internal void ShowFarDropMark(Point mousePosition)
        {
            int itemsCount = this.Items.Count;

            if (itemsCount < 1)
            {
                if (m_dropMarkAdorner == null)
                {
                    DataGridContext dataGridContext = DataGridControl.GetDataGridContext(this);

                    DataGridControl grid = (dataGridContext != null)
            ? dataGridContext.DataGridControl
            : null;

                    Pen pen = UIViewBase.GetDropMarkPen(this);

                    if ((pen == null) && (grid != null))
                    {
                        UIViewBase uiViewBase = grid.GetView() as UIViewBase;
                        pen = uiViewBase.DefaultDropMarkPen;
                    }

                    DropMarkOrientation orientation = UIViewBase.GetDropMarkOrientation(this);

                    if ((orientation == DropMarkOrientation.Default) && (grid != null))
                    {
                        UIViewBase uiViewBase = grid.GetView() as UIViewBase;

                        orientation = uiViewBase.DefaultDropMarkOrientation;
                    }

                    m_dropMarkAdorner = new DropMarkAdorner(this, pen, orientation);

                    AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(this);

                    if (adornerLayer != null)
                    {
                        adornerLayer.Add(m_dropMarkAdorner);
                    }
                }
                // We Only want the drop mark to be displayed at the end of the HierarchicalGroupByControlNode
                m_dropMarkAdorner.ForceAlignment(DropMarkAlignment.Far);
            }
            else
            {
                HierarchicalGroupByItem hierarchicalGroupByItem = this.ItemContainerGenerator.ContainerFromIndex(itemsCount - 1) as HierarchicalGroupByItem;

                Debug.Assert(hierarchicalGroupByItem != null);

                GroupLevelDescription groupLevelDescription = hierarchicalGroupByItem.Content as GroupLevelDescription;

                Debug.Assert(groupLevelDescription != null);

                // Show Far DropMark only if not already grouped
                if (this.Items.Contains(groupLevelDescription) == false)
                {
                    hierarchicalGroupByItem.ShowFarDropMark(mousePosition);
                }
            }
        }
        private void DragSourceManager_DragOutsideQueryCursor(object sender, QueryCursorEventArgs e)
        {
            HierarchicalGroupByControlNode hierarchicalGroupByControlNode = HierarchicalGroupByItem.GetParentHierarchicalGroupByControlNode(this);

            if ((hierarchicalGroupByControlNode == null) ||
                (!hierarchicalGroupByControlNode.IsGroupingModificationAllowed))
            {
                return;
            }

            DataGridContext dataGridContext = DataGridControl.GetDataGridContext(this);

            if ((dataGridContext != null) && (dataGridContext.DataGridControl != null))
            {
                UIViewBase uiViewBase = dataGridContext.DataGridControl.GetView() as UIViewBase;

                e.Cursor = (uiViewBase != null)
          ? uiViewBase.RemovingGroupCursor
          : UIViewBase.DefaultGroupDraggedOutsideCursor;
            }
            else
            {
                e.Cursor = UIViewBase.DefaultGroupDraggedOutsideCursor;
            }
        }
示例#3
0
            internal HierarchicalGroupByItemToggleColumnSortCommand(HierarchicalGroupByItem target)
                : base()
            {
                if (target == null)
                {
                    throw new ArgumentNullException("owner");
                }

                m_target = new WeakReference(target);

                if (target.ParentDataGridContext != null)
                {
                    m_dataGridContext = new WeakReference(target.ParentDataGridContext);
                }

                DataGridContext groupByItemDataGridContext = DataGridControl.GetDataGridContext(target);

                ToggleColumnSortCommand.ThrowIfNull(groupByItemDataGridContext, "groupByItemDataGridContext");

                DataGridControl dataGridControl = groupByItemDataGridContext.DataGridControl;

