private static void DoMouseButtonDown(object sender, MouseButtonEventArgs e)
{
m_DragInfo = null;
// Ignore the click if clickCount != 1 or the user has clicked on a scrollbar.
var elementPosition = e.GetPosition((IInputElement)sender);
if (e.ClickCount != 1 ||
(sender as UIElement).IsDragSourceIgnored() ||
(e.Source as UIElement).IsDragSourceIgnored() ||
(e.OriginalSource as UIElement).IsDragSourceIgnored() ||
(sender is TabControl) && !HitTestUtilities.HitTest4Type <TabPanel>(sender, elementPosition) ||
HitTestUtilities.HitTest4Type <RangeBase>(sender, elementPosition) ||
HitTestUtilities.HitTest4Type <TextBoxBase>(sender, elementPosition) ||
HitTestUtilities.HitTest4Type <PasswordBox>(sender, elementPosition) ||
HitTestUtilities.HitTest4Type <ComboBox>(sender, elementPosition) ||
HitTestUtilities.HitTest4GridViewColumnHeader(sender, elementPosition) ||
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, otherwise dragging multiple items
// is made impossible.
var itemsControl = sender as ItemsControl;
if ((Keyboard.Modifiers & ModifierKeys.Shift) == 0 && (Keyboard.Modifiers & ModifierKeys.Control) == 0 && dragInfo.VisualSourceItem != null && itemsControl != null && itemsControl.CanSelectMultipleItems())
{
var selectedItems = itemsControl.GetSelectedItems().OfType <object>().ToList();
if (selectedItems.Count > 1 && selectedItems.Contains(dragInfo.SourceItem))
{
m_ClickSupressItem = dragInfo.SourceItem;
e.Handled = true;
}
}
m_DragInfo = dragInfo;
}
/// <summary>
/// Gets the drag handler from the drag info or from the sender, if the drag info is null
/// </summary>
/// <param name="dragInfo">the drag info object</param>
/// <param name="sender">the sender from an event, e.g. mouse down, mouse move</param>
/// <returns></returns>
private static IDragSource TryGetDragHandler(DragInfo dragInfo, UIElement sender)
{
IDragSource dragHandler = null;
if (dragInfo != null && dragInfo.VisualSource != null)
{
dragHandler = GetDragHandler(dragInfo.VisualSource);
}
if (dragHandler == null && sender != null)
{
dragHandler = GetDragHandler(sender);
}
return(dragHandler ?? DefaultDragHandler);
}
/// <summary>
/// Initializes a new instance of the DropInfo class.
/// </summary>
///
/// <param name="sender">
/// The sender of the drag event.
/// </param>
///
/// <param name="e">
/// The drag event.
/// </param>
///
/// <param name="dragInfo">
/// Information about the source of the drag, if the drag came from within the framework.
/// </param>
///
/// <param name="eventType">
/// The type of the underlying event (tunneled or bubbled).
/// </param>
public DropInfo(object sender, DragEventArgs e, [CanBeNull] DragInfo dragInfo, EventType eventType)
{
this.DragInfo = dragInfo;
this.KeyStates = e.KeyStates;
this.EventType = eventType;
var dataFormat = dragInfo?.DataFormat;
this.Data = dataFormat != null && e.Data.GetDataPresent(dataFormat.Name) ? e.Data.GetData(dataFormat.Name) : e.Data;
this.VisualTarget = sender as UIElement;
// if there is no drop target, find another
if (!this.VisualTarget.IsDropTarget())
{
// try to find next element
var element = this.VisualTarget.TryGetNextAncestorDropTargetElement();
if (element != null)
{
this.VisualTarget = element;
}
}
// try find ScrollViewer
var dropTargetScrollViewer = DragDrop.GetDropTargetScrollViewer(this.VisualTarget);
if (dropTargetScrollViewer != null)
{
this.TargetScrollViewer = dropTargetScrollViewer;
}
else if (this.VisualTarget is TabControl)
{
var tabPanel = this.VisualTarget.GetVisualDescendent <TabPanel>();
this.TargetScrollViewer = tabPanel?.GetVisualAncestor <ScrollViewer>();
}
else
{
this.TargetScrollViewer = this.VisualTarget?.GetVisualDescendent <ScrollViewer>();
}
this.TargetScrollingMode = this.VisualTarget != null?DragDrop.GetDropScrollingMode(this.VisualTarget) : ScrollingMode.Both;
// visual target can be null, so give us a point...
