JTabbedPane TabComponent 默认选项卡突出显示

Question

我对 swing 中的自定义选项卡组件有疑问。

以下代码将添加3个自定义标签组件：

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);
  }
}

现在的问题是默认选项卡行为停止工作。通常，当您将鼠标移到选项卡上时，它会通过更改背景颜色自动突出显示。但是一旦JTextField 被击中，选项卡很可能会注册一个mouseExited Event 并停止突出显示选项卡。因此，当您将鼠标移到选项卡上时，选项卡会闪烁。

我现在的问题是： 有没有办法（不实现新的突出显示机制）突出显示自定义 tabComponent 所在的选项卡？

Answer 1

• 这是我的尝试：
  • 使用JLayer 将MouseMotionEvent 从选项卡分派到父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));
  }
}