java - 如何防止Boxlayout/Box拉伸(stretch)子组件？

Question

正如您在下面的可运行代码中看到的，我尝试拥有一个带有可扩展子框的框。 children 的盒子可以改变它们的大小，这一切都很好。主要问题是大小始终相对于父级。但我希望它们有一个特定的大小，以防万一没有地方再使用 JScrollPane。目前他们只缩小其他子盒子。

我尝试了胶水和填充剂，但没有用。胶水没有任何作用，而填充物有副作用，总是保持在某个位置(即使 ScrollPane 正在运行)。有这么多可用空间真是太难看了。

那么，你知道有什么好方法可以防止盒子拉伸(stretch) children 吗？

提前谢谢您!

import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.border.TitledBorder;


public class ExpandableMenueDemo {
    Box allBoxes; 
    ExpandableMenueDemo(){
        allBoxes = Box.createVerticalBox();

        TitledBorder title;
        title = BorderFactory.createTitledBorder("Filter");
        allBoxes.setBorder(title);

        for (int i = 0 ;i<3;i++){
            //generate collapsable components
            SubBox b = new SubBox("SubBox"+i);
            allBoxes.add(b.getSwingBox());

        }
        allBoxes.add(Box.createVerticalGlue());
    }

    public Container getMenue(){
        return allBoxes;
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        ExpandableMenueDemo m = new ExpandableMenueDemo();
        Box mainBox = Box.createHorizontalBox();

        mainBox.add(new JScrollPane(m.getMenue()));
        mainBox.add(new JTable(20,5));

        frame.setContentPane(mainBox);
        frame.pack();
        frame.setVisible(true);
    }


    class SubBox{
        Box box;
        Box header; 
        String name; 
        JButton cBtn;
        boolean isCollapsed = true;
        JLabel headerLine; 

        SubBox(String name) {
            this.name= name;
            box = Box.createVerticalBox();

            headerLine = new JLabel(name+" () :");

            header= Box.createHorizontalBox();
            cBtn = new JButton("v");
            cBtn.addActionListener(new ActionListener(){

                @Override
                public void actionPerformed(ActionEvent arg0) {
                    if (isCollapsed)show();
                    else collapse();
                }
            });
            collapse();

            header.add(cBtn);
            header.add(Box.createHorizontalStrut(10));
            header.add(headerLine);
            header.add(Box.createHorizontalGlue());

        }

        Box getSwingBox() {
            Box b = Box.createVerticalBox();    
            b.add(header);
            b.add(box);
            return b;
        }

        public void collapse(){
            System.out.println("collapse");
            box.removeAll();
            this.isCollapsed=true;
            cBtn.setText("v");
        }

        public void show(){
            System.out.println("show");
            box.removeAll();
            this.isCollapsed=false;
            cBtn.setText("^");

            for (int i = 0; i<3;i++) { 
               Box b = Box.createHorizontalBox();
               b.add(Box.createHorizontalStrut(20));
               b.add(new JCheckBox("checkBox "+i));
               b.add(Box.createHorizontalGlue());
               box.add(b);
            }
        }
    }
}

Answer 1

BoxLayout可以接受setXxxSize ,

也许是更好的展开/折叠示例 JPanels又嵌套JComponents

import java.awt.*;
import java.awt.event.*;
import java.awt.font.*;
import java.awt.image.BufferedImage;
import javax.swing.*;

public class ExpandingPanels extends MouseAdapter {

    private ActionPanel[] aps;
    private JPanel[] panels;

    public ExpandingPanels() {
        assembleActionPanels();
        assemblePanels();
    }

    @Override
    public void mousePressed(MouseEvent e) {
        ActionPanel ap = (ActionPanel) e.getSource();
        if (ap.target.contains(e.getPoint())) {
            ap.toggleSelection();
            togglePanelVisibility(ap);
        }
    }

    private void togglePanelVisibility(ActionPanel ap) {
        int index = getPanelIndex(ap);
        if (panels[index].isShowing()) {
            panels[index].setVisible(false);
        } else {
            panels[index].setVisible(true);
        }
        ap.getParent().validate();
    }

    private int getPanelIndex(ActionPanel ap) {
        for (int j = 0; j < aps.length; j++) {
            if (ap == aps[j]) {
                return j;
            }
        }
        return -1;
    }

    private void assembleActionPanels() {
        String[] ids = {"level 1", "level 2", "level 3", "level 4"};
        aps = new ActionPanel[ids.length];
        for (int j = 0; j < aps.length; j++) {
            aps[j] = new ActionPanel(ids[j], this);
        }
    }

