如何在ItemsSource =自定义对象集合时选择/展开TreeView节点？

Question

我TreeView打算在两个级别上操作.对于他我有两个HierarchicalDataTemplate和两个自定义类型.在ItemsSource链接到ObservableCollection,一切工作正常.我无法想象如何从代码隐藏中选择或扩展节点.在某处提到了一个非常好的想法,即绑定IsExpanded和IsSelected属性到我的自定义类型中的相应属性.唯一的问题是HierarchicalDataTemplate没有TreeViewItem直接实现,所以如何在以下代码中访问这些属性？

<TreeView Name="treeViewNotes" AllowDrop="True" PreviewMouseLeftButtonDown="treeViewNotes_PreviewMouseLeftButtonDown" PreviewMouseMove="treeViewNotes_PreviewMouseMove" Drop="treeViewNotes_Drop" DragEnter="treeViewNotes_DragEnter">
    <TreeView.Resources>
        <HierarchicalDataTemplate DataType="{x:Type dataclasses:NoteFolder}" ItemsSource="{Binding Notes}">
            <StackPanel Orientation="Horizontal">
                <Image Height="16" Source="{Binding TreeViewIcon}" Tag="{Binding Self}"/>
                <TextBlock Text="{Binding Title}" Tag="{Binding Self}" Margin="3"/>
            </StackPanel>
        </HierarchicalDataTemplate>
        <HierarchicalDataTemplate DataType="{x:Type dataclasses:Note}">
            <StackPanel Orientation="Horizontal">
                <Image Height="16" Source="{Binding TreeViewIcon}" Tag="{Binding Self}"/>
                <TextBlock Text="{Binding Title}" Tag="{Binding Self}" Margin="3"/>
            </StackPanel>
        </HierarchicalDataTemplate>
    </TreeView.Resources>
</TreeView>

我的目标是创建和添加新的时候Note一些NoteFolder,使这个Note选择和Folder扩展.同样需要进一步改进拖放时的UI响应.

Answer 1

您可以尝试以下列方式更改TreeView的ItemContainerStyle,以便其IsExpanded和IsSelected属性将绑定到DataContext的IsExpanded和IsSelected:

<TreeView x:Name="..." ItemsSource="{Binding RootNode}">
    <TreeView.ItemContainerStyle>
        <Style TargetType="{x:Type TreeViewItem}">
            <!-- Items in the ItemsSource need to have these properties for the binding to work -->
            <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
            <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
            <!-- You can also optionally change some style values based on IsSelected and IsExpanded values -->
            <Style.Triggers>
                <DataTrigger Binding="{Binding IsSelected}" Value="True">
                    <Setter Property="BorderThickness" Value="4 0 0 1"/>
                    <Setter Property="BorderBrush" Value="DeepSkyBlue"/>
                </DataTrigger>
                <DataTrigger Binding="{Binding IsSelected}" Value="False">
                    <Setter Property="BorderThickness" Value="4 0 0 1 "/>
                    <Setter Property="BorderBrush" Value="Transparent"/>
                </DataTrigger>
            </Style.Triggers>
         </Style>
     </TreeView.ItemContainerStyle>
     <TreeView.Resources>
        <HierarchicalDataTemplate>
             ...
        </HierarchicalDataTemplate>
     </TreeView.Resources>
</TreeView>

当然,然后来自ItemSource并出现在层次结构中的每个项目都需要具有这些属性.