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package javax.swing;

import java.awt.FocusTraversalPolicy;
import java.awt.Component;
import java.awt.Container;
import java.awt.Window;
import java.util.HashMap;
import java.util.HashSet;
import java.io.*;


A FocusTraversalPolicy which provides support for legacy applications which handle focus traversal via JComponent.setNextFocusableComponent or by installing a custom DefaultFocusManager. If a specific traversal has not been hard coded, then that traversal is provided either by the custom DefaultFocusManager, or by a wrapped FocusTraversalPolicy instance.
Author:David Mendenhall
/** * A FocusTraversalPolicy which provides support for legacy applications which * handle focus traversal via JComponent.setNextFocusableComponent or by * installing a custom DefaultFocusManager. If a specific traversal has not * been hard coded, then that traversal is provided either by the custom * DefaultFocusManager, or by a wrapped FocusTraversalPolicy instance. * * @author David Mendenhall */
final class LegacyGlueFocusTraversalPolicy extends FocusTraversalPolicy implements Serializable { private transient FocusTraversalPolicy delegatePolicy; private transient DefaultFocusManager delegateManager; private HashMap<Component, Component> forwardMap = new HashMap<Component, Component>(), backwardMap = new HashMap<Component, Component>(); LegacyGlueFocusTraversalPolicy(FocusTraversalPolicy delegatePolicy) { this.delegatePolicy = delegatePolicy; } LegacyGlueFocusTraversalPolicy(DefaultFocusManager delegateManager) { this.delegateManager = delegateManager; } void setNextFocusableComponent(Component left, Component right) { forwardMap.put(left, right); backwardMap.put(right, left); } void unsetNextFocusableComponent(Component left, Component right) { forwardMap.remove(left); backwardMap.remove(right); } public Component getComponentAfter(Container focusCycleRoot, Component aComponent) { Component hardCoded = aComponent, prevHardCoded; HashSet<Component> sanity = new HashSet<Component>(); do { prevHardCoded = hardCoded; hardCoded = forwardMap.get(hardCoded); if (hardCoded == null) { if (delegatePolicy != null && prevHardCoded.isFocusCycleRoot(focusCycleRoot)) { return delegatePolicy.getComponentAfter(focusCycleRoot, prevHardCoded); } else if (delegateManager != null) { return delegateManager. getComponentAfter(focusCycleRoot, aComponent); } else { return null; } } if (sanity.contains(hardCoded)) { // cycle detected; bail return null; } sanity.add(hardCoded); } while (!accept(hardCoded)); return hardCoded; } public Component getComponentBefore(Container focusCycleRoot, Component aComponent) { Component hardCoded = aComponent, prevHardCoded; HashSet<Component> sanity = new HashSet<Component>(); do { prevHardCoded = hardCoded; hardCoded = backwardMap.get(hardCoded); if (hardCoded == null) { if (delegatePolicy != null && prevHardCoded.isFocusCycleRoot(focusCycleRoot)) { return delegatePolicy.getComponentBefore(focusCycleRoot, prevHardCoded); } else if (delegateManager != null) { return delegateManager. getComponentBefore(focusCycleRoot, aComponent); } else { return null; } } if (sanity.contains(hardCoded)) { // cycle detected; bail return null; } sanity.add(hardCoded); } while (!accept(hardCoded)); return hardCoded; } public Component getFirstComponent(Container focusCycleRoot) { if (delegatePolicy != null) { return delegatePolicy.getFirstComponent(focusCycleRoot); } else if (delegateManager != null) { return delegateManager.getFirstComponent(focusCycleRoot); } else { return null; } } public Component getLastComponent(Container focusCycleRoot) { if (delegatePolicy != null) { return delegatePolicy.getLastComponent(focusCycleRoot); } else if (delegateManager != null) { return delegateManager.getLastComponent(focusCycleRoot); } else { return null; } } public Component getDefaultComponent(Container focusCycleRoot) { if (delegatePolicy != null) { return delegatePolicy.getDefaultComponent(focusCycleRoot); } else { return getFirstComponent(focusCycleRoot); } } private boolean accept(Component aComponent) { if (!(aComponent.isVisible() && aComponent.isDisplayable() && aComponent.isFocusable() && 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; } } } return true; } private void writeObject(ObjectOutputStream out) throws IOException { out.defaultWriteObject(); if (delegatePolicy instanceof Serializable) { out.writeObject(delegatePolicy); } else { out.writeObject(null); } if (delegateManager instanceof Serializable) { out.writeObject(delegateManager); } else { out.writeObject(null); } } private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { in.defaultReadObject(); delegatePolicy = (FocusTraversalPolicy)in.readObject(); delegateManager = (DefaultFocusManager)in.readObject(); } }