Class Graph2DUndoManager provides undo/redo support for Graph2D changes of both structural and graphical nature. It implements the interfaces GraphListener and Graph2D.BackupRealizersHandler, and is accordingly registered twice with a Graph2D object.

Figure 6.54. Class complex around undo/redo functionality

For graphical changes Graph2DUndoManager relies on the correct replication behavior of realizers since the actual undo mechanism keeps backup copies of all node and edge realizers that are associated with modified or even deleted graph elements.

To reduce the number of actual undo/redo steps, sequences of graph changes can be grouped into single undo/redo commands. So-called pre-event and post-event commands provided by class GraphEvent serve as special bracketing indicators. Class Graph offers direct support to insert these commands into the undo/redo history, see the methods listed in API Excerpt 6.67, “Support for undo/redo history bracketing”.

// Open the bracket, i.e., insert a pre-event command into the undo/redo 
// history. 
// The subsequent commands present a single undo/redo step. 
firePreEvent()
// Close the bracket, i.e., insert a post-event command into the undo/redo 
// history. 
firePostEvent()

Graph2DUndoManager has getter methods that return complete Swing Actions for integration of both undo and redo operations into an application's context.

UndoRedoDemo.java is a tutorial demo that shows the yFiles support for undo/redo functionality in an application context.

Class Graph2DClipboard provides clipboard functionality for Graph2D objects. The clipboard can be used to create a copy of selected parts of a Graph2D instance, and can also be used to paste a previously copied subgraph back into a graph again.

Figure 6.55. Clipboard classes hierarchy

Graph2DClipboard provides Swing Actions that encapsulate all necessary clipboard functionality, namely the three operations cut, copy, and paste. Copies of graph elements are created by means of a GraphFactory object. By default, this factory is an instance of class Graph2DCopyFactory.

Graph hierarchies, i.e., graphs with an associated HierarchyManager object, use a specialized clipboard variant, class Graph2DHierarchyClipboard. It supports copy and paste functionality for grouped nodes and nested graph structures in a consistent manner.

ClipboardDemo.java is a tutorial demo that shows the yFiles clipboard functionality in an application context.

Class LayoutMorpher is an implementation of the general animation concept defined by interface AnimationObject. It generates a smooth animation that shows a graph's transformation from one layout to another. To this end class LayoutMorpher utilizes an object of type GraphLayout that is expected to hold positional information for all graph elements from the original graph which is displayed by the associated Graph2DView.

Figure 6.56. Usage relations for class LayoutMorpher

LayoutMorpher provides methods to optionally animate changes in the viewport's clipping and zoom level, or to end the animation with a specific node being in the center of the view. To start the generated animation method execute() has to be called.

Note that the calculated animation highlights changes in the locations of nodes and the locations of control points of edges. In contrast, changes in width or height of any node are not animated.