問題描述
我有一個 ObservableCollection 項目綁定到我的視圖中的列表控件.
I have an ObservableCollection of items that is bound to a list control in my view.
我有一種情況，我需要在集合的開頭添加一大塊值.Collection<T>.Insert 文檔將每個插入指定為 O(n) 操作，并且每個插入還會生成一個 CollectionChanged 通知.
I have a situation where I need to add a chunk of values to the start of the collection.
Collection<T>.Insert documentation specifies each insert as an O(n) operation, and each insert also generates a CollectionChanged notification.
因此，理想情況下，我希望一次插入整個項目范圍，這意味著只對底層列表進行一次隨機播放，并希望有一個 CollectionChanged 通知(可能是重置").
Therefore I would ideally like to insert the whole range of items in one move, meaning only one shuffle of the underlying list, and hopefully one CollectionChanged notification (presumably a "reset").
Collection<T> 沒有公開任何執行此操作的方法.ListInsertRange()，但是 IListCollectionItems 屬性沒有.
Collection<T> does not expose any method for doing this. List<T> has InsertRange(), but IList<T>, that Collection<T> exposes via its Items property does not.
有沒有辦法做到這一點?
Is there any way at all to do this?
推薦答案
ObservableCollection 公開了一個受保護的 Items 屬性，該屬性是沒有通知語義的底層集合.這意味著您可以通過繼承 ObservableCollection 來構建一個可以滿足您需求的集合:
The ObservableCollection exposes an protected Items property which is the underlying collection without the notification semantics. This means you can build a collection that does what you want by inheriting ObservableCollection:
class RangeEnabledObservableCollection<T> : ObservableCollection<T>
{
public void InsertRange(IEnumerable<T> items)
{
this.CheckReentrancy();
foreach(var item in items)
this.Items.Add(item);
this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
}
用法:
void Main()
{
var collection = new RangeEnabledObservableCollection<int>();
collection.CollectionChanged += (s,e) => Console.WriteLine("Collection changed");
collection.InsertRange(Enumerable.Range(0,100));
Console.WriteLine("Collection contains {0} items.", collection.Count);
}
這篇關于有效地將一系列值添加到 ObservableCollection的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！