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WPF TreeView数据绑定详解

一、绑定方式

在使用WPF TreeView进行数据绑定的时候,常见的几种方式有以下几种。

1. 使用静态数据源


    <TreeView>
        <TreeViewItem Header="节点1">
            <TreeViewItem Header="节点1子节点1" />
            <TreeViewItem Header="节点1子节点2" />
        </TreeViewItem>
        <TreeViewItem Header="节点2">
            <TreeViewItem Header="节点2子节点1" />
            <TreeViewItem Header="节点2子节点2" />
        </TreeViewItem>
    </TreeView>

2. 使用Binding绑定动态数据源


    public class TreeNode
    {
        public string Header { get; set; }
        public ObservableCollection<TreeNode> Children { get; set; }
    }
    
    public class TreeViewModel
    {
        public ObservableCollection<TreeNode> RootNodes { get; set; }
    }
    
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new TreeViewModel() { RootNodes = /*your observable collection here*/ };
        }
    }
    
    <Window>
        <TreeView ItemsSource="{Binding RootNodes}">
            <TreeView.ItemTemplate>
                <HierarchicalDataTemplate ItemsSource="{Binding Children}">
                    <TextBlock Text="{Binding Header}" />
                </HierarchicalDataTemplate>
            </TreeView.ItemTemplate>
        </TreeView>
    </Window>

二、绑定到TreeViewItem

有时候,需要将数据绑定到TreeViewItem本身,并使用该数据去匹配TreeViewItem的模板。可以使用DataTemplate。


    <Window.Resources>
        <DataTemplate DataType="{x:Type local:TreeNode}">
            <TextBlock Text="{Binding Header}" />
        </DataTemplate>
    </Window.Resources>
    
    <Window>
        <TreeView ItemsSource="{Binding RootNodes}">
            <TreeView.ItemContainerStyle>
                <Style TargetType="{x:Type TreeViewItem}">
                    <Setter Property="IsExpanded" Value="True" />
                    <Setter Property="Header" Value="{Binding}" />
                </Style>
            </TreeView.ItemContainerStyle>
        </TreeView>
    </Window>

三、绑定到TreeViewItem的Header

另外一种常见的Treeview数据绑定方式,是将数据绑定到TreeViewItem的Header属性,方法同样是使用DataTemplate。这种方式可以在TreeView显示多种风格和数据类型的节点。


    <Window>
        <Window.Resources>
            <DataTemplate DataType="{x:Type local:TreeNode}">
                <StackPanel Orientation="Horizontal">
                    <Image Source="{Binding ImageUri}" Width="16" Height="16" />
                    <TextBlock Margin="5,0,0,0" Text="{Binding Header}" />
                </StackPanel>
            </DataTemplate>
        </Window.Resources>

        <TreeView ItemsSource="{Binding RootNodes}">
            <TreeView.ItemContainerStyle>
                <Style TargetType="{x:Type TreeViewItem}">
                    <Setter Property="IsExpanded" Value="True" />
                </Style>
            </TreeView.ItemContainerStyle>
        </TreeView>
    </Window>

四、MVVM绑定

在MVVM模式中,ViewModel是数据的源头,View则是呈现数据的界面,二者通过数据绑定实现解耦。使用MVVM模式实现WPF TreeView数据绑定是非常常见的,以下是一个简单的示例。


    public class TreeNodeViewModel
    {
        public string Header { get; set; }
        public ObservableCollection<TreeNodeViewModel> Children { get; set; }
    }
    
    public class TreeViewViewModel : INotifyPropertyChanged
    {
        public ObservableCollection<TreeNodeViewModel> RootNodes { get; set; }
    
        private TreeNodeViewModel _selectedNode;
        public TreeNodeViewModel SelectedNode
        {
            get { return _selectedNode; }
            set
            {
                _selectedNode = value;
                OnPropertyChanged("SelectedNode");
            }
        }
    
        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string propertyName)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new TreeViewViewModel() { RootNodes = /*your observable collection here*/ };
        }
    }
    
    <Window>
        <TreeView ItemsSource="{Binding RootNodes}" SelectedItem="{Binding SelectedNode}">
            <TreeView.ItemTemplate>
                <HierarchicalDataTemplate ItemsSource="{Binding Children}">
                    <TextBlock Text="{Binding Header}" />
                </HierarchicalDataTemplate>
            </TreeView.ItemTemplate>
        </TreeView>
    </Window>

五、数据排序

WPF TreeView提供了对节点的默认排序,可以按字母顺序排序、降序排序等。此外,也可以实现自定义排序。


    public class TreeNode : IComparable
    {
        public string Header { get; set; }
        public ObservableCollection<TreeNode> Children { get; set; }
    
        public int CompareTo(object obj)
        {
            TreeNode other = obj as TreeNode;
            if (other == null) return 0;
            return Header.CompareTo(other.Header);
        }
    }
    
    <Window>
        <TreeView ItemsSource="{Binding RootNodes}">
            <TreeView.ItemTemplate>
                <HierarchicalDataTemplate ItemsSource="{Binding Children}">
                    <TextBlock Text="{Binding Header}" />
                </HierarchicalDataTemplate>
            </TreeView.ItemTemplate>
            <TreeView.ItemContainerStyle>
                <Style TargetType="{x:Type TreeViewItem}">
                    <Setter Property="IsExpanded" Value="True" />
                </Style>
            </TreeView.ItemContainerStyle>
            <TreeView.Items.SortDescriptions>
                <scm:SortDescription PropertyName="Header" Direction="Ascending" />
            </TreeView.Items.SortDescriptions>
        </TreeView>
    </Window>