Wpf empty ListBox template + drag-and-drop

Question

Following WPF listbox empty datatemplate answer, I vertical and horizontal aligned the TextBlock to center.

However, when the empty template is shown, I cannot drag and drop items into the ListBox, except when I mouse over the actual TextBlock. I want to be able to drag item in any place inside ListBox.

MainWindow.xaml

<Window x:Class="EmptyListBoxWithDragAndDrop.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:gong="clr-namespace:GongSolutions.Wpf.DragDrop;assembly=GongSolutions.Wpf.DragDrop"
    Title="MainWindow" Height="600" Width="800" WindowStartupLocation="CenterScreen">

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="200"/>
        <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>

    <ListBox Grid.Column="0" ItemsSource="{Binding Source}"
             gong:DragDrop.IsDragSource="True"/>

    <ListBox Grid.Column="1" ItemsSource="{Binding Target}"
             AllowDrop="True" gong:DragDrop.IsDropTarget="True" gong:DragDrop.DropHandler="{Binding}">
        <ListBox.Style>
            <Style  TargetType="ListBox" BasedOn="{StaticResource {x:Type ListBox}}">
                <Style.Triggers>
                    <Trigger Property="HasItems" Value="False">
                        <Setter Property="Template">
                            <Setter.Value>
                                <ControlTemplate>
                                    <TextBlock Text="Drag items from left ListBox" VerticalAlignment="Center" HorizontalAlignment="Center"/>
                                </ControlTemplate>
                            </Setter.Value>
                        </Setter>
                    </Trigger>
                </Style.Triggers>
            </Style>
        </ListBox.Style>
    </ListBox>
</Grid>

ViewModel.cs

using GongSolutions.Wpf.DragDrop;
using System.Collections.ObjectModel;

namespace EmptyListBoxWithDragAndDrop
{
public class ViewModel : IDropTarget
{
    public ViewModel()
    {
        Source = new ObservableCollection<string>();
        Target = new ObservableCollection<string>();

        Source.Add("Item 1");
        Source.Add("Item 2");
        Source.Add("Item 3");
        Source.Add("Item 4");
        Source.Add("Item 5");
        Source.Add("Item 6");
        Source.Add("Item 7");
    }

    public ObservableCollection<string> Source { get; private set; }
    public ObservableCollection<string> Target { get; private set; }

    public void DragOver(IDropInfo dropInfo)
    {
        if (dropInfo.Data is string)
            dropInfo.Effects = System.Windows.DragDropEffects.Copy;
    }

    public void Drop(IDropInfo dropInfo)
    {
        if (dropInfo.Data is string)
        {
            Target.Add((string)dropInfo.Data);
        }
    }
}
}

I'm using gong-wpf-dragdrop lib. Anyone know how to solve this?

punker76 punker76 · Accepted Answer · 2016-08-25T14:23:59

You should give your custom template a background to allow target drop at the whole client size.

<ControlTemplate>
    <Grid Background="{TemplateBinding Background}">
        <TextBlock Text="Drag items from left ListBox" VerticalAlignment="Center" HorizontalAlignment="Center"/>
    </Grid>
</ControlTemplate>

Hope this helps!

Wpf empty ListBox template + drag-and-drop

1 Answers