/// <summary>
/// When overridden in a derived class, participates in rendering operations that are directed by the layout system.
/// The rendering instructions for this element are not used directly when this method is invoked, and are instead preserved for
/// later asynchronous use by layout and drawing.
/// </summary>
/// <param name="drawingContext">The drawing instructions for a specific element. This context is provided to the layout system.</param>
protected override void OnRender(DrawingContext drawingContext)
{
var dropInfo = DropInfo;
if (dropInfo.VisualTarget is ItemsControl itemsControl)
{
// Get the position of the item at the insertion index. If the insertion point is
// to be after the last item, then get the position of the last item and add an
// offset later to draw it at the end of the list.
var visualTargetItem = dropInfo.VisualTargetItem;
var itemParent = visualTargetItem != null?ItemsControl.ItemsControlFromItemContainer(visualTargetItem) : itemsControl;
// this could be happen with a thread scenario where items are removed very quickly
if (itemParent == null)
{
return;
}
var itemsCount = itemParent.Items.Count;
var index = Math.Min(dropInfo.InsertIndex, itemsCount - 1);
var lastItemInGroup = false;
var targetGroup = dropInfo.TargetGroup;
if (targetGroup != null && targetGroup.IsBottomLevel && dropInfo.InsertPosition.HasFlag(RelativeInsertPosition.AfterTargetItem))
{
var indexOf = targetGroup.Items.IndexOf(dropInfo.TargetItem);
lastItemInGroup = indexOf == targetGroup.ItemCount - 1;
if (lastItemInGroup && dropInfo.InsertIndex != itemsCount)
{
index--;
}
}
var itemContainer = (UIElement)itemParent.ItemContainerGenerator.ContainerFromIndex(index);
var showAlwaysDropTargetAdorner = itemContainer == null && DragDrop.GetShowAlwaysDropTargetAdorner(itemParent);
if (showAlwaysDropTargetAdorner)
{
itemContainer = itemParent;
}
if (itemContainer != null)
{
var itemRect = new Rect(itemContainer.TranslatePoint(new Point(), AdornedElement), itemContainer.RenderSize);
Point point1,
point2;
double rotation = 0;
var viewportWidth = DropInfo.TargetScrollViewer?.ViewportWidth ?? double.MaxValue;
var viewportHeight = DropInfo.TargetScrollViewer?.ViewportHeight ?? double.MaxValue;
if (dropInfo.VisualTargetOrientation == Orientation.Vertical)
{
if ((dropInfo.InsertIndex == itemsCount) || lastItemInGroup)
{
if (itemsCount > 0)
{
itemRect.Y += itemContainer.RenderSize.Height;
}
else
{
if ((itemsControl as ListView)?.View is GridView)
{
var header = itemsControl.GetVisualDescendent <GridViewHeaderRowPresenter>();
if (header != null)
{
itemRect.Y += header.RenderSize.Height;
}
}
else if (itemsControl is DataGrid)
{
var header = itemsControl.GetVisualDescendent <DataGridColumnHeadersPresenter>();
if (header != null)
{
itemRect.Y += header.RenderSize.Height;
}
}
itemRect.Y += Pen.Thickness;
}
}
var itemRectRight = Math.Min(itemRect.Right, viewportWidth);
var itemRectLeft = itemRect.X < 0 ? 0 : itemRect.X;
point1 = new Point(itemRectLeft, itemRect.Y);
point2 = new Point(itemRectRight, itemRect.Y);
}
else
{
if (dropInfo.VisualTargetFlowDirection == FlowDirection.LeftToRight && dropInfo.InsertIndex == itemsCount)
{
if (itemsCount > 0)
{
itemRect.X += itemContainer.RenderSize.Width;
}
else
{
itemRect.X += Pen.Thickness;
}
}
else if (dropInfo.VisualTargetFlowDirection == FlowDirection.RightToLeft && dropInfo.InsertIndex != itemsCount)
{
if (itemsCount > 0)
{
itemRect.X += itemContainer.RenderSize.Width;
}
else
{
itemRect.X += Pen.Thickness;
}
}
var itemRectTop = itemRect.Y < 0 ? 0 : itemRect.Y;
var itemRectBottom = Math.Min(itemRect.Bottom, viewportHeight);
point1 = new Point(itemRect.X, itemRectTop);
point2 = new Point(itemRect.X, itemRectBottom);
rotation = 90;
}
drawingContext.DrawLine(Pen, point1, point2);
DrawTriangle(drawingContext, point1, rotation);
DrawTriangle(drawingContext, point2, 180 + rotation);
}
}
}
/// <summary>
/// Initializes a new instance of the DragInfo class.
