/// <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 = this.DropInfo;
var itemsControl = dropInfo.VisualTarget as ItemsControl;
if (itemsControl != null)
{
// 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.
ItemsControl itemParent;
var visualTargetItem = dropInfo.VisualTargetItem;
if (visualTargetItem != null)
{
itemParent = ItemsControl.ItemsControlFromItemContainer(visualTargetItem);
}
else
{
itemParent = 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(), this.AdornedElement), itemContainer.RenderSize);
Point point1,
point2;
double rotation = 0;
// I really don't know why I did this
//
// var viewportWidth = double.MaxValue;
// var viewportHeight = double.MaxValue;
// if (DropInfo.TargetScrollViewer != null)
// {
// if (DropInfo.TargetScrollViewer.ScrollableWidth != 0)
// {
// viewportWidth = DropInfo.TargetScrollViewer.ViewportWidth;
// }
//
// if (DropInfo.TargetScrollViewer.ScrollableHeight != 0)
// {
// viewportHeight = DropInfo.TargetScrollViewer.ViewportHeight;
// }
// }
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 += this.Pen.Thickness;
}
}
var itemRectRight = itemRect.Right; //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 += this.Pen.Thickness;
}
}
else if (dropInfo.VisualTargetFlowDirection == FlowDirection.RightToLeft && dropInfo.InsertIndex != itemsCount)
{
if (itemsCount > 0)
{
itemRect.X += itemContainer.RenderSize.Width;
}
else
{
itemRect.X += this.Pen.Thickness;
}
}
var itemRectTop = itemRect.Y < 0 ? 0 : itemRect.Y;
var itemRectBottom = itemRect.Bottom; //Math.Min(itemRect.Bottom, viewportHeight);
point1 = new Point(itemRect.X, itemRectTop);
point2 = new Point(itemRect.X, itemRectBottom);
rotation = 90;
}
drawingContext.DrawLine(this.Pen, point1, point2);
this.DrawTriangle(drawingContext, point1, rotation);
this.DrawTriangle(drawingContext, point2, 180 + rotation);
}
}
}
/// <inheritdoc />
public virtual void Drop(IDropInfo dropInfo)
{
if (dropInfo == null || dropInfo.DragInfo == null)
{
return;
}
var insertIndex = dropInfo.UnfilteredInsertIndex;
var itemsControl = dropInfo.VisualTarget as ItemsControl;
if (itemsControl != null)
{
var editableItems = itemsControl.Items as IEditableCollectionView;
if (editableItems != null)
{
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)
{
var cloneable = o as ICloneable;
if (cloneable != null)
{
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>
///
/// <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;
}
}
/// <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)
{
this.Effects = DragDropEffects.None;
this.MouseButton = e.ChangedButton;
this.VisualSource = sender as UIElement;
this.DragStartPosition = e.GetPosition(this.VisualSource);
this.DragDropCopyKeyState = DragDrop.GetDragDropCopyKeyState(this.VisualSource);
var dataFormat = DragDrop.GetDataFormat(this.VisualSource);
if (dataFormat != null)
{
this.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)
{
sourceElement = ((FrameworkContentElement)e.OriginalSource).Parent as UIElement;
}
if (sender is ItemsControl)
{
var itemsControl = (ItemsControl)sender;
this.SourceGroup = itemsControl.FindGroup(this.DragStartPosition);
this.VisualSourceFlowDirection = itemsControl.GetItemsPanelFlowDirection();
UIElement item = null;
if (sourceElement != null)
{
item = itemsControl.GetItemContainer(sourceElement);
}
if (item == null)
{
if (DragDrop.GetDragDirectlySelectedOnly(this.VisualSource))
{
item = itemsControl.GetItemContainerAt(e.GetPosition(itemsControl));
}
else
{
item = itemsControl.GetItemContainerAt(e.GetPosition(itemsControl), itemsControl.GetItemsPanelOrientation());
}
}
if (item != null)
{
// Remember the relative position of the item being dragged
this.PositionInDraggedItem = e.GetPosition(item);
