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/* * @(#)LayoutFocusTraversalPolicy.java 1.12 06/08/04 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package javax.swing; import java.awt.Component; import java.awt.Container; import java.awt.ComponentOrientation; import java.util.Comparator; import java.io.*; /** * A SortingFocusTraversalPolicy which sorts Components based on their size, * position, and orientation. Based on their size and position, Components are * roughly categorized into rows and columns. For a Container with horizontal * orientation, columns run left-to-right or right-to-left, and rows run top- * to-bottom. For a Container with vertical orientation, columns run top-to- * bottom and rows run left-to-right or right-to-left. See * <code>ComponentOrientation</code> for more information. All columns in a * row are fully traversed before proceeding to the next row. * * @version 1.12, 08/04/06 * @author David Mendenhall * * @see java.awt.ComponentOrientation * @since 1.4 */ public class LayoutFocusTraversalPolicy extends SortingFocusTraversalPolicy implements Serializable { // Delegate most of our fitness test to Default so that we only have to // code the algorithm once. private static final SwingDefaultFocusTraversalPolicy fitnessTestPolicy = new SwingDefaultFocusTraversalPolicy(); /** * Constructs a LayoutFocusTraversalPolicy. */ public LayoutFocusTraversalPolicy() { super(new LayoutComparator()); } /** * Constructs a LayoutFocusTraversalPolicy with the passed in * <code>Comparator</code>. */ LayoutFocusTraversalPolicy(Comparator c) { super(c); } /** * Returns the Component that should receive the focus after aComponent. * aContainer must be a focus cycle root of aComponent. * <p> * By default, LayoutFocusTraversalPolicy implicitly transfers focus down- * cycle. That is, during normal focus traversal, the Component * traversed after a focus cycle root will be the focus-cycle-root's * default Component to focus. This behavior can be disabled using the * <code>setImplicitDownCycleTraversal</code> method. * <p> * If aContainer is <a href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus * traversal policy provider</a>, the focus is always transferred down-cycle. * * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider * @param aComponent a (possibly indirect) child of aContainer, or * aContainer itself * @return the Component that should receive the focus after aComponent, or * null if no suitable Component can be found * @throws IllegalArgumentException if aContainer is not a focus cycle * root of aComponent or a focus traversal policy provider, or if either aContainer or * aComponent is null */ public Component getComponentAfter(Container aContainer, Component aComponent) { if (aContainer == null || aComponent == null) { throw new IllegalArgumentException("aContainer and aComponent cannot be null"); } Comparator comparator = getComparator(); if (comparator instanceof LayoutComparator) { ((LayoutComparator)comparator). setComponentOrientation(aContainer. getComponentOrientation()); } return super.getComponentAfter(aContainer, aComponent); } /** * Returns the Component that should receive the focus before aComponent. * aContainer must be a focus cycle root of aComponent. * <p> * By default, LayoutFocusTraversalPolicy implicitly transfers focus down- * cycle. That is, during normal focus traversal, the Component * traversed after a focus cycle root will be the focus-cycle-root's * default Component to focus. This behavior can be disabled using the * <code>setImplicitDownCycleTraversal</code> method. * <p> * If aContainer is <a href="../../java/awt/doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus * traversal policy provider</a>, the focus is always transferred down-cycle. * * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider * @param aComponent a (possibly indirect) child of aContainer, or * aContainer itself * @return the Component that should receive the focus before aComponent, * or null if no suitable Component can be found * @throws IllegalArgumentException if aContainer is not a focus cycle * root of aComponent or a focus traversal policy provider, or if either aContainer or * aComponent is null */ public Component getComponentBefore(Container aContainer, Component aComponent) { if (aContainer == null || aComponent == null) { throw new IllegalArgumentException("aContainer and aComponent cannot be null"); } Comparator comparator = getComparator(); if (comparator instanceof LayoutComparator) { ((LayoutComparator)comparator). setComponentOrientation(aContainer. getComponentOrientation()); } return