问题描述
在我正在使用的其中一个应用程序中，我需要使用自定义地图图钉，并且已遵循Xamarin上的指南"> https://developer.xamarin.com/guides/xamarin-forms/application-fundamentals/custom-renderer/map/customized -pin/，并借用了示例代码来尝试创建自己的示例.
In one of the apps I'm working on I require the use of custom map pins and I've followed the guide on Xamarin https://developer.xamarin.com/guides/xamarin-forms/application-fundamentals/custom-renderer/map/customized-pin/ as well as borrowed their sample code to try and make my own example.
在某种程度上可以使信息窗口实际更新为自定义布局，但是地图图钉永远不会改变.
It works to a degree in such that the info window is actually updated to the custom layout but the map pin never changes.
我的CustomMapRenderer:
My CustomMapRenderer:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using Android.Content;
using Android.Gms.Maps;
using Android.Gms.Maps.Model;
using Android.Widget;
using Xamarin.Forms;
using Xamarin.Forms.Maps;
using Xamarin.Forms.Maps.Android;
using WorkingWithMaps.Droid.Renderers;
using WorkingWithMaps;
[assembly: ExportRenderer(typeof(CustomMap), typeof(CustomMapRenderer))]
namespace WorkingWithMaps.Droid.Renderers
{
public class CustomMapRenderer : MapRenderer, GoogleMap.IInfoWindowAdapter, IOnMapReadyCallback
{
GoogleMap map;
List<CustomPin> customPins;
bool isDrawn;
protected override void OnElementChanged(Xamarin.Forms.Platform.Android.ElementChangedEventArgs<Map> e)
{
base.OnElementChanged(e);
if (e.OldElement != null)
{
map.InfoWindowClick -= OnInfoWindowClick;
}
if (e.NewElement != null)
{
var formsMap = (CustomMap)e.NewElement;
customPins = formsMap.CustomPins;
((MapView)Control).GetMapAsync(this);
}
}
void IOnMapReadyCallback.OnMapReady(GoogleMap googleMap)
{
map = googleMap;
map.SetInfoWindowAdapter(this);
map.InfoWindowClick += OnInfoWindowClick;
this.NativeMap = googleMap;
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (e.PropertyName.Equals("VisibleRegion") && !isDrawn)
{
map.Clear();
foreach (var pin in customPins)
{
var marker = new MarkerOptions();
marker.SetPosition(new LatLng(pin.Pin.Position.Latitude, pin.Pin.Position.Longitude));
marker.SetTitle(pin.Pin.Label);
marker.SetSnippet(pin.Pin.Address);
marker.SetIcon(BitmapDescriptorFactory.FromResource(Resource.Drawable.pin));
map.AddMarker(marker);
}
isDrawn = true;
}
}
protected override void OnLayout(bool changed, int l, int t, int r, int b)
{
base.OnLayout(changed, l, t, r, b);
if (changed)
{
isDrawn = false;
}
}
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.Id == "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.Pin.Position == position)
{
return pin;
}
}
return null;
}
}
}
和我的地图页面，也大量借鉴了Xamarin的使用地图指南"
and my map page, also heavily borrowed from Xamarin's working with maps guide
using Plugin.Geolocator;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using Xamarin.Forms;
using Xamarin.Forms.Maps;
using Xamarin.Forms.Xaml;
namespace WorkingWithMaps
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class MainPage : ContentPage
{
CustomMap map;
Geocoder geoCoder;
String navAdd;
public MainPage()
{
InitializeComponent();
var maplocator = CrossGeolocator.Current;
maplocator.DesiredAccuracy = 1;
geoCoder = new Geocoder();
map = new CustomMap
{
HeightRequest = 100,
WidthRequest = 960,
VerticalOptions = LayoutOptions.FillAndExpand,
IsShowingUser = true
};
map.MapType = MapType.Street;
map.MoveToRegion(MapSpan.FromCenterAndRadius(new Position(55.237208, 10.479160), Distance.FromMeters(500)));
map.IsShowingUser = true;
