ResetValueCommand.java

/*******************************************************************************
 * Copyright (c) 2000, 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.gef.ui.properties;

import org.eclipse.ui.views.properties.IPropertySource;
import org.eclipse.ui.views.properties.IPropertySource2;

import org.eclipse.gef.commands.Command;
import org.eclipse.gef.internal.GEFMessages;

/**
 * A Command used to restore the default value of a property.
 * @author Pratik Shah
 */
class ResetValueCommand 
	extends Command 
{

/** the property that has to be reset */
protected Object propertyName;
/** the current non-default value of the property */
protected Object undoValue;
/** the property source whose property has to be reset */
protected IPropertySource target;

/**
 * Default Constructor: Sets the label for the Command
 * @since 3.1
 */
public ResetValueCommand() {
	super(GEFMessages.RestoreDefaultValueCommand_Label);
}

/**
 * Returns <code>true</code> IFF:<br>
 * 1) the target and property have been specified<br>
 * 2) the property has a default value<br>
 * 3) the value set for that property is not the default
 * @see org.eclipse.gef.commands.Command#canExecute()
 */
public boolean canExecute() {
	boolean answer = false;
	if (target != null && propertyName != null) {
		answer = target.isPropertySet(propertyName);
		if (target instanceof IPropertySource2)
			answer = answer 
					&& (((IPropertySource2)target).isPropertyResettable(propertyName));
	}
	return answer;
}

/**
 * Caches the undo value and invokes redo()
 * @see org.eclipse.gef.commands.Command#execute()
 */
public void execute() {
	undoValue = target.getPropertyValue(propertyName);
	if (undoValue instanceof IPropertySource)
		undoValue = ((IPropertySource)undoValue).getEditableValue();
	redo();
}

/**
 * Sets the IPropertySource.
 * @param propSource the IPropertySource whose property has to be reset
 */
public void setTarget(IPropertySource propSource) {
	target = propSource;
}

/**
 * Resets the specified property on the specified IPropertySource
 * @see org.eclipse.gef.commands.Command#redo()
 */
public void redo() {
	target.resetPropertyValue(propertyName);
}

/**
 * Sets the property that is to be reset.
 * @param pName the property to be reset
 */
public void setPropertyId(Object pName) {
	propertyName = pName;
}

/**
 * Restores the non-default value that was reset. 
 * @see org.eclipse.gef.commands.Command#undo()
 */
public void undo() {
	target.setPropertyValue(propertyName, undoValue);
}

}