c# - 更改 ICollectionView 中的项目组

Question

我有 ICollectionView 看起来像

public ICollectionView UsersCollectionView
{
    get
    {
        var view = CollectionViewSource.GetDefaultView(this);
        view.GroupDescriptions.Add(new PropertyGroupDescription("SeriesName"));
        view.SortDescriptions.Add(new SortDescription("CreationDate", ListSortDirection.Ascending));
        view.SortDescriptions.Add(new SortDescription("DocumentTypeId", ListSortDirection.Ascending));
        return view;
    }
}

我想使用拖放来更改项目系列名称和列表中的位置查看任何想法如何做到这一点，例如

--- ScienceFiction
------------> Book1 
------------> Book2
--- History 
------------> Book3 
------------> Book4

如果 Idraged and drop book3 in ScienceFiction 输出应该是

--- ScienceFiction
------------> Book1 
------------> Book2
------------> Book3 
--- History 
------------> Book4

我使用这样的 xaml 代码:

    <UserControl.Resources>
    <Style x:Key="ContainerStyle" TargetType="{x:Type GroupItem}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate>
                    <Expander Header="{Binding Name}" IsExpanded="True">
                        <ItemsPresenter />
                    </Expander>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</UserControl.Resources>
<Grid>
    <ListBox x:Name="lbPersonList" Margin="19,17,162,25" AlternationCount="2" ItemsSource="{Binding}">
        <ListBox.GroupStyle>
            <GroupStyle ContainerStyle="{StaticResource ContainerStyle}"/>
        </ListBox.GroupStyle>
        <ListBox.ItemTemplate>
            <DataTemplate>
                <TextBlock Text="{Binding Name}"/>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>

</Grid>

Answer 1

AMH，

首先修改ListviewItem Style。它是包含列表框每一行(数据模板实例化)的容器。这是在行级别管理拖放的好地方(不是行的控件，DataTemplate 中可能有很多)。 在 Visual Studio 中，选择列表框，右键单击，编辑其他模板/编辑生成的项目容器(ItemContainerStyle)/编辑副本

在创建的 ListBoxItemStyle 中，将这三个声明添加到 setter 中:

        <EventSetter Event="ListBoxItem.DragOver" Handler="ListBoxItemDragOver"/>
        <EventSetter Event="ListBoxItem.Drop" Handler="ListBoxItemDrop"/>
        <EventSetter Event="ListBoxItem.PreviewMouseMove" Handler="ListBoxItemPreviewMouseMove"/>

将 ListBox 的 AllowDrop 属性设置为 true :

<ListBox x:Name="listboxBooks" AllowDrop="True">

然后在 .xaml.cs 代码中实现处理程序:

    #region DnD management

    private Book sourceBook;
    private void ListBoxItemPreviewMouseMove(object sender, MouseEventArgs e)
    {
        if (e.LeftButton != MouseButtonState.Pressed)
            return;
        var listboxItem = sender as ListBoxItem;
        if (listboxItem == null)
            return;
        sourceBook = listboxItem.DataContext as Book;
        if (sourceBook == null)
            return;
        var data = new DataObject();
        data.SetData(sourceBook);
        // provide some data for DnD in other applications (Word, ...)
        data.SetData(DataFormats.StringFormat, sourceBook.ToString());
        DragDropEffects effect = DragDrop.DoDragDrop(listboxItem, data, DragDropEffects.Move | DragDropEffects.Copy);
    }
    private void ListBoxItemDrop(object sender, DragEventArgs e)
    {
        if (!e.Data.GetDataPresent(typeof(Book)))
            return;
        var listBoxItem = sender as ListBoxItem;
        if (listBoxItem == null)
            return;
        var targetBook = listBoxItem.DataContext as Book;
        if (targetBook != null)
        {
            viewModel.RecategorizeBook(sourceBook, targetBook.Category);
        }
        e.Handled = true;
    }
    private void ListBoxItemDragOver(object sender, DragEventArgs e)
    {
        Debug.WriteLine(e.Effects);
        if (!e.Data.GetDataPresent(typeof(Book)))
        {
            e.Effects = DragDropEffects.None;
            e.Handled = true;
        }
    }
    private void GroupItemDrop(object sender, DragEventArgs e)
    {
        if (!e.Data.GetDataPresent(typeof(Book)))
            return;
        var groupItem = sender as GroupItem;
        if (groupItem == null)
            return;
        dynamic targetGroup = groupItem.DataContext;
        if (targetGroup != null)
        {
            // here I change the category of the book
            // and refresh the view of the collectionViewSource ( see link to project zipped further)
            viewModel.RecategorizeBook(sourceBook, targetGroup.Name as String);
        }
        e.Handled = true;
    }
    #endregion

请注意，我还在处理程序中对组 header 实现了 Drop 管理。 因此处理程序需要在 XAML groupstyle 中声明:

<ListBox.GroupStyle>
    <GroupStyle>
        <GroupStyle.ContainerStyle>
            <Style TargetType="{x:Type GroupItem}">
                <EventSetter Event="GroupItem.Drop" Handler="GroupItemDrop"/>
                <EventSetter Event="GroupItem.PreviewMouseMove" Handler="ListBoxItemPreviewMouseMove"/>

有效，这里是完整的工作代码:http://1drv.ms/1FhBZwr

祝你代码尽可能好