                ToggleColumnSortCommand.ThrowIfNull(dataGridControl, "dataGridControl");

                m_dataGridControl = new WeakReference(dataGridControl);
            }
        void IDropTarget.DragLeave(UIElement draggedElement)
        {
            ColumnManagerCell cell = draggedElement as ColumnManagerCell;

            if (cell != null)
            {
                HierarchicalGroupByControlNode hierarchicalGroupByControlNode = this.GetHierarchicalGroupByControlNodeFromColumnManagerCell(cell);

                // It may not be visible
                if (hierarchicalGroupByControlNode != null)
                {
                    hierarchicalGroupByControlNode.HideFarDropMark();
                }
            }
            else
            {
                HierarchicalGroupByItem hierarchicalGroupByItem = draggedElement as HierarchicalGroupByItem;
                if (hierarchicalGroupByItem == null)
                {
                    return;
                }

                HierarchicalGroupByControlNode hierarchicalGroupByControlNode = this.GetHierarchicalGroupByControlNodeFromHierarchicalGroupByItem(hierarchicalGroupByItem);

                Debug.Assert(hierarchicalGroupByControlNode != null, "CanDrop should have returned false");
                if (hierarchicalGroupByControlNode == null)
                {
                    throw new DataGridInternalException("A HierarchicalGroupByControlNode must exist for every level.");
                }

                hierarchicalGroupByControlNode.HideFarDropMark();
            }
        }
        internal void ShowFarDropMark(ColumnManagerCell cell, Point mousePosition)
        {
            Debug.Assert(cell != null);
            if (cell == null)
            {
                return;
            }

            DataGridContext cellDataGridContext = DataGridControl.GetDataGridContext(cell);

            Debug.Assert(cellDataGridContext != null);
            if (cellDataGridContext == null)
            {
                throw new DataGridInternalException("DataGridContext cannot be null on ColumnManagerCell.");
            }

            // We already have GroupLevelDescriptions for this level, we should show DropMark on the last HierarchicalGroupByItem
            if (cellDataGridContext.GroupLevelDescriptions.Count > 0)
            {
                Debug.Assert(cellDataGridContext.GroupLevelDescriptions == this.GroupLevelDescriptions);

                if (cellDataGridContext.GroupLevelDescriptions != this.GroupLevelDescriptions)
                {
                    return;
                }

                int lastIndex = this.GroupLevelDescriptions.Count - 1;

                // If there
                if (lastIndex > -1)
                {
                    HierarchicalGroupByItem hierarchicalGroupByItem = this.ItemContainerGenerator.ContainerFromItem(this.GroupLevelDescriptions[lastIndex]) as HierarchicalGroupByItem;

                    Debug.Assert(hierarchicalGroupByItem != null);
                    if (hierarchicalGroupByItem == null)
                    {
                        return;
                    }

                    hierarchicalGroupByItem.ShowFarDropMark(mousePosition);
                }
                else
                {
                    this.ShowFarDropMark(mousePosition);
                }
            }
            else
            {
                this.ShowFarDropMark(mousePosition);
            }
        }
        protected override void PrepareContainerForItemOverride(DependencyObject element, object item)
        {
            DataGridContext dataGridContext = DataGridControl.GetDataGridContext(this);

            DataGridControl grid = (dataGridContext != null)
        ? dataGridContext.DataGridControl
        : null;

            base.PrepareContainerForItemOverride(element, item);

            if (grid != null)
            {
                HierarchicalGroupByItem groupByItem = ( HierarchicalGroupByItem )element;
                groupByItem.PrepareDefaultStyleKey(grid.GetView());
            }
        }
        private void DragSourceManager_DroppedOutside(object sender, EventArgs e)
        {
            HierarchicalGroupByControlNode hierarchicalGroupByControlNode = HierarchicalGroupByItem.GetParentHierarchicalGroupByControlNode(this);

            if (hierarchicalGroupByControlNode == null)
            {
                throw new DataGridInternalException();
            }

            bool allowGroupingModification = hierarchicalGroupByControlNode.IsGroupingModificationAllowed;

            if (!allowGroupingModification)
            {
                return;
            }

