/// <summary>
/// Clear local variable and set selected items wh when mouse button up
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private static void DoMouseButtonUp(object sender, MouseButtonEventArgs e)
{
var elementPosition = e.GetPosition((IInputElement)sender);
if ((sender is TabControl) && !HitTestUtilities.HitTest4Type <TabPanel>(sender, elementPosition))
{
m_DragInfo = null;
m_ClickSupressItem = null;
return;
}
var dragInfo = m_DragInfo;
// If we prevented the control's default selection handling in DragSource_PreviewMouseLeftButtonDown
// by setting 'e.Handled = true' and a drag was not initiated, manually set the selection here.
if (sender is ItemsControl itemsControl && dragInfo != null && m_ClickSupressItem != null && m_ClickSupressItem == dragInfo.SourceItem)
{
if ((Keyboard.Modifiers & ModifierKeys.Control) != 0)
{
itemsControl.SetItemSelected(dragInfo.SourceItem, false);
}
else if ((Keyboard.Modifiers & ModifierKeys.Shift) == 0)
{
itemsControl.SetSelectedItem(dragInfo.SourceItem);
}
}
m_DragInfo = null;
m_ClickSupressItem = null;
}
/// <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?.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.
/// <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;
}
}
/// <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;
}
/// <summary>
/// Raise on mouse move at source ItemsControl
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private static void DragSourceOnMouseMove(object sender, MouseEventArgs e)
{
var dragInfo = m_DragInfo;
// if we not release the mouse button while we moving our mouse...
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 (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) > GetMinimumHorizontalDragDistance(dragInfo.VisualSource) ||
Math.Abs(position.Y - dragStart.Y) > GetMinimumVerticalDragDistance(dragInfo.VisualSource)))
{
// Ensure SourceItems is latest selected items
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;
}
}
}
}
}
}