this.DropPosition = this.VisualTarget != null?e.GetPosition(this.VisualTarget) : new Point();
if (this.VisualTarget is TabControl)
{
if (!HitTestUtilities.HitTest4Type <TabPanel>(this.VisualTarget, this.DropPosition))
{
return;
}
}
if (this.VisualTarget is ItemsControl)
{
var itemsControl = (ItemsControl)this.VisualTarget;
//System.Diagnostics.Debug.WriteLine(">>> Name = {0}", itemsControl.Name);
// get item under the mouse
item = itemsControl.GetItemContainerAt(this.DropPosition);
var directlyOverItem = item != null;
this.TargetGroup = itemsControl.FindGroup(this.DropPosition);
this.VisualTargetOrientation = itemsControl.GetItemsPanelOrientation();
this.VisualTargetFlowDirection = itemsControl.GetItemsPanelFlowDirection();
if (item == null)
{
// ok, no item found, so maybe we can found an item at top, left, right or bottom
item = itemsControl.GetItemContainerAt(this.DropPosition, this.VisualTargetOrientation);
directlyOverItem = DropPosition.DirectlyOverElement(this.item, itemsControl);
}
if (item == null && this.TargetGroup != null && this.TargetGroup.IsBottomLevel)
{
var itemData = this.TargetGroup.Items.FirstOrDefault();
if (itemData != null)
{
item = itemsControl.ItemContainerGenerator.ContainerFromItem(itemData) as UIElement;
directlyOverItem = DropPosition.DirectlyOverElement(this.item, itemsControl);
}
}
if (item != null)
{
itemParent = ItemsControl.ItemsControlFromItemContainer(item);
this.VisualTargetOrientation = itemParent.GetItemsPanelOrientation();
this.VisualTargetFlowDirection = itemParent.GetItemsPanelFlowDirection();
this.InsertIndex = itemParent.ItemContainerGenerator.IndexFromContainer(item);
this.TargetCollection = itemParent.ItemsSource ?? itemParent.Items;
var tvItem = item as TreeViewItem;
if (directlyOverItem || tvItem != null)
{
this.VisualTargetItem = item;
this.TargetItem = itemParent.ItemContainerGenerator.ItemFromContainer(item);
}
var expandedTVItem = tvItem != null && tvItem.HasHeader && tvItem.HasItems && tvItem.IsExpanded;
var itemRenderSize = expandedTVItem ? tvItem.GetHeaderSize() : item.RenderSize;
if (this.VisualTargetOrientation == Orientation.Vertical)
{
var currentYPos = e.GetPosition(item).Y;
var targetHeight = itemRenderSize.Height;
var topGap = targetHeight * 0.25;
var bottomGap = targetHeight * 0.75;
if (currentYPos > targetHeight / 2)
{
if (expandedTVItem && (currentYPos < topGap || currentYPos > bottomGap))
{
this.VisualTargetItem = tvItem.ItemContainerGenerator.ContainerFromIndex(0) as UIElement;
this.TargetItem = this.VisualTargetItem != null?tvItem.ItemContainerGenerator.ItemFromContainer(this.VisualTargetItem) : null;
this.TargetCollection = tvItem.ItemsSource ?? tvItem.Items;
this.InsertIndex = 0;
this.InsertPosition = RelativeInsertPosition.BeforeTargetItem;
}
else
{
this.InsertIndex++;
this.InsertPosition = RelativeInsertPosition.AfterTargetItem;
}
}
else
{
this.InsertPosition = RelativeInsertPosition.BeforeTargetItem;
}
if (currentYPos > topGap && currentYPos < bottomGap)
{
if (tvItem != null)
{
this.TargetCollection = tvItem.ItemsSource ?? tvItem.Items;
this.InsertIndex = this.TargetCollection != null?this.TargetCollection.OfType <object>().Count() : 0;
}
this.InsertPosition |= RelativeInsertPosition.TargetItemCenter;
}
//System.Diagnostics.Debug.WriteLine("==> DropInfo: pos={0}, idx={1}, Y={2}, Item={3}", this.InsertPosition, this.InsertIndex, currentYPos, item);
}
else
{
var currentXPos = e.GetPosition(item).X;
var targetWidth = itemRenderSize.Width;
if (this.VisualTargetFlowDirection == FlowDirection.RightToLeft)
{
if (currentXPos > targetWidth / 2)
{
this.InsertPosition = RelativeInsertPosition.BeforeTargetItem;
}
else
{
this.InsertIndex++;
this.InsertPosition = RelativeInsertPosition.AfterTargetItem;
}
}
else if (this.VisualTargetFlowDirection == FlowDirection.LeftToRight)
{
if (currentXPos > targetWidth / 2)
{
this.InsertIndex++;
this.InsertPosition = RelativeInsertPosition.AfterTargetItem;
}
else
{
this.InsertPosition = RelativeInsertPosition.BeforeTargetItem;
}
}
if (currentXPos > targetWidth * 0.25 && currentXPos < targetWidth * 0.75)
{
if (tvItem != null)
{
this.TargetCollection = tvItem.ItemsSource ?? tvItem.Items;
this.InsertIndex = this.TargetCollection != null?this.TargetCollection.OfType <object>().Count() : 0;
}
this.InsertPosition |= RelativeInsertPosition.TargetItemCenter;
}
//System.Diagnostics.Debug.WriteLine("==> DropInfo: pos={0}, idx={1}, X={2}, Item={3}", this.InsertPosition, this.InsertIndex, currentXPos, item);
}
}
else
{
this.TargetCollection = itemsControl.ItemsSource ?? itemsControl.Items;
this.InsertIndex = itemsControl.Items.Count;
//System.Diagnostics.Debug.WriteLine("==> DropInfo: pos={0}, item=NULL, idx={1}", this.InsertPosition, this.InsertIndex);
}
}
else
{
this.VisualTargetItem = this.VisualTarget;
}
}
