editor.undo

Class AtomicUndoManager

java.lang.Object

javax.swing.undo.AbstractUndoableEdit

javax.swing.undo.CompoundEdit

javax.swing.undo.UndoManager

editor.undo.AtomicUndoManager

All Implemented Interfaces:

Serializable, EventListener, UndoableEditListener, UndoableEdit

public class AtomicUndoManager
extends UndoManager

This class extends UndoManager providing nested atomic (or scoped) undo/redo operations. Note undo/redo operations are captured in StateEditable implementations.

A generic application of this class follows:

 ...
 _undoMgr = new AtomicUndoManager( 1000 );
 ...
 //
 // This method decorates a typical change operation with undo/redo capability.
 // Notice the XXXOperationUndoItem class.  You'll need to create one of these
 // for each undo operation.  Basically these UndoItem classes are extensions
 // of StateEditable.  They are responsible for capturing the state
 // before and after an operation and also for restoring the state as directed
 // by this undo manager.
 //
 void performUndoableXXXOperation( ... )
 {
   XXXOperationUndoItem undoItem = new XXXOperationUndoItem( ... );
   StateEdit transaction = new StateEdit( undoItem, "XXX Operation" );

   performXXXOperation( ... );

   transaction.end();
   _undoMgr.addEdit( transaction );
 }

 // Your typical change operation.
 void performXXXOperation( ... )
 {
   // do whatever it is you do...
 }

 //
 // This method exercises the atomic and nested features of AtomicUndoManager.
 // The atomic boundaries should be enforced with the try/finally idiom so
 // a failed atomic operation can be safely (and optionally) "rolled back".
 //
 void performUndoableZZZOperation
 {
   try
   {
     _undoMgr.beginUndoAtom( "ZZZ Operation" );

     performUndoableXXXOperation( ... );
     performUndoableYYYOperation( ... );
     ...
   }
   finally
   {
     _undoMgr.endUndoAtom();
   }
 }


 //
 // Create ui components using Actions such as these:
 //
 class UndoAction extends AbstractAction
 {
   UndoAction( String strName, Icon icon )
   {
     super( strName, icon );
   }

   public void actionPerformed( ActionEvent e )
   {
     _undoMgr.undo();
   }

   public boolean isEnabled()
   {
     return _undoMgr.canUndo();
   }
 }

 class RedoAction extends AbstractAction
 {
   RedoAction( String strName, Icon icon )
   {
     super( strName, icon );
   }

   public void actionPerformed( ActionEvent e )
   {
     _undoMgr.redo();
   }

   public boolean isEnabled()
   {
     return _undoMgr.canRedo();
   }
 }

See Also:

Serialized Form

Field Summary

Fields inherited from class javax.swing.undo.CompoundEdit

edits

Fields inherited from class javax.swing.undo.AbstractUndoableEdit

RedoName, UndoName

Constructor Summary

Constructors

Constructor and Description
AtomicUndoManager() An AtomicUndoManager with a default limit of 1000 edits.
AtomicUndoManager(int iUndoLimit)

Method Summary

Modifier and Type	Method and Description
void	addChangeListener(ChangeListener listener)
boolean	addEdit(UndoableEdit edit)
void	beginUndoAtom() Begin an atomic undo boundary.
CompoundEdit	beginUndoAtom(String strDisplayName) Begin an atomic undo boundary.
void	discardAllEdits()
void	endUndoAtom() Ends the active atomic undo boundary.
void	endUndoAtom(CompoundEdit undoAtom)
long	getLastUndoTime()
editor.undo.AtomicUndoManager.DisplayableCompoundEdit	getUndoAtom()
boolean	isPaused()
void	recordChange(StateEditable change) Utility method that records a change that can be undone/redone.
void	redo()
protected void	redoTo(UndoableEdit edit)
void	removeChangeListener(ChangeListener listener)
void	removeEdit(UndoableEdit edit)
void	setPaused(boolean bPaused) Sets the paused state of the undo manager.
void	undo()
void	undoOrRedo()
protected void	undoTo(UndoableEdit edit)

