覆盖面板（在另一个上面） [英] Overlay panel (above another)

问题描述

我正在学习如何使用Swing并发现自己很难完成任务。

I am learning how to use Swing and found myself quite difficult task.

我想要完成的任务：我想拥有面板（称之为菜单面板）在左侧（比如100px宽度）和第二个面板（称之为内容面板），其中剩下的可用位置。

What I am trying to accomplish: I want to have panel (call it menu panel) on the left side (let's say 100px width) and the second panel (call it content panel), which takes the rest of available place.

在菜单面板中有3个纽扣。当我按下它们时，在菜单面板的右侧（在内容面板上）应出现第二个菜单面板（子菜单）（它应该在按下的按钮中间开始）。

In menu panel there are 3 buttons. When I press on of them, to the right side of menu panel (over content panel) second menu panel (submenu) should appear (and it should start in the middle of button which was pressed).

可能很难理解，所以我创建了简单的草稿：

It may be hard to understand, so I've created simple draft:

我尝试过JLayeredPane，但是调整窗口大小时出现问题（分层窗格中的元素没有调整大小）。

I tried JLayeredPane but there were problems with resizing window (elements in Layered Pane didn't resize).

推荐答案

JLayeredPane 错过 LayoutManager ，您必须手动为 setPreferredSize 或 setBounds 调整大小/放置 JComponents ，

JLayeredPane miss implementations for LayoutManager, you have to setPreferredSize or setBounds manually for sizing/place JComponents,

有一种可能的解决方法，你可以添加 ComponentListener 到 JFrame ，然后在 componentResized（ComponentEvent e）你可以调整大小/替换 JComponent（s ）到期望的界限s

there is one possible workaround you can add ComponentListener to the JFrame, then on componentResized(ComponentEvent e) you can resize/replace JComponent(s) to the desired Bounds

例如

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;

public class LayeredPaneWithOverlap {

    private JTextArea textArea = new JTextArea(2, 10);
    private JPanel textPanel = new JPanel(new BorderLayout());
    private JTable table = new JTable(30, 5);
    private JScrollPane scroll = new JScrollPane(table);
    private JLayeredPane layer = new JLayeredPane();
    private JFrame frame = new JFrame("Frame with resiziable JLayeredPane");

    public void makeUI() {
        textArea.setBorder(new LineBorder(Color.DARK_GRAY));
        textArea.setText("Frame with resiziable JLayeredPane");
        textPanel.setOpaque(false);
        textPanel.add(textArea, BorderLayout.NORTH);
        Font font = textArea.getFont();
        FontMetrics fontMetrics = textArea.getFontMetrics(font);
        int h = fontMetrics.getHeight() + frame.getInsets().top + 
                textPanel.getInsets().top + textArea.getInsets().top
                + textArea.getInsets().bottom;
        scroll.setBounds(0, h, 400, 300);
        layer.add(textPanel, new Integer(2));
        layer.add(scroll, new Integer(1));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(600, 400);
        frame.addComponentListener(new ComponentAdapter() {

            @Override
            public void componentResized(ComponentEvent e) {

                SwingUtilities.invokeLater(new Runnable() {

                    @Override
                    public void run() {
                        resizeAll();
                    }
                });
            }
        });
        frame.setLocationRelativeTo(null);
        frame.add(layer);
        resizeAll();
        frame.setVisible(true);
    }

    void resizeAll() {
        Insets insets = frame.getInsets();
        int w = frame.getWidth() - insets.left - insets.right;
        int h = frame.getHeight() - insets.top - insets.bottom;
        textPanel.setSize(w, h);
        scroll.setSize(w, h - scroll.getY());
        layer.revalidate();
        layer.repaint();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new LayeredPaneWithOverlap().makeUI();
            }
        });
    }
}

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