/// <summary>
/// Event raised when the user starts to drag a connector.
/// </summary>
private void ExecutionConnectorItem_DragStarted(object source, ExecutionConnectorItemDragStartedEventArgs e)
{
this.Focus();
e.Handled = true;
this.IsDragging = true;
this.IsNotDragging = false;
this.IsDraggingExecutionConnection = true;
this.IsNotDraggingExecutionConnection = false;
this.draggedOutExecutionConnectorItem = (ExecutionConnectorItem)e.OriginalSource;
var nodeItem = this.draggedOutExecutionConnectorItem.ParentNodeItem;
this.draggedOutNodeDataContext = nodeItem.DataContext != null ? nodeItem.DataContext : nodeItem;
this.draggedOutExecutionConnectorDataContext = this.draggedOutExecutionConnectorItem.DataContext != null ? this.draggedOutExecutionConnectorItem.DataContext : this.draggedOutExecutionConnectorItem;
//
// Raise an event so that application code can create a connection and
// add it to the view-model.
//
ExecutionConnectionDragStartedEventArgs eventArgs = new ExecutionConnectionDragStartedEventArgs(ExecutionConnectionDragStartedEvent, this, this.draggedOutNodeDataContext, this.draggedOutExecutionConnectorDataContext);
RaiseEvent(eventArgs);
//
// Retrieve the the view-model object for the connection was created by application code.
//
this.draggingExecutionConnectionDataContext = eventArgs.ExecutionConnection;
if (draggingExecutionConnectionDataContext == null)
{
//
// Application code didn't create any connection.
//
e.Cancel = true;
return;
}
}
/// <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 == this.draggedOutConnectorItem);
Point 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, this.draggedOutNodeDataContext, this.draggingConnectionDataContext, this.draggedOutConnectorDataContext, connectorDataContextDraggedOver));
this.IsDragging = false;
this.IsNotDragging = true;
this.IsDraggingExecutionConnection = false;
this.IsDraggingConnection = false;
this.IsNotDraggingExecutionConnection = true;
this.IsNotDraggingConnection = true;
this.draggedOutExecutionConnectorDataContext = null;
this.draggedOutConnectorDataContext = null;
this.draggedOutNodeDataContext = null;
this.draggedOutExecutionConnectorItem = null;
this.draggedOutConnectorItem = null;
this.draggingExecutionConnectionDataContext = null;
this.draggingConnectionDataContext = null;
}
/// <summary>
/// This function does a hit test to determine which connector, if any, is under 'hitPoint'.
/// </summary>
private bool DetermineExecutionConnectorItemDraggedOver(Point hitPoint, out ExecutionConnectorItem executionConnectorItemDraggedOver, out object executionConnectorDataContextDraggedOver)
{
executionConnectorItemDraggedOver = null;
executionConnectorDataContextDraggedOver = 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 executionConnectorItem = WpfUtils.FindVisualParentWithType<ExecutionConnectorItem>(hitItem);
if (executionConnectorItem == null)
{
return false;
}
var networkView = executionConnectorItem.ParentNetworkView;
if (networkView != this)
{
//
// Ensure that dragging over a connector in another NetworkView doesn't
// return a positive result.
//
return false;
}
object executionConnectorDataContext = executionConnectorItem;
if (executionConnectorItem.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.
//
executionConnectorDataContext = executionConnectorItem.DataContext;
}
executionConnectorItemDraggedOver = executionConnectorItem;
executionConnectorDataContextDraggedOver = executionConnectorDataContext;
return true;
}
