| /* |
| * Copyright (c) 2000, 2004, 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 java.awt; |
| |
| import java.awt.peer.ComponentPeer; |
| |
| |
| /** |
| * A FocusTraversalPolicy that determines traversal order based on the order |
| * of child Components in a Container. From a particular focus cycle root, the |
| * policy makes a pre-order traversal of the Component hierarchy, and traverses |
| * a Container's children according to the ordering of the array returned by |
| * <code>Container.getComponents()</code>. Portions of the hierarchy that are |
| * not visible and displayable will not be searched. |
| * <p> |
| * If client code has explicitly set the focusability of a Component by either |
| * overriding <code>Component.isFocusTraversable()</code> or |
| * <code>Component.isFocusable()</code>, or by calling |
| * <code>Component.setFocusable()</code>, then a DefaultFocusTraversalPolicy |
| * behaves exactly like a ContainerOrderFocusTraversalPolicy. If, however, the |
| * Component is relying on default focusability, then a |
| * DefaultFocusTraversalPolicy will reject all Components with non-focusable |
| * peers. This is the default FocusTraversalPolicy for all AWT Containers. |
| * <p> |
| * The focusability of a peer is implementation-dependent. Sun recommends that |
| * all implementations for a particular native platform construct peers with |
| * the same focusability. The recommendations for Windows and Unix are that |
| * Canvases, Labels, Panels, Scrollbars, ScrollPanes, Windows, and lightweight |
| * Components have non-focusable peers, and all other Components have focusable |
| * peers. These recommendations are used in the Sun AWT implementations. Note |
| * that the focusability of a Component's peer is different from, and does not |
| * impact, the focusability of the Component itself. |
| * <p> |
| * Please see |
| * <a href="http://java.sun.com/docs/books/tutorial/uiswing/misc/focus.html"> |
| * How to Use the Focus Subsystem</a>, |
| * a section in <em>The Java Tutorial</em>, and the |
| * <a href="../../java/awt/doc-files/FocusSpec.html">Focus Specification</a> |
| * for more information. |
| * |
| * @author David Mendenhall |
| * |
| * @see Container#getComponents |
| * @see Component#isFocusable |
| * @see Component#setFocusable |
| * @since 1.4 |
| */ |
| public class DefaultFocusTraversalPolicy |
| extends ContainerOrderFocusTraversalPolicy |
| { |
| /* |
| * serialVersionUID |
| */ |
| private static final long serialVersionUID = 8876966522510157497L; |
| |
| /** |
| * Determines whether a Component is an acceptable choice as the new |
| * focus owner. The Component must be visible, displayable, and enabled |
| * to be accepted. If client code has explicitly set the focusability |
| * of the Component by either overriding |
| * <code>Component.isFocusTraversable()</code> or |
| * <code>Component.isFocusable()</code>, or by calling |
| * <code>Component.setFocusable()</code>, then the Component will be |
| * accepted if and only if it is focusable. If, however, the Component is |
| * relying on default focusability, then all Canvases, Labels, Panels, |
| * Scrollbars, ScrollPanes, Windows, and lightweight Components will be |
| * rejected. |
| * |
| * @param aComponent the Component whose fitness as a focus owner is to |
| * be tested |
| * @return <code>true</code> if aComponent meets the above requirements; |
| * <code>false</code> otherwise |
| */ |
| protected boolean accept(Component aComponent) { |
| if (!(aComponent.isVisible() && aComponent.isDisplayable() && |
| aComponent.isEnabled())) |
| { |
| return false; |
| } |
| |
| // Verify that the Component is recursively enabled. Disabling a |
| // heavyweight Container disables its children, whereas disabling |
| // a lightweight Container does not. |
| if (!(aComponent instanceof Window)) { |
| for (Container enableTest = aComponent.getParent(); |
| enableTest != null; |
| enableTest = enableTest.getParent()) |
| { |
| if (!(enableTest.isEnabled() || enableTest.isLightweight())) { |
| return false; |
| } |
| if (enableTest instanceof Window) { |
| break; |
| } |
| } |
| } |
| |
| boolean focusable = aComponent.isFocusable(); |
| if (aComponent.isFocusTraversableOverridden()) { |
| return focusable; |
| } |
| |
| ComponentPeer peer = aComponent.getPeer(); |
| return (peer != null && peer.isFocusable()); |
| } |
| } |