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，以及在列表视图中的位置知道如何做到这一点，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 xaml 这样的代码 :

    <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

遗憾的是 .net 尚未提供 "easy to use" 拖放的实现。你必须自己构建一堆东西。起点是 Behavior 开始拖动，ContentControl 是用户可以放置东西的区域。定义了这些之后，您可以轻松地重用这个概念。在下面的示例中，StackPanel 可以 "dragged" 到 TextBlock 周围的不可见 "area" 上。这样你就可以实现手动排序你的书（将书放在鼠标指针下before/behind）。

如果你想把书放到你的 headers 上，用 DropArea 包围它们。您也可以采用这两种方式。

您的 xaml 将如下所示：

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
[...]
<ListBox x:Name="lbPersonList" Margin="19,17,162,25" AlternationCount="2" ItemsSource="{Binding}">
    <ListBox.GroupStyle>
        <GroupStyle ContainerStyle="{StaticResource ContainerStyle}"/>
    </ListBox.GroupStyle>
    <ListBox.ItemTemplate>
        <DataTemplate>
            <StackPanel>
                <myOwn:DropArea>
                    <TextBlock Text="{Binding Name}"/>
                </myOwn:DropArea>
                <i:Interaction.Behaviors>
                    <myOwn:DragBehavior/>
                </i:Interaction.Behaviors>
            </StackPanel>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

DragBehavior 看起来像：

public class DragBehavior : Behavior<FrameworkElement>
    [...]
    protected override void OnAttached()
    {
        AssociatedObject.MouseMove += AssociatedObject_MouseMove;
        AssociatedObject.MouseDown += AssociatedObject_MouseLeftButtonDown;
        AssociatedObject.MouseLeave += AssociatedObject_MouseLeave;
        base.OnAttached();
    }
    protected override void OnDetaching()
    {
        AssociatedObject.MouseMove -= AssociatedObject_MouseMove;
        AssociatedObject.MouseDown -= AssociatedObject_MouseLeftButtonDown;
        AssociatedObject.MouseLeave -= AssociatedObject_MouseLeave;
        base.OnDetaching();
    }
    protected virtual void AssociatedObject_MouseMove(object sender, MouseEventArgs e)
    {
        if (some condition of mouse button states or mouse moves)
        {
                DataObject data = new DataObject();
                data.SetData(typeof(anyKeyType), anyData);
                data.SetData(typeof(anyOtherKeyType), anyOtherData);
                DragDrop.DoDragDrop(fe, data, DragDropEffects.Move);                
        }
    }

DropArea 看起来像：

public class DropArea : ContentControl
    [...]
    public DropArea()
    {
        DragEnter += AssociatedObjectDragEnter;
        DragLeave += AssociatedObjectDragLeave;
        DragOver += AssociatedObjectDragOver;
        IsTabStop = false;
        AllowDrop = true;
    }
    protected override void AssociatedObjectDrop(object sender, DragEventArgs e)
    {
        object o = e.Data.GetData(typeof(anyKeyType));
        //handle dropped data
    }

希望对您有所帮助。可能有任何框架或库可以解决该问题，但您可以通过这种方式满足自己的需求。

Answer 2

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、select列表框，右击，编辑附加templates/Edit Generated Item Container(ItemContainerStyle)/编辑一个副本

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"/>

在 ListBox 上将 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 实施了 Drop 管理。所以处理程序需要在 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，这是完整的工作代码：http://1drv.ms/1FhBZwr

祝你代码尽可能好

更改 ICollectionView 中的项目组

change the group of item in ICollectionView

c#

wpf

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