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*
* This code is distributed in the hope that it will be useful, but WITHOUT
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package java.awt;
import java.util.List;
import java.util.ArrayList;
import sun.util.logging.PlatformLogger;
/**
* 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>
* By default, ContainerOrderFocusTraversalPolicy implicitly transfers focus
* down-cycle. That is, during normal forward 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>
* By default, methods of this class will return a Component only if it is
* visible, displayable, enabled, and focusable. Subclasses can modify this
* behavior by overriding the <code>accept</code> method.
* <p>
* This policy takes into account <a
* href="doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus traversal
* policy providers</a>. When searching for first/last/next/previous Component,
* if a focus traversal policy provider is encountered, its focus traversal
* policy is used to perform the search operation.
*
* @author David Mendenhall
*
* @see Container#getComponents
* @since 1.4
*/
public class ContainerOrderFocusTraversalPolicy extends FocusTraversalPolicy
implements java.io.Serializable
{
private static final PlatformLogger log = PlatformLogger.getLogger("java.awt.ContainerOrderFocusTraversalPolicy");
final private int FORWARD_TRAVERSAL = 0;
final private int BACKWARD_TRAVERSAL = 1;
/*
* JDK 1.4 serialVersionUID
*/
private static final long serialVersionUID = 486933713763926351L;
private boolean implicitDownCycleTraversal = true;
/**
* Used by getComponentAfter and getComponentBefore for efficiency. In
* order to maintain compliance with the specification of
* FocusTraversalPolicy, if traversal wraps, we should invoke
* getFirstComponent or getLastComponent. These methods may be overriden in
* subclasses to behave in a non-generic way. However, in the generic case,
* these methods will simply return the first or last Components of the
* sorted list, respectively. Since getComponentAfter and
* getComponentBefore have already built the list before determining
* that they need to invoke getFirstComponent or getLastComponent, the
* list should be reused if possible.
*/
transient private Container cachedRoot;
transient private List<Component> cachedCycle;
/*
* We suppose to use getFocusTraversalCycle & getComponentIndex methods in order
* to divide the policy into two parts:
* 1) Making the focus traversal cycle.
* 2) Traversing the cycle.
* The 1st point assumes producing a list of components representing the focus
* traversal cycle. The two methods mentioned above should implement this logic.
* The 2nd point assumes implementing the common concepts of operating on the
* cycle: traversing back and forth, retrieving the initial/default/first/last
* component. These concepts are described in the AWT Focus Spec and they are
* applied to the FocusTraversalPolicy in general.
* Thus, a descendant of this policy may wish to not reimplement the logic of
* the 2nd point but just override the implementation of the 1st one.
* A striking example of such a descendant is the javax.swing.SortingFocusTraversalPolicy.
*/
/*protected*/ private List<Component> getFocusTraversalCycle(Container aContainer) {
List<Component> cycle = new ArrayList<Component>();
enumerateCycle(aContainer, cycle);
return cycle;
}
/*protected*/ private int getComponentIndex(List<Component> cycle, Component aComponent) {
return cycle.indexOf(aComponent);
}
private void enumerateCycle(Container container, List<Component> cycle) {
if (!(container.isVisible() && container.isDisplayable())) {
return;
}
cycle.add(container);
Component[] components = container.getComponents();
for (int i = 0; i < components.length; i++) {
Component comp = components[i];
if (comp instanceof Container) {
Container cont = (Container)comp;
if (!cont.isFocusCycleRoot() && !cont.isFocusTraversalPolicyProvider()) {
enumerateCycle(cont, cycle);
continue;
}
}
cycle.add(comp);
}
}
private Container getTopmostProvider(Container focusCycleRoot, Component aComponent) {
Container aCont = aComponent.getParent();
Container ftp = null;
while (aCont != focusCycleRoot && aCont != null) {
if (aCont.isFocusTraversalPolicyProvider()) {
ftp = aCont;
}
aCont = aCont.getParent();
}
if (aCont == null) {
return null;
}
return ftp;
}
/*
* Checks if a new focus cycle takes place and returns a Component to traverse focus to.
