import java.awt.*;

import java.awt.event.*;

import java.util.*;

import javax.swing.*;

import javax.swing.event.*;

/**

* The <code>RXCardLayout</code> provides some extensions to the

* CardLayout class. In particular adding support for:

*

* a) setting focus on the card when it is displayed

* b) getting the currently displayed Card

* c) Next and Previous Actions

*

* This added support will only work when a JComponent is added as a Card.

*/

public class RXCardLayout extends CardLayout implements HierarchyListener

{

private ArrayList<JComponent> cards = new ArrayList<JComponent>();

private JComponent firstCard;

private JComponent lastCard;

private JComponent currentCard;

private boolean isRequestFocusOnCard = true;

private Action nextAction;

private Action previousAction;

/**

* Creates a new card layout with gaps of size zero.

*/

public RXCardLayout()

{

this(0, 0);

}

/**

* Creates a new card layout with the specified horizontal and

* vertical gaps. The horizontal gaps are placed at the left and

* right edges. The vertical gaps are placed at the top and bottom

* edges.

* @param hgap the horizontal gap.

* @param vgap the vertical gap.

*/

public RXCardLayout(int hgap, int vgap)

{

super(hgap, vgap);

}

// Overridden methods

public void addLayoutComponent(Component comp, Object constraints)

{

super.addLayoutComponent(comp, constraints);

if (! (comp instanceof JComponent)) return;

JComponent component = (JComponent)comp;

cards.add(component);

if (firstCard == null)

firstCard = component;

lastCard = component;

component.addHierarchyListener(this);

}

public void removeLayoutComponent(Component comp)

{

super.removeLayoutComponent(comp);

if (! (comp instanceof JComponent)) return;

JComponent component = (JComponent)comp;

component.removeHierarchyListener(this);

cards.remove(component);

if (component.equals(firstCard)

&& cards.size() > 0)

{

firstCard = cards.get(0);

}

if (component.equals(lastCard)

&& cards.size() > 0)

{

lastCard = cards.get(cards.size() - 1);

}

}

// New methods

public JComponent getCurrentCard()

{

return currentCard;

}

public Action getNextAction()

{

return getNextAction("Next");

}

public Action getNextAction(String name)

{

if (nextAction == null)

{

nextAction = new CardAction(name, true);

nextAction.putValue(Action.MNEMONIC_KEY, (int)name.charAt(0));

nextAction.setEnabled( isNextCardAvailable() );

}

return nextAction;

}

public Action getPreviousAction()

{

return getPreviousAction("Previous");

}

public Action getPreviousAction(String name)

{

if (previousAction == null)

{

previousAction = new CardAction(name, false);

previousAction.putValue(Action.MNEMONIC_KEY, (int)name.charAt(0));

previousAction.setEnabled( isNextCardAvailable() );

}

return previousAction;

}

public boolean isNextCardAvailable()

{

return currentCard != lastCard;

}

public boolean isPreviousCardAvailable()

{

return currentCard != firstCard;

}

public boolean isRequestFocusOnCard()

{

return isRequestFocusOnCard;

}

public void setRequestFocusOnCard(boolean isRequestFocusOnCard)

{

this.isRequestFocusOnCard = isRequestFocusOnCard;

}

// Implement Hierarchy Listener

@Override

public void hierarchyChanged(HierarchyEvent e)

{

JComponent component = (JComponent)e.getSource();

if ((HierarchyEvent.SHOWING_CHANGED & e.getChangeFlags()) != 0

&& component.isShowing())

{

currentCard = component;

if (isRequestFocusOnCard)

currentCard.transferFocus();

if (nextAction != null)

nextAction.setEnabled( isNextCardAvailable() );

if (previousAction != null)

previousAction.setEnabled( isPreviousCardAvailable() );

}

}

class CardAction extends AbstractAction

{

private boolean isNext;

public CardAction(String text, boolean isNext)

{

super(text);

this.isNext = isNext;

putValue( Action.SHORT_DESCRIPTION, getValue(Action.NAME) );

}

public void actionPerformed(ActionEvent e)

{

Container parent = getCurrentCard().getParent();

if (isNext)

next(parent);

else

previous(parent);

}

}

}