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Wpf listview drag multiple items

Just wondering if anyone has any ideas on how to do this. I want the user to be able to select multiple items by clicking and dragging the mouse (without releasing the click). Let's say the user clicks on item 1, and then drags it to point 10; points 1-10 should be selected as if he clicked on element 1, then shift + click on element 10.

Let me know thanks!

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3 answers

Ok, here is my solution, I created a helper class that handles PreviewLeftMouseButtonDown and MouseLeftButtonUp for ListView and a little style for ListViewItems, which when the mouse is over it, indicates the helper class, so it can decide whether it selects or not (based on left click or not). Anyway, here is the complete project:

XAML:

<Window x:Class="DragSelectListBox.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:DragSelectListBox" Title="Window1" Height="300" Width="300"> <Window.Resources> <Style TargetType="{x:Type ListBoxItem}"> <Setter Property="local:DragSelectionHelper.IsDragSelecting" Value="False" /> <Style.Triggers> <Trigger Property="ListBoxItem.IsMouseOver" Value="True"> <Setter Property="local:DragSelectionHelper.IsDragSelecting" Value="True" /> </Trigger> </Style.Triggers> </Style> </Window.Resources> <Grid Background="AliceBlue"> <ListBox Margin="8" local:DragSelectionHelper.IsDragSelectionEnabled="true"> <ListBoxItem Content="Item 1" /> <ListBoxItem Content="Item 2" /> <ListBoxItem Content="Item 3" /> <ListBoxItem Content="Item 4" /> <ListBoxItem Content="Item 5" /> <ListBoxItem Content="Item 6" /> <ListBoxItem Content="Item 7" /> <ListBoxItem Content="Item 8" /> <ListBoxItem Content="Item 9" /> <ListBoxItem Content="Item 10" /> <ListBoxItem Content="Item 11" /> <ListBoxItem Content="Item 12" /> <ListBoxItem Content="Item 13" /> <ListBoxItem Content="Item 14" /> <ListBoxItem Content="Item 15" /> <ListBoxItem Content="Item 16" /> <ListBoxItem Content="Item 17" /> <ListBoxItem Content="Item 18" /> <ListBoxItem Content="Item 19" /> <ListBoxItem Content="Item 20" /> <ListBoxItem Content="Item 21" /> <ListBoxItem Content="Item 22" /> <ListBoxItem Content="Item 23" /> <ListBoxItem Content="Item 24" /> <ListBoxItem Content="Item 25" /> <ListBoxItem Content="Item 26" /> <ListBoxItem Content="Item 27" /> <ListBoxItem Content="Item 28" /> <ListBoxItem Content="Item 29" /> <ListBoxItem Content="Item 30" /> </ListBox> </Grid> </Window>

FROM#:

 using System.Windows; using System.Windows.Controls; using System.Windows.Input; namespace DragSelectListBox { /// <summary> /// Interaction logic for Window1.xaml /// </summary> public partial class Window1 : Window { public Window1() { InitializeComponent(); } } // CARLO 20100519: Helper class for DragSelection public class DragSelectionHelper : DependencyObject { #region Random Static Properties // need a static reference to the listbox otherwise it can't be accessed // (this only happened in the project I'm working on, if you're using a regular ListBox, with regular ListBoxItems you can get the ListBox from the ListBoxItems) public static ListBox ListBox { get; private set; } #endregion Random Static Properties #region IsDragSelectionEnabledProperty public static bool GetIsDragSelectionEnabled(DependencyObject obj) { return (bool)obj.GetValue(IsDragSelectionEnabledProperty); } public static void SetIsDragSelectionEnabled(DependencyObject obj, bool value) { obj.SetValue(IsDragSelectionEnabledProperty, value); } public static readonly DependencyProperty IsDragSelectionEnabledProperty = DependencyProperty.RegisterAttached("IsDragSelectingEnabled", typeof(bool), typeof(DragSelectionHelper), new UIPropertyMetadata(false, IsDragSelectingEnabledPropertyChanged)); public static void IsDragSelectingEnabledPropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e) { ListBox listBox = o as ListBox; bool isDragSelectionEnabled = DragSelectionHelper.GetIsDragSelectionEnabled(listBox); // if DragSelection is enabled if (isDragSelectionEnabled) { // set the listbox selection mode to multiple ( didn't work with extended ) listBox.SelectionMode = SelectionMode.Multiple; // set the static listbox property DragSelectionHelper.ListBox = listBox; // and subscribe to the required events to handle the drag selection and the attached properties listBox.PreviewMouseLeftButtonDown += new MouseButtonEventHandler(DragSelectionHelper.listBox_PreviewMouseLeftButtonDown); listBox.PreviewMouseRightButtonDown += new MouseButtonEventHandler(listBox_PreviewMouseRightButtonDown); listBox.MouseLeftButtonUp += new MouseButtonEventHandler(DragSelectionHelper.listBox_MouseLeftButtonUp); } else // is selection is disabled { // set selection mode to the default listBox.SelectionMode = SelectionMode.Single; // dereference the listbox DragSelectionHelper.ListBox = null; // unsuscribe from the events listBox.PreviewMouseLeftButtonDown -= new MouseButtonEventHandler(DragSelectionHelper.listBox_PreviewMouseLeftButtonDown); listBox.MouseLeftButtonUp -= new MouseButtonEventHandler(DragSelectionHelper.listBox_MouseLeftButtonUp); listBox.MouseLeftButtonUp -= new MouseButtonEventHandler(DragSelectionHelper.listBox_MouseLeftButtonUp); } } static void listBox_PreviewMouseRightButtonDown(object sender, MouseButtonEventArgs e) { // to prevent the listbox from selecting / deselecting wells on right click e.Handled = true; } private static void listBox_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e) { // notify the helper class that the listbox has initiated the drag click DragSelectionHelper.SetIsDragClickStarted(DragSelectionHelper.ListBox, true); } private static void listBox_MouseLeftButtonUp(object sender, MouseButtonEventArgs e) { // notify the helper class that the list box has terminated the drag click DragSelectionHelper.SetIsDragClickStarted(DragSelectionHelper.ListBox, false); } #endregion IsDragSelectionEnabledProperty #region IsDragSelectinProperty public static bool GetIsDragSelecting(DependencyObject obj) { return (bool)obj.GetValue(IsDragSelectingProperty); } public static void SetIsDragSelecting(DependencyObject obj, bool value) { obj.SetValue(IsDragSelectingProperty, value); } public static readonly DependencyProperty IsDragSelectingProperty = DependencyProperty.RegisterAttached("IsDragSelecting", typeof(bool), typeof(DragSelectionHelper), new UIPropertyMetadata(false, IsDragSelectingPropertyChanged)); public static void IsDragSelectingPropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e) { ListBoxItem item = o as ListBoxItem; bool clickInitiated = DragSelectionHelper.GetIsDragClickStarted(DragSelectionHelper.ListBox); // this is where the item.Parent was null, it was supposed to be the ListBox, I guess it null because items are not // really ListBoxItems but are wells if (clickInitiated) { bool isDragSelecting = DragSelectionHelper.GetIsDragSelecting(item); if (isDragSelecting) { // using the ListBox static reference because could not get to it through the item.Parent property DragSelectionHelper.ListBox.SelectedItems.Add(item); } } } #endregion IsDragSelectinProperty #region IsDragClickStartedProperty public static bool GetIsDragClickStarted(DependencyObject obj) { return (bool)obj.GetValue(IsDragClickStartedProperty); } public static void SetIsDragClickStarted(DependencyObject obj, bool value) { obj.SetValue(IsDragClickStartedProperty, value); } public static readonly DependencyProperty IsDragClickStartedProperty = DependencyProperty.RegisterAttached("IsDragClickStarted", typeof(bool), typeof(DragSelectionHelper), new UIPropertyMetadata(false, IsDragClickStartedPropertyChanged)); public static void IsDragClickStartedPropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e) { bool isDragClickStarted = DragSelectionHelper.GetIsDragClickStarted(DragSelectionHelper.ListBox); // if click has been drag click has started, clear the current selected items and start drag selection operation again if (isDragClickStarted) DragSelectionHelper.ListBox.SelectedItems.Clear(); } #endregion IsDragClickInitiatedProperty } }

So, as you can see, all you have to do is add a style to your xaml and install:

local: DragSelectionHelper.IsDragSelectionEnabled = "true"

The attached property is a ListView, and that will take care of everything.

Thanks!

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Also note that with SelectionMode=Extended this is already possible if the user holds the SHIFT key before clicking the mouse button.

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Based on Carlo's answer, I changed some of his code, now you can use CTRL to continue the selection without clearing the current selection and use SHIFT to select items such as "Extended" mode.