/// </summary>
///
/// <param name="sender">
/// The sender of the mouse event that initiated the drag.
/// </param>
///
/// <param name="e">
/// The mouse event that initiated the drag.
/// </param>
public DragInfo(object sender, MouseButtonEventArgs e)
{
Effects = DragDropEffects.None;
MouseButton = e.ChangedButton;
VisualSource = sender as UIElement;
DragStartPosition = e.GetPosition(VisualSource);
DragDropCopyKeyState = DragDrop.GetDragDropCopyKeyState(VisualSource);
var dataFormat = DragDrop.GetDataFormat(VisualSource);
if (dataFormat != null)
{
DataFormat = dataFormat;
}
var sourceElement = e.OriginalSource as UIElement;
// If we can't cast object as a UIElement it might be a FrameworkContentElement, if so try and use its parent.
if (sourceElement == null && e.OriginalSource is FrameworkContentElement element)
{
sourceElement = element.Parent as UIElement;
}
if (sender is ItemsControl itemsControl)
{
SourceGroup = itemsControl.FindGroup(DragStartPosition);
VisualSourceFlowDirection = itemsControl.GetItemsPanelFlowDirection();
UIElement item = null;
if (sourceElement != null)
{
item = itemsControl.GetItemContainer(sourceElement);
}
if (item == null)
{
item = DragDrop.GetDragDirectlySelectedOnly(VisualSource) ? itemsControl.GetItemContainerAt(e.GetPosition(itemsControl)) : itemsControl.GetItemContainerAt(e.GetPosition(itemsControl), itemsControl.GetItemsPanelOrientation());
}
if (item != null)
{
// Remember the relative position of the item being dragged
PositionInDraggedItem = e.GetPosition(item);
var itemParent = ItemsControl.ItemsControlFromItemContainer(item);
if (itemParent != null)
{
SourceCollection = itemParent.ItemsSource ?? itemParent.Items;
if (itemParent != itemsControl)
{
if (item is TreeViewItem tvItem)
{
var tv = tvItem.GetVisualAncestor <TreeView>();
if (tv != null && !Equals(tv, itemsControl) && !tv.IsDragSource())
{
return;
}
}
else if (itemsControl.ItemContainerGenerator.IndexFromContainer(itemParent) < 0 && !itemParent.IsDragSource())
{
return;
}
}
SourceIndex = itemParent.ItemContainerGenerator.IndexFromContainer(item);
SourceItem = itemParent.ItemContainerGenerator.ItemFromContainer(item);
}
else
{
SourceIndex = -1;
}
var selectedItems = itemsControl.GetSelectedItems().OfType <object>().Where(i => i != CollectionView.NewItemPlaceholder).ToList();
SourceItems = selectedItems;
// Some controls (I'm looking at you TreeView!) haven't updated their
// SelectedItem by this point. Check to see if there 1 or less item in
// the SourceItems collection, and if so, override the control's SelectedItems with the clicked item.
//
// The control has still the old selected items at the mouse down event, so we should check this and give only the real selected item to the user.
if (selectedItems.Count <= 1 || SourceItem != null && !selectedItems.Contains(SourceItem))
{
SourceItems = Enumerable.Repeat(SourceItem, 1);
}
VisualSourceItem = item;
}
else
{
SourceCollection = itemsControl.ItemsSource ?? itemsControl.Items;
}
}
else
{
SourceItem = (sender as FrameworkElement)?.DataContext;
if (SourceItem != null)
{
SourceItems = Enumerable.Repeat(SourceItem, 1);
}
VisualSourceItem = sourceElement;
PositionInDraggedItem = sourceElement != null?e.GetPosition(sourceElement) : DragStartPosition;
}
if (SourceItems == null)
{
SourceItems = Enumerable.Empty <object>();
}
}
/// <summary>
/// Performs a drop.
