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/*
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* Copyright 2000-2006 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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package javax.swing;
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import java.awt.Component;
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import java.awt.Container;
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import java.awt.ComponentOrientation;
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import java.util.Comparator;
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import java.io.*;
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/**
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* A SortingFocusTraversalPolicy which sorts Components based on their size,
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* position, and orientation. Based on their size and position, Components are
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* roughly categorized into rows and columns. For a Container with horizontal
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* orientation, columns run left-to-right or right-to-left, and rows run top-
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* to-bottom. For a Container with vertical orientation, columns run top-to-
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* bottom and rows run left-to-right or right-to-left. See
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* <code>ComponentOrientation</code> for more information. All columns in a
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* row are fully traversed before proceeding to the next row.
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*
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* @author David Mendenhall
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*
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* @see java.awt.ComponentOrientation
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* @since 1.4
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*/
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public class LayoutFocusTraversalPolicy extends SortingFocusTraversalPolicy
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implements Serializable
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{
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// Delegate most of our fitness test to Default so that we only have to
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// code the algorithm once.
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private static final SwingDefaultFocusTraversalPolicy fitnessTestPolicy =
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new SwingDefaultFocusTraversalPolicy();
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/**
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* Constructs a LayoutFocusTraversalPolicy.
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*/
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public LayoutFocusTraversalPolicy() {
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super(new LayoutComparator());
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}
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/**
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* Constructs a LayoutFocusTraversalPolicy with the passed in
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* <code>Comparator</code>.
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*/
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LayoutFocusTraversalPolicy(Comparator c) {
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super(c);
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}
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/**
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* Returns the Component that should receive the focus after aComponent.
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* aContainer must be a focus cycle root of aComponent.
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* <p>
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* By default, LayoutFocusTraversalPolicy implicitly transfers focus down-
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* cycle. That is, during normal focus traversal, the Component
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* traversed after a focus cycle root will be the focus-cycle-root's
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* default Component to focus. This behavior can be disabled using the
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* <code>setImplicitDownCycleTraversal</code> method.
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* <p>
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* If aContainer is <a href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus
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* traversal policy provider</a>, the focus is always transferred down-cycle.
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*
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* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider
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* @param aComponent a (possibly indirect) child of aContainer, or
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* aContainer itself
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* @return the Component that should receive the focus after aComponent, or
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* null if no suitable Component can be found
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* @throws IllegalArgumentException if aContainer is not a focus cycle
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* root of aComponent or a focus traversal policy provider, or if either aContainer or
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* aComponent is null
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*/
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public Component getComponentAfter(Container aContainer,
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Component aComponent) {
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if (aContainer == null || aComponent == null) {
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throw new IllegalArgumentException("aContainer and aComponent cannot be null");
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}
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Comparator comparator = getComparator();
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if (comparator instanceof LayoutComparator) {
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((LayoutComparator)comparator).
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setComponentOrientation(aContainer.
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getComponentOrientation());
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}
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return super.getComponentAfter(aContainer, aComponent);
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}
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/**
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* Returns the Component that should receive the focus before aComponent.
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* aContainer must be a focus cycle root of aComponent.
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* <p>
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* By default, LayoutFocusTraversalPolicy implicitly transfers focus down-
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* cycle. That is, during normal focus traversal, the Component
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* traversed after a focus cycle root will be the focus-cycle-root's
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* default Component to focus. This behavior can be disabled using the
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* <code>setImplicitDownCycleTraversal</code> method.
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* <p>
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* If aContainer is <a href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus
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* traversal policy provider</a>, the focus is always transferred down-cycle.
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*
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* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider
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* @param aComponent a (possibly indirect) child of aContainer, or
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* aContainer itself
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* @return the Component that should receive the focus before aComponent,
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* or null if no suitable Component can be found
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* @throws IllegalArgumentException if aContainer is not a focus cycle
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* root of aComponent or a focus traversal policy provider, or if either aContainer or
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* aComponent is null
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*/
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public Component getComponentBefore(Container aContainer,
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Component aComponent) {
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if (aContainer == null || aComponent == null) {
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throw new IllegalArgumentException("aContainer and aComponent cannot be null");
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}
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Comparator comparator = getComparator();
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if (comparator instanceof LayoutComparator) {
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((LayoutComparator)comparator).
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setComponentOrientation(aContainer.
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getComponentOrientation());
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}
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return super.getComponentBefore(aContainer, aComponent);
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}
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/**
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* Returns the first Component in the traversal cycle. This method is used
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* to determine the next Component to focus when traversal wraps in the
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* forward direction.