var itemParent = ItemsControl.ItemsControlFromItemContainer(item);
if (itemParent != null)
{
this.SourceCollection = itemParent.ItemsSource ?? itemParent.Items;
if (itemParent != itemsControl)
{
var tvItem = item as TreeViewItem;
if (tvItem != null)
{
var tv = tvItem.GetVisualAncestor <TreeView>();
if (tv != null && tv != itemsControl && !tv.IsDragSource())
{
return;
}
}
else if (itemsControl.ItemContainerGenerator.IndexFromContainer(itemParent) < 0 && !itemParent.IsDragSource())
{
return;
}
}
this.SourceIndex = itemParent.ItemContainerGenerator.IndexFromContainer(item);
this.SourceItem = itemParent.ItemContainerGenerator.ItemFromContainer(item);
}
else
{
this.SourceIndex = -1;
}
var selectedItems = itemsControl.GetSelectedItems().OfType <object>().Where(i => i != CollectionView.NewItemPlaceholder).ToList();
this.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 || this.SourceItem != null && !selectedItems.Contains(this.SourceItem))
{
this.SourceItems = Enumerable.Repeat(this.SourceItem, 1);
}
this.VisualSourceItem = item;
}
else
{
this.SourceCollection = itemsControl.ItemsSource ?? itemsControl.Items;
}
}
else
{
this.SourceItem = (sender as FrameworkElement)?.DataContext;
if (this.SourceItem != null)
{
this.SourceItems = Enumerable.Repeat(this.SourceItem, 1);
}
this.VisualSourceItem = sourceElement;
this.PositionInDraggedItem = sourceElement != null?e.GetPosition(sourceElement) : this.DragStartPosition;
}
if (this.SourceItems == null)
{
this.SourceItems = Enumerable.Empty <object>();
}
}
private static void DragSourceOnMouseMove(object sender, MouseEventArgs e)
{
var dragInfo = m_DragInfo;
if (dragInfo != null && !m_DragInProgress)
{
// the start from the source
var dragStart = dragInfo.DragStartPosition;
// do nothing if mouse left/right button is released or the pointer is captured
if (dragInfo.MouseButton == MouseButton.Left && e.LeftButton == MouseButtonState.Released)
{
m_DragInfo = null;
return;
}
if (DragDrop.GetCanDragWithMouseRightButton(dragInfo.VisualSource) && dragInfo.MouseButton == MouseButton.Right && e.RightButton == MouseButtonState.Released)
{
m_DragInfo = null;
return;
}
// current mouse position
var position = e.GetPosition((IInputElement)sender);
// prevent selection changing while drag operation
dragInfo.VisualSource?.ReleaseMouseCapture();
// only if the sender is the source control and the mouse point differs from an offset
if (dragInfo.VisualSource == sender &&
(Math.Abs(position.X - dragStart.X) > DragDrop.GetMinimumHorizontalDragDistance(dragInfo.VisualSource) ||
Math.Abs(position.Y - dragStart.Y) > DragDrop.GetMinimumVerticalDragDistance(dragInfo.VisualSource)))
{
dragInfo.RefreshSelectedItems(sender, e);
var dragHandler = TryGetDragHandler(dragInfo, sender as UIElement);
if (dragHandler.CanStartDrag(dragInfo))
{
dragHandler.StartDrag(dragInfo);
if (dragInfo.Effects != DragDropEffects.None)
{
var dataObject = dragInfo.DataObject;
if (dataObject == null)
{
if (dragInfo.Data == null)
{
// it's bad if the Data is null, cause the DataObject constructor will raise an ArgumentNullException
m_DragInfo = null; // maybe not necessary or should not set here to null
return;
}
dataObject = new DataObject(dragInfo.DataFormat.Name, dragInfo.Data);
}
try
{
m_DragInProgress = true;
var dragDropHandler = dragInfo.DragDropHandler ?? System.Windows.DragDrop.DoDragDrop;
var dragDropEffects = dragDropHandler(dragInfo.VisualSource, dataObject, dragInfo.Effects);
if (dragDropEffects == DragDropEffects.None)
{
dragHandler.DragCancelled();
}
dragHandler.DragDropOperationFinished(dragDropEffects, dragInfo);
}
catch (Exception ex)
{
if (!dragHandler.TryCatchOccurredException(ex))
{
throw;
}
}
finally
{
m_DragInProgress = false;
m_DragInfo = null;
}
}
}
}
}
}