var street = new Button { Text = "Street" };
var hybrid = new Button { Text = "Hybrid" };
var satellite = new Button { Text = "Satellite" };
street.Clicked += HandleClickedAsync;
hybrid.Clicked += HandleClickedAsync;
//satellite.Clicked += OnReverseGeocodeButtonClicked;
var segments = new StackLayout
{
Spacing = 30,
HorizontalOptions = LayoutOptions.CenterAndExpand,
Orientation = StackOrientation.Horizontal,
Children = { street, hybrid, satellite }
};
Content = new StackLayout
{
HorizontalOptions = LayoutOptions.Center,
Children = { map, segments }
};
Device.BeginInvokeOnMainThread(async () =>
{
try
{
//var currentpos = await maplocator.GetPositionAsync(1000);
//map.MoveToRegion(MapSpan.FromCenterAndRadius(new Position(currentpos.Latitude, currentpos.Longitude), Distance.FromMeters(500)));
if (!maplocator.IsListening)
{
await maplocator.StartListeningAsync(1000, 50, true);
}
}
catch (Exception ex)
{
Debug.WriteLine("Fail" + ex);
}
});
var pin = new CustomPin
{
Pin = new Pin
{
Type = PinType.Place,
Position = new Position(55.240121, 10.469895),
Label = "Testing Pins"
}
};
map.CustomPins = new List<CustomPin> { pin };
map.Pins.Add(pin.Pin);
map.PropertyChanged += (sender, e) =>
{
Debug.WriteLine(e.PropertyName + " just changed!");
if (e.PropertyName == "VisibleRegion" && map.VisibleRegion != null)
CalculateBoundingCoordinates(map.VisibleRegion);
};
maplocator.PositionChanged += (sender, e) =>
{
var position = e.Position;
map.MoveToRegion(MapSpan.FromCenterAndRadius(new Position(position.Latitude, position.Longitude), Distance.FromKilometers(2)));
};
}
/// <summary>
///
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
//async void OnReverseGeocodeButtonClicked(object sender, EventArgs e)
//{
// var possibleAddresses = await geoCoder.GetAddressesForPositionAsync(pin.Position);
// navAdd += possibleAddresses.ElementAt(0) + "\n";
// switch (Device.OS)
// {
// case TargetPlatform.iOS:
// Device.OpenUri(new Uri(string.Format("http://maps.apple.com/?q={0}", WebUtility.UrlEncode(navAdd))));
// break;
// case TargetPlatform.Android:
// Device.OpenUri(new Uri(string.Format("geo:0,0?q={0}", WebUtility.UrlEncode(navAdd))));
// break;
// case TargetPlatform.Windows:
// case TargetPlatform.WinPhone:
// Device.OpenUri(new Uri(string.Format("bingmaps:?where={0}", Uri.EscapeDataString(navAdd))));
// break;
// }
//}
void HandleClickedAsync(object sender, EventArgs e)
{
var b = sender as Button;
switch (b.Text)
{
case "Street":
map.MapType = MapType.Street;
break;
case "Hybrid":
map.MapType = MapType.Hybrid;
break;
case "Satellite":
map.MapType = MapType.Satellite;
break;
}
}
static void CalculateBoundingCoordinates(MapSpan region)
{
var center = region.Center;
var halfheightDegrees = region.LatitudeDegrees / 2;
var halfwidthDegrees = region.LongitudeDegrees / 2;
var left = center.Longitude - halfwidthDegrees;
var right = center.Longitude + halfwidthDegrees;
var top = center.Latitude + halfheightDegrees;
var bottom = center.Latitude - halfheightDegrees;
if (left < -180) left = 180 + (180 + left);
if (right > 180) right = (right - 180) - 180;
Debug.WriteLine("Bounding box:");
Debug.WriteLine(" " + top);
Debug.WriteLine(" " + left + " " + right);
Debug.WriteLine(" " + bottom);
}
}
}
除了上述问题之外，该实现还导致IsShowingUser = True不再正常运行
On top of the mentioned issue the implementation has also caused IsShowingUser = True to no longer function as well as
var currentpos = await maplocator.GetPositionAsync(1000);
引发异常.
