414 lines
13 KiB
Java
414 lines
13 KiB
Java
/* ContainerOrderFocusTraversalPolicy.java --
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Copyright (C) 2002, 2005 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.awt;
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import java.io.Serializable;
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/**
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* ContainerOrderFocusTraversalPolicy defines a focus traversal order
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* based on the order in which Components were packed in a Container.
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* This policy performs a pre-order traversal of the Component
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* hierarchy starting from a given focus cycle root. Portions of the
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* hierarchy that are not visible and displayable are skipped.
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*
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* By default, this policy transfers focus down-cycle implicitly.
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* That is, if a forward traversal is requested on a focus cycle root
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* and the focus cycle root has focusable children, the focus will
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* automatically be transfered down to the lower focus cycle.
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*
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* The default implementation of accept accepts only Components that
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* are visible, displayable, enabled and focusable. Derived classes
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* can override these acceptance criteria by overriding accept.
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*
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* @author Michael Koch
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* @author Thomas Fitzsimmons (fitzsim@redhat.com)
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* @since 1.4
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*/
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public class ContainerOrderFocusTraversalPolicy extends FocusTraversalPolicy
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implements Serializable
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{
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/**
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* Compatible to JDK 1.4+
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*/
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static final long serialVersionUID = 486933713763926351L;
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/**
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* True if implicit down cycling is enabled.
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*/
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private boolean implicitDownCycleTraversal = true;
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/**
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* Creates the <code>ContainerOrderFocusTraversalPolicy</code> object.
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*/
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public ContainerOrderFocusTraversalPolicy ()
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{
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// Nothing to do here
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}
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/**
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* Returns the Component that should receive the focus after current.
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* root must be a focus cycle root of current.
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*
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* @param root a focus cycle root of current
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* @param current a (possibly indirect) child of root, or root itself
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*
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* @return the next Component in the focus traversal order for root,
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* or null if no acceptable Component exists.
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*
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* @exception IllegalArgumentException If root is not a focus cycle
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* root of current, or if either root or current is null.
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*/
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public Component getComponentAfter (Container root, Component current)
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{
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if (root == null)
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throw new IllegalArgumentException ("focus cycle root is null");
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if (current == null)
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throw new IllegalArgumentException ("current component is null");
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if (!root.isFocusCycleRoot ())
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throw new IllegalArgumentException ("root is not a focus cycle root");
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Container ancestor = current.getFocusCycleRootAncestor ();
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Container prevAncestor = ancestor;
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while (ancestor != root)
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{
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ancestor = current.getFocusCycleRootAncestor ();
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if (ancestor == prevAncestor)
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{
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// We've reached the top focus cycle root ancestor. Check
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// if it is root.
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if (ancestor != root)
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throw new IllegalArgumentException ("the given container is not"
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+ " a focus cycle root of the"
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+ " current component");
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else
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break;
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}
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prevAncestor = ancestor;
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}
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// FIXME: is this the right thing to do here? It moves the context
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// for traversal up one focus traversal cycle. We'll need a test
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// for this.
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if ((Component) root == current)
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root = current.getFocusCycleRootAncestor ();
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// Check if we've reached the top of the component hierarchy. If
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// so then we want to loop around to the first component in the
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// focus traversal cycle.
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if (current instanceof Window)
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return getFirstComponent ((Container) current);
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Container parent = current.getParent ();
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synchronized (parent.getTreeLock ())
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{
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Component[] components = parent.getComponents ();
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int componentIndex = 0;
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int numComponents = parent.getComponentCount ();
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// Find component's index.
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for (int i = 0; i < numComponents; i++)
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{
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if (components[i] == current)
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componentIndex = i;
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}
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// Search forward for the next acceptable component.
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for (int i = componentIndex + 1; i < numComponents; i++)
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{
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if (accept (components[i]))
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return components[i];
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if (components[i] instanceof Container)
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{
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Component result = getFirstComponent ((Container) components[i]);
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if (result != null
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&& implicitDownCycleTraversal)
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return result;
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}
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}
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// No focusable components after current in its Container. So go
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// to the next Component after current's Container (parent).
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Component result = getComponentAfter (root, parent);
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return result;
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}
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}
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/**
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* Returns the Component that should receive the focus before
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* <code>current</code>. <code>root</code> must be a focus cycle
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* root of current.
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*
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* @param root a focus cycle root of current
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* @param current a (possibly indirect) child of root, or root itself
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*
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* @return the previous Component in the focus traversal order for
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* root, or null if no acceptable Component exists.
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*
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* @exception IllegalArgumentException If root is not a focus cycle
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* root of current, or if either root or current is null.
