/*******************************************************************************
* Copyright (c) 2005 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.bpel.common.ui.details;
import org.eclipse.bpel.common.ui.command.ICommandFramework;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.CCombo;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Text;
/**
* An abstract IOngoingChange that is also a Listener. ChangeHelper notifies the
* details area of IOngoingChange lifecycle events on behalf of the widget(s) it
* listens to.
*/
public abstract class ChangeHelper implements IOngoingChange, Listener {
protected ICommandFramework fCommandFramework;
protected int fNonUserChange = 0;
/**
* Marks the start of a programmatic change to the widget contents. Clients must
* call startNonUserChange() before directly setting the widget contents to avoid
* unwanted IOngoingChange lifecycle events. (Only some widgets/viewers will send the
* unwanted notifications, but all clients should use this pattern anyway).
* Currently, changes may not be nested.
*
*/
public void startNonUserChange() {
fNonUserChange += 1;
}
/**
* Clients who call startNonUserChange() should call finishNonUserChange() as soon
* as possible after the change is done.
*
* @throws IllegalArgumentException if no change is in progress.
*/
@SuppressWarnings("nls")
public void finishNonUserChange() {
if (fNonUserChange == 0) {
throw new IllegalStateException("Non-matching call to finishNonUserChange()") ;
}
fNonUserChange -= 1;
}
/**
* @return true if a programmatic change is in progress.
*/
public boolean isNonUserChange() {
return fNonUserChange > 0;
}
/**
*
* @param commandFramework
*/
public ChangeHelper (ICommandFramework commandFramework) {
fCommandFramework = commandFramework;
}
/**
* @see org.eclipse.swt.widgets.Listener#handleEvent(org.eclipse.swt.widgets.Event)
*/
public void handleEvent(Event event) {
if (isNonUserChange()) {
return ;
}
switch (event.type) {
case SWT.KeyDown:
if (event.character == SWT.CR) {
finish();
}
break;
case SWT.FocusOut:
finish();
break;
case SWT.Modify:
case SWT.Selection:
case SWT.DefaultSelection:
modify();
break;
case SWT.Dispose :
abort();
break;
}
}
/**
*
*/
void finish() {
fCommandFramework.notifyChangeDone(this);
}
/**
*
*/
void modify() {
fCommandFramework.notifyChangeInProgress(this);
}
void abort () {
fCommandFramework.abortCurrentChange();
}
protected boolean isModifyBasedControl(Control c) {
if (c instanceof CCombo) {
return (c.getStyle() & SWT.READ_ONLY) == 0; // if not read only
}
return (c instanceof Text);
}
protected boolean isSelectionBasedControl(Control c) {
return !(c instanceof Text);
}
/**
* Registers this ChangeHelper with the given control to listen for events
* which indicate that a change is in progress (or done).
*
* @param controls
*/
public void startListeningTo (Control ... controls ) {
for (Control control : controls) {
control.addListener(SWT.FocusOut, this);
control.addListener(SWT.Dispose, this);
if (isModifyBasedControl(control)) {
control.addListener(SWT.Modify, this);
}
if (isSelectionBasedControl(control)) {
control.addListener(SWT.Selection, this);
control.addListener(SWT.DefaultSelection, this);
}
}
}
/**
* Registers this ChangeHelper with the given control to listen for the
* Enter key. When Enter is pressed, the change is considered done (this
* is appropriate for single-line Text widgets).
* @param controls
*/
public void startListeningForEnter (Control ... controls) {
// NOTE: KeyDown rather than KeyUp, because of similar usage in CCombo.
for(Control control : controls) {
control.addListener(SWT.KeyDown, this);
}
}
/**
* Unregisters this ChangeHelper from a control previously passed to
* startListeningTo() and/or startListeningForEnter().
* @param controls
*/
public void stopListeningTo (Control ...controls ) {
for(Control control : controls) {
control.removeListener(SWT.FocusOut, this);
if (isModifyBasedControl(control)) {
control.removeListener(SWT.Modify, this);
}
if (isSelectionBasedControl(control)) {
control.removeListener(SWT.Selection, this);
control.removeListener(SWT.DefaultSelection, this);
}
control.removeListener(SWT.KeyDown, this);
}
}
}