/*
* Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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*/
package javax.swing.undo;
import javax.swing.event.*;
import java.util.*;
/**
* A support class used for managing <code>UndoableEdit</code> listeners.
*
* @author Ray Ryan
*/
public class
UndoableEditSupport {
protected int
updateLevel;
protected
CompoundEdit compoundEdit;
protected
Vector<
UndoableEditListener>
listeners;
protected
Object realSource;
/**
* Constructs an <code>UndoableEditSupport</code> object.
*/
public
UndoableEditSupport() {
this(null);
}
/**
* Constructs an <code>UndoableEditSupport</code> object.
*
* @param r an <code>Object</code>
*/
public
UndoableEditSupport(
Object r) {
realSource =
r == null ? this :
r;
updateLevel = 0;
compoundEdit = null;
listeners = new
Vector<
UndoableEditListener>();
}
/**
* Registers an <code>UndoableEditListener</code>.
* The listener is notified whenever an edit occurs which can be undone.
*
* @param l an <code>UndoableEditListener</code> object
* @see #removeUndoableEditListener
*/
public synchronized void
addUndoableEditListener(
UndoableEditListener l) {
listeners.
addElement(
l);
}
/**
* Removes an <code>UndoableEditListener</code>.
*
* @param l the <code>UndoableEditListener</code> object to be removed
* @see #addUndoableEditListener
*/
public synchronized void
removeUndoableEditListener(
UndoableEditListener l)
{
listeners.
removeElement(
l);
}
/**
* Returns an array of all the <code>UndoableEditListener</code>s added
* to this UndoableEditSupport with addUndoableEditListener().
*
* @return all of the <code>UndoableEditListener</code>s added or an empty
* array if no listeners have been added
* @since 1.4
*/
public synchronized
UndoableEditListener[]
getUndoableEditListeners() {
return
listeners.
toArray(new
UndoableEditListener[0]);
}
/**
* Called only from <code>postEdit</code> and <code>endUpdate</code>. Calls
* <code>undoableEditHappened</code> in all listeners. No synchronization
* is performed here, since the two calling methods are synchronized.
*/
protected void
_postEdit(
UndoableEdit e) {
UndoableEditEvent ev = new
UndoableEditEvent(
realSource,
e);
Enumeration cursor = ((
Vector)
listeners.
clone()).
elements();
while (
cursor.
hasMoreElements()) {
((
UndoableEditListener)
cursor.
nextElement()).
undoableEditHappened(
ev);
}
}
/**
* DEADLOCK WARNING: Calling this method may call
* <code>undoableEditHappened</code> in all listeners.
* It is unwise to call this method from one of its listeners.
*/
public synchronized void
postEdit(
UndoableEdit e) {
if (
updateLevel == 0) {
_postEdit(
e);
} else {
// PENDING(rjrjr) Throw an exception if this fails?
compoundEdit.
addEdit(
e);
}
}
/**
* Returns the update level value.
*
* @return an integer representing the update level
*/
public int
getUpdateLevel() {
return
updateLevel;
}
/**
*
*/
public synchronized void
beginUpdate() {
if (
updateLevel == 0) {
compoundEdit =
createCompoundEdit();
}
updateLevel++;
}
/**
* Called only from <code>beginUpdate</code>.
* Exposed here for subclasses' use.
*/
protected
CompoundEdit createCompoundEdit() {
return new
CompoundEdit();
}
/**
* DEADLOCK WARNING: Calling this method may call
* <code>undoableEditHappened</code> in all listeners.
* It is unwise to call this method from one of its listeners.
*/
public synchronized void
endUpdate() {
updateLevel--;
if (
updateLevel == 0) {
compoundEdit.
end();
_postEdit(
compoundEdit);
compoundEdit = null;
}
}
/**
* Returns a string that displays and identifies this
* object's properties.
*
* @return a <code>String</code> representation of this object
*/
public
String toString() {
return super.toString() +
" updateLevel: " +
updateLevel +
" listeners: " +
listeners +
" compoundEdit: " +
compoundEdit;
}
}