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*/
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public Component getComponentBefore (Container root, Component current)
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{
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if (root == null)
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throw new IllegalArgumentException ("focus cycle root is null");
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if (current == null)
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throw new IllegalArgumentException ("current component is null");
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if (!root.isFocusCycleRoot ())
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throw new IllegalArgumentException ("root is not a focus cycle root");
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Container ancestor = current.getFocusCycleRootAncestor ();
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Container prevAncestor = ancestor;
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while (ancestor != root)
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{
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ancestor = current.getFocusCycleRootAncestor ();
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if (ancestor == prevAncestor)
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{
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// We've reached the top focus cycle root ancestor. Check
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// if it is root.
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if (ancestor != root)
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throw new IllegalArgumentException ("the given container is not"
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+ " a focus cycle root of the"
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+ " current component");
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else
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break;
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}
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prevAncestor = ancestor;
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}
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// FIXME: is this the right thing to do here? It moves the context
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// for traversal up one focus traversal cycle. We'll need a test
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// for this.
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if ((Component) root == current)
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root = current.getFocusCycleRootAncestor ();
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// Check if we've reached the top of the component hierarchy. If
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// so then we want to loop around to the last component in the
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// focus traversal cycle.
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if (current instanceof Window)
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return getLastComponent ((Container) current);
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Container parent = current.getParent ();
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synchronized (parent.getTreeLock ())
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{
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Component[] components = parent.getComponents ();
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int componentIndex = 0;
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int numComponents = parent.getComponentCount ();
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// Find component's index.
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for (int i = 0; i < numComponents; i++)
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{
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if (components[i] == current)
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componentIndex = i;
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}
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// Search backward for the next acceptable component.
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for (int i = componentIndex - 1; i >= 0; i--)
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{
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if (accept (components[i]))
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return components[i];
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if (components[i] instanceof Container)
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{
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Component result = getLastComponent ((Container) components[i]);
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if (result != null)
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return result;
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}
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}
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// No focusable components before current in its Container. So go
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// to the previous Component before current's Container (parent).
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Component result = getComponentBefore (root, parent);
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return result;
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}
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}
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/**
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* Returns the first Component of root that should receive the focus.
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*
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* @param root a focus cycle root
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*
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* @return the first Component in the focus traversal order for
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* root, or null if no acceptable Component exists.
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*
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* @exception IllegalArgumentException If root is null.
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*/
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public Component getFirstComponent(Container root)
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{
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if (root == null)
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throw new IllegalArgumentException ();
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if (!root.isVisible ()
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|| !root.isDisplayable ())
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return null;
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if (accept (root))
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return root;
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Component[] componentArray = root.getComponents ();
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for (int i = 0; i < componentArray.length; i++)
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{
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Component component = componentArray [i];
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if (accept (component))
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return component;
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if (component instanceof Container)
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{
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Component result = getFirstComponent ((Container) component);
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if (result != null)
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return result;
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}
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}
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return null;
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}
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/**
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* Returns the last Component of root that should receive the focus.
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*
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* @param root a focus cycle root
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*
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* @return the last Component in the focus traversal order for
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* root, or null if no acceptable Component exists.
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*
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* @exception IllegalArgumentException If root is null.
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*/
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public Component getLastComponent (Container root)
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{
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if (root == null)
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throw new IllegalArgumentException ();
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if (!root.isVisible ()
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|| !root.isDisplayable ())
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return null;
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if (accept (root))
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return root;
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Component[] componentArray = root.getComponents ();
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for (int i = componentArray.length - 1; i >= 0; i--)
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{
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Component component = componentArray [i];
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if (accept (component))
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return component;
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if (component instanceof Container)
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{
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Component result = getLastComponent ((Container) component);
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if (result != null)
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return result;
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}
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}
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return null;
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}
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/**
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* Returns the default Component of root that should receive the focus.
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*
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* @param root a focus cycle root
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*
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* @return the default Component in the focus traversal order for
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* root, or null if no acceptable Component exists.
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*
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* @exception IllegalArgumentException If root is null.
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*/
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public Component getDefaultComponent (Container root)
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{
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return getFirstComponent (root);
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}
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/**
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* Set whether or not implicit down cycling is enabled. If it is,
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* then initiating a forward focus traversal operation onto a focus
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* cycle root, the focus will be implicitly transferred into the
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* root container's focus cycle.
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*
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* @param value the setting for implicit down cycling
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*/
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public void setImplicitDownCycleTraversal (boolean value)
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{
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implicitDownCycleTraversal = value;
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}
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/**
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* Check whether or not implicit down cycling is enabled. If it is,
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* then initiating a forward focus traversal operation onto a focus
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* cycle root, the focus will be implicitly transferred into the
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* root container's focus cycle.
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*
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* @return true if the focus will be transferred down-cycle
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* implicitly
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*/
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public boolean getImplicitDownCycleTraversal ()
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{
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return implicitDownCycleTraversal;
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}
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/**
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* Check whether the given Component is an acceptable target for the
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* keyboard input focus.
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*
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* @param current the Component to check
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*
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* @return true if current is acceptable, false otherwise
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*/
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protected boolean accept (Component current)
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{
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return (current.visible
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&& current.isDisplayable ()
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&& current.enabled
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&& current.focusable);
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}
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}
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