 using System.Windows; using System.Windows.Controls; using System.Windows.Controls.Primitives; using System.Windows.Input; using System.Windows.Media; namespace SteamFriendsManager.Utility { public class DragSelectionHelper : DependencyObject { #region IsDragSelectionEnabledProperty public static bool GetIsDragSelectionEnabled(DependencyObject obj) { return (bool) obj.GetValue(IsDragSelectionEnabledProperty); } public static void SetIsDragSelectionEnabled(DependencyObject obj, bool value) { obj.SetValue(IsDragSelectionEnabledProperty, value); } public static readonly DependencyProperty IsDragSelectionEnabledProperty = DependencyProperty.RegisterAttached("IsDragSelectingEnabled", typeof (bool), typeof (DragSelectionHelper), new UIPropertyMetadata(false, IsDragSelectingEnabledPropertyChanged)); private static void IsDragSelectingEnabledPropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e) { var listBox = o as ListBox; if (listBox == null) return; // if DragSelection is enabled if (GetIsDragSelectionEnabled(listBox)) { // set the listbox selection mode to multiple ( didn't work with extended ) listBox.SelectionMode = SelectionMode.Multiple; // and subscribe to the required events to handle the drag selection and the attached properties listBox.PreviewMouseRightButtonDown += listBox_PreviewMouseRightButtonDown; listBox.PreviewMouseLeftButtonDown += listBox_PreviewMouseLeftButtonDown; listBox.PreviewMouseLeftButtonUp += listBox_PreviewMouseLeftButtonUp; listBox.PreviewKeyDown += listBox_PreviewKeyDown; listBox.PreviewKeyUp += listBox_PreviewKeyUp; } else // is selection is disabled { // set selection mode to the default listBox.SelectionMode = SelectionMode.Extended; // unsuscribe from the events listBox.PreviewMouseRightButtonDown -= listBox_PreviewMouseRightButtonDown; listBox.PreviewMouseLeftButtonDown -= listBox_PreviewMouseLeftButtonDown; listBox.PreviewMouseLeftButtonUp -= listBox_PreviewMouseLeftButtonUp; listBox.PreviewKeyDown -= listBox_PreviewKeyDown; listBox.PreviewKeyUp += listBox_PreviewKeyUp; } } private static void listBox_PreviewKeyDown(object sender, KeyEventArgs e) { var listBox = sender as ListBox; if (listBox == null) return; if (e.Key == Key.LeftShift || e.Key == Key.RightShift) { SetIsDragSelectionEnabled(listBox, false); } } private static void listBox_PreviewKeyUp(object sender, KeyEventArgs e) { var listBox = sender as ListBox; if (listBox == null) return; if (e.Key == Key.LeftShift || e.Key == Key.RightShift) { SetIsDragSelectionEnabled(listBox, true); } } private static void listBox_PreviewMouseRightButtonDown(object sender, MouseButtonEventArgs e) { // to prevent the listbox from selecting / deselecting wells on right click e.Handled = true; } private static void listBox_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e) { SetIsDragClickStarted(sender as DependencyObject, true); } private static void listBox_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e) { SetIsDragClickStarted(sender as DependencyObject, false); } public static DependencyObject GetParent(DependencyObject obj) { if (obj == null) return null; var ce = obj as ContentElement; if (ce == null) return VisualTreeHelper.GetParent(obj); var parent = ContentOperations.GetParent(ce); if (parent != null) return parent; var fce = ce as FrameworkContentElement; return fce != null ? fce.Parent : null; } #endregion IsDragSelectionEnabledProperty #region IsDragSelectingProperty public static bool GetIsDragSelecting(DependencyObject obj) { return (bool) obj.GetValue(IsDragSelectingProperty); } public static void SetIsDragSelecting(DependencyObject obj, bool value) { obj.SetValue(IsDragSelectingProperty, value); } public static readonly DependencyProperty IsDragSelectingProperty = DependencyProperty.RegisterAttached("IsDragSelecting", typeof (bool), typeof (DragSelectionHelper), new UIPropertyMetadata(false, IsDragSelectingPropertyChanged)); private static void IsDragSelectingPropertyChanged(DependencyObject o, DependencyPropertyChangedEventArgs e) { var listBoxItem = o as ListBoxItem; if (listBoxItem == null) return; if (!GetIsDragClickStarted(listBoxItem)) return; if (GetIsDragSelecting(listBoxItem)) { listBoxItem.IsSelected = true; } } #endregion IsDragSelectingProperty #region IsDragClickStartedProperty public static bool GetIsDragClickStarted(DependencyObject obj) { return (bool) obj.GetValue(IsDragClickStartedProperty); } public static void SetIsDragClickStarted(DependencyObject obj, bool value) { obj.SetValue(IsDragClickStartedProperty, value); } public static readonly DependencyProperty IsDragClickStartedProperty = DependencyProperty.RegisterAttached("IsDragClickStarted", typeof (bool), typeof (DragSelectionHelper), new FrameworkPropertyMetadata(false, IsDragClickStartedPropertyChanged) {Inherits = true}); private static void IsDragClickStartedPropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) { var listBox = obj as ListBox; if (listBox == null) return; if (Keyboard.IsKeyDown(Key.LeftCtrl) || Keyboard.IsKeyDown(Key.RightCtrl)) return; var hitTestResult = VisualTreeHelper.HitTest(listBox, Mouse.GetPosition(listBox)); if (hitTestResult == null) return; var element = hitTestResult.VisualHit; while (element != null) { var scrollBar = element as ScrollBar; if (scrollBar != null) { return; } element = VisualTreeHelper.GetParent(element); } if (GetIsDragClickStarted(listBox)) listBox.SelectedItems.Clear(); } #endregion IsDragClickInitiatedProperty } }

Demo: Demo

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