/// <summary>
/// Clears the current selected items and selects the given items.
/// </summary>
/// <param name="dropInfo">The drop information.</param>
/// <param name="items">The items which should be select.</param>
/// <param name="applyTemplate">if set to <c>true</c> then for all items the ApplyTemplate will be invoked.</param>
/// <param name="focusVisualTarget">if set to <c>true</c> the visual target will be focused.</param>
/// <exception cref="System.ArgumentNullException"><paramref name="dropInfo" /> is <see langword="null" /></exception>
/// <exception cref="System.ArgumentNullException"><paramref name="dropInfo" /> is <see langword="null" /></exception>
public static void SelectDroppedItems([NotNull] IDropInfo dropInfo, [NotNull] IEnumerable items, bool applyTemplate = true, bool focusVisualTarget = true)
{
if (dropInfo == null)
{
throw new ArgumentNullException(nameof(dropInfo));
}
if (items == null)
{
throw new ArgumentNullException(nameof(items));
}
if (dropInfo.VisualTarget is ItemsControl itemsControl)
{
var tvItem = dropInfo.VisualTargetItem as TreeViewItem;
var tvItemIsExpanded = tvItem != null && tvItem.HasHeader && tvItem.HasItems && tvItem.IsExpanded;
var itemsParent = tvItemIsExpanded
? tvItem
: dropInfo.VisualTargetItem != null
? ItemsControl.ItemsControlFromItemContainer(dropInfo.VisualTargetItem)
: itemsControl;
itemsParent ??= itemsControl;
(dropInfo.DragInfo.VisualSourceItem as TreeViewItem)?.ClearSelectedItems();
itemsParent.ClearSelectedItems();
var selectDroppedItems = dropInfo.VisualTarget is TabControl || (dropInfo.VisualTarget != null && DragDrop.GetSelectDroppedItems(dropInfo.VisualTarget));
if (selectDroppedItems)
{
foreach (var item in items)
{
if (applyTemplate)
{
// call ApplyTemplate for TabItem in TabControl to avoid this error:
//
// System.Windows.Data Error: 4 : Cannot find source for binding with reference
var container = itemsParent.ItemContainerGenerator.ContainerFromItem(item) as FrameworkElement;
container?.ApplyTemplate();
}
itemsParent.SetItemSelected(item, true);
}
if (focusVisualTarget)
{
itemsControl.Focus();
}
}
}
}
/// <summary>
/// Performs a drop.
/// </summary>
/// <param name="dropInfo">Information about the drop.</param>
public virtual void Drop(IDropInfo dropInfo)
{
if (dropInfo == null || dropInfo.DragInfo == null)
{
return;
}
var insertIndex = dropInfo.UnfilteredInsertIndex;
var itemsControl = dropInfo.VisualTarget as ItemsControl;
if (itemsControl != null)
{
var editableItems = itemsControl.Items as IEditableCollectionView;
if (editableItems != null)
{
var newItemPlaceholderPosition = editableItems.NewItemPlaceholderPosition;
if (newItemPlaceholderPosition == NewItemPlaceholderPosition.AtBeginning && insertIndex == 0)
{
++insertIndex;
}
else if (newItemPlaceholderPosition == NewItemPlaceholderPosition.AtEnd && insertIndex == itemsControl.Items.Count)
{
--insertIndex;
}
}
}
var destinationList = dropInfo.TargetCollection.TryGetList();
var data = ExtractData(dropInfo.Data).OfType <object>().ToList();
var copyData = ShouldCopyData(dropInfo);
if (!copyData)
{
var sourceList = dropInfo.DragInfo.SourceCollection.TryGetList();
if (sourceList != null)
{
foreach (var o in data)
{
var index = sourceList.IndexOf(o);
if (index != -1)
{
sourceList.RemoveAt(index);
// so, is the source list the destination list too ?
if (destinationList != null && Equals(sourceList, destinationList) && index < insertIndex)
{
--insertIndex;
}
}
}
}
}
if (destinationList != null)
{
var objects2Insert = new List <object>();
// check for cloning
var cloneData = dropInfo.Effects.HasFlag(DragDropEffects.Copy) || dropInfo.Effects.HasFlag(DragDropEffects.Link);
foreach (var o in data)
{
var obj2Insert = o;
if (cloneData)
{
var cloneable = o as ICloneable;
if (cloneable != null)
{
obj2Insert = cloneable.Clone();
}
}
objects2Insert.Add(obj2Insert);
destinationList.Insert(insertIndex++, obj2Insert);
}
var selectDroppedItems = itemsControl is TabControl || (itemsControl != null && DragDrop.GetSelectDroppedItems(itemsControl));
if (selectDroppedItems)
{
SelectDroppedItems(dropInfo, objects2Insert);
}
}
}
