Hi

Following is a snippet from an exception that is occurring from time to time during node resize or link creation / movement. We've yet to create full reproduction code, as we can't find a flawless trigger, but thought we'd raised it so you folks are aware of it.

Thanks


Paul


"Object reference not set to an instance of an object."
at MindFusion.Diagramming.Wpf.InteractionState.IsAllowed(Point point)
at MindFusion.Diagramming.Wpf.Behaviors.BehaviorBase.OnMouseUp(Point mousePosition, MouseButton mouseButton)
at MindFusion.Diagramming.Wpf.Diagram.x355258a28dc3da25(MouseButtonEventArgs xfbf34718e704c6bc, Point xb30c565aa19aece6)
at MindFusion.Diagramming.Wpf.Diagram.OnPreviewMouseUp(MouseButtonEventArgs e)
at System.Windows.UIElement.OnPreviewMouseUpThunk(Object sender, MouseButtonEventArgs e)
at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
at System.Windows.Input.InputManager.ProcessStagingArea()
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)

We have code in NodeModifying but it does not call CancelDrag (does very little in fact) - we are calling CancelDrag on NodeCreating though.

Thanks


Paul

We are using the lastest released version (that we're aware of) : 2.2.0.25609

We are not setting any diagram behaviour explicitly - we just use the things like disallowing self loops etc.

Hi sorry for the usual delay in my replies.

Diagram creation XAML is;
<MF:Diagram x:Name="oHypothesisDiagram" ZoomFactor="100" Width="Auto" Height="Auto" MeasureUnit="WpfPoint" Bounds="0,0,640,480" NodesExpandable="False" Background="{DynamicResource FlowBGBrush}" HorizontalAlignment="Left" VerticalAlignment="Top" AllowSelfLoops="False">
<MF:Diagram.LinkPen>
<Pen Brush="#FFFF7A08" Thickness="2"/>
</MF:Diagram.LinkPen>
</MF:Diagram>


c#;

oDiagram.NodeCreating += new NodeValidationEventHandler(oDiagram_NodeCreating);

oDiagram.LinkCreated += new LinkEventHandler(oDiagram_LinkCreated);
oDiagram.TreeCollapsed += new NodeEventHandler(oDiagram_TreeCollapsed);
oDiagram.TreeExpanded += new NodeEventHandler(oDiagram_TreeExpanded);
oDiagram.NodeModified += new NodeEventHandler(oDiagram_NodeModified);
oDiagram.LinkDeleted += new LinkEventHandler(oDiagram_LinkDeleted);
oDiagram.Background = new SolidColorBrush(Colors.Transparent);
oDiagram.RecursiveExpand = true;
oDiagram.Clicked += new DiagramEventHandler(oDiagram_Clicked);
oDiagram.NodeDeleted += new NodeEventHandler(oDiagram_NodeDeleted);
oDiagram.NodeModifying += new NodeValidationEventHandler(oDiagram_NodeModifying);
oDiagram.DragEnter += new DragEventHandler(oDiagram_DragEnter);
oDiagram.Drop += new DragEventHandler(oDiagram_Drop);
oDiagram.NodeDeleting += new NodeValidationEventHandler(oDiagram_NodeDeleting);

//' Replace clipboard related keyboard command bindings to prevent crashes
oDiagram.CommandBindings.Add(new CommandBinding(ApplicationCommands.Copy, (sender, args) => { DiagramCopy(sender, args); }));
oDiagram.CommandBindings.Add(new CommandBinding(ApplicationCommands.Cut, (sender, args) => { DiagramCut(sender, args); }));

Hi,

Unfortunately we can't save the diagram xml as we don't have serialisation working properly yet.

Our NodeCreating event calls CancelDrag in order to prevent users from drawing empty nodes on the diagram:

void oHypothesisDiagram_NodeCreating(object sender, NodeValidationEventArgs e)
{
    e.CancelDrag();
} 

I've just tried removing e.CancelDrag(); and without it, I no longer seem to be getting this error in places where I can normally replicate it. The problem is, it is then possible to draw nodes - is there another way to prevent the user doing this?

NodeModifying is not being used. Although we are using diagram.Items.Remove in a number of places, as far as I am aware none of them are called from user interaction.

Anthony (working on the same project)

It looks as though setting Behaviour = DrawLinks and removing CancelDrag from NodeCreating has fixed our problem.

Thanks for your help!