Github存储库: https://github.com/Mortp/CustomMapPinsXamarin
Github repository: https://github.com/Mortp/CustomMapPinsXamarin
推荐答案
首先，我想提供2个链接来帮助我理解问题.感谢大伙们. Xamarin.Forms.Maps 2.3.4自定义MapRenderer会禁用所有功能和 https://forums.xamarin .com/discussion/92565/android-ionmapreadycallback-forms-2-3-4
First of all I would like to provide 2 links that helped me to understand the problem. Thank you guys.Xamarin.Forms.Maps 2.3.4 custom MapRenderer disables everything and https://forums.xamarin.com/discussion/92565/android-ionmapreadycallback-forms-2-3-4
最新的Xamarin Maps通过VisibleRegion破坏了OnElementPropertyChanged.他们定义了MapRenderer现在实现了IOnMapReadyCallback，这在某种程度上打破了OnElementPropertyChanged(我没有研究如何以及为什么).如您在我提供的链接中所见，您可以使用2种方法.保持渲染器实现IOnMapReadyCallback或不实现.当我保留IOnMapReadyCallback时，我开始获得2个引脚-一个是另一个-我们的自定义引脚和常规引脚.我没有进一步研究这种情况如何，并删除了IOnMapReadyCallback.之后，事情变得非常简单，因为如果让Xamarin处理它并创建NativeMap，则可以删除一些代码并使渲染器更简单.
Latest Xamarin Maps broke OnElementPropertyChanged with VisibleRegion. They defined that MapRenderer now implements IOnMapReadyCallback and that broke somehow OnElementPropertyChanged (I didn't investigate how and why). As you can see in link I provided there are 2 methods you can go. To keep your renderer implementing IOnMapReadyCallback or not. When I kept IOnMapReadyCallback I started to get 2 pins - one of top another - our custom pin and regular pin. I didn't dig more how that happens and removed IOnMapReadyCallback. After that things became really simple because if you let Xamarin handle it and create NativeMap you can remove some code and make renderer simpler.
在发布代码之前，我还想提及一下，当我对其进行修复时，该应用程序因OutOfMemory异常而崩溃，并且我发现您的图钉图像的宽度为2000像素.我将其更改为40.下面是代码:
Before I post the code I also want to mention that when I fixed it the app started crashing with OutOfMemory exception and I found out that your pin image is 2000 pixels width. I changed it to 40. Below is the code:
public class CustomMapRenderer : MapRenderer, GoogleMap.IInfoWindowAdapter//, IOnMapReadyCallback
{
bool isDrawn;
protected override void OnElementChanged(Xamarin.Forms.Platform.Android.ElementChangedEventArgs<Map> e)
{
base.OnElementChanged(e);
if (e.OldElement != null)
{
NativeMap.InfoWindowClick -= OnInfoWindowClick;
}
}
bool isMapReady;
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (!isMapReady && (NativeMap != null))
{
NativeMap.SetInfoWindowAdapter(this);
NativeMap.InfoWindowClick += OnInfoWindowClick;
isMapReady = true;
}
if (e.PropertyName.Equals("VisibleRegion") && !isDrawn)
{
NativeMap.Clear();
foreach (var pin in ((CustomMap)Element).CustomPins)
{
var marker = new MarkerOptions();
marker.SetPosition(new LatLng(pin.Pin.Position.Latitude, pin.Pin.Position.Longitude));
marker.SetTitle(pin.Pin.Label);
marker.SetSnippet(pin.Pin.Address);
marker.SetIcon(BitmapDescriptorFactory.FromResource(Resource.Drawable.pin));
NativeMap.AddMarker(marker);
}
isDrawn = true;
}
}
protected override void OnLayout(bool changed, int l, int t, int r, int b)
{
base.OnLayout(changed, l, t, r, b);
if (changed)
{
isDrawn = false;
}
}
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.Id == "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 ((CustomMap)Element).CustomPins)
{
if (pin.Pin.Position == position)
{
return pin;
}
}
return null;
}
}
这篇关于Xamarin表单自定义地图图钉的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！