/// <summary>
/// Watches the specified source.
/// </summary>
/// <param name="source">
/// The source.
/// </param>
/// <param name="property">
/// The property.
/// </param>
/// <returns>
/// The <see cref="WeakCommandBinding"/>.
/// </returns>
/// <exception cref="System.ArgumentNullException">
/// The source can not be null.
/// </exception>
public WeakCommandBinding Watch(object source, string property)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
var bindContext = new BindContext(source, property);
var entry = new WeakEntry(null, bindContext.Source, property);
WeakEvent watchEvent;
if (this.watchEvents.ContainsKey(entry))
{
watchEvent = this.watchEvents[entry];
}
else
{
watchEvent = new WeakEvent(this);
this.watchEvents.Add(entry, watchEvent);
}
string propertyName = property.Contains(".") ? property.Right(".") : property;
watchEvent.AttachEvent(
bindContext,
WeakPropertyBinding.PropertyChangedEventName,
WatchEventCallbackMethod,
(o, args) => string.Equals(((PropertyChangedEventArgs)args).PropertyName, propertyName));
this.RaiseCanExecuteChanged();
return(this);
}
public void Test_WeakBindEvent_NormalProperty()
{
var viewModel = new TestViewModel();
var view = new TestView();
var propertyBinding = new WeakPropertyBinding(view, "Text1", viewModel, "Name")
.Initialize<WeakPropertyBinding>();
var weakEvent = new WeakEvent(viewModel);
Assert.IsFalse(weakEvent.IsAttached);
}
/// <summary>
/// Detaches the source.
/// </summary>
/// <param name="source">
/// The source.
/// </param>
protected override void DetachSource(object source)
{
base.DetachSource(source);
if (source != null && source.GetType().ContainsEvent(WeakCollectionBinding.CollectionChangedEventName))
{
if (collectionWeakEvent != null)
{
collectionWeakEvent.DetachEvent();
collectionWeakEvent = null;
}
}
}
/// <summary>
/// Attaches the source.
/// </summary>
/// <param name="source">
/// The source.
/// </param>
protected override void AttachSource(object source)
{
base.AttachSource(source);
if (source != null && source.GetType().ContainsEvent(WeakCollectionBinding.CollectionChangedEventName))
{
if (collectionWeakEvent != null)
{
collectionWeakEvent.DetachEvent();
}
if (collectionWeakEvent == null)
{
collectionWeakEvent = new WeakEvent(this);
}
collectionWeakEvent.AttachEvent(source, null, WeakCollectionBinding.CollectionChangedEventName, "OnSourceCollectionChanged");
}
}
/// <summary>
/// UnWatch the source property.
/// </summary>
/// <param name="source">
/// The source.
/// </param>
/// <param name="property">
/// The property.
/// </param>
/// <returns>
/// The <see cref="WeakCommandBinding"/>.
/// </returns>
/// <exception cref="System.ArgumentNullException">
/// The source can not be null.
/// </exception>
public WeakCommandBinding UnWatch(object source, string property)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
var bindSource = new BindContext(source, property);
var entry = new WeakEntry(null, bindSource.Source, property);
if (this.watchEvents.ContainsKey(entry))
{
WeakEvent watchEvent = this.watchEvents[entry];
watchEvent.DetachEvent();
this.watchEvents.Remove(entry);
}
this.RaiseCanExecuteChanged();
return(this);
}
/// <summary>
/// Initializes a new instance of the <see cref="WeakCommandBinding"/> class.
/// </summary>
/// <param name="target">
/// The target.
/// </param>
/// <param name="targetProperty">
/// The target property.
/// </param>
/// <param name="source">
/// The source.
/// </param>
/// <param name="sourceProperty">
/// The source property.
/// </param>
public WeakCommandBinding(object target, string targetProperty, object source, string sourceProperty)
: base(target, targetProperty, source, sourceProperty)
{
this.commandCanExecuteEvent = new WeakEvent(this);
}
/// <summary>
/// Detaches the source.
/// </summary>
/// <param name="source">
/// The source.
/// </param>
protected override void DetachSource(object source)
{
base.DetachSource(source);
if (source != null && source.GetType().ContainsEvent(WeakCollectionBinding.CollectionChangedEventName))
{
if (collectionWeakEvent != null)
{
collectionWeakEvent.DetachEvent();
collectionWeakEvent = null;
}
}
}
/// <summary>
/// Attaches the source.
/// </summary>
/// <param name="source">
/// The source.
/// </param>
protected override void AttachSource(object source)
{
base.AttachSource(source);
if (source != null && source.GetType().ContainsEvent(WeakCollectionBinding.CollectionChangedEventName))
{
if (collectionWeakEvent != null)
{
collectionWeakEvent.DetachEvent();
}
if (collectionWeakEvent == null)
{
collectionWeakEvent = new WeakEvent(this);
}
collectionWeakEvent.AttachEvent(source, null, WeakCollectionBinding.CollectionChangedEventName, "OnSourceCollectionChanged");
}
}
public void Test_MemoryLeak_WeakEvent()
{
// 1. Normal Event will hold the strong reference which prevent the GC collect.
var view = new TestView();
var viewModel = new TestViewModel();
var reference = new WeakReference(view);
viewModel.TestViewModelEvent += view.OnEventOccured;
viewModel.RaiseTestViewModelEvent();
Assert.AreEqual(1, view.EventCount);
Assert.AreEqual(1, viewModel.GetTestViewModelEventInvocationCount());
view = null;
GC.Collect();
Assert.IsTrue(reference.IsAlive); // Still live
viewModel.TestViewModelEvent -= reference.GetTarget<TestView>().OnEventOccured;
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
Assert.IsFalse(reference.IsAlive);
reference = null;
Assert.IsNull(reference.GetTarget<TestView>());
// 2. WeakEvent hold the weak reference which will not prevent GC collect.
var view2 = new TestView();
var viewModel2 = new TestViewModel();
var reference2 = new WeakReference(view2);
var weakEvent = new WeakEvent(view2);
weakEvent.AttachEvent(viewModel2, null, "TestViewModelEvent", "OnEventOccured");
viewModel2.RaiseTestViewModelEvent();
Assert.AreEqual(1, view2.EventCount);
view2 = null;
GC.Collect();
Assert.IsFalse(reference2.IsAlive);
viewModel2.RaiseTestViewModelEvent();
Assert.AreEqual(0, viewModel2.GetTestViewModelEventInvocationCount());
}
