Java JPopupMenu bug

Question

似乎我在Java中发现了一个bug：

我需要创建具有透明背景的JFrame，现在我需要显示一些用户操作的JPopupMenu。当JPopupMenu完全封装在JFrame中时，它工作得很好。但是，当JPopupMenu部分在JFrame之外时，没有一个项目是可见的。

SSCCE:

public class PopupTest {
    public static void main(String[] a) {
        final JFrame frame = new JFrame();
        frame.setSize(500, 500);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        final JPanel panel = new JPanel(new BorderLayout());
        panel.setBorder(BorderFactory.createLineBorder(Color.RED));

        panel.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                if (e.getButton() == MouseEvent.BUTTON3) {
                    JPopupMenu menu = new JPopupMenu();
                    for (int i = 0 ; i < 10; i++) {
                        menu.add(String.valueOf(i));
                    }

                    menu.show(panel, e.getX(), e.getY());
                }
            }
        });
        frame.setContentPane(panel);
        frame.setUndecorated(true);
        frame.setBackground(new Color(50, 50, 50, 200));

        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                frame.setVisible(true);
            }
        });
    }
}

有人知道怎么解决这个问题吗？

PS: JDK 7u40，Win x64

Answer 1

这是Oracle JDK 7中的bug (顺便说一下，它不能在Open 7中复制)。

要解决这个问题，您可以做一个解决方案(是的，这只是一个解决方案，不能保证它不会与某些Java更新中断)，这样为弹出菜单创建的窗口一出现就会变得不透明，然后它就会被正确显示。至少现在是这样。以下是如何在7和更高版本中这样做：

PropertyChangeListener propertyChangeListener = new PropertyChangeListener ()
{
    @Override
    public void propertyChange ( final PropertyChangeEvent evt )
    {
        if ( evt.getNewValue () == Boolean.TRUE )
        {
            // Retrieving popup menu window (we won't find it if it is inside of parent frame)
            final Window ancestor = getWindowAncestor ( popupMenu );
            if ( ancestor != null && ancestor.getClass ().getCanonicalName ().endsWith ( "HeavyWeightWindow" ) )
            {
                // Checking that parent window for our window is opaque, only then setting opacity
                final Component parent = ancestor.getParent ();
                if ( parent != null && parent instanceof Window && parent.getBackground ().getAlpha () == 0 )
                {
                    // Making popup menu window non-opaque
                    ancestor.setBackground ( new Color ( 0, 0, 0, 0 ) );
                }
            }
        }
    }

    private Window getWindowAncestor ( Component component )
    {
        if ( component == null )
        {
            return null;
        }
        if ( component instanceof Window )
        {
            return ( Window ) component;
        }
        for ( Container p = component.getParent (); p != null; p = p.getParent () )
        {
            if ( p instanceof Window )
            {
                return ( Window ) p;
            }
        }
        return null;
    }
};
popupMenu.addPropertyChangeListener ( "visible", propertyChangeListener );

如果您还想支持JDK 6-版本，您将不得不付出更多的努力，因为该代码甚至不会在早期的JDK版本上编译(在早期版本的窗口中没有"set/getBackground“方法)。

Answer 2

• 请记住，关于根窗格！== your是错误的，这也是对您的评论的回答--> JButton是什么意思?有趣的是，JButton只对JButton透明。
• this is proper of ways，这里是半透明的一切，rest是Java6和7，because isn't possible to create decorated container with changed L&F (for diff as is getSystemL&F)之间的一些二值变形。
• 我为Java6 6/7 _011、025和040编写的测试代码也没有任何LaFs的错误(只在Oracle中实现)

。

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.Painter;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;

public class PopupTest {

    private JFrame frame = new JFrame();
    private JPanel panel = new JPanel(new BorderLayout()) {
        private static final long serialVersionUID = 1L;

