组合框内Treeview的预选值

Question

我希望在一个组合框内实现一个treeview。基本上，我希望它显示为一个组合框时，折叠，但一个treeview在组合框内，当展开。当用户点击一个节点时，我希望它显示在折叠的组合框中。到目前为止，我已经把它弄好了。

我遇到的问题是，当加载这个组合框时，如何显示C#中的默认值。请帮帮我的人，因为我快没主意了：）

    <DataTemplate x:Key="TreeViewExpanded" >

        <StackPanel>
            <TreeView x:Name="DPointTree" Margin="5" ItemsSource="{Binding Datapoint}" 
                              Tag="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ComboBox}}}"
                              >
                <TreeView.ItemTemplate>
                    <HierarchicalDataTemplate ItemsSource="{Binding Field}">
                        <TextBlock Text="{Binding Name}"/>
                                <HierarchicalDataTemplate.ItemTemplate>
                                    <DataTemplate>
                                        <TextBlock Text="{Binding}"/>
                                    </DataTemplate>
                                </HierarchicalDataTemplate.ItemTemplate>
                            </HierarchicalDataTemplate>
                </TreeView.ItemTemplate>
            </TreeView>
        </StackPanel>
        <DataTemplate.Triggers>
            <DataTrigger Binding = "{Binding Path=SelectedFieldName, Mode=TwoWay}" Value = "">
                <Setter Property = "Visibility"  Value = "Collapsed"/>
            </DataTrigger>
        </DataTemplate.Triggers>
</DataTemplate>

下面是Xaml

 <ComboBox Name="cmbFieldName" Width="150" Background="White" ItemsSource="{Binding}" SelectedItem="{Binding SelectedFieldName , Mode=TwoWay}" >
            <ComboBox.ItemTemplateSelector>
                <local:TreeViewSelector/>
            </ComboBox.ItemTemplateSelector>
        </ComboBox>

下面是传递给此的数据集。

Datapoint _datapoint2 = new Datapoint();
        _datapoint2.Name = "Alpha";
        _datapoint2.FieldID.Add("Contains Elements");
        _datapoint2.Field.Add("1 Year");
        _datapoint2.Field.Add("2 Year");
        _datapoint2.Field.Add("3 Year");

Answer 1

它并不漂亮，但可以在树中选择一个节点

// in code behind after the tree is declared, e.g. after InitializeComponent();
SynchronizationContext.Current.Post(delegate
{
    // expand the tree to the selected node after loading
    treeView.ExpandAll(); // or if path is known treeView.ExpandPath(...);
    SynchronizationContext.Current.Post(delegate
    {
        treeView.GetContainerFromItem(root.Children[0]).IsSelected = true;
    }, null);
}, null);