static void DragSource_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
// If we prevented the control's default selection handling in DragSource_PreviewMouseLeftButtonDown
// by setting 'e.Handled = true' and a drag was not initiated, manually set the selection here.
ItemsControl itemsControl = sender as ItemsControl;
if (itemsControl != null && m_DragInfo != null && m_ClickSupressItem == m_DragInfo.SourceItem)
{
if ((Keyboard.Modifiers & ModifierKeys.Control) != 0)
{
itemsControl.SetItemSelected(m_DragInfo.SourceItem, false);
}
else
{
itemsControl.SetSelectedItem(m_DragInfo.SourceItem);
}
}
if (m_DragInfo != null)
{
m_DragInfo = null;
}
m_ClickSupressItem = null;
}
static void DragSource_PreviewMouseMove(object sender, MouseEventArgs e)
{
if (m_DragInfo != null && !m_DragInProgress)
{
Point dragStart = m_DragInfo.DragStartPosition;
Point position = e.GetPosition(null);
if (Math.Abs(position.X - dragStart.X) > SystemParameters.MinimumHorizontalDragDistance ||
Math.Abs(position.Y - dragStart.Y) > SystemParameters.MinimumVerticalDragDistance)
{
IDragSource dragHandler = GetDragHandler(m_DragInfo.VisualSource);
if (dragHandler != null)
{
dragHandler.StartDrag(m_DragInfo);
}
else
{
DefaultDragHandler.StartDrag(m_DragInfo);
}
if (m_DragInfo.Effects != DragDropEffects.None && m_DragInfo.Data != null)
{
DataObject data = new DataObject(DataFormat.Name, m_DragInfo.Data);
try
{
m_DragInProgress = true;
System.Windows.DragDrop.DoDragDrop(m_DragInfo.VisualSource, data, m_DragInfo.Effects);
}
finally
{
m_DragInProgress = false;
}
m_DragInfo = null;
}
}
}
}
static void DragSource_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
// Ignore the click if the user has clicked on a scrollbar.
if (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<object> selectedItems = itemsControl.GetSelectedItems().Cast<object>();
if (selectedItems.Count() > 1 && selectedItems.Contains(m_DragInfo.SourceItem))
{
m_ClickSupressItem = m_DragInfo.SourceItem;
e.Handled = true;
}
}
}