super.getComponentBefore(aContainer, aComponent); } /** * Returns the first Component in the traversal cycle. This method is used * to determine the next Component to focus when traversal wraps in the * forward direction. * * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider whose * first Component is to be returned * @return the first Component in the traversal cycle of aContainer, * or null if no suitable Component can be found * @throws IllegalArgumentException if aContainer is null */ public Component getFirstComponent(Container aContainer) { if (aContainer == null) { throw new IllegalArgumentException("aContainer cannot be null"); } Comparator comparator = getComparator(); if (comparator instanceof LayoutComparator) { ((LayoutComparator)comparator). setComponentOrientation(aContainer. getComponentOrientation()); } return super.getFirstComponent(aContainer); } /** * Returns the last Component in the traversal cycle. This method is used * to determine the next Component to focus when traversal wraps in the * reverse direction. * * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider whose * last Component is to be returned * @return the last Component in the traversal cycle of aContainer, * or null if no suitable Component can be found * @throws IllegalArgumentException if aContainer is null */ public Component getLastComponent(Container aContainer) { if (aContainer == null) { throw new IllegalArgumentException("aContainer cannot be null"); } Comparator comparator = getComparator(); if (comparator instanceof LayoutComparator) { ((LayoutComparator)comparator). setComponentOrientation(aContainer. getComponentOrientation()); } return super.getLastComponent(aContainer); } /** * Determines whether the specified <code>Component</code> * is an acceptable choice as the new focus owner. * This method performs the following sequence of operations: * <ol> * <li>Checks whether <code>aComponent</code> is visible, displayable, * enabled, and focusable. If any of these properties is * <code>false</code>, this method returns <code>false</code>. * <li>If <code>aComponent</code> is an instance of <code>JTable</code>, * returns <code>true</code>. * <li>If <code>aComponent</code> is an instance of <code>JComboBox</code>, * then returns the value of * <code>aComponent.getUI().isFocusTraversable(aComponent)</code>. * <li>If <code>aComponent</code> is a <code>JComponent</code> * with a <code>JComponent.WHEN_FOCUSED</code> * <code>InputMap</code> that is neither <code>null</code> * nor empty, returns <code>true</code>. * <li>Returns the value of * <code>DefaultFocusTraversalPolicy.accept(aComponent)</code>. * </ol> * * @param aComponent the <code>Component</code> whose fitness * as a focus owner is to be tested * @see java.awt.Component#isVisible * @see java.awt.Component#isDisplayable * @see java.awt.Component#isEnabled * @see java.awt.Component#isFocusable * @see javax.swing.plaf.ComboBoxUI#isFocusTraversable * @see javax.swing.JComponent#getInputMap * @see java.awt.DefaultFocusTraversalPolicy#accept * @return <code>true</code> if <code>aComponent</code> is a valid choice * for a focus owner; * otherwise <code>false</code> */ protected boolean accept(Component aComponent) { if (!super.accept(aComponent)) { return false; } else if (aComponent instanceof JTable) { // JTable only has ancestor focus bindings, we thus force it // to be focusable by returning true here. return true; } else if (aComponent instanceof JComboBox) { JComboBox box = (JComboBox)aComponent; return box.getUI().isFocusTraversable(box); } else if (aComponent instanceof JComponent) { JComponent jComponent = (JComponent)aComponent; InputMap inputMap = jComponent.getInputMap(JComponent.WHEN_FOCUSED, false); while (inputMap != null && inputMap.size() == 0) { inputMap = inputMap.getParent(); } if (inputMap != null) { return true; } // Delegate to the fitnessTestPolicy, this will test for the // case where the developer has overriden isFocusTraversable to // return true. } return fitnessTestPolicy.accept(aComponent); } private void writeObject(ObjectOutputStream out) throws IOException { out.writeObject(getComparator()); out.writeBoolean(getImplicitDownCycleTraversal()); } private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { setComparator((Comparator)in.readObject()); setImplicitDownCycleTraversal(in.readBoolean()); } } // Create our own subclass and change accept to public so that we can call // accept. class SwingDefaultFocusTraversalPolicy extends java.awt.DefaultFocusTraversalPolicy { public boolean accept(Component aComponent) { return super.accept(aComponent); } }