RadDiagramThumbnail Does Not Update For Node Visibility Changes

[Michael]

I am using the RadDiagramThumbnail to show a thumbnail overview of the diagram, how it is implemented is very much like the example in the documentation for the DiagramNavigationPane (i.e. not a complicated or custom implementation).  Associated with the diagram is a treeview control by which the user can show/hide nodes by checking/unchecking in the tree (again, not too complicated I just have a node view model property bound to each node's Visibility property).  But I have noticed the following behavior with the RadDiagramThumbnail pane:

If the thumbnail/navigation pane is open and the user moves a node in the diagram, the thumbnail will update, but if the user change's a nodes visibility (e.g. collapses one or more nodes), then the thumbnail does not update.  If nodes in the diagram are moved after a visibility change, then the thumbnail will update accordingly.

How do I enable the thumbnail view to update when a node's visibility has been changed?

Thanks,

Mike

[Martin Ivanov]

Hi Michael,

In order to achieve the desired effect you can use the RadDiagramNaigationPane's RefreshThumbnail() method when you change the visibility. 

this.navigationPane.RefreshThumbnail();

Please let me know if you need any further assistance.

Regards,
Martin
Telerik

[Michael]

Martin,

Thanks for the answer, now I just have a few questions on how to implement it in my solution.  I am using an MVVM approach with the diagram.GraphSource bound to a object that inherits from ObservableGraphSourceBase.  Since I want to keep the view model as de-coupled as possible, I have been trying to attach event handlers to the shapes and connections and watch for a change in the Visibility property:

//this is from the code behind file
public BT()
{
  InitializeComponent();

  diagram.GraphSourceChanged += new EventHandler(diagram_GraphSourceChanged);
  DataContext = new BTViewModel(new ClientServiceProvider());
}

void diagram_GraphSourceChanged(object sender, EventArgs e)
{
  foreach(var shape in diagram.Shapes)
    shape.PropertyChanged += shape_PropertyChanged;
  foreach (var conn in diagram.Connections)
    conn.PropertyChanged += connection_PropertyChanged;
}

void shape_PropertyChanged(object sender, PropertyEventArgs e)
{
  if (string.Compare(e.PropertyName, "Visibility")==0 && navigationPane.Visibility == Visibility.Visible)
    navigationPane.RefreshThumbnail();
}

void connection_PropertyChanged(object sender, PropertyEventArgs e)
{
  if (string.Compare(e.PropertyName, "Visibility") == 0 && navigationPane.Visibility == Visibility.Visible)
    navigationPane.RefreshThumbnail();
}

But, when a shape or connection has it's Visibility property changed, the PropertyChanged event is not fired and neither of the navigationPane.RefreshThumbnail() lines in the example above get called.  I did notice that when a shape is moved, the navigationPane does get refreshed and shows and updated view of the Diagram.  Is there a way I can get the default implementation of RadDiagramShape and RadDiagramConnection to fire the PropertyChanged event when Visibility is changed?  Or should I inherit from them to override the Visibility property (but in doing this I am not sure what other implications overriding Visibility would have):

 

public class RadDiagramResourceShape : RadDiagramShape
{
  public new Visibility Visibility
  {
    get
    {
      return base.Visibility;
    }
    set
    {
      if (base.Visibility != value)
      {
        base.Visibility = value;
        base.OnPropertyChanged("Visibility");
      }
    }
  }
}

public class RadDiagramRelationConnection : RadDiagramConnection
{
  public new Visibility Visibility
  {
    get
    {
      return base.Visibility;
    }
    set
    {
      if (base.Visibility != value)
      {
        base.Visibility = value;
        base.OnPropertyChanged("Visibility");
      }
    }
  }
}

 

Any advice is much appreciated!

 

Mike

[Martin Ivanov]

Hi Michael,

Instead of subscribing for the PropertyChanged of the shapes and connection you can use the PropertyChanged event of their view models. Here is an example:

void diagram_GraphSourceChanged(object sender, EventArgs e)
{
    var source = diagram.GraphSource as MyGraphSource;
    foreach(var node in source.InternalItems)
        node.PropertyChanged += node_PropertyChanged;
    foreach (var conn in source.InternalLinks)
        conn.PropertyChanged += link_PropertyChanged;
}

Please try this and let me know if it works for you.

Regards,
Martin
Telerik