/// <summary>
/// This scrolls the items control when we hit a boundary
/// </summary>
/// <param name="itemsControl"></param>
/// <param name="e"></param>
private void HandleDragScrolling(ItemsControl itemsControl, DragEventArgs e)
{
bool?isMouseAtTop = DragUtilities.IsMousePointerAtTop(itemsControl, e.GetPosition(itemsControl));
if (isMouseAtTop.HasValue)
{
if (this._dragScrollWaitCounter == DragWaitCounterThreshold)
{
this._dragScrollWaitCounter = 0;
ScrollViewer scrollViewer = DragUtilities.FindScrollViewer(itemsControl);
if (scrollViewer != null && scrollViewer.CanContentScroll &&
scrollViewer.ComputedVerticalScrollBarVisibility == Visibility.Visible)
{
scrollViewer.ScrollToVerticalOffset((isMouseAtTop.Value) ? scrollViewer.VerticalOffset - 1.0 : scrollViewer.VerticalOffset + 1.0);
e.Effects = DragDropEffects.Scroll;
}
}
else
{
this._dragScrollWaitCounter++;
}
}
else
{
e.Effects = GetDropEffectType(e.AllowedEffects, e.KeyStates);
}
}
/// <summary>
/// Update the position of the insertion point marker
/// </summary>
/// <param name="itemsControl"></param>
/// <param name="e"></param>
private void UpdateInsertAdorner(ItemsControl itemsControl, DragEventArgs e)
{
if (this._insertAdorner != null)
{
this._insertAdorner.InTopHalf = DragUtilities.IsPointInTopHalf(itemsControl, e);
this._insertAdorner.InvalidateVisual();
}
}
/// <summary>
/// Determine the proper insertion index
/// </summary>
/// <param name="itemsControl"></param>
/// <param name="e"></param>
/// <returns></returns>
private static int FindInsertionIndex(ItemsControl itemsControl, DragEventArgs e)
{
UIElement dropTargetContainer = DragUtilities.GetItemContainerFromPoint(itemsControl, e.GetPosition(itemsControl));
if (dropTargetContainer != null)
{
int index = itemsControl.ItemContainerGenerator.IndexFromContainer(dropTargetContainer);
return(DragUtilities.IsPointInTopHalf(itemsControl, e) ? index : index + 1);
}
return(itemsControl.Items.Count);
}
/// <summary>
/// Drop started
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void PreviewDrop(object sender, DragEventArgs e)
{
var itemsControl = (ItemsControl)sender;
this.DestroyAdorners();
e.Handled = true;
if (e.Data.GetDataPresent(this.ItemTypeKey))
{
int index = FindInsertionIndex(itemsControl, e);
DragInfo data = e.Data.GetData(this.ItemTypeKey) as DragInfo;
if (data != null && (!data.AllowOnlySelf || itemsControl == data.Source))
{
var allowedEffects = e.AllowedEffects;
if (this.DropInitiated != null)
{
DragDropEventArgs de = new DragDropEventArgs(data.Source, itemsControl, data.Data, index)
{
AllowedEffects = allowedEffects
};
this.DropInitiated(this, de);
allowedEffects = de.AllowedEffects;
if (de.Cancel)
{
e.Effects = DragDropEffects.None;
return;
}
}
object itemToAdd = data.Data;
e.Effects = GetDropEffectType(allowedEffects, e.KeyStates);
if (DragUtilities.DoesItemExists(itemsControl, itemToAdd) &&
(e.Effects == DragDropEffects.Move ||
(e.Effects & DragDropEffects.Move) > 0 && (e.KeyStates & DragDropKeyStates.ControlKey) > 0))
{
DragUtilities.RemoveItem(itemsControl, itemToAdd);
// Recalc our position based on the removal
index = FindInsertionIndex(itemsControl, e);
}
DragUtilities.AddItem(itemsControl, itemToAdd, index);
DragUtilities.SelectItem(itemsControl, index);
}
else
{
e.Effects = DragDropEffects.None;
}
}
else
{
e.Effects = DragDropEffects.None;
}
}
/// <summary>
/// Starts the drag/drop operation.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
var itemsControl = (ItemsControl)sender;
Point p = e.GetPosition(itemsControl);
this._data = DragUtilities.GetDataObjectFromItemsControl(itemsControl, p);
if (this._data != null)
{
this._isMouseDown = true;
this._dragStartPosition = p;
}
}
/// <summary>
/// Initialize the insertion point marker
/// </summary>
/// <param name="itemsControl"></param>
/// <param name="e"></param>
private void InitializeInsertAdorner(ItemsControl itemsControl, DragEventArgs e)
{
if (this._insertAdorner == null && this.ShowInsertAdorner)
{
UIElement itemContainer = DragUtilities.GetItemContainerFromPoint(itemsControl, e.GetPosition(itemsControl));
if (itemContainer != null)
{
this._insertAdorner = new InsertAdorner(DragUtilities.IsPointInTopHalf(itemsControl, e),
DragUtilities.IsItemControlOrientationHorizontal(itemsControl),
itemContainer, AdornerLayer.GetAdornerLayer(itemsControl), itemsControl);
}
}
}
/// <summary>
/// New drop target identified
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void PreviewDragEnter(object sender, DragEventArgs e)
{
e.Handled = true;
e.Effects = DragDropEffects.None;
var itemsControl = (ItemsControl)sender;
// Do not allow if sorted.
