private static void DropTargetOnDragOver(object sender, DragEventArgs e, EventType eventType)
{
var elementPosition = e.GetPosition((IInputElement)sender);
var dragInfo = m_DragInfo;
var dropInfo = new DropInfo(sender, e, dragInfo, eventType);
var dropHandler = TryGetDropHandler(dropInfo, sender as UIElement);
var itemsControl = dropInfo.VisualTarget;
dropHandler.DragOver(dropInfo);
if (DragAdorner == null && dragInfo != null)
{
CreateDragAdorner(dropInfo);
}
// Moves DragAdorner following with mouse point
DragAdorner?.Move(e.GetPosition(DragAdorner.AdornedElement), dragInfo != null ? GetDragMouseAnchorPoint(dragInfo.VisualSource) : default(Point), ref _adornerMousePosition, ref _adornerSize);
Scroll(dropInfo, e);
if (HitTestUtilities.HitTest4Type <ScrollBar>(sender, elementPosition) ||
HitTestUtilities.HitTest4GridViewColumnHeader(sender, elementPosition) ||
HitTestUtilities.HitTest4DataGridTypesOnDragOver(sender, elementPosition))
{
e.Effects = DragDropEffects.None;
e.Handled = true;
return;
}
// If the target is an ItemsControl then update the drop target adorner.
if (itemsControl != null)
{
// Display the adorner in the control's ItemsPresenter. If there is no
// ItemsPresenter provided by the style, try getting hold of a
// ScrollContentPresenter and using that.
UIElement adornedElement = null;
if (itemsControl is TabControl)
{
adornedElement = itemsControl.FindVisualChild <TabPanel>();
}
else if (itemsControl is DataGrid || (itemsControl as ListView)?.View is GridView)
{
adornedElement = itemsControl.FindVisualChild <ScrollContentPresenter>() ?? itemsControl.FindVisualChild <ItemsPresenter>() ?? itemsControl;
}
else
{
adornedElement = itemsControl.FindVisualChild <ItemsPresenter>() ?? itemsControl.FindVisualChild <ScrollContentPresenter>() ?? itemsControl;
}
if (adornedElement != null)
{
if (dropInfo.DropTargetAdorner == null)
{
DropTargetAdorner = null;
}
else if (!dropInfo.DropTargetAdorner.IsInstanceOfType(DropTargetAdorner))
{
DropTargetAdorner = DropTargetAdorner.Create(dropInfo.DropTargetAdorner, adornedElement, dropInfo);
}
var adorner = DropTargetAdorner;
if (adorner != null)
{
var adornerBrush = GetDropTargetAdornerBrush(dropInfo.VisualTarget);
if (adornerBrush != null)
{
adorner.Pen.Brush = adornerBrush;
}
adorner.DropInfo = dropInfo;
adorner.InvalidateVisual();
}
}
}
// Set the drag effect adorner if there is one
if (dragInfo != null && (EffectAdorner == null || EffectAdorner.Effects != dropInfo.Effects))
{
CreateEffectAdorner(dropInfo);
}
EffectAdorner?.Move(e.GetPosition(EffectAdorner.AdornedElement), default(Point), ref _effectAdornerMousePosition, ref _effectAdornerSize);
e.Effects = dropInfo.Effects;
e.Handled = !dropInfo.NotHandled;
if (!dropInfo.IsSameDragDropContextAsSource)
{
e.Effects = DragDropEffects.None;
}
}
/// <summary>
/// Set base drag info when mouse left button down
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private static void DoMouseButtonDown(object sender, MouseButtonEventArgs e)
{
m_DragInfo = null;
// Gets the position of the mouse relative to source control
var elementPosition = e.GetPosition((IInputElement)sender);
// Ignore the click if clickCount != 1 or the user has clicked on a scrollbar or the control while editing.
if (e.ClickCount != 1 ||
(sender as UIElement).IsDragSourceIgnored() ||
(e.Source as UIElement).IsDragSourceIgnored() ||
(e.OriginalSource as UIElement).IsDragSourceIgnored()
// Ignore TabControl's content presenter
|| (sender is TabControl) && !HitTestUtilities.HitTest4Type <TabPanel>(sender, elementPosition)
// Ignore scroll bar
|| HitTestUtilities.HitTest4Type <RangeBase>(sender, elementPosition)
// Ignore the control while editing.
|| HitTestUtilities.HitTest4Type <TextBoxBase>(sender, elementPosition) ||
HitTestUtilities.HitTest4Type <PasswordBox>(sender, elementPosition) ||
HitTestUtilities.HitTest4Type <ComboBox>(sender, elementPosition)
// Ignore grid column header
|| HitTestUtilities.HitTest4GridViewColumnHeader(sender, elementPosition)
// Ignore user reordering DataGrid columns and drag row header gripper to chang row header height
|| HitTestUtilities.HitTest4DataGridTypes(sender, elementPosition) ||
HitTestUtilities.IsNotPartOfSender(sender, e))
{
return;
}
var dragInfo = new DragInfo(sender, e);
if (dragInfo.VisualSource is ItemsControl control && control.CanSelectMultipleItems())
{
control.Focus();
}
if (dragInfo.VisualSourceItem == null)
{
return;
}
var dragHandler = TryGetDragHandler(dragInfo, sender as UIElement);
if (!dragHandler.CanStartDrag(dragInfo))
{
return;
}
// If the sender is a list box that allows multiple selections, ensure that clicking on an
// already selected item does not change the selection(didn't click a shift key or control key at the same time),
// otherwise dragging multiple items is made impossible.
if ((Keyboard.Modifiers & ModifierKeys.Shift) == 0 && (Keyboard.Modifiers & ModifierKeys.Control) == 0 && dragInfo.VisualSourceItem != null && sender is ItemsControl itemsControl && itemsControl.CanSelectMultipleItems())
{
var selectedItems = itemsControl.GetSelectedItems().OfType <object>().ToList();
// we haven't pressed control key and shift key, set clicked current item
if (selectedItems.Count > 1 && selectedItems.Contains(dragInfo.SourceItem))
{
m_ClickSupressItem = dragInfo.SourceItem;
e.Handled = true;
}
}
m_DragInfo = dragInfo;
}