            ObservableCollection <GroupDescription> groupDescriptions = this.ParentGroupDescriptions;

            if (groupDescriptions != null)
            {
                // Get the HierarchicalGroupByControl before removing us from it
                HierarchicalGroupByControl parentGBC = GroupingHelper.GetHierarchicalGroupByControl(this);

                GroupLevelDescription groupLevelDescription = this.Content as GroupLevelDescription;

                DataGridContext dataGridContext = DataGridControl.GetDataGridContext(this);

                DataGridControl parentDataGridControl = (dataGridContext != null)
          ? dataGridContext.DataGridControl
          : null;

                GroupingHelper.RemoveGroupDescription(groupDescriptions, groupLevelDescription, parentDataGridControl);

                // Notify groups have changed for NoGroupContent
                parentGBC.UpdateHasGroups();

                // Update the HasGroups property
                Debug.Assert(parentGBC != null);
                if (parentGBC == null)
                {
                    throw new DataGridInternalException("The hierarchical group-by item must be rooted by a HierarchicalGroupByControl.");
                }
            }
        }
        internal void HideFarDropMark()
        {
            int itemsCount = this.Items.Count;

            if (itemsCount > 0)
            {
                HierarchicalGroupByItem hierarchicalGroupByItem = null;
                if (itemsCount > 1)
                {
                    // Hide the before last item's DropMark if any in case
                    hierarchicalGroupByItem = this.ItemContainerGenerator.ContainerFromIndex(itemsCount - 2) as HierarchicalGroupByItem;

                    Debug.Assert(hierarchicalGroupByItem != null);

                    if (hierarchicalGroupByItem != null)
                    {
                        hierarchicalGroupByItem.HideDropMark();
                    }
                }

                // Hide last item's DropMark if any
                hierarchicalGroupByItem = this.ItemContainerGenerator.ContainerFromIndex(itemsCount - 1) as HierarchicalGroupByItem;

                Debug.Assert(hierarchicalGroupByItem != null);

                if (hierarchicalGroupByItem != null)
                {
                    hierarchicalGroupByItem.HideDropMark();
                }
            }

            if (m_dropMarkAdorner != null)
            {
                AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(this);

                if (adornerLayer != null)
                {
                    adornerLayer.Remove(m_dropMarkAdorner);
                }

                m_dropMarkAdorner = null;
            }
        }
    internal HierarchicalGroupByControlNode GetHierarchicalGroupByControlNodeFromHierarchicalGroupByItem( HierarchicalGroupByItem hierarchicalGroupByItem )
    {
      Debug.Assert( hierarchicalGroupByItem != null );
      if( hierarchicalGroupByItem == null )
        return null;

      TreeView treeView = this.GetTemplateChild( @"PART_HierarchicalGroupByControlTreeView" ) as TreeView;

      if( treeView == null )
        return null;

      if( treeView.Items.Count == 0 )
        throw new DataGridInternalException( "The HierarchicalGroupByControl should contain at least one grouping level." );

      // The first item is always the top level HierarchicalGroupByControlNode
      TreeViewItem rootItem = treeView.ItemContainerGenerator.ContainerFromItem( treeView.Items[ 0 ] ) as TreeViewItem;

      if( rootItem == null )
        throw new DataGridInternalException( "The root item is null." );

      GroupLevelDescription detailGroupLevelDescription = hierarchicalGroupByItem.Content as GroupLevelDescription;

      Debug.Assert( detailGroupLevelDescription != null );

      TreeViewItem dropMarkedTreeViewItem = null;

      DataGridContext rootDataGridContext = rootItem.Header as DataGridContext;

