Closable Tab in JTabbedPane

Question

Hi
I trying to develop a Closable Tab in JTabbedPane. The close button should appear after/before the tab title all the time (like in JBuilder IDE).
I know the trick where close button appears when the mouse is in that area, but i want it to be displayed all the time irrespective of the mouse position.
How i should be able to create this component??
I am very new to swing please help...
Thanks for your help...
-Vinod

Answer 1

Thanks Stas,
Your code was really helpfull.
I've improved it a litte bit. So I'd like to share It.
To use it, just create a ClosableTabbedPane.
If you need to change the default action (remove the tab) then use the method setCloseTabAction(CloseTabAction) to change the action.
Cheers,
Rafa
================================
The TabbedPaneUI
================================
import java.awt.Color;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.plaf.basic.BasicTabbedPaneUI;
public class ClosableTabbedPaneUI extends BasicTabbedPaneUI
     public final static int BUTTON_SIZE = 12;
     public final static int BORDER_SIZE = 3;
     public ClosableTabbedPaneUI()
          super();
     protected void paintTab(Graphics g, int tabPlacement, Rectangle[] rects, int tabIndex, Rectangle iconRect, Rectangle textRect)
          super.paintTab(g,tabPlacement,rects,tabIndex,iconRect,textRect);
          Rectangle rect=rects[tabIndex];
          int yPosition = (rect.height-BUTTON_SIZE)/2;
          int xPosition = rect.x+rect.width-Math.round(BUTTON_SIZE*1.5f);
          g.setColor(Color.BLACK);
          g.drawRect(xPosition,yPosition,BUTTON_SIZE,BUTTON_SIZE);
          g.setColor(Color.black);
          g.drawLine(xPosition+BORDER_SIZE,yPosition+BORDER_SIZE,xPosition+BUTTON_SIZE-BORDER_SIZE,yPosition-BORDER_SIZE+BUTTON_SIZE);
          g.drawLine(xPosition+BORDER_SIZE,yPosition-BORDER_SIZE+BUTTON_SIZE,xPosition+BUTTON_SIZE-BORDER_SIZE,yPosition+BORDER_SIZE);
     protected int getTabLabelShiftX(int tabPlacement, int tabIndex, boolean isSelected)
          return super.getTabLabelShiftX(tabPlacement, tabIndex, isSelected)-BUTTON_SIZE;     
     protected int calculateTabWidth(int tabPlacement, int tabIndex, FontMetrics metrics)
          return super.calculateTabWidth(tabPlacement,tabIndex,metrics)+BUTTON_SIZE;
     protected MouseListener createMouseListener()
          return new MyMouseHandler();
     class MyMouseHandler extends MouseHandler
          public MyMouseHandler()
               super();
          public void mouseClicked(MouseEvent e)
               int x=e.getX();
               int y=e.getY();
               int tabIndex=-1;
               int tabCount = tabPane.getTabCount();
               for (int i = 0; i < tabCount; i++)
                    if (rects[ i ].contains(x, y))
                         tabIndex= i;
                         break;
               if (tabIndex >= 0)
                    Rectangle rect = rects[tabIndex];
                    int yPosition = (rect.height-BUTTON_SIZE)/2;
                    int xPosition = rect.x+rect.width-Math.round(BUTTON_SIZE*1.5f);
                    if( new Rectangle(xPosition,yPosition,BUTTON_SIZE,BUTTON_SIZE).contains(x,y))
                         if( tabPane instanceof ClosableTabbedPane )
                              ClosableTabbedPane closableTabbedPane = (ClosableTabbedPane)tabPane;
                              CloseTabAction closeTabAction = closableTabbedPane.getCloseTabAction();
                              if(closeTabAction != null)
                                   closeTabAction.act(closableTabbedPane, tabIndex);
                         else
                              // If somebody use this class as UI like setUI(new ClosableTabbedPaneUI())
                              tabPane.removeTabAt(tabIndex);
======================================
The Closable TabbedPane
======================================
public class ClosableTabbedPane extends JTabbedPane
     private CloseTabAction closeTabAction = null;
     public ClosableTabbedPane()
          super();
          init();
     public ClosableTabbedPane(int arg0)
          super(arg0);
          init();
     public ClosableTabbedPane(int arg0, int arg1)
          super(arg0, arg1);
          init();
     private void init()
          setUI(new ClosableTabbedPaneUI());
          closeTabAction = new CloseTabAction()
               public void act(ClosableTabbedPane closableTabbedPane, int tabIndex)
                    closableTabbedPane.removeTabAt(tabIndex);
     public CloseTabAction getCloseTabAction()
          return closeTabAction;
     public void setCloseTabAction(CloseTabAction action)
          closeTabAction = action;
=========================
The Action
=========================
public interface CloseTabAction
     public void act(ClosableTabbedPane closableTabbedPane, int tabIndex);