GlyphMetrics.java

/*******************************************************************************
 * Copyright (c) 2000, 2008, 2012 IBM Corporation, Gerhardt Informatics Kft. 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
 *     Gerhardt Informatics Kft. - GEFGWT port
 *******************************************************************************/
package org.eclipse.swt.graphics;

import org.eclipse.swt.SWT;

/**
 * Instances of this class represent glyph metrics.
 * <p>
 * The hashCode() method in this class uses the values of the public fields to
 * compute the hash value. When storing instances of the class in hashed
 * collections, do not modify these fields after the object has been inserted.
 * </p>
 * <p>
 * Application code does <em>not</em> need to explicitly release the resources
 * managed by each instance when those instances are no longer required, and
 * thus no <code>dispose()</code> method is provided.
 * </p>
 * 
 * @see TextStyle
 * @see TextLayout
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further
 *      information</a>
 * 
 * @since 3.2
 */
public final class GlyphMetrics {

	/**
	 * the ascent of the GlyphMetrics
	 */
	public int ascent;

	/**
	 * the descent of the GlyphMetrics
	 */
	public int descent;

	/**
	 * the width of the GlyphMetrics
	 */
	public int width;

	/**
	 * Constructs an instance of this class with the given ascent, descent and
	 * width values.
	 * 
	 * @param ascent
	 *            the GlyphMetrics ascent
	 * @param descent
	 *            the GlyphMetrics descent
	 * @param width
	 *            the GlyphMetrics width
	 * 
	 * @exception IllegalArgumentException
	 *                <ul>
	 *                <li>ERROR_INVALID_ARGUMENT - if the ascent, descent or
	 *                width argument is negative</li>
	 *                </ul>
	 */
	public GlyphMetrics(int ascent, int descent, int width) {
		if (ascent < 0 || descent < 0 || width < 0) {
			SWT.error(SWT.ERROR_INVALID_ARGUMENT);
		}
		this.ascent = ascent;
		this.descent = descent;
		this.width = width;
	}

	/**
	 * Compares the argument to the receiver, and returns true if they represent
	 * the <em>same</em> object using a class specific comparison.
	 * 
	 * @param object
	 *            the object to compare with this object
	 * @return <code>true</code> if the object is the same as this object and
	 *         <code>false</code> otherwise
	 * 
	 * @see #hashCode()
	 */
	public boolean equals(Object object) {
		if (object == this)
			return true;
		if (!(object instanceof GlyphMetrics))
			return false;
		GlyphMetrics metrics = (GlyphMetrics) object;
		return metrics.ascent == ascent && metrics.descent == descent
				&& metrics.width == width;
	}

	/**
	 * Returns an integer hash code for the receiver. Any two objects that
	 * return <code>true</code> when passed to <code>equals</code> must return
	 * the same value for this method.
	 * 
	 * @return the receiver's hash
	 * 
	 * @see #equals(Object)
	 */
	public int hashCode() {
		return ascent ^ descent ^ width;
	}

	/**
	 * Returns a string containing a concise, human-readable description of the
	 * receiver.
	 * 
	 * @return a string representation of the <code>GlyphMetrics</code>
	 */
	public String toString() {
		return "GlyphMetrics {" + ascent + ", " + descent + ", " + width + "}"; //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
	}

}