可见时更新JPopupMenu高度

Question

我的应用程序中有一个弹出菜单，我想用一个自定义的菜单替换它，这样它就能与应用程序的其他部分相匹配。从本质上说，我不想在弹出窗口中使用普通的菜单项，而是想重用应用程序中其他地方已经存在的组件，该组件允许您以“分页”的方式而不是子菜单来导航项的层次结构。因此，如果单击列表中包含子项的项，则将显示下一页，用所单击项的子项列表替换列表中的当前项。

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;

public class PopupSizeTestFrame extends JFrame {

    private static final int PREFFERED_WIDTH = 300;
    private static JPanel resizingPanel;
    private static JPopupMenu popupMenu;
    private static PopupSizeTestFrame frame;

    private static void resizePopupMenu() {
        // What should I do here so that the size of the popup menu is updated?

        /**
         * Calling pack() works in this example, but I cannot call pack in the
         * actual application since there is a smooth transition animation when
         * clicking on the inner panel and pack() essentially re-adds the
         * components of the popup menu (removeNotify and addNotify is called),
         * which interferes with the animation and causes the menu to flicker.
         * The flickering when clicking the inner panel can also be seen in this
         * example when uncommenting the pack() call.
         */
        //popupMenu.pack();
        // 
        // I tried combinations of the following, without success:
        //popupMenu.invalidate();
        //popupMenu.revalidate();
        //popupMenu.validate();
        //popupMenu.doLayout();

        // Repaint
        popupMenu.repaint();
    }

    public static void main(String args[]) {
        // Create popup child panel with height that changes when clicked
        resizingPanel = new JPanel(new BorderLayout());
        int initialHeight = 30;
        final JLabel label = new JLabel("Click me (" + initialHeight + "px)");
        resizingPanel.add(label);
        resizingPanel.setBackground(Color.GREEN);
        resizingPanel.setPreferredSize(new Dimension(PREFFERED_WIDTH, initialHeight));
        resizingPanel.addMouseListener(new MouseAdapter() {
            private int clickCount = 0;

            @Override
            public void mouseClicked(MouseEvent e) {
                int height = ((clickCount % 3) + 1) * 50;
                resizingPanel.setPreferredSize(new Dimension(PREFFERED_WIDTH, height));
                clickCount++;
                label.setText("Click me (" + height + "px)");
                resizePopupMenu();
            }
        });

        // Create popup
        popupMenu = new JPopupMenu();
        popupMenu.setLayout(new BorderLayout());
        popupMenu.add(new JLabel("Header"), BorderLayout.NORTH);
        popupMenu.add(resizingPanel, BorderLayout.CENTER);
        popupMenu.add(new JLabel("Footer"), BorderLayout.SOUTH);

        // Create frame
        frame = new PopupSizeTestFrame();
        frame.setLayout(new BorderLayout());
        frame.setPreferredSize(new Dimension(400, 400));
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.addMouseListener(new MouseAdapter() {

            @Override
            public void mouseReleased(MouseEvent e) {
                if (e.isPopupTrigger()) {
                    popupMenu.show(frame, e.getX(), e.getY());
                }
            }
        });

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

当运行上面的示例时，您将看到，如果在单击内部面板后关闭和打开弹出菜单，则弹出菜单的大小会被更新，但当弹出菜单可见时，弹出菜单的大小不会被更新。

我可以在resizePopupMenu（）中做什么来更新JPopupMenu的高度？

Answer 1

对于问题中的测试应用程序，弹出窗口始终是一个重量级组件，下面的工作（正如mKorbel所建议的）

private static void resizePopupMenu() {
    SwingUtilities.getWindowAncestor(popupMenu).pack();
}

对于实际应用程序，当弹出窗口在应用程序的边界内时，它被创建为一个轻量级组件，这就防止了它被pack()调整大小，也防止了它的大小超过应用程序的边界。

我尝试设置此属性...

JPopupMenu.setDefaultLightWeightPopupEnabled(false);

// Set owner to component on which popup is shown or any of its parents
final Component owner = ...; 
AccessController.doPrivileged(new PrivilegedAction<Void>() {
    @Override
    public Void run() {
        try {
            Field field;
            if (System.getProperty("java.version").startsWith("1.6.0")) {
                Class clazz = Class.forName("javax.swing.PopupFactory");
                field = clazz.getDeclaredField("forceHeavyWeightPopupKey");
            } else { //JDK 1.7.0, 1.8.0
                Class clazz = Class.forName("javax.swing.ClientPropertyKey");
                field = clazz.getDeclaredField("PopupFactory_FORCE_HEAVYWEIGHT_POPUP");
            }
            field.setAccessible(true);
            owner.putClientProperty(field.get(null), Boolean.TRUE);
        } catch (Exception ex) {
            Exceptions.printStackTrace(ex);
        }
        return null;
    }
});

在强制弹出菜单始终为重量级组件后，此

SwingUtilities.getWindowAncestor(popupMenu).pack();

还更新了弹出窗口的大小，甚至超出了应用程序的范围。