我想做的是FreezableCollection.AddRange(collectionToAdd)
每次我添加到 FreezableCollection 时,都会引发一个事件并发生一些事情。现在我有一个新的收藏,我想添加,但这次我想要集合更改事件FreezableCollection 的值仅触发一次。
循环并添加它们将为每个新项目引发事件。
有没有一种方法可以像 List.AddRange 一样一次性添加到 FreezableCollection?
从集合派生并覆盖您想要更改的行为。我能够这样做:
public class PrestoObservableCollection<T> : ObservableCollection<T>
{
private bool _delayOnCollectionChangedNotification { get; set; }
/// <summary>
/// Add a range of IEnumerable items to the observable collection and optionally delay notification until the operation is complete.
/// </summary>
/// <param name="itemsToAdd"></param>
public void AddRange(IEnumerable<T> itemsToAdd)
{
if (itemsToAdd == null) throw new ArgumentNullException("itemsToAdd");
if (itemsToAdd.Any() == false) { return; } // Nothing to add.
_delayOnCollectionChangedNotification = true;
try
{
foreach (T item in itemsToAdd) { this.Add(item); }
}
finally
{
ResetNotificationAndFireChangedEvent();
}
}
/// <summary>
/// Clear the items in the ObservableCollection and optionally delay notification until the operation is complete.
/// </summary>
public void ClearItemsAndNotifyChangeOnlyWhenDone()
{
try
{
if (!this.Any()) { return; } // Nothing available to remove.
_delayOnCollectionChangedNotification = true;
this.Clear();
}
finally
{
ResetNotificationAndFireChangedEvent();
}
}
/// <summary>
/// Override the virtual OnCollectionChanged() method on the ObservableCollection class.
/// </summary>
/// <param name="e">Event arguments</param>
protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
{
if (_delayOnCollectionChangedNotification) { return; }
base.OnCollectionChanged(e);
}
private void ResetNotificationAndFireChangedEvent()
{
// Turn delay notification off and call the OnCollectionChanged() method and tell it we had a change in the collection.
_delayOnCollectionChangedNotification = false;
this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
}
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