      Debug.Assert( rootDataGridContext != null );

      if( rootDataGridContext.GroupLevelDescriptions.Contains( detailGroupLevelDescription ) )
      {
        dropMarkedTreeViewItem = rootItem;
      }
      else
      {
        dropMarkedTreeViewItem = HierarchicalGroupByControl.GetTreeViewItemFromGroupLevelDescription( rootItem, detailGroupLevelDescription );
      }


      // If null, it means the cell does not belong to this detail
      if( dropMarkedTreeViewItem == null )
        return null;

      ContentPresenter treeViewItemHeader = dropMarkedTreeViewItem.Template.FindName( "PART_Header", dropMarkedTreeViewItem ) as ContentPresenter;

      Debug.Assert( treeViewItemHeader != null );
      if( treeViewItemHeader == null )
        throw new DataGridInternalException( "An error occurred while retrieving the PART_Header template part of an item containing a HierarchicalGroupByControlNode." );

      HierarchicalGroupByControlNode hierarchicalGroupByControlNode = HierarchicalGroupByControl.GetHierarchicalGroupByControlNode( treeViewItemHeader );

      return hierarchicalGroupByControlNode;
    }
        void IDropTarget.Drop(UIElement draggedElement)
        {
            ColumnManagerCell draggedColumnManagerCell = draggedElement as ColumnManagerCell;

            if (m_dropMarkAdorner != null)
            {
                GroupLevelDescription draggedOverGroupLevelDescription = this.Content as GroupLevelDescription;

                DropMarkAlignment alignment = m_dropMarkAdorner.Alignment;
                this.HideDropMark();

                if (draggedColumnManagerCell != null)
                {
                    DataGridContext dataGridContext = DataGridControl.GetDataGridContext(this);

                    DataGridControl parentGrid = (dataGridContext != null)
            ? dataGridContext.DataGridControl
            : null;

                    GroupingHelper.AddNewGroupFromColumnManagerCell(draggedColumnManagerCell, draggedOverGroupLevelDescription, alignment, parentGrid);
                }
                else
                {
                    HierarchicalGroupByItem draggedGroupByItem = draggedElement as HierarchicalGroupByItem;

                    if (draggedGroupByItem == null)
                    {
                        return;
                    }

                    GroupLevelDescription draggedGroupLevelDescription = draggedGroupByItem.Content as GroupLevelDescription;

                    DataGridContext dataGridContext = DataGridControl.GetDataGridContext(this);

                    DataGridControl parentDataGridControl = (dataGridContext != null)
            ? dataGridContext.DataGridControl
            : null;

                    GroupLevelDescription destinationGroupLevelDescription = this.Content as GroupLevelDescription;

                    GroupingHelper.MoveGroupDescription(this.ParentColumns, this.ParentGroupDescriptions,
                                                        destinationGroupLevelDescription, alignment,
                                                        draggedGroupLevelDescription, parentDataGridControl);
                }
            }
            else
            {
                // We try to add a new Group which is not in the current GroupLevelDescriptions
                if (draggedColumnManagerCell == null)
                {
                    return;
                }

                DataGridContext dataGridContext = DataGridControl.GetDataGridContext(this);

                DataGridControl parentGrid = (dataGridContext != null)
          ? dataGridContext.DataGridControl
          : null;

                GroupingHelper.AppendNewGroupFromColumnManagerCell(draggedColumnManagerCell, parentGrid);
            }

            HierarchicalGroupByControl parentGBC = GroupingHelper.GetHierarchicalGroupByControl(this);

            Debug.Assert(parentGBC != null);
            if (parentGBC == null)
            {
                throw new DataGridInternalException("A hierarchical group-by item must be rooted by a HierarchicalGroupByControl.");
            }

