/// <summary>
/// Event raised when the user starts to drag a connector.
/// </summary>
private void ConnectorItem_DragStarted(object source, ConnectorItemDragStartedEventArgs e)
{
Focus();
e.Handled = true;
IsDragging = true;
IsNotDragging = false;
IsDraggingConnection = true;
IsNotDraggingConnection = false;
_draggedOutConnectorItem = (ConnectorItem)e.OriginalSource;
var nodeItem = _draggedOutConnectorItem.ParentNodeItem;
_draggedOutNodeDataContext = nodeItem.DataContext != null ? nodeItem.DataContext : nodeItem;
_draggedOutConnectorDataContext = _draggedOutConnectorItem.DataContext != null ? _draggedOutConnectorItem.DataContext : _draggedOutConnectorItem;
//
// Raise an event so that application code can create a connection and
// add it to the view-model.
//
var eventArgs = new ConnectionDragStartedEventArgs(ConnectionDragStartedEvent, this, _draggedOutNodeDataContext, _draggedOutConnectorDataContext);
RaiseEvent(eventArgs);
//
// Retrieve the the view-model object for the connection was created by application code.
//
_draggingConnectionDataContext = eventArgs.Connection;
if (_draggingConnectionDataContext == null)
{
//
// Application code didn't create any connection.
//
e.Cancel = true;
}
}
/// <summary>
/// The mouse cursor has been moved.
/// </summary>
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
if (_isDragging)
{
//
// Raise the event to notify that dragging is in progress.
//
var curMousePoint = e.GetPosition(ParentNetworkView);
var offset = curMousePoint - _lastMousePoint;
if (Math.Abs(offset.X) > Epsilon &&
Math.Abs(offset.Y) > Epsilon)
{
_lastMousePoint = curMousePoint;
RaiseEvent(new ConnectorItemDraggingEventArgs(ConnectorDraggingEvent, this, offset.X, offset.Y));
}
e.Handled = true;
}
else if (_isLeftMouseDown)
{
if (ParentNetworkView != null &&
ParentNetworkView.EnableConnectionDragging)
{
//
// The user is left-dragging the connector and connection dragging is enabled,
// but don't initiate the drag operation until
// the mouse cursor has moved more than the threshold distance.
//
var curMousePoint = e.GetPosition(ParentNetworkView);
var dragDelta = curMousePoint - _lastMousePoint;
var 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.
//
var eventArgs = new ConnectorItemDragStartedEventArgs(ConnectorDragStartedEvent, this);
RaiseEvent(eventArgs);
if (eventArgs.Cancel)
{
//
// Handler of the event disallowed dragging of the node.
//
_isLeftMouseDown = false;
return;
}
_isDragging = true;
CaptureMouse();
e.Handled = true;
}
}
}
}
