMethod;

                        break;
                    }

                    if (currentMethod.Name.EndsWith(".OnMapReady", StringComparison.Ordinal))
                    {
                        onMapReadyMethodInfo = currentMethod;

                        break;
                    }
                }
            }

            if (onMapReadyMethodInfo != null)
            {
                onMapReadyMethodInfo.Invoke(this, new[] { googleMap });
            }
        }


        void IOnMapReadyCallback.OnMapReady(GoogleMap googleMap)
        {
            InvokeOnMapReadyBaseClassHack(googleMap);
            _map = googleMap;
            if (_map != null)
            {
                _map = googleMap;
                this.NativeMap = googleMap;
                _map.MapClick += googleMap_MapClick;
                _map.MapLongClick += googleMap_MapLongClick;

                ((ExtendedMap)Element).OnReady();
            }
        }
        protected override void OnElementChanged(ElementChangedEventArgs<Map> e)
        {
            if (_map != null)
                _map.MapClick -= googleMap_MapClick;
            base.OnElementChanged(e);
            if (Control != null)
                ((MapView)Control).GetMapAsync(this);
        }

        private void googleMap_MapClick(object sender, GoogleMap.MapClickEventArgs e)
        {
            ((ExtendedMap)Element).OnTap(new Position(e.Point.Latitude, e.Point.Longitude));
        }


        private void googleMap_MapLongClick(object sender, GoogleMap.MapLongClickEventArgs e)
        {
            ((ExtendedMap)Element).OnLongTap(new Position(e.Point.Latitude, e.Point.Longitude));
        }
    }
}

Answer 1

我会仔细检查您应用程序清单中的Google Maps API密钥！

<meta-data android:name="com.google.android.maps.v2.API_KEY" android:value="AIzr3yCpVgSOXvTgri29nC6KqFbdO73QmoVQWEw" />

以及您在Google API凭据信息中心上的密钥库的SHA-1密钥。