如何在WPF ItemsControl中覆盖预定义的依赖属性ItemsSource的PropertyChangedCal
本文关键字:依赖 属性 ItemsSource PropertyChangedCal 预定义 覆盖 WPF ItemsControl | 更新日期: 2023-09-27 18:07:50
如何在WPF ItemsControl
中重写 PropertyChangedCallback
的预定义依赖属性 ItemsSource
。
ItemsControl
的WPF自定义控件。在这里,我使用了预定义的依赖属性 ItemsSource
。在这方面,我需要监控和检查数据,一旦 Collection
得到更新。
我在谷歌上搜索了很多,但我找不到任何相关的解决方案来满足我的要求。
https://msdn.microsoft.com/en-us/library/system.windows.controls.itemscontrol.itemssource (v = vs.110) . aspx
请帮助我,要覆盖的方法名称是什么…
在派生的ItemsSource类的静态构造函数中调用OverrideMetadata
:
public class MyItemsControl : ItemsControl
{
static MyItemsControl()
{
ItemsSourceProperty.OverrideMetadata(
typeof(MyItemsControl),
new FrameworkPropertyMetadata(OnItemsSourcePropertyChanged));
}
private static void OnItemsSourcePropertyChanged(
DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
((MyItemsControl)obj).OnItemsSourcePropertyChanged(e);
}
private void OnItemsSourcePropertyChanged(DependencyPropertyChangedEventArgs e)
{
var oldCollectionChanged = e.OldValue as INotifyCollectionChanged;
var newCollectionChanged = e.NewValue as INotifyCollectionChanged;
if (oldCollectionChanged != null)
{
oldCollectionChanged.CollectionChanged -= OnItemsSourceCollectionChanged;
}
if (newCollectionChanged != null)
{
newCollectionChanged.CollectionChanged += OnItemsSourceCollectionChanged;
// in addition to adding a CollectionChanged handler
// any already existing collection elements should be processed here
}
}
private void OnItemsSourceCollectionChanged(
object sender, NotifyCollectionChangedEventArgs e)
{
// handle collection changes here
}
}