gistfile1.txt

- (CPDragOperation)outlineView:(CPOutlineView)theOutlineView validateDrop:(id)info proposedItem:(id)item proposedChildIndex:(CPInteger)childIndex
{
    if(CPLOG_ON) CPLog.debug(self + _cmd + item + " proposedChildIndex:" + childIndex);

    // This method validates whether or not the proposal is a valid one.
    // We start out by assuming that we will do a "generic" drag operation, which means we are accepting the drop. If we return CPDragOperationNone, then we are not accepting the drop.
    var result = CPDragOperationGeneric;


    if ([self onlyAcceptDropOnRoot:info])
    {
        // We are going to accept the drop, but we want to retarget the drop item to be "on" the entire outlineView
        [theOutlineView setDropItem:nil dropChildIndex:CPOutlineViewDropOnItemIndex];
    }
    else
    {
        // Check to see what we are proposed to be dropping on
        var targetNode = item;
        // A target of "nil" means we are on the main root tree
        if (targetNode == nil)
            targetNode = rootTreeNode;

        var nodeData = [targetNode representedObject];
        if (nodeData.container)
        {
            // See if we allow dropping "on" or "between"
            if (childIndex == CPOutlineViewDropOnItemIndex)
            {
                if (![self allowOnDropOnContainer:nodeData info:info])// Refuse to drop on a container if we are not allowing that
                    result = CPDragOperationNone;
            }
            else
            {
                if (![self allowBetweenDrop:info]) // Refuse to drop between an item if we are not allowing that
                    result = CPDragOperationNone;
            }
        }
        else
        {
            // The target node is not a container, but a leaf. See if we allow dropping on a leaf. If we don't, refuse the drop (we may get called again with a between)
            if (childIndex == CPOutlineViewDropOnItemIndex && ![self allowOnDropOnLeaf:nodeData info:info])
                result = CPDragOperationNone;
        }
        
        // If we are allowing the drop, we see if we are draggng from ourselves and dropping into a descendent, which wouldn't be allowed...
        if (result != CPDragOperationNone)
        {
            if ([info draggingSource] == theOutlineView)
            {
                // Yup, the drag is originating from ourselves. See if the appropriate drag information is available on the pasteboard
                if (targetNode != rootTreeNode && [[info draggingPasteboard] availableTypeFromArray:[CPArray arrayWithObject:SIMPLE_PBOARD_TYPE]] != nil)
                {
                    var count = [draggedNodes count];
                    for (var i = 0; i < count; i++)
                    {   
                        var draggedNode = [draggedNodes objectAtIndex:i];
                        if ([self treeNode:targetNode isDescendantOfNode:draggedNode])
                        {
                            // Yup, it is, refuse it.
                            result = CPDragOperationNone;
                            break;
                        }
                    }
                }
            }
        }
    }
    // To see what we decide to return, uncomment this line
    // if(CPLOG_ON) CPLog(result == CPDragOperationNone ? self + _cmd + @" - Refusing drop" : self + _cmd + @" + Accepting drop");
    
    return result;    
}