bundles/org.eclipse.gef/src/org/eclipse/gef/requests/AlignmentRequest.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.requests;

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

/**
 * A request to align multiple objects.
 */
public class AlignmentRequest extends ChangeBoundsRequest {

	private int alignment;
	private Rectangle alignmentRect;

	/**
	 * Default constructor.
	 */
	public AlignmentRequest() {
	}

	/**
	 * Constructs a new AlignmentRequest with the new type.
	 * 
	 * @param type
	 *            the type
	 */
	public AlignmentRequest(Object type) {
		super(type);
	}

	private void doNormalAlignment(Rectangle result, Rectangle reference) {
		switch (alignment) {
		case PositionConstants.LEFT:
			result.x = reference.x;
			break;
		case PositionConstants.RIGHT:
			result.x = reference.x + reference.width - result.width;
			break;
		case PositionConstants.TOP:
			result.y = reference.y;
			break;
		case PositionConstants.BOTTOM:
			result.y = reference.y + reference.height - result.height;
			break;
		case PositionConstants.CENTER:
			result.x = reference.x + (reference.width / 2) - (result.width / 2);
			break;
		case PositionConstants.MIDDLE:
			result.y = reference.y + (reference.height / 2)
					- (result.height / 2);
			break;
		}
	}

	private void doPrecisionAlignment(PrecisionRectangle result,
			PrecisionRectangle reference) {
		switch (alignment) {
		case PositionConstants.LEFT:
			result.setPreciseX(reference.preciseX());
			break;
		case PositionConstants.RIGHT:
			result.setPreciseX(reference.preciseX() + reference.preciseWidth()
					- result.preciseWidth());
			break;
		case PositionConstants.TOP:
			result.setPreciseY(reference.preciseY());
			break;
		case PositionConstants.BOTTOM:
			result.setPreciseY(reference.preciseY() + reference.preciseHeight()
					- result.preciseHeight());
			break;
		case PositionConstants.CENTER:
			result.setPreciseX(reference.preciseX()
					+ (reference.preciseWidth() / 2)
					- (result.preciseWidth() / 2));
			break;
		case PositionConstants.MIDDLE:
			result.setPreciseY(reference.preciseY()
					+ (reference.preciseHeight() / 2)
					- (result.preciseHeight() / 2));
			break;
		}

	}

	/**
	 * Returns the alignment. Possible values are {@link PositionConstants#LEFT}
	 * , {@link PositionConstants#RIGHT}, {@link PositionConstants#TOP} and
	 * {@link PositionConstants#BOTTOM}.
	 * 
	 * @return the alignment
	 */
	public int getAlignment() {
		return alignment;
	}

	/**
	 * Returns the rectangle used to align the edit part with.
	 * 
	 * @return the alignment rectangle
	 */
	public Rectangle getAlignmentRectangle() {
		return alignmentRect;
	}

	/**
	 * @see ChangeBoundsRequest#getTransformedRectangle(Rectangle)
	 */
	public Rectangle getTransformedRectangle(Rectangle rect) {
		Rectangle result = rect.getCopy();
		Rectangle reference = getAlignmentRectangle();

		if (result instanceof PrecisionRectangle) {
			if (reference instanceof PrecisionRectangle)
				doPrecisionAlignment((PrecisionRectangle) result,
						(PrecisionRectangle) reference);
			else
				doPrecisionAlignment((PrecisionRectangle) result,
						new PrecisionRectangle(reference));
		} else
			doNormalAlignment(result, reference);
		return result;
	}

	/**
	 * Sets the alignment.
	 * 
	 * @param align
	 *            the alignment
	 * @see #getAlignment()
	 */
	public void setAlignment(int align) {
		alignment = align;
	}

	/**
	 * Sets the alignment rectangle.
	 * 
	 * @param rect
	 *            the alignment rectangle
	 * @see #getAlignmentRectangle()
	 */
	public void setAlignmentRectangle(Rectangle rect) {
		alignmentRect = rect;
	}

}