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*
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* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider whose
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* first Component is to be returned
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* @return the first Component in the traversal cycle of aContainer,
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* or null if no suitable Component can be found
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* @throws IllegalArgumentException if aContainer is null
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*/
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public Component getFirstComponent(Container aContainer) {
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if (aContainer == null) {
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throw new IllegalArgumentException("aContainer cannot be null");
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}
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Comparator comparator = getComparator();
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if (comparator instanceof LayoutComparator) {
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((LayoutComparator)comparator).
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setComponentOrientation(aContainer.
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getComponentOrientation());
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}
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return super.getFirstComponent(aContainer);
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}
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/**
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* Returns the last Component in the traversal cycle. This method is used
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* to determine the next Component to focus when traversal wraps in the
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* reverse direction.
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*
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* @param aContainer a focus cycle root of aComponent or a focus traversal policy provider whose
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* last Component is to be returned
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* @return the last Component in the traversal cycle of aContainer,
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* or null if no suitable Component can be found
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* @throws IllegalArgumentException if aContainer is null
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*/
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public Component getLastComponent(Container aContainer) {
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if (aContainer == null) {
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throw new IllegalArgumentException("aContainer cannot be null");
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}
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Comparator comparator = getComparator();
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if (comparator instanceof LayoutComparator) {
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((LayoutComparator)comparator).
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setComponentOrientation(aContainer.
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getComponentOrientation());
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}
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return super.getLastComponent(aContainer);
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}
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/**
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* Determines whether the specified <code>Component</code>
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* is an acceptable choice as the new focus owner.
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* This method performs the following sequence of operations:
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* <ol>
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* <li>Checks whether <code>aComponent</code> is visible, displayable,
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* enabled, and focusable. If any of these properties is
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* <code>false</code>, this method returns <code>false</code>.
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* <li>If <code>aComponent</code> is an instance of <code>JTable</code>,
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* returns <code>true</code>.
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* <li>If <code>aComponent</code> is an instance of <code>JComboBox</code>,
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* then returns the value of
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* <code>aComponent.getUI().isFocusTraversable(aComponent)</code>.
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* <li>If <code>aComponent</code> is a <code>JComponent</code>
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* with a <code>JComponent.WHEN_FOCUSED</code>
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* <code>InputMap</code> that is neither <code>null</code>
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* nor empty, returns <code>true</code>.
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* <li>Returns the value of
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* <code>DefaultFocusTraversalPolicy.accept(aComponent)</code>.
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* </ol>
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*
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* @param aComponent the <code>Component</code> whose fitness
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* as a focus owner is to be tested
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* @see java.awt.Component#isVisible
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* @see java.awt.Component#isDisplayable
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* @see java.awt.Component#isEnabled
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* @see java.awt.Component#isFocusable
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* @see javax.swing.plaf.ComboBoxUI#isFocusTraversable
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* @see javax.swing.JComponent#getInputMap
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* @see java.awt.DefaultFocusTraversalPolicy#accept
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* @return <code>true</code> if <code>aComponent</code> is a valid choice
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* for a focus owner;
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* otherwise <code>false</code>
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*/
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protected boolean accept(Component aComponent) {
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if (!super.accept(aComponent)) {
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return false;
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} else if (aComponent instanceof JTable) {
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// JTable only has ancestor focus bindings, we thus force it
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// to be focusable by returning true here.
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return true;
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} else if (aComponent instanceof JComboBox) {
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JComboBox box = (JComboBox)aComponent;
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return box.getUI().isFocusTraversable(box);
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} else if (aComponent instanceof JComponent) {
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JComponent jComponent = (JComponent)aComponent;
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InputMap inputMap = jComponent.getInputMap(JComponent.WHEN_FOCUSED,
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false);
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while (inputMap != null && inputMap.size() == 0) {
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inputMap = inputMap.getParent();
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}
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if (inputMap != null) {
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return true;
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}
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// Delegate to the fitnessTestPolicy, this will test for the
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// case where the developer has overriden isFocusTraversable to
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// return true.
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}
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return fitnessTestPolicy.accept(aComponent);
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}
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private void writeObject(ObjectOutputStream out) throws IOException {
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out.writeObject(getComparator());
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out.writeBoolean(getImplicitDownCycleTraversal());
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}
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private void readObject(ObjectInputStream in)
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throws IOException, ClassNotFoundException
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{
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setComparator((Comparator)in.readObject());
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setImplicitDownCycleTraversal(in.readBoolean());
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}
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}
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// Create our own subclass and change accept to public so that we can call
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// accept.
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class SwingDefaultFocusTraversalPolicy
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extends java.awt.DefaultFocusTraversalPolicy
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{
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public boolean accept(Component aComponent) {
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return super.accept(aComponent);
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}
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}
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