swingx-master/swingx-core/src/main/java/org/jdesktop/swingx/decorator/AlignmentHighlighter.java
/*
 * $Id$
 *
 * Copyright 2009 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */
package org.jdesktop.swingx.decorator;

import java.awt.Component;

import javax.swing.AbstractButton;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;

/**
 * A Highlighter which sets the horizontal alignment.
 * 
 * @author Jeanette Winzenburg (slight cleanup)
 * @author original contributed by swingx member martinm1000
 */
public class AlignmentHighlighter extends AbstractHighlighter {
    private static final int defaultAlignment = SwingConstants.LEADING; 
    private int alignment;

    
    /**
     * Instantiates a AlignmentHighlighter with default alignment LEADING. The Highlighter is 
     * applied always.
     */
    public AlignmentHighlighter() {
        this(defaultAlignment);
    }
    
    
    /**
     * Instantiates a AlignmentHighlighter with the specified alignment. The Highlighter is 
     * applied always.
     * 
     * @param alignment the horizontal alignment to use.
     * @throws IllegalArgumentException if not one of the constants allowed as horizontal alignment,
     * that is one of LEADING, LEFT, CENTER, RIGHT, TRAILING
     */
    public AlignmentHighlighter(int alignment) {
        this(null, alignment);
    }


    /**
     * Instantiates a FontHighlighter with the given HighlightPredicate and default 
     * horizontal alignement.
     * 
     * @param predicate the HighlightPredicate to use, may be null to default to ALWAYS.
     */
    public AlignmentHighlighter(HighlightPredicate predicate) {
        this(predicate, defaultAlignment);
    }
    

    /**
     * Instantiates a FontHighlighter with the given HighlightPredicate and null Font.
     * 
     * @param predicate the HighlightPredicate to use, may be null to default to ALWAYS.
     * @param alignment the horizontal alignment to use.
     * @throws IllegalArgumentException if not one of the constants allowed as horizontal alignment,
     * that is one of LEADING, LEFT, CENTER, RIGHT, TRAILING
     */
    public AlignmentHighlighter(HighlightPredicate predicate, int alignment) {
        super(predicate);
        this.alignment = checkHorizontalAlignment(alignment);
    }

    /**
     * Returns the alignment which is applied.
     * @return the alignment
     */
    public int getHorizontalAlignment() {
        return alignment;
    }

    
    /**
     * Sets the horizontal alignment to apply.
     * 
     * @param alignment the horizontal alignment to set
     * @throws IllegalArgumentException if not one of the constants allowed as horizontal alignment,
     * that is one of LEADING, LEFT, CENTER, RIGHT, TRAILING
     */
    public void setHorizontalAlignment(int alignment) {
        if (getHorizontalAlignment() == alignment) return;
        this.alignment = checkHorizontalAlignment(alignment);
        fireStateChanged();
    }


    /**
     * Checks if the horizontal alignment is valid.
     * 
     * @param alignment the horizontal alignment to check
     * @throws IllegalArgumentException if not one of the constants allowed as horizontal alignment,
     * that is one of LEADING, LEFT, CENTER, RIGHT, TRAILING
     */
    private int checkHorizontalAlignment(int alignment) {
        if ((alignment == SwingConstants.LEFT) ||
                (alignment == SwingConstants.CENTER) ||
                (alignment == SwingConstants.RIGHT) ||
                (alignment == SwingConstants.LEADING) ||
                (alignment == SwingConstants.TRAILING)) {
                return alignment;
            }
            else {
                throw new IllegalArgumentException("invalid horizontal alignment, expected one of "
                      + SwingConstants.LEFT + " / " + SwingConstants.CENTER + 
                      " / " + SwingConstants.RIGHT + " / " + SwingConstants.LEADING + 
                      " / " + SwingConstants.TRAILING + " but was: " + alignment);
            }
    }

    /**
     * {@inheritDoc} <p>
     * 
     * Implemented to set the horizontal alignement of the rendering component.
     */
    @Override
    protected Component doHighlight(Component renderer, ComponentAdapter adapter) {
        if (renderer instanceof JLabel) {
            ((JLabel) renderer).setHorizontalAlignment(getHorizontalAlignment());
        } else if (renderer instanceof AbstractButton ) {
            ((AbstractButton) renderer).setHorizontalAlignment(getHorizontalAlignment());
        } else {
            ((JTextField) renderer).setHorizontalAlignment(getHorizontalAlignment());
        }
        return renderer;
    }

    /**
     * {@inheritDoc} <p>
     * 
     * Implemented to return true for components of type JLabel, AbstractButton or JTextField, 
     * false otherwise.
     */
    @Override
    protected boolean canHighlight(Component component, ComponentAdapter adapter) {
        return (component instanceof JLabel) 
            || (component instanceof AbstractButton)
            || (component instanceof JTextField)
            ;
    }
}
