java/12 : java.desktop/javax/swing/DefaultListCellRenderer.java

DefaultListCellRenderer
https://openjdk.java.net/
GPLv2 + Classpath Exception
/*
 * Copyright (c) 1998, 2017, 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;
import sun.swing.SwingUtilities2;

Renders an item in a list.

Implementation Note:
This class overrides
invalidate,
validate,
revalidate,
repaint,
isOpaque,
and
firePropertyChange
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.

Warning:
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™
has been added to the java.beans package. Please see XMLEncoder. 
Author: Philip Milne, Hans Muller
Since: 1.2/**
 * Renders an item in a list.
 * <p>
 * <strong><a id="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&trade;
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @author Philip Milne
 * @author Hans Muller
 * @since 1.2
 */
@SuppressWarnings("serial") // Same-version serialization only
public class DefaultListCellRenderer extends JLabel
    implements ListCellRenderer<Object>, Serializable
{

   An empty Border. This field might not be used. To change the
Border used by this renderer override the
getListCellRendererComponent method and set the border
of the returned component directly.
/**
    * 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);
    No focus border
/**
     * No focus border
     */
    protected static Border noFocusBorder = DEFAULT_NO_FOCUS_BORDER;

    Constructs a default renderer object for an item
in a list.
/**
     * 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 Implementation Note
for more information.
Since: 1.5
Returns: true if the background is completely opaque
        and differs from the JList's background;
        false otherwise/**
     * 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 Implementation Note
for more information.
/**
    * 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 Implementation Note
for more information.
Since: 1.5/**
    * 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 Implementation Note
for more information.
Since: 1.5/**
    * 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 Implementation Note
for more information.
/**
    * 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 Implementation Note
for more information.
/**
    * 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 Implementation Note
for more information.
/**
    * 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 Implementation Note
for more information.
/**
    * 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"
            || ((SwingUtilities2.isScaleChanged(propertyName, oldValue, newValue)
                    || 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 Implementation Note
for more information.
/**
    * 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 Implementation Note
for more information.
/**
    * 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 Implementation Note
for more information.
/**
    * 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 Implementation Note
for more information.
/**
    * 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 Implementation Note
for more information.
/**
    * 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 Implementation Note
for more information.
/**
    * 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 Implementation Note
for more information.
/**
    * 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 Implementation Note
for more information.
/**
    * 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.

Warning:
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™
has been added to the java.beans package. Please see XMLEncoder. /**
     * 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&trade;
     * has been added to the <code>java.beans</code> package.
     * Please see {@link java.beans.XMLEncoder}.
     */
    @SuppressWarnings("serial") // Same-version serialization only
    public static class UIResource extends DefaultListCellRenderer
        implements javax.swing.plaf.UIResource
    {
    }
}
Since:	1.5
Returns:	`true` if the background is completely opaque and differs from the JList's background; `false` otherwise
/

java/ 12/ java.desktop/javax/swing/DefaultListCellRenderer.java