            // Notify groups have changed for NoGroupContent
            parentGBC.UpdateHasGroups();
        }
        internal HierarchicalGroupByControlNode GetHierarchicalGroupByControlNodeFromHierarchicalGroupByItem(HierarchicalGroupByItem hierarchicalGroupByItem)
        {
            Debug.Assert(hierarchicalGroupByItem != null);
            if (hierarchicalGroupByItem == null)
            {
                return(null);
            }

            TreeView treeView = this.GetTemplateChild(@"PART_HierarchicalGroupByControlTreeView") as TreeView;

            if (treeView == null)
            {
                return(null);
            }

            if (treeView.Items.Count == 0)
            {
                throw new DataGridInternalException("The HierarchicalGroupByControl should contain at least one grouping level.");
            }

            // The first item is always the top level HierarchicalGroupByControlNode
            TreeViewItem rootItem = treeView.ItemContainerGenerator.ContainerFromItem(treeView.Items[0]) as TreeViewItem;

            if (rootItem == null)
            {
                throw new DataGridInternalException("The root item is null.");
            }

            GroupLevelDescription detailGroupLevelDescription = hierarchicalGroupByItem.Content as GroupLevelDescription;

            Debug.Assert(detailGroupLevelDescription != null);

            TreeViewItem dropMarkedTreeViewItem = null;

            DataGridContext rootDataGridContext = rootItem.Header as DataGridContext;

            Debug.Assert(rootDataGridContext != null);

            if (rootDataGridContext.GroupLevelDescriptions.Contains(detailGroupLevelDescription))
            {
                dropMarkedTreeViewItem = rootItem;
            }
            else
            {
                dropMarkedTreeViewItem = HierarchicalGroupByControl.GetTreeViewItemFromGroupLevelDescription(rootItem, detailGroupLevelDescription);
            }


            // If null, it means the cell does not belong to this detail
            if (dropMarkedTreeViewItem == null)
            {
                return(null);
            }

            ContentPresenter treeViewItemHeader = dropMarkedTreeViewItem.Template.FindName("PART_Header", dropMarkedTreeViewItem) as ContentPresenter;

            Debug.Assert(treeViewItemHeader != null);
            if (treeViewItemHeader == null)
            {
                throw new DataGridInternalException("An error occurred while retrieving the PART_Header template part of an item containing a HierarchicalGroupByControlNode.");
            }

            HierarchicalGroupByControlNode hierarchicalGroupByControlNode = HierarchicalGroupByControl.GetHierarchicalGroupByControlNode(treeViewItemHeader);

            return(hierarchicalGroupByControlNode);
        }
        private static void OnSortDirectionInternalChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
        {
            HierarchicalGroupByItem groupByItem = ( HierarchicalGroupByItem )sender;

            groupByItem.OnPropertyChanged(new PropertyChangedEventArgs("SortDirection"));
        }
        bool IDropTarget.CanDropElement(UIElement draggedElement)
        {
            bool canDrop = this.AllowGroupingModification;

            ColumnManagerCell       cell = null;
            HierarchicalGroupByItem hierarchicalGroupByItem = null;

            if (canDrop)
            {
                cell = draggedElement as ColumnManagerCell;

                if (cell != null)
                {
                    ColumnBase parentColumn = cell.ParentColumn;

                    if ((parentColumn == null) || (!parentColumn.AllowGroup))
                    {
                        return(false);
                    }

                    // Check if already grouped using the cell's DataGridContext
                    canDrop = !GroupingHelper.IsAlreadyGroupedBy(cell);

                    if (canDrop)
                    {
                        DataGridContext thisDataGridContext = DataGridControl.GetDataGridContext(this);

                        if (thisDataGridContext.Items != null)
                        {
                            canDrop = thisDataGridContext.Items.CanGroup;
                        }

                        if (canDrop)
                        {
                            canDrop = GroupingHelper.IsColumnManagerCellInDataGridContext(thisDataGridContext, cell);

