在GridBagLayout中設置任意寬度

Question

我試圖製作一個鍵盤佈局，其中可以指定按鈕的寬度。因此，我嘗試了GridBagLayout但沒有成功。 爲了說明我的問題，我做了一個簡單的例子，在那裏我有望獲得這個（Button2的，將Button4，Button5，Button6）：

而是我得到的將Button4和雙倍寬度的Button6。

的代碼是：

package views; 

import java.awt.BorderLayout; 
import java.awt.EventQueue; 
import java.awt.GridBagConstraints; 
import java.awt.GridBagLayout; 

import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 

public class TestLayout extends JFrame { 

    public static void main(String[] args) { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       new TestLayout().setVisible(true); 
      } 
     }); 
    } 

    public TestLayout() { 
     JButton btn; 
     setBounds(0, 0, 444, 111); 
     setLayout(new GridBagLayout()); 
     GridBagConstraints gbc = new GridBagConstraints(); 
     gbc.fill = GridBagConstraints.BOTH; 

     gbc.gridy = 1;//ROW 1 
     btn = new JButton("Button 1");gbc.gridx = 0;gbc.gridwidth = 1;add(btn, gbc); 
     btn = new JButton("Button 2");gbc.gridx = 1;gbc.gridwidth = 2;add(btn, gbc); 
     btn = new JButton("Button 3");gbc.gridx = 3;gbc.gridwidth = 1;add(btn, gbc); 
     btn = new JButton("Button 4");gbc.gridx = 4;gbc.gridwidth = 2;add(btn, gbc); 

     gbc.gridy = 2;//ROW 2 
     btn = new JButton("Button 5");gbc.gridx = 0;gbc.gridwidth = 2;add(btn, gbc); 
     btn = new JButton("Button 6");gbc.gridx = 2;gbc.gridwidth = 2;add(btn, gbc); 
     btn = new JButton("Button 7");gbc.gridx = 4;gbc.gridwidth = 1;add(btn, gbc); 
     btn = new JButton("Button 8");gbc.gridx = 5;gbc.gridwidth = 1;add(btn, gbc); 
    } 
} 

而且，我的目標是定義鍵盤這樣的事情，與排之間沒有相關性，這是我不能用這個佈局管理器來實現的：

Answer 1

我把這件事交給了Why does this GridBagLayout not appear as planned? & camickr用一個虛擬的組件行來解決它，每個組件都有1 gridwidth寬。

這些2個圖像顯示：

1. 在底部，代碼的 '極簡' 版本使用1px的高透明圖像。
2. 在頂部，更明顯的版本使用了5像素高的純黑色圖像。

---

import java.awt.*; 
import java.awt.image.BufferedImage; 
import javax.swing.*; 
import javax.swing.border.*; 

public class KeyBoardLayout { 

    private JComponent ui = null; 

    KeyBoardLayout(boolean lowImpact) { 
     initUI(lowImpact); 
    } 

    public void initUI(boolean lowImpact) { 
     if (ui != null) { 
      return; 
     } 

     ui = new JPanel(new GridBagLayout()); 
     ui.setBorder(new EmptyBorder(4, 4, 4, 4)); 
     GridBagConstraints gbc = new GridBagConstraints(); 
     gbc.weightx = .5; 
     gbc.weighty = .5; 
     gbc.fill = GridBagConstraints.BOTH; 

     /* This code adds a dummy (invisible) row of components, 1 per 
     single gridwidth column. It has the effect of forcing the GBL width 
     to the size we would expect, proportional to each gridwidth assigned. 
     The problem with this (simple) approach is that the perfect 
     width will change according to PLAF and the content/preferred 
     size of the visible components. */ 
     // TODO! improve on use of 'magic numbers' 
     int w = 30; // adjust width per requirement 
     int h = lowImpact ? 1 : 5; // 1 for small height/border, 5 for large 
     // TYPE_INT_RGB for black 
     // TYPE_INT_ARGB for invisible 
     int t = lowImpact ? 
       BufferedImage.TYPE_INT_ARGB : 
       BufferedImage.TYPE_INT_RGB; 
     // an icon for the dummy row 
     ImageIcon ii = new ImageIcon(new BufferedImage(w, h, t)); 
     ui.setBorder(new CompoundBorder(
       ui.getBorder(), new EmptyBorder(0, 0, h, 0))); 
     // put a 'padding cell' in each column of the top row 
     // to force the layout to respect each individual column 
     for (int i = 0; i < 22; i++) { 
      gbc.gridx = i; 
      gbc.gridy = 4; 
      ui.add(new JLabel(ii)); 
     } 

     gbc.gridx = 0; 
     gbc.gridy = 1; 
     gbc.gridwidth = 3; 
     ui.add(new JButton("1,1 (3)"), gbc); 

