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using System;
using System.ComponentModel;
using System.Linq;
using System.Reflection;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.UI.Xaml;
#if WINDOWS_UWP
namespace Xamarin.Forms.Platform.UWP
#else
namespace Xamarin.Forms.Platform.WinRT
#endif
{
class NativeEventWrapper : INotifyPropertyChanged
{
static string TargetProperty { get; set; }
static readonly MethodInfo s_handlerinfo = typeof(NativeEventWrapper).GetRuntimeMethods().Single(mi => mi.Name == nameof(OnPropertyChanged) && mi.IsPublic == false);
public NativeEventWrapper(object target, string targetProperty, string updateSourceEventName)
{
TargetProperty = targetProperty;
try {
var updateSourceEvent = target.GetType().GetRuntimeEvent(updateSourceEventName);
MethodInfo addMethod = updateSourceEvent.AddMethod;
MethodInfo removeMethod = updateSourceEvent.RemoveMethod;
ParameterInfo[] addParameters = addMethod.GetParameters();
Type delegateType = addParameters[0].ParameterType;
var handlerDelegate = s_handlerinfo.CreateDelegate(delegateType, this);
Func<object, EventRegistrationToken> add = a => (EventRegistrationToken)addMethod.Invoke(target, new object[] { handlerDelegate });
Action<EventRegistrationToken> remove = t => removeMethod.Invoke(target, new object[] { t });
WindowsRuntimeMarshal.AddEventHandler(add, remove, s_handlerinfo);
}
catch (Exception) {
Log.Warning(nameof(NativeEventWrapper), "Can not attach NativeEventWrapper.");
}
}
void OnPropertyChanged(object sender, RoutedEventArgs e)
{
PropertyChanged?.Invoke(sender, new PropertyChangedEventArgs(TargetProperty));
}
public event PropertyChangedEventHandler PropertyChanged;
}
}
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