// If the types of the dragged data and ItemsControl's source are compatible,
// there are 3 situations to have into account when deciding the drop target:
// 1. mouse is over an items container
// 2. mouse is over the empty part of an ItemsControl, but ItemsControl is not empty
// 3. mouse is over an empty ItemsControl.
// The goal of this method is to decide on the values of the following properties:
// targetItemContainer, insertionIndex and isInFirstHalf.
private void DecideDropTarget(DragEventArgs e)
{
int targetItemsControlCount = _target.Items.Count;
object draggedItem = e.Data.GetData(ItemsControlDragDrop.Format.Name);
if (IsDropDataTypeAllowed(draggedItem))
{
if (targetItemsControlCount > 0)
{
_hasVerticalOrientation = HasVerticalOrientation(_target.ItemContainerGenerator.ContainerFromIndex(0) as FrameworkElement);
_targetItemContainer = _target.ContainerFromElement((DependencyObject)e.OriginalSource) as FrameworkElement;
if (_targetItemContainer != null)
{
Point positionRelativeToItemContainer = e.GetPosition(_targetItemContainer);
_isInFirstHalf = IsInFirstHalf(_targetItemContainer, positionRelativeToItemContainer, _hasVerticalOrientation);
_insertionIndex = _target.ItemContainerGenerator.IndexFromContainer(_targetItemContainer);
if (!_isInFirstHalf)
{
_insertionIndex++;
}
}
else
{
_targetItemContainer = _target.ItemContainerGenerator.ContainerFromIndex(targetItemsControlCount - 1) as FrameworkElement;
_isInFirstHalf = false;
_insertionIndex = targetItemsControlCount;
}
}
else
{
_targetItemContainer = null;
_insertionIndex = 0;
}
var droppingItem = new CanDropItemEventArgs(draggedItem, _insertionIndex);
_target.RaiseEvent(droppingItem);
if (!droppingItem.CanDrop)
{
_targetItemContainer = null;
_insertionIndex = -1;
e.Effects = DragDropEffects.None;
}
}
else
{
_targetItemContainer = null;
_insertionIndex = -1;
e.Effects = DragDropEffects.None;
}
}
private void ListBox_OnCanDropItem(object sender, CanDropItemEventArgs e)
{
var segs = (IList<WordSegmentViewModel>) ListBox.ItemsSource;
e.CanDrop = (e.Index == segs.Count || !segs[e.Index].IsBoundary) && (e.Index == 0 || !segs[e.Index - 1].IsBoundary);
e.Handled = true;
}
// If the types of the dragged data and ItemsControl's source are compatible,
// there are 3 situations to have into account when deciding the drop target:
// 1. mouse is over an items container
// 2. mouse is over the empty part of an ItemsControl, but ItemsControl is not empty
// 3. mouse is over an empty ItemsControl.
// The goal of this method is to decide on the values of the following properties:
// targetItemContainer, insertionIndex and isInFirstHalf.
private void DecideDropTarget(DragEventArgs e)
{
int targetItemsControlCount = _target.Items.Count;
object draggedItem = e.Data.GetData(ItemsControlDragDrop.Format.Name);
if (IsDropDataTypeAllowed(draggedItem))
{
if (targetItemsControlCount > 0)
{
_hasVerticalOrientation = HasVerticalOrientation(_target.ItemContainerGenerator.ContainerFromIndex(0) as FrameworkElement);
_targetItemContainer = _target.ContainerFromElement((DependencyObject)e.OriginalSource) as FrameworkElement;
if (_targetItemContainer != null)
{
Point positionRelativeToItemContainer = e.GetPosition(_targetItemContainer);
_isInFirstHalf = IsInFirstHalf(_targetItemContainer, positionRelativeToItemContainer, _hasVerticalOrientation);
_insertionIndex = _target.ItemContainerGenerator.IndexFromContainer(_targetItemContainer);
if (!_isInFirstHalf)
_insertionIndex++;
}
else
{
_targetItemContainer = _target.ItemContainerGenerator.ContainerFromIndex(targetItemsControlCount - 1) as FrameworkElement;
_isInFirstHalf = false;
_insertionIndex = targetItemsControlCount;
}
}
else
{
_targetItemContainer = null;
_insertionIndex = 0;
}
var droppingItem = new CanDropItemEventArgs(draggedItem, _insertionIndex);
_target.RaiseEvent(droppingItem);
if (!droppingItem.CanDrop)
{
_targetItemContainer = null;
_insertionIndex = -1;
e.Effects = DragDropEffects.None;
}
}
else
{
_targetItemContainer = null;
_insertionIndex = -1;
e.Effects = DragDropEffects.None;
}
}
