XYLayoutEditPolicy.java

/*******************************************************************************
 * Copyright (c) 2000, 2010 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.editpolicies;

import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.XYLayout;
import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.Rectangle;

import org.eclipse.gef.GraphicalEditPart;
import org.eclipse.gef.Request;
import org.eclipse.gef.requests.ChangeBoundsRequest;
import org.eclipse.gef.requests.CreateRequest;

/**
 * An EditPolicy for use with <code>Figures</code> in {@link XYLayout}. The
 * constraint for XYLayout is a {@link org.eclipse.draw2d.geometry.Rectangle}.
 * 
 * Created on :Nov 12, 2002
 * 
 * @author hudsonr
 * @author msorens
 * @author anyssen
 * 
 * @since 2.0
 */
public abstract class XYLayoutEditPolicy extends ConstrainedLayoutEditPolicy {

	private static final Dimension PREFERRED_SIZE = new Dimension(-1, -1);

	private XYLayout xyLayout;

	/**
	 * Overridden to preserve existing width and height (as well as preferred
	 * sizes) during MOVE requests.
	 * 
	 * @see org.eclipse.gef.editpolicies.ConstrainedLayoutEditPolicy#getConstraintFor(org.eclipse.gef.Request,
	 *      org.eclipse.gef.GraphicalEditPart,
	 *      org.eclipse.draw2d.geometry.Rectangle)
	 */
	protected Object getConstraintFor(Request request, GraphicalEditPart child,
			Rectangle rect) {
		if (request instanceof ChangeBoundsRequest) {
			if (((ChangeBoundsRequest) request).getSizeDelta().width == 0
					&& ((ChangeBoundsRequest) request).getSizeDelta().height == 0) {
				if (getCurrentConstraintFor(child) != null) {
					// Bug 86473 allows for unintended use of this method
					rect.setSize(getCurrentConstraintFor(child).getSize());
				}
			} else {
				// for backwards compatibility, ensure minimum size is respected
				rect.setSize(Dimension.max(getMinimumSizeFor(child),
						rect.getSize()));
			}
		}
		return super.getConstraintFor(request, child, rect);
	}

	/**
	 * Returns a Rectangle at the given Point with width and height of -1.
	 * <code>XYLayout</code> uses width or height equal to '-1' to mean use the
	 * figure's preferred size.
	 * 
	 * @param p
	 *            the input Point
	 * @return a Rectangle
	 */
	public Object getConstraintFor(Point p) {
		return new Rectangle(p, PREFERRED_SIZE);
	}

	/**
	 * Returns a new Rectangle equivalent to the passed Rectangle.
	 * 
	 * @param r
	 *            the input Rectangle
	 * @return a copy of the input Rectangle
	 */
	public Object getConstraintFor(Rectangle r) {
		return new Rectangle(r);
	}

	/**
	 * Retrieves the child's current constraint from the
	 * <code>LayoutManager</code>.
	 * 
	 * @param child
	 *            the child
	 * @return the current constraint
	 */
	protected Rectangle getCurrentConstraintFor(GraphicalEditPart child) {
		IFigure fig = child.getFigure();
		return (Rectangle) fig.getParent().getLayoutManager()
				.getConstraint(fig);
	}

	/**
	 * Returns {@link XYLayout#getOrigin(IFigure)}.
	 * 
	 * @see ConstrainedLayoutEditPolicy#getLayoutOrigin()
	 */
	protected Point getLayoutOrigin() {
		return getXYLayout().getOrigin(getLayoutContainer());
	}

	/**
	 * @return the XYLayout layout manager set on the
	 *         {@link LayoutEditPolicy#getLayoutContainer() container}
	 */
	protected XYLayout getXYLayout() {
		if (xyLayout == null) {
			IFigure container = getLayoutContainer();
			xyLayout = (XYLayout) container.getLayoutManager();
		}
		return xyLayout;
	}

	/**
	 * @param xyLayout
	 *            The xyLayout to set.
	 */
	public void setXyLayout(XYLayout xyLayout) {
		this.xyLayout = xyLayout;
	}

	/**
	 * @see org.eclipse.gef.editpolicies.LayoutEditPolicy#showSizeOnDropFeedback(org.eclipse.gef.requests.CreateRequest)
	 */
	protected void showSizeOnDropFeedback(CreateRequest request) {
		Point p = new Point(request.getLocation().getCopy());
		Dimension size = request.getSize().getCopy();
		Rectangle feedbackBounds = new Rectangle(p, size);
		IFigure feedback = getSizeOnDropFeedback(request);
		feedback.translateToRelative(feedbackBounds);
		feedback.setBounds(feedbackBounds
				.expand(getCreationFeedbackOffset(request)));
		feedback.validate();
	}

	/**
	 * Determines the <em>minimum</em> size that the specified child can be
	 * resized to. Called from
	 * {@link #getConstraintFor(ChangeBoundsRequest, GraphicalEditPart)}. By
	 * default, a small <code>Dimension</code> is returned.
	 * 
	 * @param child
	 *            the child
	 * @return the minimum size
	 * 
	 * @deprecated Clients should no longer extend this method. Instead, the
	 *             resize tracker, constructed by the 'satellite' primary drag
	 *             edit policy should be parameterized with max and min size
	 *             constraints.
	 */
	protected Dimension getMinimumSizeFor(GraphicalEditPart child) {
		return new Dimension(8, 8);
	}

}