如何使用CollectionView功能处理CompositeCollection? [英] How to handle a CompositeCollection with CollectionView features?

问题描述

当CompositeCollection的当前位置更改时，是否有办法得到通知?

Is there a way to get notified when CompositeCollection's current location changes?

我需要由CollectionView监视CompositeCollection，欢迎提出任何想法.

I need to have the CompositeCollection monitored by a CollectionView, any ideas are welcommed.

推荐答案

您可以通过监视CollectionView的ICollectionView.CurrentChanged事件来检测当前项何时已更改.以下代码对我有用:

You can detect when the current item has changed by monitoring the ICollectionView.CurrentChanged event of your CollectionView. The following code works for me:

CompositeCollection cc = new CompositeCollection();
cc.Add(new CollectionContainer { Collection = new string[] { "Oh No!", "Fie" } });
cc.Add(new CollectionContainer { Collection = new string[] { "Zounds", "Ods Bodikins" } });
CollectionViewSource cvs = new CollectionViewSource { Source = cc };

// Subscribing to CurrentChanged on the ICollectionView
cvs.View.CurrentChanged += (o, e) => MessageBox.Show("current changed");

lb.ItemsSource = cvs.View;  // lb is a ListBox with IsSynchronizedWithCurrentItem="True"

当我在列表框中更改选择时，将显示消息框.

When I change the selection in the ListBox, the message box displays.

关于过滤，排序和分组，按照Aron的回答，这些在CompositeCollection的视图上不可用.但是，为了记录在案，您可以通过以下方法检测对做支持这些功能的视图的更改:

Regarding filtering, sorting and grouping, as per Aron's answer these are not available on a view over a CompositeCollection. But for the record here are the ways you can detect changes for views that do support these features:

• 尽管我找不到该文档，但看起来当过滤器更改时您会收到一个CollectionChanged事件.
• SortDescriptions是SortDescriptionCollection，它是INotifyCollectionChanged，因此请在SortDescriptions属性上连接CollectionChanged事件处理程序.
• GroupDescriptions是ObservableCollection<GroupDescription>，因此请在GroupDescriptions属性上连接CollectionChanged事件处理程序.

• It looks like you'll get a CollectionChanged event when the filter changes, though I can't find this documented.
• SortDescriptions is SortDescriptionCollection which is INotifyCollectionChanged, so hook up a CollectionChanged event handler on the SortDescriptions property.
• GroupDescriptions is ObservableCollection<GroupDescription>, so hook up a CollectionChanged event handler on the GroupDescriptions property.

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