* @param comp a possible focus cycle root or policy provider
* @param traversalDirection the direction of the traversal
* @return a Component to traverse focus to if {@code comp} is a root or provider
* and implicit down-cycle is set, otherwise {@code null}
*/
private Component getComponentDownCycle(Component comp, int traversalDirection) {
Component retComp = null;
if (comp instanceof Container) {
Container cont = (Container)comp;
if (cont.isFocusCycleRoot()) {
if (getImplicitDownCycleTraversal()) {
retComp = cont.getFocusTraversalPolicy().getDefaultComponent(cont);
if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Transfered focus down-cycle to " + retComp +
" in the focus cycle root " + cont);
}
} else {
return null;
}
} else if (cont.isFocusTraversalPolicyProvider()) {
retComp = (traversalDirection == FORWARD_TRAVERSAL ?
cont.getFocusTraversalPolicy().getDefaultComponent(cont) :
cont.getFocusTraversalPolicy().getLastComponent(cont));
if (retComp != null && log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Transfered focus to " + retComp + " in the FTP provider " + cont);
}
}
}
return retComp;
}
/**
* Returns the Component that should receive the focus after aComponent.
* aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.
* <p>
* By default, ContainerOrderFocusTraversalPolicy implicitly transfers
* focus down-cycle. That is, during normal forward 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="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 focus traversal policy provider, or if either aContainer or
* aComponent is null
*/
public Component getComponentAfter(Container aContainer, Component aComponent) {
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Searching in " + aContainer + " for component after " + aComponent);
}
if (aContainer == null || aComponent == null) {
throw new IllegalArgumentException("aContainer and aComponent cannot be null");
}
if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");
} else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
}
synchronized(aContainer.getTreeLock()) {
if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
return null;
}
// Before all the ckecks below we first see if it's an FTP provider or a focus cycle root.
// If it's the case just go down cycle (if it's set to "implicit").
Component comp = getComponentDownCycle(aComponent, FORWARD_TRAVERSAL);
if (comp != null) {
return comp;
}
// See if the component is inside of policy provider.
Container provider = getTopmostProvider(aContainer, aComponent);
if (provider != null) {
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Asking FTP " + provider + " for component after " + aComponent);
}
// FTP knows how to find component after the given. We don't.
FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
Component afterComp = policy.getComponentAfter(provider, aComponent);
// Null result means that we overstepped the limit of the FTP's cycle.
// In that case we must quit the cycle, otherwise return the component found.
if (afterComp != null) {
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### FTP returned " + afterComp);
}
return afterComp;
}
aComponent = provider;
}
List<Component> cycle = getFocusTraversalCycle(aContainer);
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Cycle is " + cycle + ", component is " + aComponent);
}
int index = getComponentIndex(cycle, aComponent);
if (index < 0) {
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
}
return getFirstComponent(aContainer);
}
for (index++; index < cycle.size(); index++) {
comp = cycle.get(index);
if (accept(comp)) {
return comp;
} else if ((comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null) {
return comp;
}
}
if (aContainer.isFocusCycleRoot()) {
this.cachedRoot = aContainer;
this.cachedCycle = cycle;
comp = getFirstComponent(aContainer);
this.cachedRoot = null;
this.cachedCycle = null;
return comp;
}
}
return null;
}
/**
* Returns the Component that should receive the focus before aComponent.
* aContainer must be a focus cycle root of aComponent or a <a
* href="doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus traversal policy
* provider</a>.
*
* @param aContainer a focus cycle root of aComponent or 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 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");
}
if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");
} else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
}
synchronized(aContainer.getTreeLock()) {
if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
return null;
}
// See if the component is inside of policy provider.
Container provider = getTopmostProvider(aContainer, aComponent);
if (provider != null) {
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Asking FTP " + provider + " for component after " + aComponent);
}
// FTP knows how to find component after the given. We don't.
FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
Component beforeComp = policy.getComponentBefore(provider, aComponent);
// Null result means that we overstepped the limit of the FTP's cycle.
// In that case we must quit the cycle, otherwise return the component found.
if (beforeComp != null) {
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### FTP returned " + beforeComp);
}
return beforeComp;
}
aComponent = provider;
// If the provider is traversable it's returned.
if (accept(aComponent)) {
return aComponent;
}
}
List<Component> cycle = getFocusTraversalCycle(aContainer);
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Cycle is " + cycle + ", component is " + aComponent);
}
int index = getComponentIndex(cycle, aComponent);
if (index < 0) {
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
}
return getLastComponent(aContainer);
}
Component comp = null;
Component tryComp = null;
for (index--; index>=0; index--) {
comp = cycle.get(index);
if (comp != aContainer && (tryComp = getComponentDownCycle(comp, BACKWARD_TRAVERSAL)) != null) {
return tryComp;
} else if (accept(comp)) {
return comp;
}
}
if (aContainer.isFocusCycleRoot()) {
this.cachedRoot = aContainer;
this.cachedCycle = cycle;
comp = getLastComponent(aContainer);
this.cachedRoot = null;
this.cachedCycle = null;
return comp;
}
}
return null;
}
/**
* 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 the focus cycle root or 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) {
List<Component> cycle;
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Getting first component in " + aContainer);
}
if (aContainer == null) {
throw new IllegalArgumentException("aContainer cannot be null");
}
synchronized(aContainer.getTreeLock()) {
if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
return null;
}
if (this.cachedRoot == aContainer) {
cycle = this.cachedCycle;
} else {
cycle = getFocusTraversalCycle(aContainer);
}
if (cycle.size() == 0) {
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Cycle is empty");
}
return null;
}
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Cycle is " + cycle);
}
for (Component comp : cycle) {
if (accept(comp)) {
return comp;
} else if (comp != aContainer &&
(comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null)
{
return comp;
}
}
}
return null;
}
/**
* 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 the focus cycle root or 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) {
List<Component> cycle;
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Getting last component in " + aContainer);
}
if (aContainer == null) {
throw new IllegalArgumentException("aContainer cannot be null");
}
synchronized(aContainer.getTreeLock()) {
if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
return null;
}
if (this.cachedRoot == aContainer) {
cycle = this.cachedCycle;
} else {
cycle = getFocusTraversalCycle(aContainer);
}
if (cycle.size() == 0) {
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Cycle is empty");
}
return null;
}
if (log.isLoggable(PlatformLogger.Level.FINE)) {
log.fine("### Cycle is " + cycle);
}
for (int i= cycle.size() - 1; i >= 0; i--) {
Component comp = cycle.get(i);
if (accept(comp)) {
return comp;
} else if (comp instanceof Container && comp != aContainer) {
Container cont = (Container)comp;
if (cont.isFocusTraversalPolicyProvider()) {
return cont.getFocusTraversalPolicy().getLastComponent(cont);
}
}
}
}
return null;
}
/**
* Returns the default Component to focus. This Component will be the first
* to receive focus when traversing down into a new focus traversal cycle
* rooted at aContainer. The default implementation of this method
* returns the same Component as <code>getFirstComponent</code>.
*
* @param aContainer the focus cycle root or focus traversal policy provider whose default
* Component is to be returned
* @return the default Component in the traversal cycle of aContainer,
* or null if no suitable Component can be found
* @see #getFirstComponent
* @throws IllegalArgumentException if aContainer is null
*/
public Component getDefaultComponent(Container aContainer) {
return getFirstComponent(aContainer);
}
/**
* Sets whether this ContainerOrderFocusTraversalPolicy transfers focus
* down-cycle implicitly. If <code>true</code>, during normal forward focus
* traversal, the Component traversed after a focus cycle root will be the
* focus-cycle-root's default Component to focus. If <code>false</code>,
* the next Component in the focus traversal cycle rooted at the specified
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