1 /* DefaultFocusTraversalPolicy.java -- 2 Copyright (C) 2002, 2005 Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package java.awt; 40 41 /** 42 * DefaultFocusTraversalPolicy is the default focus traversal policy 43 * used by Containers. 44 * 45 * This policy sharpens ContainerOrderFocusTraversalPolicy's 46 * acceptance criteria, to reject those Components that have 47 * unfocusable peers. Despite this extra strictness, this policy will 48 * always accept a Component that has explicitly been set focusable by 49 * any means. 50 * 51 * This AWT implementation assumes that the peers of the following 52 * Components are not focusable: Canvas, Panel, Label, ScrollPane, 53 * Scrollbar, Window, and any lightweight Component. 54 * 55 * A Component's focusability is independent of the focusability of 56 * its peer. 57 * 58 * @author Thomas Fitzsimmons (fitzsim@redhat.com) 59 * @since 1.4 60 */ 61 public class DefaultFocusTraversalPolicy 62 extends ContainerOrderFocusTraversalPolicy 63 { 64 private static final long serialVersionUID = 8876966522510157497L; 65 66 /** 67 * Construct a default focus traversal policy. 68 */ DefaultFocusTraversalPolicy()69 public DefaultFocusTraversalPolicy () 70 { 71 } 72 73 /** 74 * Check whether a given Component would be acceptable as a focus 75 * owner. The Component must be displayable, visible and enabled to 76 * be acceptable. If the Component's focus traversability has been 77 * overridden, by overriding Component.isFocusTraversable or 78 * Component.isFocusable, or by calling Component.setFocusable, then 79 * the Component will be accepted if it is focusable. If the 80 * Component uses the default focus traversable behaviour, then 81 * <code>comp</code> will always be rejected if it is a Canvas, 82 * Panel, Label, ScrollPane, Scrollbar, Window or lightweight 83 * Component. 84 * 85 * @param comp the Component to check 86 * 87 * @return true if the Component is an acceptable target for 88 * keyboard input focus, false otherwise 89 */ accept(Component comp)90 protected boolean accept (Component comp) 91 { 92 if (comp.visible 93 && comp.isDisplayable () 94 && comp.enabled) 95 { 96 if (comp.isFocusTraversableOverridden != 0 97 && (comp.isFocusTraversable () || comp.isFocusable())) 98 return true; 99 100 if (!(comp instanceof Canvas 101 || comp instanceof Panel 102 || comp instanceof Label 103 || comp instanceof ScrollPane 104 || comp instanceof Scrollbar 105 || comp instanceof Window 106 || comp.isLightweight ())) 107 return true; 108 } 109 return false; 110 } 111 } 112