Methods inherited from class javax.swing.undo.UndoManager

canRedo, canUndo, canUndoOrRedo, editToBeRedone, editToBeUndone, end, getLimit, getRedoPresentationName, getUndoOrRedoPresentationName, getUndoPresentationName, setLimit, toString, trimEdits, trimForLimit, undoableEditHappened

Methods inherited from class javax.swing.undo.CompoundEdit

die, getPresentationName, isInProgress, isSignificant, lastEdit

Methods inherited from class javax.swing.undo.AbstractUndoableEdit

replaceEdit

Methods inherited from class java.lang.Object

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

Constructor Detail

AtomicUndoManager

public AtomicUndoManager()

An AtomicUndoManager with a default limit of 1000 edits.

AtomicUndoManager

public AtomicUndoManager(int iUndoLimit)

Parameters:

iUndoLimit - The maximum number of edits this undo manager will hold.

Method Detail

isPaused

public boolean isPaused()

Returns:

Is this undo manager in a Paused state? i.e., are edits being ignored?

setPaused

public void setPaused(boolean bPaused)

Sets the paused state of the undo manager. If paused, undo operations are ignored

Parameters:

bPaused - The paused state.

addEdit

public boolean addEdit(UndoableEdit edit)

Specified by:

addEdit in interface UndoableEdit

Overrides:

addEdit in class UndoManager

Parameters:

edit - The edit to be added. Note nested edits are supported.

removeEdit

public void removeEdit(UndoableEdit edit)

Parameters:

edit - The edit to be removed.

discardAllEdits

public void discardAllEdits()

Overrides:

discardAllEdits in class UndoManager

beginUndoAtom

public void beginUndoAtom()

Begin an atomic undo boundary. Edits added to this undo mananger after this call are considered "subatomic" -- they become part of the atom defined by the boundary. The atom's boundary ends with a call to endUndoAtom().

Note undo atoms can contain other undo atoms allowing for unlimited nesting of atomic undo operations.

beginUndoAtom

public CompoundEdit beginUndoAtom(String strDisplayName)

Begin an atomic undo boundary. Edits added to this undo mananger after this call are considered "subatomic" -- they become part of the atom defined by the boundary. The atom's boundary ends with a call to endUndoAtom().

Note undo atoms can contain other undo atoms allowing for unlimited nesting of atomic undo operations.

Parameters:

strDisplayName - The name associated with the undo atom. A user interface typically displays this name in Undo/Redo menu items or toolbar button text.

See Also:

UndoManager.getUndoPresentationName()

endUndoAtom

public void endUndoAtom()

Ends the active atomic undo boundary.

See Also:

beginUndoAtom()

endUndoAtom

public void endUndoAtom(CompoundEdit undoAtom)

getUndoAtom

public editor.undo.AtomicUndoManager.DisplayableCompoundEdit getUndoAtom()

Returns:

The undo atom currently in progress.

redo

public void redo()
          throws CannotRedoException

Specified by:

redo in interface UndoableEdit

Overrides:

redo in class UndoManager

Throws:

CannotRedoException

undo

public void undo()
          throws CannotUndoException

Specified by:

undo in interface UndoableEdit

Overrides:

undo in class UndoManager

Throws:

CannotUndoException

getLastUndoTime

public long getLastUndoTime()

undoOrRedo

public void undoOrRedo()
                throws CannotRedoException,
                       CannotUndoException

Overrides:

undoOrRedo in class UndoManager

Throws:

CannotRedoException

CannotUndoException

undoTo

protected void undoTo(UndoableEdit edit)
               throws CannotUndoException

Overrides:

undoTo in class UndoManager

Throws:

CannotUndoException

redoTo

protected void redoTo(UndoableEdit edit)
               throws CannotRedoException

Overrides:

redoTo in class UndoManager

Throws:

CannotRedoException

addChangeListener

public void addChangeListener(ChangeListener listener)

removeChangeListener

public void removeChangeListener(ChangeListener listener)

recordChange

public void recordChange(StateEditable change)

Utility method that records a change that can be undone/redone.