static void DragSource_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
// Ignore the click if the user has clicked on a scrollbar.
if (DragDrop.HitTestScrollBar(sender, e))
{
m_DragInfo = null;
return;
}
m_DragInfo = new DragInfo(sender, e);
// If the sender is a list box that allows multiple selections, ensure that clicking on an
// already selected item does not change the selection, otherwise dragging multiple items
// is made impossible.
ItemsControl itemsControl = sender as ItemsControl;
if (m_DragInfo.VisualSourceItem != null && itemsControl != null && itemsControl.CanSelectMultipleItems())
{
IEnumerable selectedItems = itemsControl.GetSelectedItems();
if (selectedItems.Cast <object>().Contains(m_DragInfo.SourceItem))
{
// TODO: Re-raise the supressed event if the user didn't initiate a drag.
e.Handled = true;
}
}
}
public virtual void StartDrag(DragInfo dragInfo)
{
int itemCount = dragInfo.SourceItems.Cast <object>().Count();
if (itemCount == 1)
{
dragInfo.Data = dragInfo.SourceItems.Cast <object>().First();
}
else if (itemCount > 1)
{
dragInfo.Data = TypeUtilities.CreateDynamicallyTypedList(dragInfo.SourceItems);
}
dragInfo.Effects = (dragInfo.Data != null) ?
DragDropEffects.Copy | DragDropEffects.Move :
DragDropEffects.None;
}
public DropInfo(object sender, DragEventArgs e, DragInfo dragInfo, string dataFormat)
{
this.Data = (e.Data.GetDataPresent(dataFormat)) ? e.Data.GetData(dataFormat) : e.Data;
this.DragInfo = dragInfo;
this.VisualTarget = sender as UIElement;
if (sender is ItemsControl)
{
ItemsControl itemsControl = (ItemsControl)sender;
UIElement item = itemsControl.GetItemContainerAt(e.GetPosition(itemsControl));
this.VisualTargetOrientation = itemsControl.GetItemsPanelOrientation();
if (item != null)
{
ItemsControl itemParent = ItemsControl.ItemsControlFromItemContainer(item);
this.InsertIndex = itemParent.ItemContainerGenerator.IndexFromContainer(item);
this.TargetCollection = itemParent.ItemsSource ?? itemParent.Items;
this.TargetItem = itemParent.ItemContainerGenerator.ItemFromContainer(item);
this.VisualTargetItem = item;
if (this.VisualTargetOrientation == Orientation.Vertical)
{
if (e.GetPosition(item).Y > item.RenderSize.Height / 2)
{
this.InsertIndex++;
}
}
else
{
if (e.GetPosition(item).X > item.RenderSize.Width / 2)
{
this.InsertIndex++;
}
}
}
else
{
this.TargetCollection = itemsControl.ItemsSource ?? itemsControl.Items;
this.InsertIndex = itemsControl.Items.Count;
}
}
}
