GraphEditorInputMode directly supports grouping and ungrouping of selected nodes using keyboard shortcuts. The GroupSelectionAllowed and UngroupSelectionAllowed properties can be used to enable or disable these shortcuts.

Additionally, whether re-parenting of nodes is allowed in a grouped graph can be easily enabled or disabled by means of the ReparentNodesAllowed property. Fine-grained control over re-parenting, depending, for example, on the involved node to be re-parented and its new group node, can be achieved by setting a custom implementation of interface IReparentNodeHandler with the ReparentNodeHandler property.

Example 3.9, “Customizing the re-parenting gesture” illustrates an IMapper-based scheme of a custom re-parenting gesture.

protected virtual IInputMode CreateEditorMode(IGraph graph) {
  return new GraphEditorInputMode {
      ReparentNodeHandler = new MyReparentNodeHandler()
  };
}

public class MyReparentNodeHandler : ReparentNodeHandler {
  // Only re-parent, if the new group node allows so.
  public override bool IsValidParent(IInputModeContext context,
                                     INode node, INode newParent) {
    var graph = context.GetGraph();
    if (graph != null) {
      var validReparentTarget =
          graph.MapperRegistry.GetMapper<INode, bool>("validReparentTarget");
      if (validReparentTarget != null) {
        return validReparentTarget.GetValue(newParent);
      }
    }
    return false;
  }
}

By default, GraphEditorInputMode allows re-parenting of all nodes in a grouped graph. It recognizes the re-parenting mouse gesture when the Control key is pressed while moving nodes.

Class NavigationInputMode supports collapsing and expanding of selected group nodes in a folding-enabled graph via routed commands. The CollapsingGroupsAllowed and ExpandingGroupsAllowed properties can be used to enable or disable these commands.

NavigationInputMode furthermore provides convenient access to IFoldedGraph's functionality for collapsing or expanding group nodes by means of the following methods:

void CollapseGroup(INode groupNode)
void ExpandGroup(INode groupNode)

Collapsing and expanding can also be controlled on a per-group node basis by overriding the following predicate methods:

protected virtual bool ShouldCollapseGroup(INode groupNode)
protected virtual bool ShouldExpandGroup(INode groupNode)

Navigation in a hierarchy, i.e., entering group nodes or exiting the current group node, is supported by NavigationInputMode through routed commands also. The EnteringGroupsAllowed and ExitingGroupAllowed properties can be used to enable or disable these navigation facilities.

Controlling navigation on a per-group node basis can be achieved by using the following methods. In particular, for complete customization of the behavior, the predicate methods can be easily overridden.

void EnterGroup(INode groupNode)
void ExitGroup()

protected virtual bool ShouldEnterGroup(INode groupNode)
protected virtual bool ShouldExitGroup()

GraphCommands provides a number of graph hierarchy-related commands that can be used for command binding. Note that all commands are of type RoutedUICommand.

Note that commands that support a command parameter allow to specify a group node (or a set of group nodes) to be used instead of the current selection.

By default, these commands are used for command binding by class GraphEditorInputMode which binds them upon installation.