                            if (canDrop == true)
                            {
                                canDrop = GroupingHelper.ValidateMaxGroupDescriptions(DataGridControl.GetDataGridContext(draggedElement));
                            }
                        }
                    }
                }
                else
                {
                    hierarchicalGroupByItem = draggedElement as HierarchicalGroupByItem;

                    if (hierarchicalGroupByItem == null)
                    {
                        canDrop = false;
                    }

                    if (canDrop)
                    {
                        // Try to get the HierarchicalGroupByControlNode in which this HierarchicalGroupByItem can be added using the parent HierarchicalGroupByControl => null it can't
                        HierarchicalGroupByControlNode draggedHierarchicalGroupByControlNode = this.GetHierarchicalGroupByControlNodeFromHierarchicalGroupByItem(hierarchicalGroupByItem);

                        if (draggedHierarchicalGroupByControlNode == null)
                        {
                            canDrop = false;
                        }
                    }
                }
            }

            bool returnedValue = ((cell != null) || (hierarchicalGroupByItem != null)) && // ColumnManagerCell or HierarchicalGroupByItem
                                 (canDrop);


            return(returnedValue);
        }
        bool IDropTarget.CanDropElement(UIElement draggedElement)
        {
            ColumnManagerCell       cell = null;
            HierarchicalGroupByItem hierarchicalGroupByItem = null;
            bool canDrop = this.AllowGroupingModification;

            if (canDrop)
            {
                cell = draggedElement as ColumnManagerCell;

                if (cell != null)
                {
                    ColumnBase parentColumn = cell.ParentColumn;

                    if ((parentColumn == null) || (!parentColumn.AllowGroup))
                    {
                        return(false);
                    }

                    // Check if already grouped using the cell's DataGridContext
                    canDrop = !GroupingHelper.IsAlreadyGroupedBy(cell);

                    if (canDrop)
                    {
                        // Get the HierarchicalGroupByControl for this HierarchicalGroupByControlNode
                        HierarchicalGroupByControl parentGBC = GroupingHelper.GetHierarchicalGroupByControl(this);

                        if (parentGBC == null)
                        {
                            throw new DataGridInternalException("The hierarchical group-by control node must be rooted by a HierarchicalGroupByControl.");
                        }

                        DataGridContext parentGBCDataGridContext = DataGridControl.GetDataGridContext(parentGBC);

                        Debug.Assert(parentGBCDataGridContext != null);

                        if (parentGBCDataGridContext.Items != null)
                        {
                            canDrop = parentGBCDataGridContext.Items.CanGroup;
                        }

                        if (canDrop)
                        {
                            canDrop = GroupingHelper.IsColumnManagerCellInDataGridContext(parentGBCDataGridContext, cell);

                            if (canDrop == true)
                            {
                                canDrop = GroupingHelper.ValidateMaxGroupDescriptions(DataGridControl.GetDataGridContext(draggedElement));
                            }
                        }
                    }
                }
                else
                {
                    hierarchicalGroupByItem = draggedElement as HierarchicalGroupByItem;

                    if (hierarchicalGroupByItem == null)
                    {
                        canDrop = false;
                    }

                    if (canDrop)
                    {
                        HierarchicalGroupByControl parentGBC = GroupingHelper.GetHierarchicalGroupByControl(this);

                        if (parentGBC == null)
                        {
                            throw new DataGridInternalException("The hierarchical group-by control node must be rooted by a HierarchicalGroupByControl.");
                        }

                        // Try to get the HierarchicalGroupByControlNode in which this HierarchicalGroupByItem can be added using the parent HierarchicalGroupByControl => null it can't
                        HierarchicalGroupByControlNode draggedHierarchicalGroupByControlNode = parentGBC.GetHierarchicalGroupByControlNodeFromHierarchicalGroupByItem(hierarchicalGroupByItem);

