/// <summary>
/// Event raised when the user starts to drag a node.
/// </summary>
private void NodeItem_DragStarted(object source, NodeDragStartedEventArgs e)
{
e.Handled = true;
if(dragWasDoubleclick)
{
dragWasDoubleclick = false;
e.Cancel = true;
return;
}
this.IsDragging = true;
this.IsNotDragging = false;
this.IsDraggingNode = true;
this.IsNotDraggingNode = false;
var eventArgs = new NodeDragStartedEventArgs(NodeDragStartedEvent, this, this.SelectedNodes);
RaiseEvent(eventArgs);
e.Cancel = eventArgs.Cancel;
}
/// <summary>
/// Called when the mouse cursor is moved.
/// </summary>
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
if (isDragging)
{
//
// Raise the event to notify that dragging is in progress.
//
Point curMousePoint = e.GetPosition(this.ParentNetworkView);
object item = this;
if (DataContext != null)
{
item = DataContext;
}
Vector offset = curMousePoint - lastMousePoint;
if (offset.X != 0.0 ||
offset.Y != 0.0)
{
lastMousePoint = curMousePoint;
RaiseEvent(new NodeDraggingEventArgs(NodeDraggingEvent, this, new object[] { item }, offset.X, offset.Y));
}
}
else if (isLeftMouseDown && this.ParentNetworkView.EnableNodeDragging)
{
//
// The user is left-dragging the node,
// but don't initiate the drag operation until
// the mouse cursor has moved more than the threshold distance.
//
Point curMousePoint = e.GetPosition(this.ParentNetworkView);
var dragDelta = curMousePoint - lastMousePoint;
double dragDistance = Math.Abs(dragDelta.Length);
if (dragDistance > DragThreshold)
{
//
// When the mouse has been dragged more than the threshold value commence dragging the node.
//
//
// Raise an event to notify that that dragging has commenced.
//
NodeDragStartedEventArgs eventArgs = new NodeDragStartedEventArgs(NodeDragStartedEvent, this, new NodeItem[] { this });
RaiseEvent(eventArgs);
if (eventArgs.Cancel)
{
//
// Handler of the event disallowed dragging of the node.
//
isLeftMouseDown = false;
isLeftMouseAndControlDown = false;
return;
}
isDragging = true;
this.CaptureMouse();
e.Handled = true;
}
}
}
