Whether or not to perform an "implicit DownCycle" when selecting * successor components within a focus cycle.
* *When this is true, requesting the "next" component following a * component which is a focus cycle root (and, necessarily, a container) * will enter the focus cycle root of that container, and return its * default focus.
* *When this property is false, requesting the "next" component will * simply advance within the containing focus cycle, subject to the * {@link #comparator} order and the {@link #accept} judgment.
* * @see #getImplicitDownCycleTraversal() */ boolean implicitDownCycleTraversal = true; /** * Creates a newSortingFocusTraversalPolicy with no
* comparator set.
*/
protected SortingFocusTraversalPolicy()
{
// Do nothing here.
}
/**
* Creates a new SortingFocusTraversalPolicy with the given
* comparator set.
*
* @param comparator the comparator to set
*/
public SortingFocusTraversalPolicy(Comparator comparator)
{
this.comparator = comparator;
}
/**
* Decide whether a component is an acceptable focus owner.
*
* @param comp The component which is a candidate for focus ownership.
*
* @return true if the component is focusable, displayable, visible, and
* enabled; otherwise false
*/
protected boolean accept(Component comp)
{
return (comp.isVisible()
&& comp.isDisplayable()
&& comp.isEnabled()
&& comp.isFocusable());
}
/**
* Get the current value of the {@link #comparator} property.
*
* @return the current value of the property
*
* @see #setComparator
*/
protected Comparator getComparator()
{
return comparator;
}
/**
* Set the current value of the {@link #comparator} property.
*
* @param comparator the new value of the property
*
* @see #getComparator
*/
protected void setComparator(Comparator comparator)
{
this.comparator = comparator;
}
private TreeSet getSortedCycle(Container root, TreeSet set)
{
if (set == null)
set = (getComparator() == null
? new TreeSet()
: new TreeSet(getComparator()));
if (root != null)
{
Component[] comps = root.getComponents();
for (int i = 0; i < comps.length; ++i)
{
Component c = comps[i];
if (accept(c))
set.add(c);
if (c instanceof Container)
getSortedCycle((Container) c, set);
}
}
return set;
}
/**
* Return the component which follows the specified component in this
* focus cycle, relative to the order imposed by {@link
* #comparator}. Candidate components are only considered if they are
* accepted by the {@link #accept} method.
*
* If {@link #getImplicitDownCycleTraversal} is true and the
* comp is a focus cycle root, an "implicit DownCycle"
* occurs and the method returns the
* getDefaultComponent(comp).
*
* @param root the focus cycle root to search for a successor within
* @param comp the component to search for the successor of
*
* @return the component following the specified component under
* the specified root, or null if no such component is found
*
* @throws IllegalArgumentException if either argument is null, or
* if the root is not a focus cycle root of the component
*/
public Component getComponentAfter(Container root,
Component comp)
{
if (comp == null || root == null || !comp.isFocusCycleRoot(root))
throw new IllegalArgumentException();
if (getImplicitDownCycleTraversal()
&& comp instanceof Container
&& ((Container)comp).isFocusCycleRoot())
{
return getDefaultComponent((Container) comp);
}
TreeSet set = getSortedCycle(root, null);
Iterator i = set.iterator();
while (i.hasNext())
{
Component c = (Component) i.next();
if (c != null && c.equals(comp))
{
if (i.hasNext())
return (Component) i.next();
break;
}
}
return null;
}
/**
* Return the component which precedes the specified component in this
* focus cycle, relative to the order imposed by {@link
* #comparator}. Candidate components are only considered if they are
* accepted by the {@link #accept} method.
*
* @param root the focus cycle root to search for a predecessor within
* @param comp the component to search for the predecessor of
*
* @return the component preceding the specified component under the
* specified root, or null if no such component is found
*
* @throws IllegalArgumentException if either argument is null, or
* if the root is not a focus cycle root of the component
*/
public Component getComponentBefore(Container root,
Component comp)
{
if (comp == null || root == null || !comp.isFocusCycleRoot(root))
throw new IllegalArgumentException();
TreeSet set = getSortedCycle(root, null);
Iterator i = set.iterator();
Component prev = null;
while (i.hasNext())
{
Component c = (Component) i.next();
if (c != null && c.equals(comp))
break;
prev = c;
}
return prev;
}
/**
* Return the default component of root, which is by default
* the same as the first component, returned by {@link
* #getFirstComponent}.
*
* @param root the focus cycle root to return the default component of
*
* @return the default focus component for root
*
* @throws IllegalArgumentException if root is null
*/
public Component getDefaultComponent(Container root)
{
return getFirstComponent(root);
}
/**
* Return the first focusable component of the focus cycle root
* comp under the ordering imposed by the {@link
* #comparator} property. Candidate components are only considered if
* they are accepted by the {@link #accept} method.
*
* @param root the focus cycle root to search for the first component of
*
* @return the first component under root, or null if
* no components are found.
*
* @throws IllegalArgumentException if root is null
*/
public Component getFirstComponent(Container root)
{
if (root == null)
throw new IllegalArgumentException();
TreeSet set = getSortedCycle(root, null);
Iterator i = set.iterator();
if (i.hasNext())
return (Component) i.next();
return null;
}
/**
* Return the last focusable component of the focus cycle root
* comp under the ordering imposed by the {@link
* #comparator} property. Candidate components are only considered if
* they are accepted by the {@link #accept} method.
*
* @param root the focus cycle root to search for the last component of
*
* @return the last component under root, or null if
* no components are found.
*
* @throws IllegalArgumentException if root is null
*/
public Component getLastComponent(Container root)
{
if (root == null)
throw new IllegalArgumentException();
TreeSet set = getSortedCycle(root, null);
Iterator i = set.iterator();
Component last = null;
while (i.hasNext())
last = (Component) i.next();
return last;
}
/**
* Return the current value of the {@link #implicitDownCycleTraversal}
* property.
*
* @return the current value of the property
*
* @see #setImplicitDownCycleTraversal
*/
public boolean getImplicitDownCycleTraversal()
{
return implicitDownCycleTraversal;
}
/**
* Set the current value of the {@link #implicitDownCycleTraversal}
* property.
*
* @param down the new value of the property
*
* @see #getImplicitDownCycleTraversal
*/
public void setImplicitDownCycleTraversal(boolean down)
{
implicitDownCycleTraversal = down;
}
}