CODEWITHSUNDEEP
javaswingtabsjtextfieldjtabbedpane
Code Monkey
Code Monkey

Reputation: 78

JTabbedPane TabComponent default tab highlighting

I have a question regarding custom tab components in swing.

The following code will add 3 custom tab components:

public class TabbedExample extends JPanel {
  public static void main(String... args) {
    EventQueue.invokeLater(new Runnable() {
      @Override public void run() {
        createUI();
      }
    }
  }
  public static void createUI() {
    try {
      for(LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
        if("Nimbus".equals(info.getName())) {
          UIManager.setLookAndFeel(info.getClassName());
          break;
        }
      }
    } catch(Exception e) {}
    JFrame frame = new JFrame("Tab Test");
    frame.setMinimumSize(new Dimension(256,200));
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    frame.getContentPane().add(new TabbedExample());
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }

  public TabbedExample() {
    super(new BorderLayout());

    JTabbedPane pane = new JTabbedPane();
    pane.addTab("tmp", new JTextField());
    pane.addTab("tmp", new JTextField());
    pane.addTab("tmp", new JTextField());
    for(int i = 0; i < 3; i++) {
      JPanel tabPanel = new JPanel();
      tabPanel.setBackground(new Color(0,0,0,0));
      tabPanel.setLayout(new BoxLayout(tabPanel, BoxLayout.X_AXIS));
      JTextField textField = new JTextField("Tab " + i);
      textField.setOpaque(false);
      textField.setBackground(new Color(0,0,0,0));
      textField.setBorder(new EmptyBorder(0,0,0,0));
      tabPanel.add(label);
      tabPanel.add(new JButton(Integer.toString(i)));
      pane.setTabComponentAt(i, tabPanel);
    }
    add(pane, BorderLayout.CENTER);
  }
}

the problem now is that the default tab behaviour stops working. normally, when you move your mouse over a tab, it automagically gets highlight by changing the background color. but as soon as the JTextField is hit, the tab most likely registers a mouseExited Event and stops the highlighting of the tab. so the tab will flicker when you move your mouse over the tab.

my question now is: Is there a way (without implementing a new highlighting mechanism) to highlight the tab, where the custom tabComponent is located?

Upvotes: 2

Views: 426

Answers (1)

aterai
aterai

Reputation: 9833

  • Here's my attempt:
    • Using a JLayer to dispatch the MouseMotionEvent from the tabs to the parent JTabbedPane:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.plaf.*;

public class TabbedExample2 extends JPanel {
  public static void main(String... args) {
    EventQueue.invokeLater(() -> {
      createUI();
    });
  }
  public static void createUI() {
    try {
      for (UIManager.LookAndFeelInfo laf: UIManager.getInstalledLookAndFeels()) {
        if ("Nimbus".equals(laf.getName())) {
          UIManager.setLookAndFeel(laf.getClassName());
        }
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
    JFrame frame = new JFrame("Tab Test");
    frame.setMinimumSize(new Dimension(256, 200));
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    frame.getContentPane().add(new TabbedExample2());
    frame.setSize(320, 240);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }

  public TabbedExample2() {
    super(new BorderLayout());
    JTabbedPane pane = new JTabbedPane();
    pane.addTab("tmp", new JTextField(16));
    pane.addTab("tmp", new JTextField(16));
    pane.addTab("tmp", new JTextField(16));
    for (int i = 0; i < 3; i++) {
      JPanel tabPanel = new JPanel();
      tabPanel.setOpaque(false);
      //tabPanel.setBackground(new Color(0,0,0,0));
      tabPanel.setLayout(new BoxLayout(tabPanel, BoxLayout.X_AXIS));
      JTextField textField = new JTextField("Tab " + i);
      //textField.setBackground(new Color(0,0,0,0));
      //textField.setBorder(new EmptyBorder(0,0,0,0));
      //tabPanel.add(label); //???
      tabPanel.add(textField);
      tabPanel.add(new JButton(Integer.toString(i)));
      pane.setTabComponentAt(
          i, new JLayer<JPanel>(tabPanel, new DispatchEventLayerUI()));
    }
    add(pane);
  }
}

class DispatchEventLayerUI extends LayerUI<JPanel> {
  @Override
  public void installUI(JComponent c) {
    super.installUI(c);
    if (c instanceof JLayer) {
      ((JLayer) c).setLayerEventMask(AWTEvent.MOUSE_MOTION_EVENT_MASK);
      //TEST:
      //((JLayer) c).setLayerEventMask(
      //    AWTEvent.MOUSE_EVENT_MASK | AWTEvent.MOUSE_MOTION_EVENT_MASK);
    }
  }
  @Override
  public void uninstallUI(JComponent c) {
    if (c instanceof JLayer) {
      ((JLayer) c).setLayerEventMask(0);
    }
    super.uninstallUI(c);
  }
//   //TEST:
//   @Override
//   protected void processMouseEvent(MouseEvent e, JLayer<? extends JPanel> l) {
//     dispatchEvent(e);
//   }
  @Override
  protected void processMouseMotionEvent(MouseEvent e, JLayer<? extends JPanel> l) {
    dispatchEvent(e);
  }
  private void dispatchEvent(MouseEvent e) {
    Component src = e.getComponent();
    Container tgt = SwingUtilities.getAncestorOfClass(JTabbedPane.class, src);
    tgt.dispatchEvent(SwingUtilities.convertMouseEvent(src, e, tgt));
  }
}

Upvotes: 2

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