/// <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>
/// Event raised when the user has finished dragging a connector.
/// </summary>
private void ConnectorItem_DragCompleted(object source, ConnectorItemDragCompletedEventArgs e)
{
e.Handled = true;
Trace.Assert((ConnectorItem)e.OriginalSource == _draggedOutConnectorItem);
var mousePoint = Mouse.GetPosition(this);
//
// Figure out if the end of the connection was dropped on a connector.
//
ConnectorItem connectorDraggedOver = null;
object connectorDataContextDraggedOver = null;
DetermineConnectorItemDraggedOver(mousePoint, out connectorDraggedOver, out connectorDataContextDraggedOver);
//
// Now that connection dragging has completed, don't any feedback adorner.
//
ClearFeedbackAdorner();
//
// Raise an event to inform application code that connection dragging is complete.
// The application code can determine if the connection between the two connectors
// is valid and if so it is free to make the appropriate connection in the view-model.
//
RaiseEvent(new ConnectionDragCompletedEventArgs(ConnectionDragCompletedEvent, this, _draggedOutNodeDataContext, _draggingConnectionDataContext, _draggedOutConnectorDataContext, connectorDataContextDraggedOver));
IsDragging = false;
IsNotDragging = true;
IsDraggingConnection = false;
IsNotDraggingConnection = true;
_draggedOutConnectorDataContext = null;
_draggedOutNodeDataContext = null;
_draggedOutConnectorItem = null;
_draggingConnectionDataContext = null;
}
/// <summary>
/// Event raised while the user is dragging a connector.
/// </summary>
private void ConnectorItem_Dragging(object source, ConnectorItemDraggingEventArgs e)
{
e.Handled = true;
Trace.Assert((ConnectorItem)e.OriginalSource == _draggedOutConnectorItem);
var mousePoint = Mouse.GetPosition(this);
//
// Raise an event so that application code can compute intermediate connection points.
//
var connectionDraggingEventArgs =
new ConnectionDraggingEventArgs(ConnectionDraggingEvent, this,
_draggedOutNodeDataContext, _draggingConnectionDataContext,
_draggedOutConnectorDataContext);
RaiseEvent(connectionDraggingEventArgs);
//
// Figure out if the connection has been dragged over a connector.
//
ConnectorItem connectorDraggedOver = null;
object connectorDataContextDraggedOver = null;
var dragOverSuccess = DetermineConnectorItemDraggedOver(mousePoint, out connectorDraggedOver, out connectorDataContextDraggedOver);
if (connectorDraggedOver != null)
{
//
// Raise an event so that application code can specify if the connector
// that was dragged over is valid or not.
//
var queryFeedbackEventArgs =
new QueryConnectionFeedbackEventArgs(QueryConnectionFeedbackEvent, this, _draggedOutNodeDataContext, _draggingConnectionDataContext,
_draggedOutConnectorDataContext, connectorDataContextDraggedOver);
RaiseEvent(queryFeedbackEventArgs);
if (queryFeedbackEventArgs.FeedbackIndicator != null)
{
//
// A feedback indicator was specified by the event handler.
// This is used to indicate whether the connection is good or bad!
//
AddFeedbackAdorner(connectorDraggedOver, queryFeedbackEventArgs.FeedbackIndicator);
}
else
{
//
// No feedback indicator specified by the event handler.
// Clear any existing feedback indicator.
//
ClearFeedbackAdorner();
}
}
else
{
//
// Didn't drag over any valid connector.
// Clear any existing feedback indicator.
//
ClearFeedbackAdorner();
}
}
/// <summary>
/// This function does a hit test to determine which connector, if any, is under 'hitPoint'.
/// </summary>
private bool DetermineConnectorItemDraggedOver(Point hitPoint, out ConnectorItem connectorItemDraggedOver, out object connectorDataContextDraggedOver)
{
connectorItemDraggedOver = null;
connectorDataContextDraggedOver = null;
//
// Run a hit test
//
HitTestResult result = null;
VisualTreeHelper.HitTest(_nodeItemsControl, null,
//
// Result callback delegate.
// This method is called when we have a result.
//
delegate(HitTestResult hitTestResult)
{
result = hitTestResult;
return(HitTestResultBehavior.Stop);
},
new PointHitTestParameters(hitPoint));
if (result == null || result.VisualHit == null)
{
// Hit test failed.
return(false);
}
//
// Actually want a reference to a 'ConnectorItem'.
// The hit test may have hit a UI element that is below 'ConnectorItem' so
// search up the tree.
//
var hitItem = result.VisualHit as FrameworkElement;
if (hitItem == null)
{
return(false);
}
var connectorItem = WpfUtils.FindVisualParentWithType <ConnectorItem>(hitItem);
if (connectorItem == null)
{
return(false);
}
var networkView = connectorItem.ParentNetworkView;
if (networkView != this)
{
//
// Ensure that dragging over a connector in another NetworkView doesn't
// return a positive result.
//
return(false);
}
object connectorDataContext = connectorItem;
if (connectorItem.DataContext != null)
{
//
// If there is a data-context then grab it.
// When we are using a view-model then it is the view-model
// object we are interested in.
//
connectorDataContext = connectorItem.DataContext;
}
connectorItemDraggedOver = connectorItem;
connectorDataContextDraggedOver = connectorDataContext;
return(true);
}
