You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
129 lines
4.5 KiB
129 lines
4.5 KiB
/*
|
|
* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
|
|
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*/
|
|
package java.awt;
|
|
|
|
import java.awt.peer.ComponentPeer;
|
|
|
|
|
|
/**
|
|
* A FocusTraversalPolicy that determines traversal order based on the order
|
|
* of child Components in a Container. From a particular focus cycle root, the
|
|
* policy makes a pre-order traversal of the Component hierarchy, and traverses
|
|
* a Container's children according to the ordering of the array returned by
|
|
* <code>Container.getComponents()</code>. Portions of the hierarchy that are
|
|
* not visible and displayable will not be searched.
|
|
* <p>
|
|
* If client code has explicitly set the focusability of a Component by either
|
|
* overriding <code>Component.isFocusTraversable()</code> or
|
|
* <code>Component.isFocusable()</code>, or by calling
|
|
* <code>Component.setFocusable()</code>, then a DefaultFocusTraversalPolicy
|
|
* behaves exactly like a ContainerOrderFocusTraversalPolicy. If, however, the
|
|
* Component is relying on default focusability, then a
|
|
* DefaultFocusTraversalPolicy will reject all Components with non-focusable
|
|
* peers. This is the default FocusTraversalPolicy for all AWT Containers.
|
|
* <p>
|
|
* The focusability of a peer is implementation-dependent. Sun recommends that
|
|
* all implementations for a particular native platform construct peers with
|
|
* the same focusability. The recommendations for Windows and Unix are that
|
|
* Canvases, Labels, Panels, Scrollbars, ScrollPanes, Windows, and lightweight
|
|
* Components have non-focusable peers, and all other Components have focusable
|
|
* peers. These recommendations are used in the Sun AWT implementations. Note
|
|
* that the focusability of a Component's peer is different from, and does not
|
|
* impact, the focusability of the Component itself.
|
|
* <p>
|
|
* Please see
|
|
* <a href="https://docs.oracle.com/javase/tutorial/uiswing/misc/focus.html">
|
|
* How to Use the Focus Subsystem</a>,
|
|
* a section in <em>The Java Tutorial</em>, and the
|
|
* <a href="../../java/awt/doc-files/FocusSpec.html">Focus Specification</a>
|
|
* for more information.
|
|
*
|
|
* @author David Mendenhall
|
|
*
|
|
* @see Container#getComponents
|
|
* @see Component#isFocusable
|
|
* @see Component#setFocusable
|
|
* @since 1.4
|
|
*/
|
|
public class DefaultFocusTraversalPolicy
|
|
extends ContainerOrderFocusTraversalPolicy
|
|
{
|
|
/*
|
|
* serialVersionUID
|
|
*/
|
|
private static final long serialVersionUID = 8876966522510157497L;
|
|
|
|
/**
|
|
* Determines whether a Component is an acceptable choice as the new
|
|
* focus owner. The Component must be visible, displayable, and enabled
|
|
* to be accepted. If client code has explicitly set the focusability
|
|
* of the Component by either overriding
|
|
* <code>Component.isFocusTraversable()</code> or
|
|
* <code>Component.isFocusable()</code>, or by calling
|
|
* <code>Component.setFocusable()</code>, then the Component will be
|
|
* accepted if and only if it is focusable. If, however, the Component is
|
|
* relying on default focusability, then all Canvases, Labels, Panels,
|
|
* Scrollbars, ScrollPanes, Windows, and lightweight Components will be
|
|
* rejected.
|
|
*
|
|
* @param aComponent the Component whose fitness as a focus owner is to
|
|
* be tested
|
|
* @return <code>true</code> if aComponent meets the above requirements;
|
|
* <code>false</code> otherwise
|
|
*/
|
|
protected boolean accept(Component aComponent) {
|
|
if (!(aComponent.isVisible() && aComponent.isDisplayable() &&
|
|
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;
|
|
}
|
|
}
|
|
}
|
|
|
|
boolean focusable = aComponent.isFocusable();
|
|
if (aComponent.isFocusTraversableOverridden()) {
|
|
return focusable;
|
|
}
|
|
|
|
ComponentPeer peer = aComponent.getPeer();
|
|
return (peer != null && peer.isFocusable());
|
|
}
|
|
}
|