                        if (draggedHierarchicalGroupByControlNode == null)
                        {
                            canDrop = false;
                        }
                    }
                }
            }

            bool returnedValue = ((cell != null) || (hierarchicalGroupByItem != null)) &&// ColumnManagerCell or HierarchicalGroupByItem
                                 (canDrop);


            return(returnedValue);
        }
        void IDropTarget.DragOver(UIElement draggedElement, Point mousePosition)
        {
            ColumnManagerCell cell = draggedElement as ColumnManagerCell;

            if (cell != null)
            {
                DataGridContext draggedCellDataGridContext = DataGridControl.GetDataGridContext(cell);

                HierarchicalGroupByControlNode draggedOverHierarchicalGroupByControlNode = HierarchicalGroupByItem.GetParentHierarchicalGroupByControlNode(this);

                if (draggedCellDataGridContext == null)
                {
                    throw new DataGridInternalException("A ColumnManagerCell must have a DataGridContext.");
                }

                if (draggedOverHierarchicalGroupByControlNode == null)
                {
                    throw new DataGridInternalException();
                }

                if (draggedOverHierarchicalGroupByControlNode.GroupLevelDescriptions == draggedCellDataGridContext.GroupLevelDescriptions)
                {
                    this.ShowDropMark(mousePosition);
                }
                else
                {
                    // This ColumnManagerCell does not belong this parent HierarchicalGroupByControlNode, display the DropMark on the correct one
                    HierarchicalGroupByControl parentGBC = GroupingHelper.GetHierarchicalGroupByControl(draggedOverHierarchicalGroupByControlNode);

                    if (parentGBC == null)
                    {
                        throw new DataGridInternalException("The hierarchical group-by item must be rooted by a HierarchicalGroupByControl.");
                    }

                    HierarchicalGroupByControlNode hierarchicalGroupByControlNode = parentGBC.GetHierarchicalGroupByControlNodeFromColumnManagerCell(cell);

                    Debug.Assert(hierarchicalGroupByControlNode != null, "CanDrop should have returned false");
                    if (hierarchicalGroupByControlNode == null)
                    {
                        throw new DataGridInternalException("A HierarchicalGroupByControlNode must exist for every level.");
                    }

                    hierarchicalGroupByControlNode.ShowFarDropMark(cell, mousePosition);
                }
            }
            else
            {
                HierarchicalGroupByItem hierarchicalGroupByItem = draggedElement as HierarchicalGroupByItem;

                if (hierarchicalGroupByItem == null)
                {
                    return;
                }

                HierarchicalGroupByControlNode draggedHierarchicalGroupByControlNode = HierarchicalGroupByItem.GetParentHierarchicalGroupByControlNode(hierarchicalGroupByItem);

                HierarchicalGroupByControlNode draggedOverHierarchicalGroupByControlNode = HierarchicalGroupByItem.GetParentHierarchicalGroupByControlNode(this);

                if (draggedHierarchicalGroupByControlNode == null)
                {
                    throw new DataGridInternalException();
                }

                if (draggedOverHierarchicalGroupByControlNode == null)
                {
                    throw new DataGridInternalException();
                }

                if (draggedHierarchicalGroupByControlNode.GroupLevelDescriptions == draggedOverHierarchicalGroupByControlNode.GroupLevelDescriptions)
                {
                    this.ShowDropMark(mousePosition);
                }
                else
                {
                    // This HierarchicalGroupByItem does not belong this parent HierarchicalGroupByControlNode, display the DropMark on the correct one
                    HierarchicalGroupByControl parentGBC = GroupingHelper.GetHierarchicalGroupByControl(draggedOverHierarchicalGroupByControlNode);

                    if (parentGBC == null)
                    {
                        throw new DataGridInternalException("A hierarchical group-by item must be rooted by a HierarchicalGroupByControl.");
                    }

                    HierarchicalGroupByControlNode hierarchicalGroupByControlNode = parentGBC.GetHierarchicalGroupByControlNodeFromHierarchicalGroupByItem(hierarchicalGroupByItem);

