bool IDropTarget.CanDropElement(UIElement draggedElement)
{
bool canDrop = true;
// Check if this HierarchicalGroupByItem parent HierarchicalGroupByControlNode allows grouping modifications, default yes
HierarchicalGroupByControlNode parentHierarchicalGroupByControlNode = HierarchicalGroupByItem.GetParentHierarchicalGroupByControlNode(this);
if (parentHierarchicalGroupByControlNode != null)
{
canDrop = parentHierarchicalGroupByControlNode.IsGroupingModificationAllowed;
}
ColumnManagerCell cell = draggedElement as ColumnManagerCell;
HierarchicalGroupByItem hierarchicalGroupByItem = null;
if (canDrop)
{
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 HierarchicalGroupByItem
HierarchicalGroupByControl parentGBC = GroupingHelper.GetHierarchicalGroupByControl(parentHierarchicalGroupByControlNode);
if (parentGBC == null)
{
throw new DataGridInternalException("The hierarchical group-by item must be rooted by a HierarchicalGroupByControl.");
}
DataGridContext parentGBCDataGridContext = DataGridControl.GetDataGridContext(parentGBC);
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(parentHierarchicalGroupByControlNode);
if (parentGBC == null)
{
throw new DataGridInternalException("The hierarchical group-by item 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
(draggedElement != this) &&
(canDrop);
return(returnedValue);
}
void IDropTarget.DragLeave(UIElement draggedElement)
{
ColumnManagerCell cell = draggedElement as ColumnManagerCell;
if (cell != null)
{
DataGridContext draggedCellDataGridContext = DataGridControl.GetDataGridContext(cell);
HierarchicalGroupByControlNode draggedOverHierarchicalGroupByControlNode = HierarchicalGroupByItem.GetParentHierarchicalGroupByControlNode(this);
if (draggedOverHierarchicalGroupByControlNode == null)
{
throw new DataGridInternalException("We should never be dragged over and not contained inside a HierarchicalGroupByControlNode.");
}
if (draggedOverHierarchicalGroupByControlNode.GroupLevelDescriptions == draggedCellDataGridContext.GroupLevelDescriptions)
{
this.HideDropMark();
}
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("A 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.HideFarDropMark(cell);
}
}
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("draggedHierarchicalGroupByControlNode is null.");
}
if (draggedOverHierarchicalGroupByControlNode == null)
{
throw new DataGridInternalException("draggedOverHierarchicalGroupByControlNode is null.");
}
if (draggedHierarchicalGroupByControlNode.GroupLevelDescriptions == draggedOverHierarchicalGroupByControlNode.GroupLevelDescriptions)
{
this.HideDropMark();
}
else
{
// This HierarchicalGroupByItem does not belong this parent HierarchicalGroupByControlNode, display the DropMark on the correct one
HierarchicalGroupByControl parentGBC = GroupingHelper.GetHierarchicalGroupByControl(draggedOverHierarchicalGroupByControlNode);
Debug.Assert(parentGBC != null);
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.HideFarDropMark();
}
}
}
void IDropTarget.DragOver(UIElement draggedElement, Point mousePosition)
{
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.ShowFarDropMark(cell, mousePosition);
}
else
{
HierarchicalGroupByItem hierarchicalGroupByItem = draggedElement as HierarchicalGroupByItem;
if (hierarchicalGroupByItem == null)
{
return;
}
HierarchicalGroupByControlNode draggedHierarchicalGroupByControlNode = HierarchicalGroupByItem.GetParentHierarchicalGroupByControlNode(hierarchicalGroupByItem);
if (draggedHierarchicalGroupByControlNode == null)
{
throw new DataGridInternalException();
}
if (draggedHierarchicalGroupByControlNode.GroupLevelDescriptions == this.GroupLevelDescriptions)
{
this.ShowFarDropMark(mousePosition);
}
else
{
// This HierarchicalGroupByItem does not belong this parent HierarchicalGroupByControlNode, display the DropMark on the correct one
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.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);
}
}
}
