/* * Copyright (c) 1998, 2007, Oracle and/or its affiliates. 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.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing; import javax.swing.*;import javax.swing.event.*;import javax.swing.border.*; import java.awt.Component;import java.awt.Color;import java.awt.Rectangle; import java.io.Serializable;import sun.swing.DefaultLookup;  /** * Renders an item in a list. * <p> * <strong><a name="override">Implementation Note:</a></strong> * This class overrides * <code>invalidate</code>, * <code>validate</code>, * <code>revalidate</code>, * <code>repaint</code>, * <code>isOpaque</code>, * and * <code>firePropertyChange</code> * solely to improve performance. * If not overridden, these frequently called methods would execute code paths * that are unnecessary for the default list cell renderer. * If you write your own renderer, * take care to weigh the benefits and * drawbacks of overriding these methods. * * <p> * * <strong>Warning:</strong> * Serialized objects of this class will not be compatible with * future Swing releases. The current serialization support is * appropriate for short term storage or RMI between applications running * the same version of Swing.  As of 1.4, support for long term storage * of all JavaBeans<sup><font size="-2">TM</font></sup> * has been added to the <code>java.beans</code> package. * Please see {@link java.beans.XMLEncoder}. * * @author Philip Milne * @author Hans Muller */public class DefaultListCellRenderer extends JLabel    implements ListCellRenderer<Object>, Serializable{    /**    * An empty <code>Border</code>. This field might not be used. To change the    * <code>Border</code> used by this renderer override the    * <code>getListCellRendererComponent</code> method and set the border    * of the returned component directly.    */    private static final Border SAFE_NO_FOCUS_BORDER = new EmptyBorder(1, 1, 1, 1);    private static final Border DEFAULT_NO_FOCUS_BORDER = new EmptyBorder(1, 1, 1, 1);    protected static Border noFocusBorder = DEFAULT_NO_FOCUS_BORDER;     /**     * Constructs a default renderer object for an item     * in a list.     */    public DefaultListCellRenderer() {        super();        setOpaque(true);        setBorder(getNoFocusBorder());        setName("List.cellRenderer");    }     private Border getNoFocusBorder() {        Border border = DefaultLookup.getBorder(this, ui, "List.cellNoFocusBorder");        if (System.getSecurityManager() != null) {            if (border != null) return border;            return SAFE_NO_FOCUS_BORDER;        } else {            if (border != null &&                    (noFocusBorder == null ||                    noFocusBorder == DEFAULT_NO_FOCUS_BORDER)) {                return border;            }            return noFocusBorder;        }    }     public Component getListCellRendererComponent(        JList<?> list,        Object value,        int index,        boolean isSelected,        boolean cellHasFocus)    {        setComponentOrientation(list.getComponentOrientation());         Color bg = null;        Color fg = null;         JList.DropLocation dropLocation = list.getDropLocation();        if (dropLocation != null                && !dropLocation.isInsert()                && dropLocation.getIndex() == index) {             bg = DefaultLookup.getColor(this, ui, "List.dropCellBackground");            fg = DefaultLookup.getColor(this, ui, "List.dropCellForeground");             isSelected = true;        }         if (isSelected) {            setBackground(bg == null ? list.getSelectionBackground() : bg);            setForeground(fg == null ? list.getSelectionForeground() : fg);        }        else {            setBackground(list.getBackground());            setForeground(list.getForeground());        }         if (value instanceof Icon) {            setIcon((Icon)value);            setText("");        }        else {            setIcon(null);            setText((value == null) ? "" : value.toString());        }         setEnabled(list.isEnabled());        setFont(list.getFont());         Border border = null;        if (cellHasFocus) {            if (isSelected) {                border = DefaultLookup.getBorder(this, ui, "List.focusSelectedCellHighlightBorder");            }            if (border == null) {                border = DefaultLookup.getBorder(this, ui, "List.focusCellHighlightBorder");            }        } else {            border = getNoFocusBorder();        }        setBorder(border);         return this;    }     /**     * Overridden for performance reasons.     * See the <a href="#override">Implementation Note</a>     * for more information.     *     * @since 1.5     * @return <code>true</code> if the background is completely opaque     *         and differs from the JList's background;     *         <code>false</code> otherwise     */    @Override    public boolean isOpaque() {        Color back = getBackground();        Component p = getParent();        if (p != null) {            p = p.getParent();        }        // p should now be the JList.        boolean colorMatch = (back != null) && (p != null) &&            back.equals(p.getBackground()) &&                        p.isOpaque();        return !colorMatch && super.isOpaque();    }    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void validate() {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    *    * @since 1.5    */    @Override    public void invalidate() {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    *    * @since 1.5    */    @Override    public void repaint() {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void revalidate() {}   /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void repaint(long tm, int x, int y, int width, int height) {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void repaint(Rectangle r) {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    protected void firePropertyChange(String propertyName, Object oldValue, Object newValue) {        // Strings get interned...        if (propertyName == "text"                || ((propertyName == "font" || propertyName == "foreground")                    && oldValue != newValue                    && getClientProperty(javax.swing.plaf.basic.BasicHTML.propertyKey) != null)) {             super.firePropertyChange(propertyName, oldValue, newValue);        }    }    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void firePropertyChange(String propertyName, byte oldValue, byte newValue) {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void firePropertyChange(String propertyName, char oldValue, char newValue) {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void firePropertyChange(String propertyName, short oldValue, short newValue) {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void firePropertyChange(String propertyName, int oldValue, int newValue) {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void firePropertyChange(String propertyName, long oldValue, long newValue) {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void firePropertyChange(String propertyName, float oldValue, float newValue) {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void firePropertyChange(String propertyName, double oldValue, double newValue) {}    /**    * Overridden for performance reasons.    * See the <a href="#override">Implementation Note</a>    * for more information.    */    @Override    public void firePropertyChange(String propertyName, boolean oldValue, boolean newValue) {}     /**     * A subclass of DefaultListCellRenderer that implements UIResource.     * DefaultListCellRenderer doesn't implement UIResource     * directly so that applications can safely override the     * cellRenderer property with DefaultListCellRenderer subclasses.     * <p>     * <strong>Warning:</strong>     * Serialized objects of this class will not be compatible with     * future Swing releases. The current serialization support is     * appropriate for short term storage or RMI between applications running     * the same version of Swing.  As of 1.4, support for long term storage     * of all JavaBeans<sup><font size="-2">TM</font></sup>     * has been added to the <code>java.beans</code> package.     * Please see {@link java.beans.XMLEncoder}.     */    public static class UIResource extends DefaultListCellRenderer        implements javax.swing.plaf.UIResource    {    }}