Hi Stoyo

I have seen the Drag-Drop between two diagram controsl few days back.

I am also using Telrik Controls in my application and there latest control supports drag-drop for any control (control which captures mouse events also works with new telerik version).

I adpted this new controls for drag-drop between multiple controls. With Telrik Drag-Drop manager I can perform following actions -

1.  Dragging any node and dropping on any other control ( it doesn't matter whether the node/shape is selected or not).

2. When node is selected then Telrik drag-drop work well if I press the mouse button on adjustment handles.
Mouse down on adjustment handle allows me to resize my node or mouse down on center adjustment handle allows me to reposition the node ( This is as per my requirement)

Now, the issue is when I select multiple nodes and select the center or any adjustment handle for one of the node it starts repositioning all nodes. ( This is also ok for me)

But when my mouse button is down on one of the node (not on any adjustment handle) with mouse move events diagramlite starts re-positioing the control. At the same time Telerik control starts its drag operation. 
In this situation I want to cancel the Diagramlite reposition functionality.

Can you tell me how one can prevent re-positioning when multiple nodes are selected. There is no node modified event occurs when multiple nodes are selected.

Perhaps the easiest way to do that is through a custom LinkShapesBehavior -derived class, whose StartDraw method returns null in the situations when drag-and-drop should start, otherwise returns base.StartDraw(). E.g. it could look like this

public override InteractionState StartDraw(Point point)
{
	if (App.ShouldDragAndDrop)
		return null;
	return base.StartDraw(point);
}

diagram.CustomBehavior = new MyBehavior(diagram);
 

Setting item.Locked also deselects the item, so to lock all selected items:

var selectedItems = new DiagramItemCollection(diagram.Selection.Items);
foreach (DiagramItem item in selectedItems)
	item.Locked = true;
 

I hope that helps,
Stoyan

Hi Rajesh,

Ok, it seems starting to move the selection is something that works the same for all behaviors, and it does not happen in StartDraw but in OnMouseMove. I suppose you could check for drag-and-drop in an OnMouseMove override - if you detect drag-and-drop has started, just return, otherwise call the base OnMouseMove implementation.

I hope that helps,
Stoyan

Hi Rajesh,

I've meant you should override the BehaviorBase.OnMouseMove method, not the diagram's one, and assign the behavior instance to diagram.CustomBehavior.

Stoyan

Hi,

This could happen if OnMouseMove is called one or more times before App.ShouldDragAndDrop is set. Can't you determine earlier if drag and drop would start at that position?

Stoyan

Hi Stoyo

With following code I am able to achive the drag drop as per my requirement.

    public class MyBehavirour : LinkShapesBehavior
    {
       bool bRepositionItems = false;
       public MyBehavirour(Diagram diagram)
           : base(diagram)
       {
       }

       protected override bool OnMouseDown(System.Windows.Input.MouseButtonEventArgs e)
       {
           Point? point;
           bRepositionItems = true;
           point = new Point?(e.GetPosition(base.Diagram.DocumentPlane));
           if (base.Diagram.Selection.Items.Count > 1)
           {
               bRepositionItems = false;
               if (point.HasValue)
               {
                   foreach (UIElement element in UIElements(point.Value))
                   {
                       System.Windows.Shapes.Rectangle rectangle = element as System.Windows.Shapes.Rectangle;
                       if (rectangle != null)
                       {
                           if (rectangle.Tag is AdjustmentHandle)
                           {
                               bRepositionItems = true;
                               break;
                           }
                       }
                   }
               }
           }
           return base.OnMouseDown(e);
       }

       protected override void OnMouseMove(System.Windows.Input.MouseEventArgs e)
       {
           if (bRepositionItems)
               base.OnMouseMove(e);
       }

       protected override void OnMouseUp(System.Windows.Input.MouseButtonEventArgs e)
       {
           bRepositionItems = true;
           base.OnMouseUp(e);
       }

       private IEnumerable<UIElement> UIElements(Point _point)
       {
           return VisualTreeHelper.FindElementsInHostCoordinates(base.Diagram.DocumentPlane.GetPoi
nt(_point), base.Diagram.DocumentPlane);
       }
    }


Is it not possible that version 1.3 should provide one more property which disables draging of multiple items unless it is done by adjustment handles ?

-Rajesh