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(500, 500);
        }
    };
    private JButton button = new JButton("Close me");

    public PopupTest() {
        //panel.setOpaque(false);        
        panel.setBorder(BorderFactory.createLineBorder(Color.RED));
        panel.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                if (e.getButton() == MouseEvent.BUTTON3) {
                    JPopupMenu menu = new JPopupMenu();
                    for (int i = 0; i < 56; i++) {//only FHD display
                        menu.add(String.valueOf(i));
                    }
                    menu.show(panel, e.getX(), e.getY());
                }
            }
        });
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                System.exit(0);
            }
        });
        button.setOpaque(false);
        panel.add(button, BorderLayout.SOUTH);
        frame.setLocation(150, 150);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //frame.add(panel);
        frame.setContentPane(panel);
        frame.setUndecorated(true);
        frame.pack();
        frame.setBackground(new Color(150, 50, 50, 200));
        frame.setVisible(true);
    }

    public static void main(String[] a) {
        try {
            for (UIManager.LookAndFeelInfo laf : UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(laf.getName())) {
                    UIManager.setLookAndFeel(laf.getClassName());
                    UIManager.getLookAndFeelDefaults().put("PopupMenu[Enabled].backgroundPainter",
                            new FillPainter(new Color(127, 255, 191)));
                    UIManager.getLookAndFeelDefaults().put("text", new Color(255, 0, 0));
                    //UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                    //UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
                    //UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsClassicLookAndFeel");
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new PopupTest();
            }
        });
    }
}

class FillPainter implements Painter<JComponent> {

    private final Color color;

    FillPainter(Color c) {
        color = c;
    }

    @Override
    public void paint(Graphics2D g, JComponent object, int width, int height) {
        g.setColor(color);
        g.fillRect(0, 0, width - 1, height - 1);
    }
}

Answer 3

谢谢你给我一个很好的解决方案，你帮我解决了一个类似的问题！我想分享我的解决方案-基于米克尔的-有一点不同，这在我的情况下是有意义的。

我想要的是: JPopupMenu后面透明的、未装饰的窗口(我的自定义弹出窗口是用花哨的语音气球边框显示的，所以后面的窗口应该是不可见的)。

有一件事情在PropertyChangeListener中运行得不够好:在窗口显示在屏幕上之后，窗口外观得到了调整。在MacOSX10.10上，在弹出窗口后面有java 8窗口，首先显示为白色背景和细边框(L&F默认值)，然后进行调整(大约0.1-0.3秒)。很烦人。

看了一会儿调整代码后，我想出了以下简单的解决方案:在菜单被添加到窗口之后，在显示窗口之前，立即调整窗口。下面的示例演示如何扩展JPopupMenu以实现这一点：

import java.awt.Color;
import java.awt.Window;
import javax.swing.JPopupMenu;
import javax.swing.Popup;
import javax.swing.RootPaneContainer;
import javax.swing.SwingUtilities;
import javax.swing.plaf.PopupMenuUI;

public class MyPopup extends JPopupMenu
{
    public MyPopup()
    {
        super();
        //...
        setUI(new MyPopupMenuUI());
    }

    //...

    private void adjustHeavyWeightWindowIfThereIsOne()
    {
        // Retrieve popup menu window
        // on Windows we won't find it if this popup is inside of parent frame
        // on Mac we may find it even when DefaultLightWeightPopupEnabled is set to true
        final Window ancestor = SwingUtilities.getWindowAncestor(MyPopup.this);
        if (ancestor != null && ancestor.getClass().getCanonicalName().endsWith("HeavyWeightWindow"))
        {
            adjustWindowAppearance(ancestor);
        }
    }

    private void adjustWindowAppearance(Window w)
    {
        w.setBackground(new Color(0, 0, 0, 0));
        if (w instanceof RootPaneContainer)
        {
            ((RootPaneContainer)w).getRootPane().setBorder(null);
            ((RootPaneContainer)w).getRootPane().setBackground(new Color(0, 0, 0, 0));
        }
    }

    class MyPopupMenuUI extends PopupMenuUI
    {
        public Popup getPopup(JPopupMenu popup, int x, int y)
        {
            Popup toreturn = super.getPopup(popup, x, y);
            adjustHeavyWeightWindowIfThereIsOne();
            return toreturn;
        }
    }
}

实际上，扩展JPopupMenu并不是必要的，但是设置触发调整的自定义PopupMenuUI是必不可少的。窗口调整代码可以很容易地修改，以满足特定的需要，并可以移动到自定义PopupMenuUI。