RelativeLocator.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.draw2d;

import org.eclipse.draw2d.geometry.Dimension;
import org.eclipse.draw2d.geometry.PrecisionRectangle;
import org.eclipse.draw2d.geometry.Rectangle;

/**
 * Places a handle relative to a figure's bounds. The placement is determined by
 * indicating the figure to which the placement is relative, and two floating-point value
 * indicating the horizontal and vertical offset from that figure's top-left corner.  The
 * values (0.0, 0.0) would indicate the figure's top-left corner, while the values (1.0,
 * 1.0) would indicate the figure's bottom-right corner.
 * <P>
 * Constants such as {@link PositionConstants#NORTH NORTH} and {@link
 * PositionConstants#SOUTH SOUTH} can be used to set the placement.
 */
public class RelativeLocator
	implements Locator
{

private double  relativeX;
private double  relativeY;
private IFigure reference;

/**
 * Null constructor. The reference figure must be set before use.  The relative locations
 * will default to (0.0, 0.0).
 * @since 2.0
 */
public RelativeLocator() {
	relativeX = 0.0;
	relativeY = 0.0;
}

/**
 * Constructs a RelativeLocator with the given reference figure and relative location. The
 * location is a constant from {@link PositionConstants} used as a convenient and readable
 * way to set both the relativeX and relativeY values.
 * @param reference the reference figure
 * @param location one of NORTH, NORTH_EAST, etc.
 * @since 2.0
 */
public RelativeLocator(IFigure reference, int location) {
	setReferenceFigure(reference);
	switch (location & PositionConstants.NORTH_SOUTH) {
		case PositionConstants.NORTH:
			relativeY = 0; break;
		case PositionConstants.SOUTH:
			relativeY = 1.0; break;
		default:
			relativeY = 0.5;
	}

	switch (location & PositionConstants.EAST_WEST) {
		case PositionConstants.WEST:
			relativeX = 0; break;
		case PositionConstants.EAST:
			relativeX = 1.0; break;
		default:
			relativeX = 0.5;
	}
}

/**
 * Constructs a RelativeLocator with the given reference Figure and offset ratios.
 * @param reference the reference figure
 * @param relativeX the relative X offset
 * @param relativeY the relative Y offset
 * @since 2.0
 */
public RelativeLocator(IFigure reference, double relativeX, double relativeY) {
	setReferenceFigure(reference);
	this.relativeX = relativeX;
	this.relativeY = relativeY;
}

/**
 * Returns the Reference Box in the Reference Figure's coordinate system.
 * The returned Rectangle may be by reference, and should <b>not</b> be modified.
 * @return the reference box
 * @since 2.0
 */
protected Rectangle getReferenceBox() {
	return getReferenceFigure().getBounds();
}

/**
 * Returns the Figure this locator is relative to.
 * @return the reference figure
 * @since 2.0
 */
protected IFigure getReferenceFigure() {
	return reference;
}

/**
 * Relocates the target using the relative offset locations.
 * @see org.eclipse.draw2d.Locator#relocate(org.eclipse.draw2d.IFigure)
 */
public void relocate(IFigure target) {
	IFigure reference = getReferenceFigure();
	Rectangle targetBounds = new PrecisionRectangle(getReferenceBox().getResized(-1, -1));
	reference.translateToAbsolute(targetBounds);
	target.translateToRelative(targetBounds);
	targetBounds.resize(1, 1);

	Dimension targetSize = target.getPreferredSize();

	targetBounds.x
		+= (int) (targetBounds.width * relativeX - ((targetSize.width + 1) / 2));
	targetBounds.y
		+= (int) (targetBounds.height * relativeY - ((targetSize.height + 1) / 2));
	targetBounds.setSize(targetSize);
	target.setBounds(targetBounds);
}

/**
 * Sets the reference figure this locator uses to place the target figure.
 * @param reference the reference figure
 * @since 2.0
 */
public void setReferenceFigure(IFigure reference) {
	this.reference = reference;
}

}