/*

 * Copyright 1998-2005 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

/*

 * (C) Copyright Taligent, Inc. 1996 - 1997, All Rights Reserved

 * (C) Copyright IBM Corp. 1996 - 1998, All Rights Reserved

 *

 * The original version of this source code and documentation is

 * copyrighted and owned by Taligent, Inc., a wholly-owned subsidiary

 * of IBM. These materials are provided under terms of a License

 * Agreement between Taligent and Sun. This technology is protected

 * by multiple US and International patents.

 *

 * This notice and attribution to Taligent may not be removed.

 * Taligent is a registered trademark of Taligent, Inc.

 *

 */

package java.awt.font;

import java.awt.geom.AffineTransform;

import java.io.Serializable;

import java.io.ObjectStreamException;

/**

 * The <code>TransformAttribute</code> class provides an immutable

 * wrapper for a transform so that it is safe to use as an attribute.

 */

public final class TransformAttribute implements Serializable {

    /**

     * The <code>AffineTransform</code> for this

     * <code>TransformAttribute</code>, or <code>null</code>

     * if <code>AffineTransform</code> is the identity transform.

     */

    private AffineTransform transform;

    /**

     * Wraps the specified transform.  The transform is cloned and a

     * reference to the clone is kept.  The original transform is unchanged.

     * If null is passed as the argument, this constructor behaves as though

     * it were the identity transform.  (Note that it is preferable to use

     * {@link #IDENTITY} in this case.)

     * @param transform the specified {@link AffineTransform} to be wrapped,

     * or null.

     */

    public TransformAttribute(AffineTransform transform) {

        if (transform != null && !transform.isIdentity()) {

            this.transform = new AffineTransform(transform);

        }

    }

    /**

     * Returns a copy of the wrapped transform.

     * @return a <code>AffineTransform</code> that is a copy of the wrapped

     * transform of this <code>TransformAttribute</code>.

     */

    public AffineTransform getTransform() {

        AffineTransform at = transform;

        return (at == null) ? new AffineTransform() : new AffineTransform(at);

    }

    /**

     * Returns <code>true</code> if the wrapped transform is

     * an identity transform.

     * @return <code>true</code> if the wrapped transform is

     * an identity transform; <code>false</code> otherwise.

     * @since 1.4

     */

    public boolean isIdentity() {

        return transform == null;

    }

    /**

     * A <code>TransformAttribute</code> representing the identity transform.

     * @since 1.6

     */

    public static final TransformAttribute IDENTITY = new TransformAttribute(null);

    private void writeObject(java.io.ObjectOutputStream s)

      throws java.lang.ClassNotFoundException,

             java.io.IOException

    {

        // sigh -- 1.3 expects transform is never null, so we need to always write one out

        if (this.transform == null) {

            this.transform = new AffineTransform();

        }

        s.defaultWriteObject();

    }

    /*

     * @since 1.6

     */

    private Object readResolve() throws ObjectStreamException {

        if (transform == null || transform.isIdentity()) {

            return IDENTITY;

        }

        return this;

    }

    // Added for serial backwards compatability (4348425)

    static final long serialVersionUID = 3356247357827709530L;

    /**

     * @since 1.6

     */

    public int hashCode() {

        return transform == null ? 0 : transform.hashCode();

    }

    /**

     * Returns <code>true</code> if rhs is a <code>TransformAttribute</code>

     * whose transform is equal to this <code>TransformAttribute</code>'s

     * transform.

     * @param rhs the object to compare to

     * @return <code>true</code> if the argument is a <code>TransformAttribute</code>

     * whose transform is equal to this <code>TransformAttribute</code>'s

     * transform.

     * @since 1.6

     */

    public boolean equals(Object rhs) {

        try {

            TransformAttribute that = (TransformAttribute)rhs;

            if (transform == null) {

                return that.transform == null;

            }

            return transform.equals(that.transform);

        }

        catch (ClassCastException e) {

        }

        return false;

    }

}