| /* |
| * Copyright (c) 1997, 2015, 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 java.awt.*; |
| import java.beans.JavaBean; |
| import java.beans.BeanProperty; |
| |
| import javax.swing.plaf.*; |
| import javax.accessibility.*; |
| |
| import java.io.ObjectOutputStream; |
| import java.io.IOException; |
| |
| |
| /** |
| * <code>JPanel</code> is a generic lightweight container. |
| * For examples and task-oriented documentation for JPanel, see |
| * <a |
| href="http://docs.oracle.com/javase/tutorial/uiswing/components/panel.html">How to Use Panels</a>, |
| * a section in <em>The Java Tutorial</em>. |
| * <p> |
| * <strong>Warning:</strong> Swing is not thread safe. For more |
| * information see <a |
| * href="package-summary.html#threading">Swing's Threading |
| * Policy</a>. |
| * <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™ |
| * has been added to the <code>java.beans</code> package. |
| * Please see {@link java.beans.XMLEncoder}. |
| * |
| * @author Arnaud Weber |
| * @author Steve Wilson |
| * @since 1.2 |
| */ |
| @JavaBean(defaultProperty = "UI", description = "A generic lightweight container.") |
| @SuppressWarnings("serial") // Same-version serialization only |
| public class JPanel extends JComponent implements Accessible |
| { |
| /** |
| * @see #getUIClassID |
| * @see #readObject |
| */ |
| private static final String uiClassID = "PanelUI"; |
| |
| /** |
| * Creates a new JPanel with the specified layout manager and buffering |
| * strategy. |
| * |
| * @param layout the LayoutManager to use |
| * @param isDoubleBuffered a boolean, true for double-buffering, which |
| * uses additional memory space to achieve fast, flicker-free |
| * updates |
| */ |
| public JPanel(LayoutManager layout, boolean isDoubleBuffered) { |
| setLayout(layout); |
| setDoubleBuffered(isDoubleBuffered); |
| setUIProperty("opaque", Boolean.TRUE); |
| updateUI(); |
| } |
| |
| /** |
| * Create a new buffered JPanel with the specified layout manager |
| * |
| * @param layout the LayoutManager to use |
| */ |
| public JPanel(LayoutManager layout) { |
| this(layout, true); |
| } |
| |
| /** |
| * Creates a new <code>JPanel</code> with <code>FlowLayout</code> |
| * and the specified buffering strategy. |
| * If <code>isDoubleBuffered</code> is true, the <code>JPanel</code> |
| * will use a double buffer. |
| * |
| * @param isDoubleBuffered a boolean, true for double-buffering, which |
| * uses additional memory space to achieve fast, flicker-free |
| * updates |
| */ |
| public JPanel(boolean isDoubleBuffered) { |
| this(new FlowLayout(), isDoubleBuffered); |
| } |
| |
| /** |
| * Creates a new <code>JPanel</code> with a double buffer |
| * and a flow layout. |
| */ |
| public JPanel() { |
| this(true); |
| } |
| |
| /** |
| * Resets the UI property with a value from the current look and feel. |
| * |
| * @see JComponent#updateUI |
| */ |
| public void updateUI() { |
| setUI((PanelUI)UIManager.getUI(this)); |
| } |
| |
| /** |
| * Returns the look and feel (L&amp;F) object that renders this component. |
| * |
| * @return the PanelUI object that renders this component |
| * @since 1.4 |
| */ |
| public PanelUI getUI() { |
| return (PanelUI)ui; |
| } |
| |
| |
| /** |
| * Sets the look and feel (L&F) object that renders this component. |
| * |
| * @param ui the PanelUI L&F object |
| * @see UIDefaults#getUI |
| * @since 1.4 |
| */ |
| @BeanProperty(hidden = true, visualUpdate = true, description |
| = "The UI object that implements the Component's LookAndFeel.") |
| public void setUI(PanelUI ui) { |
| super.setUI(ui); |
| } |
| |
| /** |
| * Returns a string that specifies the name of the L&F class |
| * that renders this component. |
| * |
| * @return "PanelUI" |
| * @see JComponent#getUIClassID |
| * @see UIDefaults#getUI |
| */ |
| @BeanProperty(bound = false, expert = true, description |
| = "A string that specifies the name of the L&F class.") |
| public String getUIClassID() { |
| return uiClassID; |
| } |
| |
| |
| /** |
| * See readObject() and writeObject() in JComponent for more |
| * information about serialization in Swing. |
| */ |
| private void writeObject(ObjectOutputStream s) throws IOException { |
| s.defaultWriteObject(); |
| if (getUIClassID().equals(uiClassID)) { |
| byte count = JComponent.getWriteObjCounter(this); |
| JComponent.setWriteObjCounter(this, --count); |
| if (count == 0 && ui != null) { |
| ui.installUI(this); |
| } |
| } |
| } |
| |
| |
| /** |
| * Returns a string representation of this JPanel. This method |
| * is intended to be used only for debugging purposes, and the |
| * content and format of the returned string may vary between |
| * implementations. The returned string may be empty but may not |
| * be <code>null</code>. |
| * |
| * @return a string representation of this JPanel. |
| */ |
| protected String paramString() { |
| return super.paramString(); |
| } |
| |
| ///////////////// |
| // Accessibility support |
| //////////////// |
| |
| /** |
| * Gets the AccessibleContext associated with this JPanel. |
| * For JPanels, the AccessibleContext takes the form of an |
| * AccessibleJPanel. |
| * A new AccessibleJPanel instance is created if necessary. |
| * |
| * @return an AccessibleJPanel that serves as the |
| * AccessibleContext of this JPanel |
| */ |
| @BeanProperty(bound = false) |
| public AccessibleContext getAccessibleContext() { |
| if (accessibleContext == null) { |
| accessibleContext = new AccessibleJPanel(); |
| } |
| return accessibleContext; |
| } |
| |
| /** |
| * This class implements accessibility support for the |
| * <code>JPanel</code> class. It provides an implementation of the |
| * Java Accessibility API appropriate to panel user-interface |
| * elements. |
| * <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™ |
| * has been added to the <code>java.beans</code> package. |
| * Please see {@link java.beans.XMLEncoder}. |
| */ |
| @SuppressWarnings("serial") // Same-version serialization only |
| protected class AccessibleJPanel extends AccessibleJComponent { |
| |
| /** |
| * Get the role of this object. |
| * |
| * @return an instance of AccessibleRole describing the role of the |
| * object |
| */ |
| public AccessibleRole getAccessibleRole() { |
| return AccessibleRole.PANEL; |
| } |
| } |
| } |