ListBox Grouping的研究（三）：Grouping 级联

延续上文，我又对代码略作了改动：

（1）改写了Data类，增加了Level1、Level2两个属性，可以让数据先根据Level1 Grouping，然后在根据Level2 Grouping。

（2）对GroupItem 的 ControlTemplate 增加了Marging和Padding，好让UI看上去有层次感。除此之外，我没有做任何改动！

数据结构：

    class Data
    {
        public string Level1 { get; set; }
        public string Level2 { get; set; }
        public string Value { get { return String.Format("Level {0}-{1}", Level1, Level2); } }
    }

XAML:

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfApplication2"    
        Title="MainWindow" SizeToContent="WidthAndHeight">

  <Window.Resources>

    <DataTemplate DataType="{x:Type local:Data}">
      <TextBlock Text="{Binding Value}"/>
    </DataTemplate>

  </Window.Resources>

  <StackPanel Margin="5">
    <ListBox ItemsSource="{StaticResource data}">
      <ListBox.GroupStyle>
        <GroupStyle>
          <GroupStyle.ContainerStyle>
            <Style TargetType="GroupItem">
              <Setter Property="Template">
                <Setter.Value>
                  <ControlTemplate>
                    <Expander Header="{Binding Name}" Padding="3">
                      <ItemsPresenter Margin="5,0,0,0" />
                    </Expander>
                  </ControlTemplate>
                </Setter.Value>
              </Setter>
            </Style>
          </GroupStyle.ContainerStyle>
        </GroupStyle>
      </ListBox.GroupStyle>
    </ListBox>
  </StackPanel>
</Window>

代码：

    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            ObservableCollection<Data> data = new ObservableCollection<Data>();

            data.Add(new Data() { Level1 = "1-1", Level2 = "1" });
            data.Add(new Data() { Level1 = "1-1", Level2 = "1" });
            data.Add(new Data() { Level1 = "1-1", Level2 = "2" });
            data.Add(new Data() { Level1 = "1-1", Level2 = "2" });
            data.Add(new Data() { Level1 = "1-2", Level2 = "1" });
            data.Add(new Data() { Level1 = "1-2", Level2 = "1" });
            data.Add(new Data() { Level1 = "1-2", Level2 = "2" });
            data.Add(new Data() { Level1 = "1-2", Level2 = "2" });

            this.Resources.Add("data", data);
            InitializeComponent();
            ICollectionView vw = CollectionViewSource.GetDefaultView(data);
            vw.GroupDescriptions.Add(new PropertyGroupDescription("Level1"));
            vw.GroupDescriptions.Add(new PropertyGroupDescription("Level2"));
        }
    }

    class ControlStyleSelector : StyleSelector
    {
        public override Style SelectStyle(object item, DependencyObject container)
        {
            return base.SelectStyle(item, container);
        }
    }

运行截图：

     


可以看到，级联Grouping是很容易实现的，假如你要对不同的Grouping设置不同的Style也是可以的，你可以在ContainerStyleSelector增加代码逻辑，为不同的Grouping返回不同的Style。