import java.awt.event.actionevent;

import javax.swing.abstractaction;

import javax.swing.action;

import javax.swing.jeditorpane;

import javax.swing.keystroke;

import javax.swing.event.undoableeditevent;

import javax.swing.event.undoableeditlistener;

import javax.swing.text.jtextcomponent;

import javax.swing.undo.cannotredoexception;

import javax.swing.undo.cannotundoexception;

import javax.swing.undo.undomanager;
/**

* undowrapper is responsible for adding undo and redo support to text components.

* @author antonio vieiro (antonio@antonioshome.net), $author: $

* @version $revision: $

*/

public class undowrapper

implements undoableeditlistener

{

private undomanager undomanager;

private undoaction undoaction;

private redoaction redoaction;

private jeditorpane textcomponent;

/**

* creates a new instance of undowrapper

*/

public undowrapper( jeditorpane acomponent )

{

textcomponent = acomponent;

undomanager = new undomanager();

undoaction = new undoaction();

redoaction = new redoaction();

textcomponent.getdocument().addundoableeditlistener( this );

textcomponent.getinputmap().put( (keystroke) undoaction.getvalue( 

action.accelerator_key), "undo" );

textcomponent.getinputmap().put( (keystroke) redoaction.getvalue( 

action.accelerator_key), "redo" );

textcomponent.getactionmap().put( "undo", undoaction );

textcomponent.getactionmap().put( "redo", redoaction );

}

public void undoableedithappened(undoableeditevent e)

{

undomanager.addedit( e.getedit() );

undoaction.updateundostate();

redoaction.updateredostate();

}

/**

* undoaction is the action responsible for handling the undo operation.

*/

class undoaction

extends abstractaction

{

public undoaction()

{

super( "cannot undo" ); // todo: i18n

setenabled( false );

putvalue( action.accelerator_key, keystroke.getkeystroke("ctrl z") );

}

public void actionperformed(actionevent e)

{

try

{

undomanager.undo();

}

catch( cannotundoexception cue )

{

// todo: use logging?

cue.printstacktrace( system.err );

}

updateundostate();

redoaction.updateredostate();

}

void updateundostate()

{

if ( undomanager.canundo() )

{

setenabled( true );

putvalue( action.name, "undo" ); // todo i18n

}

else

{

setenabled( false );

putvalue( action.name, "cannot undo" );  // todo i18n

}

}

}

/**

* redoaction is the action responsible for handling the redo operation.

*/

class redoaction

extends abstractaction

{

public redoaction()

{

super( "cannot redo" );  // todo i18n

setenabled( false );

putvalue( action.accelerator_key, keystroke.getkeystroke("ctrl y") );

}

public void actionperformed(actionevent e)

{

try

{

undomanager.redo();

}

catch( cannotredoexception cre )

{

// todo: use logging?

cre.printstacktrace( system.err );

}

updateredostate();

undoaction.updateundostate();

}

void updateredostate()

{

if ( undomanager.canredo() )

{

setenabled( true );

putvalue( action.name, "redo" );  // todo i18n

}

else

{

setenabled( false );

putvalue( action.name, "cannot redo" );  // todo i18n

}

}

}

undoaction getundoaction()

{

return undoaction;

}

redoaction getredoaction()

{

return redoaction;

}

}

new undowrapper(editorpane);