if (!DragUtilities.CanReorderCollectionView(itemsControl))
{
return;
}
if (e.Data.GetDataPresent(this.ItemTypeKey))
{
DragInfo data = e.Data.GetData(this.ItemTypeKey) as DragInfo;
if (data != null)
{
if (!data.AllowOnlySelf || itemsControl == data.Source)
{
var allowedEffects = e.AllowedEffects;
if (itemsControl == data.Source && !this.AllowSelf)
{
allowedEffects = DragDropEffects.None;
}
else if (this.DropEnter != null)
{
DragDropEventArgs de = new DragDropEventArgs(data.Source, itemsControl, data.Data)
{
AllowedEffects = allowedEffects
};
this.DropEnter(this, de);
allowedEffects = de.AllowedEffects;
if (de.Cancel)
{
return;
}
}
this.InitializeDragAdorner(itemsControl, data.Data, e.GetPosition(itemsControl));
e.Effects = GetDropEffectType(allowedEffects, e.KeyStates);
if (e.Effects != DragDropEffects.None)
{
this.InitializeInsertAdorner(itemsControl, e);
}
}
}
}
}
/// <summary>
/// This starts the drag operation from the given ItemsControl
/// </summary>
/// <param name="itemsControl"></param>
private void DragStarted(ItemsControl itemsControl)
{
DragDropEffects allowedEffects = DragDropEffects.Copy | DragDropEffects.Move;
if (this.DragInitiated != null)
{
var dde = new DragDropEventArgs(itemsControl, null, this._data)
{
AllowedEffects = allowedEffects
};
this.DragInitiated(this, dde);
if (dde.Cancel)
{
this.ResetState();
return;
}
allowedEffects = dde.AllowedEffects;
}
UIElement draggedItemContainer = DragUtilities.GetItemContainerFromPoint(itemsControl, this._dragStartPosition);
this._isDragging = true;
DataObject dObject = new DataObject(this.ItemTypeKey, new DragInfo {
Data = this._data, Source = itemsControl, AllowOnlySelf = this.AllowOnlySelf
});
DragDropEffects e = DragDrop.DoDragDrop(itemsControl, dObject, allowedEffects);
if ((e & DragDropEffects.Move) != 0)
{
if (draggedItemContainer != null)
{
int dragItemIndex = itemsControl.ItemContainerGenerator.IndexFromContainer(draggedItemContainer);
DragUtilities.RemoveItem(itemsControl, dragItemIndex);
}
else
{
DragUtilities.RemoveItem(itemsControl, this._data);
}
}
this.ResetState();
}
/// <summary>
/// Display the drag indicator
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void PreviewMouseMove(object sender, MouseEventArgs e)
{
if (this._isMouseDown)
{
var itemsControl = (ItemsControl)sender;
Point currentPosition = e.GetPosition(itemsControl);
if ((this._isDragging == false) && (Math.Abs(currentPosition.X - this._dragStartPosition.X) > SystemParameters.MinimumHorizontalDragDistance) ||
(Math.Abs(currentPosition.Y - this._dragStartPosition.Y) > SystemParameters.MinimumVerticalDragDistance))
{
// Do not allow if sorted and we only allow this element as
// the drop target.
if (!DragUtilities.CanReorderCollectionView(itemsControl) &&
this.AllowOnlySelf)
{
return;
}
this.DragStarted(itemsControl);
}
}
}