    private void assemblePanels() {
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(2, 1, 2, 1);
        gbc.weightx = 1.0;
        gbc.weighty = 1.0;
        JPanel p1 = new JPanel(new GridBagLayout());
        gbc.gridwidth = GridBagConstraints.RELATIVE;
        p1.add(new JButton("button 1"), gbc);
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        p1.add(new JButton("button 2"), gbc);
        gbc.gridwidth = GridBagConstraints.RELATIVE;
        p1.add(new JButton("button 3"), gbc);
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        p1.add(new JButton("button 4"), gbc);
        JPanel p2 = new JPanel(new GridBagLayout());
        gbc.gridwidth = 1;
        gbc.anchor = GridBagConstraints.EAST;
        p2.add(new JLabel("enter"), gbc);
        gbc.anchor = GridBagConstraints.WEST;
        p2.add(new JTextField(8), gbc);
        gbc.anchor = GridBagConstraints.CENTER;
        p2.add(new JButton("button 1"), gbc);
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        p2.add(new JButton("button 2"), gbc);
        JPanel p3 = new JPanel(new BorderLayout());
        JTextArea textArea = new JTextArea(8, 12);
        textArea.setLineWrap(true);
        p3.add(new JScrollPane(textArea));
        JPanel p4 = new JPanel(new GridBagLayout());
        addComponents(new JLabel("label 1"), new JTextField(12), p4, gbc);
        addComponents(new JLabel("label 2"), new JTextField(16), p4, gbc);
        gbc.gridwidth = 2;
        gbc.gridy = 2;
        p4.add(new JSlider(), gbc);
        gbc.gridy++;
        JPanel p5 = new JPanel(new GridBagLayout());
        p5.add(new JButton("button 1"), gbc);
        p5.add(new JButton("button 2"), gbc);
        p5.add(new JButton("button 3"), gbc);
        p5.add(new JButton("button 4"), gbc);
        gbc.weighty = 1.0;
        gbc.fill = GridBagConstraints.BOTH;
        p4.add(p5, gbc);
        panels = new JPanel[]{p1, p2, p3, p4};
    }

    private void addComponents(Component c1, Component c2, Container c, GridBagConstraints gbc) {
        gbc.anchor = GridBagConstraints.EAST;
        gbc.gridwidth = GridBagConstraints.RELATIVE;
        c.add(c1, gbc);
        gbc.anchor = GridBagConstraints.WEST;
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        c.add(c2, gbc);
        gbc.anchor = GridBagConstraints.CENTER;
    }

    private JPanel getComponent() {
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(1, 3, 0, 3);
        gbc.weightx = 1.0;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        for (int j = 0; j < aps.length; j++) {
            panel.add(aps[j], gbc);
            panel.add(panels[j], gbc);
            panels[j].setVisible(false);
        }
        JLabel padding = new JLabel();
        gbc.weighty = 1.0;
        panel.add(padding, gbc);
        return panel;
    }

    public static void main(String[] args) {
        Runnable doRun = new Runnable() {

            @Override
            public void run() {
                ExpandingPanels test = new ExpandingPanels();
                JFrame f = new JFrame();
                f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                f.getContentPane().add(new JScrollPane(test.getComponent()));
                f.setSize(360, 500);
                f.setLocation(200, 100);
                f.setVisible(true);
            }
        };
        SwingUtilities.invokeLater(doRun);
    }
}

class ActionPanel extends JPanel {

    private static final long serialVersionUID = 1L;
    private String text;
    private Font font;
    private boolean selected;
    private BufferedImage open, closed;
    public Rectangle target;
    final int OFFSET = 30,
            PAD = 5;

    ActionPanel(String text, MouseListener ml) {
        this.text = text;
        addMouseListener(ml);
        font = new Font("sans-serif", Font.PLAIN, 12);
        selected = false;
        setBackground(new Color(200, 200, 220));
        setPreferredSize(new Dimension(200, 20));
        setBorder(BorderFactory.createRaisedBevelBorder());
        setPreferredSize(new Dimension(200, 20));
        createImages();
        setRequestFocusEnabled(true);
    }

    public void toggleSelection() {
        selected = !selected;
        repaint();
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        int w = getWidth();
        int h = getHeight();
        if (selected) {
            g2.drawImage(open, PAD, 0, this);
        } else {
            g2.drawImage(closed, PAD, 0, this);
        }
        g2.setFont(font);
        FontRenderContext frc = g2.getFontRenderContext();
        LineMetrics lm = font.getLineMetrics(text, frc);
        float height = lm.getAscent() + lm.getDescent();
        float x = OFFSET;
        float y = (h + height) / 2 - lm.getDescent();
        g2.drawString(text, x, y);
    }

    private void createImages() {
        int w = 20;
        int h = getPreferredSize().height;
        target = new Rectangle(2, 0, 20, 18);
        open = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2 = open.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(getBackground());
        g2.fillRect(0, 0, w, h);
        int[] x = {2, w / 2, 18};
        int[] y = {4, 15, 4};
        Polygon p = new Polygon(x, y, 3);
        g2.setPaint(Color.green.brighter());
        g2.fill(p);
        g2.setPaint(Color.blue.brighter());
        g2.draw(p);
        g2.dispose();
        closed = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        g2 = closed.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(getBackground());
        g2.fillRect(0, 0, w, h);
        x = new int[]{3, 13, 3};
        y = new int[]{4, h / 2, 16};
        p = new Polygon(x, y, 3);
        g2.setPaint(Color.red);
        g2.fill(p);
        g2.setPaint(Color.blue.brighter());
        g2.draw(p);
        g2.dispose();
    }
}