/// </summary>
/// <param name="dropInfo">Information about the drop.</param>
public virtual void Drop(IDropInfo dropInfo)
{
if (dropInfo?.DragInfo == null)
{
return;
}
var insertIndex = dropInfo.InsertIndex != dropInfo.UnfilteredInsertIndex ? dropInfo.UnfilteredInsertIndex : dropInfo.InsertIndex;
var itemsControl = dropInfo.VisualTarget as ItemsControl;
if (itemsControl != null)
{
if (itemsControl.Items is IEditableCollectionView editableItems)
{
var newItemPlaceholderPosition = editableItems.NewItemPlaceholderPosition;
if (newItemPlaceholderPosition == NewItemPlaceholderPosition.AtBeginning && insertIndex == 0)
{
++insertIndex;
}
else if (newItemPlaceholderPosition == NewItemPlaceholderPosition.AtEnd && insertIndex == itemsControl.Items.Count)
{
--insertIndex;
}
}
}
var destinationList = dropInfo.TargetCollection.TryGetList();
var data = ExtractData(dropInfo.Data).OfType <object>().ToList();
var copyData = ShouldCopyData(dropInfo);
if (!copyData)
{
var sourceList = dropInfo.DragInfo.SourceCollection.TryGetList();
if (sourceList != null)
{
foreach (var o in data)
{
var index = sourceList.IndexOf(o);
if (index != -1)
{
sourceList.RemoveAt(index);
// so, is the source list the destination list too ?
if (destinationList != null && Equals(sourceList, destinationList) && index < insertIndex)
{
--insertIndex;
}
}
}
}
}
if (destinationList != null)
{
var objects2Insert = new List <object>();
// check for cloning
var cloneData = dropInfo.Effects.HasFlag(DragDropEffects.Copy) || dropInfo.Effects.HasFlag(DragDropEffects.Link);
foreach (var o in data)
{
var obj2Insert = o;
if (cloneData)
{
if (o is ICloneable cloneable)
{
obj2Insert = cloneable.Clone();
}
}
objects2Insert.Add(obj2Insert);
destinationList.Insert(insertIndex++, obj2Insert);
}
var selectDroppedItems = itemsControl is TabControl || (itemsControl != null && DragDrop.GetSelectDroppedItems(itemsControl));
if (selectDroppedItems)
{
SelectDroppedItems(dropInfo, objects2Insert);
}
}
}
/// <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>
public DropInfo(object sender, DragEventArgs e, [CanBeNull] IDragInfo dragInfo)
{
DragInfo = dragInfo;
KeyStates = e.KeyStates;
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
if (VisualTarget is TabControl)
{
var tabPanel = VisualTarget.GetVisualDescendent <TabPanel>();
TargetScrollViewer = tabPanel?.GetVisualAncestor <ScrollViewer>();
}
else
{
TargetScrollViewer = VisualTarget?.GetVisualDescendent <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
var 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;
Size itemRenderSize;
if (expandedTVItem)
{
itemRenderSize = tvItem.GetHeaderSize();
}
else
{
itemRenderSize = item.RenderSize;
}
if (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 && tvItem.HasItems && 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 || (!tvItem.HasItems && expandedTVItem))
{
if (tvItem != null)
{
TargetCollection = tvItem.ItemsSource ?? tvItem.Items;
InsertIndex = TargetCollection?.OfType <object>().Count() ?? 0;
}
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 (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?.OfType <object>().Count() ?? 0;
}
InsertPosition |= RelativeInsertPosition.TargetItemCenter;
}
//System.Diagnostics.Debug.WriteLine("==> DropInfo: pos={0}, idx={1}, X={2}, Item={3}", this.InsertPosition, this.InsertIndex, currentXPos, item);
}
}
else
{
TargetCollection = itemsControl.ItemsSource ?? itemsControl.Items;
InsertIndex = itemsControl.Items.Count;
//System.Diagnostics.Debug.WriteLine("==> DropInfo: pos={0}, item=NULL, idx={1}", this.InsertPosition, this.InsertIndex);
}
}
else
{
VisualTargetItem = VisualTarget;
}
}