/// <summary> /// Initializes a new instance of the DropInfo class. /// <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> /// </summary> public DropInfo(object sender, DragEventArgs e, [CanBeNull] DragInfo dragInfo, EventType eventType) { DragInfo = dragInfo; KeyStates = e.KeyStates; EventType = eventType; var dataFormat = dragInfo?.DataFormat; Data = dataFormat != null && e.Data.GetDataPresent(dataFormat.Name) ? e.Data.GetData(dataFormat.Name) : e.Data; VisualTarget = sender as UIElement; // if there is no drop target, find another if (!VisualTarget.IsDropTarget()) { // try to find next element var element = VisualTarget.TryGetNextAncestorDropTargetElement(); if (element != null) { VisualTarget = element; } } // try find ScrollViewer var dropTargetScrollViewer = DragDrop.GetDropTargetScrollViewer(VisualTarget); if (dropTargetScrollViewer != null) { TargetScrollViewer = dropTargetScrollViewer; } else if (VisualTarget is TabControl) { var tabPanel = VisualTarget.FindVisualChild <TabPanel>(); TargetScrollViewer = tabPanel?.FindVisualParent <ScrollViewer>(); } else { TargetScrollViewer = VisualTarget?.FindVisualChild <ScrollViewer>(); } TargetScrollingMode = VisualTarget != null?DragDrop.GetDropScrollingMode(VisualTarget) : ScrollingMode.Both; // visual target can be null, so give us a point... DropPosition = VisualTarget != null?e.GetPosition(VisualTarget) : new Point(); if (VisualTarget is TabControl) { if (!HitTestUtilities.HitTest4Type <TabPanel>(VisualTarget, DropPosition)) { return; } } if (VisualTarget is ItemsControl itemsControl) { //System.Diagnostics.Debug.WriteLine(">>> Name = {0}", itemsControl.Name); // get item under the mouse item = itemsControl.GetItemContainerAt(DropPosition); var directlyOverItem = item != null; TargetGroup = itemsControl.FindGroup(DropPosition); VisualTargetOrientation = itemsControl.GetItemsPanelOrientation(); 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(DropPosition, VisualTargetOrientation); directlyOverItem = DropPosition.DirectlyOverElement(item, itemsControl); } if (item == null && TargetGroup != null && TargetGroup.IsBottomLevel) { var itemData = TargetGroup.Items.FirstOrDefault(); if (itemData != null) { item = itemsControl.ItemContainerGenerator.ContainerFromItem(itemData) as UIElement; directlyOverItem = DropPosition.DirectlyOverElement(item, itemsControl); } } if (item != null) { itemParent = ItemsControl.ItemsControlFromItemContainer(item); VisualTargetOrientation = itemParent.GetItemsPanelOrientation(); VisualTargetFlowDirection = itemParent.GetItemsPanelFlowDirection(); InsertIndex = itemParent.ItemContainerGenerator.IndexFromContainer(item); TargetCollection = itemParent.ItemsSource ?? itemParent.Items; var tvItem = item as TreeViewItem; if (directlyOverItem || tvItem != null) { VisualTargetItem = item; TargetItem = itemParent.ItemContainerGenerator.ItemFromContainer(item); } var expandedTVItem = tvItem != null && tvItem.HasHeader && tvItem.HasItems && tvItem.IsExpanded; var itemRenderSize = expandedTVItem ? tvItem.GetHeaderSize() : item.RenderSize; if (VisualTargetOrientation == Orientation.Vertical) { // Get the current position relative to the items container var currentYPos = e.GetPosition(item).Y; // Get items container height var targetHeight = itemRenderSize.Height; var topGap = targetHeight * 0.25; var bottomGap = targetHeight * 0.75; if (currentYPos > targetHeight / 2) { // If items control is tree viewer if (expandedTVItem && (currentYPos < topGap || currentYPos > bottomGap)) { VisualTargetItem = tvItem.ItemContainerGenerator.ContainerFromIndex(0) as UIElement; TargetItem = VisualTargetItem != null?tvItem.ItemContainerGenerator.ItemFromContainer(VisualTargetItem) : null; TargetCollection = tvItem.ItemsSource ?? tvItem.Items; InsertIndex = 0; InsertPosition = RelativeInsertPosition.BeforeTargetItem; } else { InsertIndex++; InsertPosition = RelativeInsertPosition.AfterTargetItem; } } else { InsertPosition = RelativeInsertPosition.BeforeTargetItem; } if (currentYPos > topGap && currentYPos < bottomGap) { if (tvItem != null) { TargetCollection = tvItem.ItemsSource ?? tvItem.Items; InsertIndex = TargetCollection != null?TargetCollection.OfType <object>().Count() : 0; } InsertPosition |= RelativeInsertPosition.TargetItemCenter; } //System.Diagnostics.Debug.WriteLine("==> DropInfo: pos={0}, idx={1}, Y={2}, Item={3}", InsertPosition, InsertIndex, currentYPos, item); } else { var currentXPos = e.GetPosition(item).X; var targetWidth = itemRenderSize.Width; if (VisualTargetFlowDirection == FlowDirection.RightToLeft) { if (currentXPos > targetWidth / 2) { InsertPosition = RelativeInsertPosition.BeforeTargetItem; } else { InsertIndex++; InsertPosition = RelativeInsertPosition.AfterTargetItem; } } else if (VisualTargetFlowDirection == FlowDirection.LeftToRight) { if (currentXPos > targetWidth / 2) { InsertIndex++; InsertPosition = RelativeInsertPosition.AfterTargetItem; } else { InsertPosition = RelativeInsertPosition.BeforeTargetItem; } } if (currentXPos > targetWidth * 0.25 && currentXPos < targetWidth * 0.75) { if (tvItem != null) { TargetCollection = tvItem.ItemsSource ?? tvItem.Items; InsertIndex = TargetCollection != null?TargetCollection.OfType <object>().Count() : 0; } InsertPosition |= RelativeInsertPosition.TargetItemCenter; } //System.Diagnostics.Debug.WriteLine("==> DropInfo: pos={0}, idx={1}, X={2}, Item={3}", InsertPosition, InsertIndex, currentXPos, item); } } else { TargetCollection = itemsControl.ItemsSource ?? itemsControl.Items; InsertIndex = itemsControl.Items.Count; //System.Diagnostics.Debug.WriteLine("==> DropInfo: pos={0}, item=NULL, idx={1}", InsertPosition, InsertIndex); } } else { VisualTargetItem = VisualTarget; } }