jdk/src/share/classes/javax/swing/JPanel.java
changeset 2 90ce3da70b43
child 5506 202f599c92aa
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/javax/swing/JPanel.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,248 @@
+/*
+ * Copyright 1997-2006 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.
+ */
+package javax.swing;
+
+import java.awt.*;
+
+import javax.swing.plaf.*;
+import javax.accessibility.*;
+
+import java.io.Serializable;
+import java.io.ObjectOutputStream;
+import java.io.ObjectInputStream;
+import java.io.IOException;
+
+
+/**
+ * <code>JPanel</code> is a generic lightweight container.
+ * For examples and task-oriented documentation for JPanel, see
+ * <a
+ href="http://java.sun.com/docs/books/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<sup><font size="-2">TM</font></sup>
+ * has been added to the <code>java.beans</code> package.
+ * Please see {@link java.beans.XMLEncoder}.
+ *
+ * @beaninfo
+ * description: A generic lightweight container.
+ *
+ * @author Arnaud Weber
+ * @author Steve Wilson
+ */
+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&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
+     * @beaninfo
+     *        bound: true
+     *       hidden: true
+     *    attribute: 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
+     * @beaninfo
+     *        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
+     */
+    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<sup><font size="-2">TM</font></sup>
+     * has been added to the <code>java.beans</code> package.
+     * Please see {@link java.beans.XMLEncoder}.
+     */
+    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;
+        }
+    }
+}