/// <summary>
/// Utility method to delete a connection from the view-model.
/// </summary>
public void DeleteConnection(ConnectionViewModel connection)
{
this.Network.Connections.Remove(connection);
}
/// <summary>
/// Called as the user continues to drag the connection.
/// </summary>
public void ConnectionDragging(Point curDragPoint, ConnectionViewModel connection)
{
if (connection.DestConnector == null)
{
connection.DestConnectorHotspot = curDragPoint;
}
else
{
connection.SourceConnectorHotspot = curDragPoint;
}
}
/// <summary>
/// Called when the user has started to drag out a connector, thus creating a new connection.
/// </summary>
public ConnectionViewModel ConnectionDragStarted(ConnectorViewModel draggedOutConnector, Point curDragPoint)
{
//
// Create a new connection to add to the view-model.
//
var connection = new ConnectionViewModel();
if (draggedOutConnector.Type == ConnectorType.Output)
{
//
// The user is dragging out a source connector (an output) and will connect it to a destination connector (an input).
//
connection.SourceConnector = draggedOutConnector;
connection.DestConnectorHotspot = curDragPoint;
}
else
{
//
// The user is dragging out a destination connector (an input) and will connect it to a source connector (an output).
//
connection.DestConnector = draggedOutConnector;
connection.SourceConnectorHotspot = curDragPoint;
}
//
// Add the new connection to the view-model.
//
this.Network.Connections.Add(connection);
return connection;
}
/// <summary>
/// Called when the user has finished dragging out the new connection.
/// </summary>
public void ConnectionDragCompleted(ConnectionViewModel newConnection, ConnectorViewModel connectorDraggedOut, ConnectorViewModel connectorDraggedOver)
{
if (connectorDraggedOver == null)
{
//
// The connection was unsuccessful.
// Maybe the user dragged it out and dropped it in empty space.
//
this.Network.Connections.Remove(newConnection);
return;
}
//
// Only allow connections from output connector to input connector (ie each
// connector must have a different type).
// Also only allocation from one node to another, never one node back to the same node.
//
bool connectionOk = connectorDraggedOut.ParentNode != connectorDraggedOver.ParentNode &&
connectorDraggedOut.Type != connectorDraggedOver.Type;
if (!connectionOk)
{
//
// Connections between connectors that have the same type,
// eg input -> input or output -> output, are not allowed,
// Remove the connection.
//
this.Network.Connections.Remove(newConnection);
return;
}
//
// The user has dragged the connection on top of another valid connector.
//
//
// Remove any existing connection between the same two connectors.
//
var existingConnection = FindConnection(connectorDraggedOut, connectorDraggedOver);
if (existingConnection != null)
{
this.Network.Connections.Remove(existingConnection);
}
//
// Finalize the connection by attaching it to the connector
// that the user dragged the mouse over.
//
if (newConnection.DestConnector == null)
{
newConnection.DestConnector = connectorDraggedOver;
}
else
{
newConnection.SourceConnector = connectorDraggedOver;
}
}
