Question

我想在列标题上方的现有WPF DataGrid中添加“drop”区域。在该区域中，我希望允许用户删除表示要分组的列的列标题，并通过从这个区域中删除它们来取消组合这些列。我无法拖动瓷砖然后掉到标签上。我的方法包括检测拖动作为MouseMove和MouseLeftButtonDown的组合，但它无法正常工作。示例代码：

    DataTable dt = new DataTable();
            dt.Columns.Add("Table", typeof(string));
            dt.Columns.Add("Scan Count", typeof(string));                
             DataRow dr = dt.NewRow();
            dr["Scan Count"] = sum.ToString();
            dr["logical reads"] = sum1.ToString();

 private void Button_Click(object sender, RoutedEventArgs e)
            {
                ICollectionView cvTasks = CollectionViewSource.GetDefaultView(GridView1.ItemsSource);
                if (cvTasks != null && cvTasks.CanGroup == true)
                {
                    cvTasks.GroupDescriptions.Clear();
                    cvTasks.GroupDescriptions.Add(new PropertyGroupDescription("Table"));                        
                }
            }
public class Tasks : ObservableCollection<Task>
    {
        //Creating the Tasks collection in this way enables data binding from XAML.            
    }

我想删除此Button并将列名称（“Table”）拖放到标签上。欢迎任何建议。谢谢！

Answer 1

你应该做的最少的事情：

1）重新设置DataGridColumnHeader样式以添加PreviewMouseMove事件处理程序 2）在事件处理程序中，启动拖放操作 3）将GroupStyle添加到DataGrid 4）对于作为放置目标的元素，处理Drop事件并更新GroupDescriptions。

XAML：

<Grid>        
    <Grid.RowDefinitions>
        <RowDefinition />
        <RowDefinition />
    </Grid.RowDefinitions>

    <ListBox x:Name="MyGroupDescriptionsList" AllowDrop="True" Drop="ListBox_Drop"/>

    <DataGrid x:Name="MyDataGrid" Grid.Row="1" ItemsSource="{Binding}" AutoGenerateColumns="False">
        <DataGrid.ColumnHeaderStyle>
            <Style TargetType="{x:Type DataGridColumnHeader}">
                <EventSetter Event="PreviewMouseMove" Handler="DataGridHeader_PreviewMouseMove"/>
            </Style>
        </DataGrid.ColumnHeaderStyle>
        <DataGrid.GroupStyle>
            <GroupStyle>
                <GroupStyle.HeaderTemplate>
                    <DataTemplate>
                        <StackPanel>
                            <TextBlock Text="{Binding Name}" />
                        </StackPanel>
                    </DataTemplate>
                </GroupStyle.HeaderTemplate>
                <GroupStyle.ContainerStyle>
                    <Style TargetType="{x:Type GroupItem}">
                        <Setter Property="Template">
                            <Setter.Value>
                                <ControlTemplate TargetType="{x:Type GroupItem}">
                                    <Expander IsExpanded="True" Header="{Binding Name}">
                                        <ItemsPresenter />
                                    </Expander>
                                </ControlTemplate>
                            </Setter.Value>
                        </Setter>
                    </Style>
                </GroupStyle.ContainerStyle>
            </GroupStyle>
        </DataGrid.GroupStyle>
        <DataGrid.Columns>
            <DataGridTextColumn Header="A" Binding="{Binding A}"/>
            <DataGridTextColumn Header="B" Binding="{Binding B}"/>
            <DataGridTextColumn Header="C" Binding="{Binding C}"/>
        </DataGrid.Columns>
    </DataGrid>
</Grid>

代码（假设，列标题只包含字符串）：

    private void DataGridHeader_PreviewMouseMove(object sender, MouseEventArgs e)
    {
        if (e.LeftButton == MouseButtonState.Pressed)
        {
            var header = e.OriginalSource as ContentControl;
            if (header != null)
            {
                DragDrop.DoDragDrop(header, new DataObject(typeof(string), header.Content.ToString()), DragDropEffects.Move);
                e.Handled = true;
            }
        }
    }

    private void ListBox_Drop(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent(typeof(string)))
        {
            var columnName = (string)e.Data.GetData(typeof(string));

            MyGroupDescriptionsList.Items.Add(columnName);

            var sourceView = CollectionViewSource.GetDefaultView(MyDataGrid.ItemsSource);
            sourceView.GroupDescriptions.Add(new PropertyGroupDescription(columnName));
            sourceView.Refresh();

            e.Handled = true;
        }
    }

取消分组是相似的。

拖动DataGrid列标题并放到标签上？

1 个答案: