TreeViewItem父节点上折叠的事件激发

Question

我有一个定义如下的WPF TreeView控件：

<TreeView x:Name="samplesTree" MouseDoubleClick="samplesTree_MouseDoubleClick"
          KeyUp="samplesTree_KeyUp"
          SelectedItemChanged="samplesTree_SelectedItemChanged"
          IsVisibleChanged="treeView_IsVisibleChanged">
</TreeView>

我使用以下代码跟踪哪些节点已经展开或折叠：

private List<object> SamplesExpandedTags = new List<object>();

private void stag_Collapsed(object sender, RoutedEventArgs e)
{
    object tag = (sender as TreeViewItem).Tag;
    if (SamplesExpandedTags.Contains(tag))
        SamplesExpandedTags.Remove(tag);
}

private void stag_Expanded(object sender, RoutedEventArgs e)
{
    object tag = (sender as TreeViewItem).Tag;
    if (!SamplesExpandedTags.Contains(tag))
        SamplesExpandedTags.Add(tag);
}

...

// Items are created in code behind, not using binding to DataSource 
TreeViewItem item = new TreeViewItem();
item.Header = tv.NazevTypuVyrobku;
item.Tag = string.Format("TV{0}",tv.TypVyrobkuID);
item.Expanded += new RoutedEventHandler(stag_Expanded);
item.Collapsed += new RoutedEventHandler(stag_Collapsed);

if ((sender as TreeViewItem).IsExpanded) return;

e.Handled = true;

subitem.Expanded += new RoutedEventHandler(stag_Expanded);
subitem.Expanded += new RoutedEventHandler(sampleOperation_Expanded);
subitem.Collapsed += new RoutedEventHandler(stag_Collapsed);

与以下代码的工作方式不同：

subitem.Expanded += new RoutedEventHandler(sampleOperation_Expanded);
subitem.Expanded += new RoutedEventHandler(stag_Expanded);
subitem.Collapsed += new RoutedEventHandler(stag_Collapsed);

在第一种情况下，sampleoperation_expanded根本不执行，因为e.handle=true；命令。我认为事件处理程序的执行顺序不应该很重要？

Answer 1

也许可以尝试在stag_collapped()方法中将e.handled设置为true。在MSDN中，“标记已处理的事件将限制事件路由中侦听器对路由事件的可见性”。

private void stag_Collapsed(object sender, RoutedEventArgs e)
{
    object tag = (sender as TreeViewItem).Tag;
    if (SamplesExpandedTags.Contains(tag))
        SamplesExpandedTags.Remove(tag);
    e.Handled = true;
}