Xamarin Android和街景API

Question

我是Xamarin的新手。我正在使用StreetView API进行项目：打开应用程序时，我想查看设备位置的街景视图。

也许正在运行。但是我想编写一个方法，当没有设备位置的街景视图时，返回一个带有“此处没有街景视图”的吐司。

有我的代码：

MainActivity.cs

using Android.App;

using Android.Support.V7.App;
using Android.Runtime;
using Android.Widget;
using Android.Gms.Maps;
using Android.Gms.Maps.Model;
using Android;
using Android.Content.PM;
using Android.Views;
using Android.OS;
using Xamarin.Essentials;
using System;

namespace StreetView
{
    [Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]
    public class MainActivity : AppCompatActivity, IOnStreetViewPanoramaReadyCallback
    {
        const int RequestLocationId = 0;
        public double latitude;
        public double longitude;

        readonly string[] LocationPermissions =
        {
        Manifest.Permission.AccessCoarseLocation,
        Manifest.Permission.AccessFineLocation
        };
        StreetViewPanoramaView streetViewPanoramaView;
        StreetViewPanorama streetPanorama;
        LatLng latlng;

        public void OnStreetViewPanoramaReady(StreetViewPanorama panorama)
        {
            this.streetPanorama = panorama;
            streetPanorama.UserNavigationEnabled = true;
            streetPanorama.StreetNamesEnabled = true;
            streetPanorama.PanningGesturesEnabled = true;
            streetPanorama.ZoomGesturesEnabled = true;

            Console.WriteLine("Coordinate: " + latlng);
            streetPanorama.SetPosition(latlng);

            /*
            if (streetPanorama.SetPosition(latlng) == ) 
            {
                Console.WriteLine("panorama location: " + panorama);
                Toast.MakeText(this, "Position...", ToastLength.Long).Show();
                streetPanorama.SetPosition(latlng);
            } else
            {
                Console.WriteLine("panorama location: " + panorama);
                Toast.MakeText(this, "There isn't StreetView here", ToastLength.Long).Show();
            }*/




        }


        public override void OnWindowFocusChanged(bool hasFocus)
        {
            base.OnWindowFocusChanged(hasFocus);
            if (hasFocus && (int)Build.VERSION.SdkInt >= 19)
            {
                Window.DecorView.SystemUiVisibility =
                  (StatusBarVisibility)(SystemUiFlags.LayoutStable
                    | SystemUiFlags.HideNavigation
                    | SystemUiFlags.LayoutFullscreen
                    | SystemUiFlags.Fullscreen
                    | SystemUiFlags.ImmersiveSticky);
            }
        }

        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Permission[] grantResults)
        {
            if (requestCode == RequestLocationId)
            {
                if ((grantResults.Length == 1) && (grantResults[0] == (int)Permission.Granted))
                {
                    // Permissions granted - display a message.
                }
                else
                {
                    base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
                }
            }
        }

        async System.Threading.Tasks.Task GetPositionAsync()
        {
            try
            {
                var location = await Geolocation.GetLastKnownLocationAsync();

                if (location != null)
                {
                    latitude = location.Latitude;
                    longitude = location.Longitude;


                }
            }
            catch (FeatureNotSupportedException fnsEx)
            {
                // Handle not supported on device exception
            }
            catch (FeatureNotEnabledException fneEx)
            {
                // Handle not enabled on device exception
            }
            catch (PermissionException pEx)
            {
                // Handle permission exception
            }
            catch (Exception ex)
            {
                // Unable to get location
            }
        }

        protected override void OnCreate(Bundle bundle)
        {
            GetPositionAsync();
            Console.WriteLine("Latitudine" + latitude + "Longitudine" + longitude);

            if (CheckSelfPermission(Manifest.Permission.AccessCoarseLocation) != (int)Permission.Granted)
            {
                RequestPermissions(new string[] { Manifest.Permission.AccessCoarseLocation, Manifest.Permission.AccessFineLocation }, 0);
            }




            base.OnCreate(bundle);
            SetContentView(Resource.Layout.activity_main);
            var lat = Intent.GetDoubleExtra("ltd", latitude);
            var lng = Intent.GetDoubleExtra("lng", longitude);

            //create LatLng to display
            latlng = new LatLng(lat, lng);
            //find our panorama view and create async.
            streetViewPanoramaView = FindViewById<StreetViewPanoramaView>(Resource.Id.panorama);

            streetViewPanoramaView.OnCreate(bundle);
            streetViewPanoramaView.GetStreetViewPanoramaAsync(this);
        }
    }
 }

在Android中，这是方法：（我的梦想）

@Override
public void onStreetViewPanoramaReady(StreetViewPanorama streetViewPanorama) {
    mPanorama.setOnStreetViewPanoramaChangeListener(new StreetViewPanorama.OnStreetViewPanoramaChangeListener() {
        @Override
        public void onStreetViewPanoramaChange(StreetViewPanoramaLocation streetViewPanoramaLocation) {
            if (streetViewPanoramaLocation != null && streetViewPanoramaLocation.links != null) {
                // location is present
            } else {
                // location not available
            }
        }
    });

任何人都可以帮助我在Xamarin和我的项目中编写此方法吗？

非常感谢！

Answer 1

在C＃中，您的Java方法如下所示。将其添加到您的OnStreetViewPanoramaReady()方法：

panorama.StreetViewPanoramaChange += (sender, args) =>
{
    if (args.Location != null && args.Location.Links != null)
    {
        // location is present
    }
    else
    {
        // location not available
    }
};

通常，在Xamarin世界中，使用C＃事件代替Java侦听器模式。当然，通过使用SetOnStreetViewPanoramaChangeListener()对象的panorama方法并实现StreetViewPanorama.IOnStreetViewPanoramaChangeListener接口，您也可以采用侦听器的方式。由于当前在C＃中，您无法像在Java中那样使用匿名类型实现接口，因此使用事件仍然是最优雅，最合理的解决方案。