CreateGuideAction.java

/*******************************************************************************
 * Copyright (c) 2004, 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.actions;

import java.util.Arrays;

import org.eclipse.jface.action.Action;

import org.eclipse.gef.EditPart;
import org.eclipse.gef.EditPartViewer;
import org.eclipse.gef.internal.GEFMessages;
import org.eclipse.gef.internal.ui.rulers.GuideEditPart;
import org.eclipse.gef.internal.ui.rulers.RulerEditPart;
import org.eclipse.gef.rulers.RulerProvider;

/**
 * An Action that creates a guide on a ruler and reveals it.
 * 
 * @author Pratik Shah
 * @since 3.0
 */
public class CreateGuideAction 
	extends Action 
{
	
private EditPartViewer viewer;
	
/**
 * Constructor
 * @param	ruler	the viewer for the ruler on which the guide is to be created 
 */
public CreateGuideAction(EditPartViewer ruler) {
	super(GEFMessages.Create_Guide_Label);
	viewer = ruler;
	setToolTipText(GEFMessages.Create_Guide_Tooltip);
}

/**
 * @see org.eclipse.jface.action.IAction#run()
 */
public void run() {
	RulerProvider provider = ((RulerEditPart)viewer.getRootEditPart().getChildren()
			.get(0)).getRulerProvider();
	
	// Determine where the guide should be created
	int[] positions = provider.getGuidePositions();
	Arrays.sort(positions);
	int index = 0;
	int newPosition = GuideEditPart.MIN_DISTANCE_BW_GUIDES + 1;
	int desiredDifference = (GuideEditPart.MIN_DISTANCE_BW_GUIDES * 2) + 1;
	boolean found = positions.length > 0 && positions[0] > desiredDifference;
	while (index < positions.length - 1 && !found) {
		if (positions[index + 1] - positions[index] > desiredDifference) {
			newPosition += positions[index];
			found = true;
		}
		index++;
	}
	if (!found && positions.length > 0)
		newPosition += positions[positions.length - 1];
			
	// Create the guide and reveal it
	viewer.getEditDomain().getCommandStack().execute(
			provider.getCreateGuideCommand(newPosition));
	viewer.reveal((EditPart)viewer.getEditPartRegistry()
			.get(provider.getGuideAt(newPosition)));
}

}