                    Debug.Assert(hierarchicalGroupByControlNode != null, "CanDrop should have returned false");
                    if (hierarchicalGroupByControlNode == null)
                    {
                        throw new DataGridInternalException("A HierarchicalGroupByControlNode must exist for every level.");
                    }

                    hierarchicalGroupByControlNode.ShowFarDropMark(mousePosition);
                }
            }
        }
        void IDropTarget.DragLeave(UIElement draggedElement)
        {
            ColumnManagerCell cell = draggedElement as ColumnManagerCell;

            if (cell != null)
            {
                HierarchicalGroupByControl parentGBC = GroupingHelper.GetHierarchicalGroupByControl(this);

                if (parentGBC == null)
                {
                    throw new DataGridInternalException("The hierarchical group-by control node must be rooted by a HierarchicalGroupByControl.");
                }

                HierarchicalGroupByControlNode hierarchicalGroupByControlNode = parentGBC.GetHierarchicalGroupByControlNodeFromColumnManagerCell(cell);

                if (hierarchicalGroupByControlNode == null)
                {
                    throw new DataGridInternalException("A HierarchicalGroupByControlNode must exist for every level.");
                }

                hierarchicalGroupByControlNode.HideFarDropMark(cell);
            }
            else
            {
                HierarchicalGroupByItem hierarchicalGroupByItem = draggedElement as HierarchicalGroupByItem;
                if (hierarchicalGroupByItem == null)
                {
                    return;
                }

                HierarchicalGroupByControlNode draggedHierarchicalGroupByControlNode = HierarchicalGroupByItem.GetParentHierarchicalGroupByControlNode(hierarchicalGroupByItem);

                if (draggedHierarchicalGroupByControlNode == null)
                {
                    throw new DataGridInternalException("draggedHierarchicalGroupByControlNode is null.");
                }

                if (draggedHierarchicalGroupByControlNode.GroupLevelDescriptions == this.GroupLevelDescriptions)
                {
                    this.HideFarDropMark();
                }
                else
                {
                    // This HierarchicalGroupByItem does not belong this parent HierarchicalGroupByControlNode, display the DropMark on the correct one
                    HierarchicalGroupByControl parentGBC = GroupingHelper.GetHierarchicalGroupByControl(this);

                    Debug.Assert(parentGBC != null);
                    if (parentGBC == null)
                    {
                        throw new DataGridInternalException("The hierarchical group-by control node must be rooted by a HierarchicalGroupByControl");
                    }

                    HierarchicalGroupByControlNode hierarchicalGroupByControlNode = parentGBC.GetHierarchicalGroupByControlNodeFromHierarchicalGroupByItem(hierarchicalGroupByItem);

                    Debug.Assert(hierarchicalGroupByControlNode != null, "CanDrop should have returned false");
                    if (hierarchicalGroupByControlNode == null)
                    {
                        throw new DataGridInternalException("A HierarchicalGroupByControlNode must exist for every level.");
                    }

                    hierarchicalGroupByControlNode.HideFarDropMark();
                }
            }
        }
      internal HierarchicalGroupByItemToggleColumnSortCommand( HierarchicalGroupByItem target )
        : base()
      {
        if( target == null )
          throw new ArgumentNullException( "owner" );

        m_target = new WeakReference( target );

        if( target.ParentDataGridContext != null )
        {
          m_dataGridContext = new WeakReference( target.ParentDataGridContext );
        }

        DataGridContext groupByItemDataGridContext = DataGridControl.GetDataGridContext( target );
        ToggleColumnSortCommand.ThrowIfNull( groupByItemDataGridContext, "groupByItemDataGridContext" );

        DataGridControl dataGridControl = groupByItemDataGridContext.DataGridControl;
        ToggleColumnSortCommand.ThrowIfNull( dataGridControl, "dataGridControl" );

        m_dataGridControl = new WeakReference( dataGridControl );
      }