Dragging nodes from a Diagram to another control

[Dylan Black]

I have a requirement to drag nodes from a Diagram to other Windows Forms controls, including other diagrams.

I've tried overriding the OnDragLeave and OnMouseLeave methods of the Diagram, but it appears that these are being blocked during a node move operation.

I've noticed other forum posts around this topic from several years ago, when it was acknowledged as a known issue, and was wondering if it has been resolved, or if there's some way to implement this now.

Thanks.

[Amsath Ali M]

Hi Dylan,

 

Thanks for your interest in Syncfusion products.

 

We are glad to inform you that we have achieved your requirement by creating a custom tool called “DragDropTool” and activated the custom tool to drag and drop an element from diagram into treeview control. Please refer the below code snippet.

Here is the code:

[C#]

public Form1()

{

    InitializeComponent();

    DragDropTool tool = new DragDropTool(this.diagram1.Controller);

    diagram1.Controller.RegisterTool(tool);

    this.dragHelper = new DragHelper();

    treeView1.AllowDrop = true;

 

    treeView1.MouseDown += new MouseEventHandler(treeView1_MouseDown);

    treeView1.MouseMove += new MouseEventHandler(treeView1_MouseMove);

    treeView1.MouseUp += new MouseEventHandler(treeView1_MouseUp);

    treeView1.QueryContinueDrag += new QueryContinueDragEventHandler(treeView1_QueryContinueDrag);

    treeView1.GiveFeedback += new GiveFeedbackEventHandler(treeView1_GiveFeedback);

    treeView1.DragDrop += new DragEventHandler(treeView1_DragDrop);

    treeView1.DragEnter += new DragEventHandler(treeView1_DragEnter);

 

    diagram1.DragEnter += new DragEventHandler(diagram1_DragEnter);

    diagram1.DragDrop += new DragEventHandler(diagram1_DragDrop);

    diagram1.MouseDown += new MouseEventHandler(diagram1_MouseDown);

    diagram1.Model.EventSink.PinPointChanging += new PinPointChangingEventHandler(EventSink_PinPointChanging);

    this.Disposed += new EventHandler(Form1_Disposed);

}

 

void diagram1_MouseDown(object sender, MouseEventArgs e)

{

    Node node = this.diagram1.Controller.GetNodeUnderMouse(e.Location) as Node;

    if (node != null && diagram1.Controller.ActiveTool is DragDropTool)

    {

        DragDropData data = new DragDropData(node);

        data.DragNodeCueEnabled = bDragNodeCueEnabled;

        diagram1.DoDragDrop(data, DragDropEffects.Copy);

    }

}

 

void treeView1_DragEnter(object sender, DragEventArgs e)

{

    e.Effect = DragDropEffects.Copy;

}

 

void treeView1_DragDrop(object sender, DragEventArgs e)

{

    TreeNode nodeToDropIn = this.treeView1.GetNodeAt(this.treeView1.PointToClient(new Point(e.X, e.Y)));

    if (nodeToDropIn == null) { return; }

    if (nodeToDropIn.Level > 0)

    {

        nodeToDropIn = nodeToDropIn.Parent;

    }

    object data = e.Data.GetData(typeof(DragDropData));           

    nodeToDropIn.Nodes.Add(((DragDropData)data).Nodes[0].Name);

    e.Effect = DragDropEffects.None;

}

 

DragDropTool.cs:

 

class DragDropTool:ZoomTool

{

    internal static string ToolName = "DragDropTool";

    public DragDropTool(DiagramController contllr)

        : base(contllr)

    {

        //Ser Arrow as Tool's action cursor

        this.ActionCursor = Cursors.Arrow;

        this.Name = ToolName;

        this.SingleActionTool = false;

    }

 

    public override Tool ProcessMouseDown(MouseEventArgs evtArgs)

    {

        Tool toolToReturn = this;

        if (this.Controller.Viewer != null && this.InAction)

        {

            this.InAction = false;

        }

        return toolToReturn;

    }

}

 

 

Please try the below attached sample and let us know if you have any queries.

 

Regards,

Amsath Ali. M

 

Treeview_14da86bb.zip

[Dylan Black]

Hi,

Thanks for getting back to me with a sample.

I can get the drag & drop to work if I use the Syncfusion DragDropData type as the argument to DoDragDrop, but if I change it to the regular .NET DataObject class, and pass a custom type as the data (i.e. not a NodeCollection or DragDropData) then the cursor flickers constantly.

Since I'm using the Diagram as part of a larger application, I  ideally need to use the DataObject class along with our own entity classes to maintain compatibility with other parts of the system.

I've updated the sample to show what I mean; the cursor flickers when you drag from the TreeView to the Diagram.

My guess would be that the code in the Diagram OnDragEnter method, which is setting a private boolean based on those passed in data types, is responsible.

Do you have any ideas on how to prevent the cursor flickering?

Thanks,

Dylan.

Treeview_6a5c1c96.zip

[Dylan Black]

I should add that when I use the DragDropData type during the drag operation that the diagram attempts to automatically insert the nodes that it contains on drop, which I don't want to happen - I would need to be able to override this if I am forced to use the DragDropData type to prevent the cursor flickering.

[Amsath Ali M]

Hi Dylan,

 

Thanks for your update.

 

We are able to reproduce the issue reported by you at our end, and the issue has been suspected to be a defect. Please create a DT incident for your query so that we can update the patch for this issue.

You can create the DT incident from the following link.
<http://www.syncfusion.com/account/dashboard>

In the interests of maintaining confidentiality, we have a policy of not sharing patches or otherwise proprietary customer specific information in the public Forum.

 

Please let us know if you have any queries.

 

Regards,

Amsath Ali. M