     gbc.gridx = 3; 
     gbc.gridwidth = 2; 
     ui.add(new JButton("2,1 (2)"), gbc); 

     gbc.gridx = 5; 
     ui.add(new JButton("3,1 (2)"), gbc); 

     gbc.gridx = 7; 
     ui.add(new JButton("4,1 (2)"), gbc); 

     gbc.gridx = 9; 
     ui.add(new JButton("5,1 (2)"), gbc); 

     gbc.gridx = 11; 
     ui.add(new JButton("6,1 (2)"), gbc); 

     gbc.gridx = 13; 
     ui.add(new JButton("7,1 (2)"), gbc); 

     gbc.gridx = 15; 
     gbc.gridwidth = 3; 
     ui.add(new JButton("8,1 (3)"), gbc); 

     gbc.gridx = 18; 
     gbc.gridwidth = 4; 
     ui.add(new JButton("9,1 (4)"), gbc); 

     gbc.gridx = 0; 
     gbc.gridy = 2; 
     ui.add(new JButton("1,2 (4)"), gbc); 

     gbc.gridx = 4; 
     gbc.gridwidth = 2; 
     ui.add(new JButton("2,2 (2)"), gbc); 

     gbc.gridx = 6; 
     ui.add(new JButton("3,2 (2)"), gbc); 

     gbc.gridx = 8; 
     ui.add(new JButton("4,2 (2)"), gbc); 

     gbc.gridx = 10; 
     ui.add(new JButton("5,2 (2)"), gbc); 

     gbc.gridx = 12; 
     ui.add(new JButton("6,2 (2)"), gbc); 

     gbc.gridx = 14; 
     ui.add(new JButton("7,2 (2)"), gbc); 

     gbc.gridx = 16; 
     ui.add(new JButton("8,2 (2)"), gbc); 

     gbc.gridx = 18; 
     gbc.gridwidth = 4; 
     ui.add(new JButton("9,2 (4)"), gbc); 

     gbc.gridx = 0; 
     gbc.gridy = 3; 
     gbc.gridwidth = 5; 
     ui.add(new JButton("1,3 (5)"), gbc); 

     gbc.gridx = 5; 
     gbc.gridwidth = 2; 
     ui.add(new JButton("2,3 (2)"), gbc); 

     gbc.gridx = 7; 
     ui.add(new JButton("3,3 (2)"), gbc); 

     gbc.gridx = 9; 
     ui.add(new JButton("4,3 (2)"), gbc); 

     gbc.gridx = 11; 
     ui.add(new JButton("5,3 (2)"), gbc); 

     gbc.gridx = 13; 
     ui.add(new JButton("6,3 (2)"), gbc); 

     gbc.gridx = 15; 
     ui.add(new JButton("7,3 (2)"), gbc); 

     gbc.gridx = 17; 
     ui.add(new JButton("8,3 (2)"), gbc); 

     gbc.gridx = 19; 
     gbc.gridwidth = 3; 
     ui.add(new JButton("9,3 (3)"), gbc); 

     gbc.gridx = 0; 
     gbc.gridy = 4; 
     gbc.gridwidth = 3; 
     ui.add(new JButton("1,4 (3)"), gbc); 

     gbc.gridx = 3; 
     ui.add(new JButton("2,4 (3)"), gbc); 

     gbc.gridx = 6; 
     gbc.gridwidth = 10; 
     ui.add(new JButton("3,4 (10)"), gbc); 

     gbc.gridx = 16; 
     gbc.gridwidth = 3; 
     ui.add(new JButton("4,4 (3)"), gbc); 

     gbc.gridx = 19; 
     ui.add(new JButton("5,4 (3)"), gbc); 

     gbc.gridx = 0; 
     gbc.gridy = 4; 
     gbc.gridwidth = 1; 
    } 

    public JComponent getUI() { 
     return ui; 
    } 

    public static void main(String[] args) { 
     Runnable r = new Runnable() { 
      @Override 
      public void run() { 
       try { 
        UIManager.setLookAndFeel(
          UIManager.getSystemLookAndFeelClassName()); 
       } catch (Exception useDefault) { 
       } 
       for (int ii = 0; ii < 2; ii++) { 
        KeyBoardLayout o = new KeyBoardLayout(ii==0); 

        JFrame f = new JFrame("Keyboard Layout"); 
        f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); 
        f.setLocationByPlatform(true); 

        f.setContentPane(o.getUI()); 
        f.pack(); 
        f.setMinimumSize(f.getSize()); 

        f.setVisible(true); 
       } 
      } 
     }; 
     SwingUtilities.invokeLater(r); 
    } 
}