如何在contextmenu的CommandParameter中传递树视图项的selectedItem

<TreeView>
    <TreeView.ItemContainerStyle>
        <Style TargetType="TreeViewItem">
            <Setter Property="ContextMenu">
                <Setter.Value>
                    <ContextMenu>
                        <!-- 上下文菜单的菜单项 -->
                    </ContextMenu>
                </Setter.Value>
            </Setter>
        </Style>
    </TreeView.ItemContainerStyle>
    <!-- 树视图项的数据绑定 -->
</TreeView>

<TreeView>
    <TreeView.ItemContainerStyle>
        <Style TargetType="TreeViewItem">
            <Setter Property="ContextMenu">
                <Setter.Value>
                    <ContextMenu>
                        <MenuItem Header="菜单项" Command="{Binding YourCommand}" CommandParameter="{Binding PlacementTarget.SelectedItem, RelativeSource={RelativeSource AncestorType=ContextMenu}}"/>
                    </ContextMenu>
                </Setter.Value>
            </Setter>
        </Style>
    </TreeView.ItemContainerStyle>
    <!-- 树视图项的数据绑定 -->
</TreeView>

public ICommand YourCommand { get; set; }

public YourViewModel()
{
    YourCommand = new RelayCommand(ExecuteYourCommand);
}

private void ExecuteYourCommand(object parameter)
{
    var selectedItem = parameter as YourTreeViewItemDataType;
    // 使用树视图项的SelectedItem进行后续操作
}