com.mxgraph.util
Class mxUndoManager

java.lang.Object
  com.mxgraph.util.mxEventSource
      com.mxgraph.util.mxUndoManager

public class mxUndoManager
extends mxEventSource

Implements an undo history. This class fires the following events: mxEvent.CLEAR fires after clear was executed. The event has no properties. mxEvent.UNDO fires afer a significant edit was undone in undo. The edit property contains the mxUndoableEdit that was undone. mxEvent.REDO fires afer a significant edit was redone in redo. The edit property contains the mxUndoableEdit that was redone. mxEvent.ADD fires after an undoable edit was added to the history. The edit property contains the mxUndoableEdit that was added.

Nested Class Summary

Nested classes/interfaces inherited from class com.mxgraph.util.mxEventSource

mxEventSource.mxIEventListener

Field Summary

protected List<mxUndoableEdit>	history List that contains the steps of the command history.
protected int	indexOfNextAdd Index of the element to be added next.
protected int	size Maximum command history size.

Fields inherited from class com.mxgraph.util.mxEventSource

eventListeners, eventsEnabled, eventSource

Constructor Summary

mxUndoManager()
Constructs a new undo manager with a default history size.

mxUndoManager(int size)
Constructs a new undo manager for the specified size.

Method Summary

boolean	canRedo() Returns true if a redo is possible.
boolean	canUndo() Returns true if an undo is possible.
void	clear() Clears the command history.
boolean	isEmpty()
void	redo() Redoes the last change.
protected void	trim() Removes all pending steps after indexOfNextAdd from the history, invoking die on each edit.
void	undo() Undoes the last change.
void	undoableEditHappened(mxUndoableEdit undoableEdit) Method to be called to add new undoable edits to the history.

Methods inherited from class com.mxgraph.util.mxEventSource

addListener, fireEvent, fireEvent, getEventSource, isEventsEnabled, removeListener, removeListener, setEventsEnabled, setEventSource

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

size

protected int size

Maximum command history size. 0 means unlimited history. Default is 100.

history

protected List<mxUndoableEdit> history

List that contains the steps of the command history.

indexOfNextAdd

protected int indexOfNextAdd

Index of the element to be added next.

Constructor Detail

mxUndoManager

public mxUndoManager()

Constructs a new undo manager with a default history size.

mxUndoManager

public mxUndoManager(int size)

Constructs a new undo manager for the specified size.

Method Detail

isEmpty

public boolean isEmpty()

clear

public void clear()

Clears the command history.

canUndo

public boolean canUndo()

Returns true if an undo is possible.

undo

public void undo()

Undoes the last change.

canRedo

public boolean canRedo()

Returns true if a redo is possible.

redo

public void redo()

Redoes the last change.

undoableEditHappened

public void undoableEditHappened(mxUndoableEdit undoableEdit)

Method to be called to add new undoable edits to the history.

trim

protected void trim()

Removes all pending steps after indexOfNextAdd from the history, invoking die on each edit. This is called from undoableEditHappened.