How to Create a Resizable Swing-Based Chess GUI in Java?

Creating a Robust, Resizable Swing Chess GUI

Swing, a Java library for creating graphical user interfaces (GUIs), offers a powerful framework for building robust and customizable applications. In this article, we'll focus on creating a resizable Swing-based Chess GUI, meeting the following requirements:

• GUI Layout:

  • Toolbar at the top with buttons for New, Save, Restore, Resign, and a message label.
  • Placeholder for future features on the left side.
  • Chess board with labels for rows and columns.
  • Square-shaped chessboard that fills the available space and maintains its aspect ratio as it resizes.

Technical Approach:

• GridLayout: A 9x9 GridLayout provides the structure for the chess board, including the first cell for a label without text.
• 8x8 Button Array: For game logic simplicity, we maintain a separate 8x8 array of buttons for the chessboard squares.
• Keyboard Functionality: Using buttons for chess board squares enables both keyboard and mouse event handling.
• Square-Shaped Chess Board: Utilizing a trick involving GridBagLayout and parent component querying, we maintain a square chess board that fits within the available space.
• Chess Piece Images: We use sprite sheets to represent the chess pieces, providing flexibility in terms of size, style, and color options.

Implementation Details:

import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
import javax.swing.border.*;
import java.net.URL;
import javax.imageio.ImageIO;

public class ChessGUI {

    private final JPanel gui = new JPanel(new BorderLayout(3, 3));
    private JButton[][] chessBoardSquares = new JButton[8][8];
    private Image[][] chessPieceImages = new Image[2][6];
    private JPanel chessBoard;
    private final JLabel message = new JLabel("Chess Champ is ready to play!");
    private static final String COLS = "ABCDEFGH";

    // Chess piece types
    public static final int QUEEN = 0, KING = 1,
            ROOK = 2, KNIGHT = 3, BISHOP = 4, PAWN = 5;
    public static final int[] STARTING_ROW = {
        ROOK, KNIGHT, BISHOP, KING, QUEEN, BISHOP, KNIGHT, ROOK
    };

    // Player colors
    public static final int BLACK = 0, WHITE = 1;

    public ChessGUI() {
        initializeGui();
    }

    public final void initializeGui() {
        createImages();

        // Main GUI layout
        gui.setBorder(new EmptyBorder(5, 5, 5, 5));
        JToolBar tools = new JToolBar();
        tools.setFloatable(false);
        gui.add(tools, BorderLayout.PAGE_START);
        // Toolbar buttons
        Action newGameAction = new AbstractAction("New") {
            @Override
            public void actionPerformed(ActionEvent e) {
                setupNewGame();
            }
        };
        tools.add(newGameAction);
        tools.add(new JButton("Save")); // Implement later
        tools.add(new JButton("Restore")); // Implement later
        tools.addSeparator();
        tools.add(new JButton("Resign")); // Implement later
        tools.addSeparator();
        tools.add(message);

        gui.add(new JLabel("?"), BorderLayout.LINE_START);

        // Chess board layout
        chessBoard = new JPanel(new GridLayout(0, 9)) {
            @Override
            public final Dimension getPreferredSize() {
                Dimension d = super.getPreferredSize();
                Dimension prefSize = null;
                Component c = getParent();
                // Adjust size to fit within parent component
                if (c == null) {
                    prefSize = new Dimension((int) d.getWidth(), (int) d.getHeight());
                } else if (c != null && c.getWidth() > d.getWidth() && c.getHeight() > d.getHeight()) {
                    prefSize = c.getSize();
                } else {
                    prefSize = d;
                }
                int w = (int) prefSize.getWidth();
                int h = (int) prefSize.getHeight();
                // Square shape
                int s = (w > h ? h : w);
                return new Dimension(s, s);
            }
        };
        chessBoard.setBorder(new CompoundBorder(new EmptyBorder(8, 8, 8, 8), new LineBorder(Color.BLACK)));
        chessBoard.setBackground(new Color(204, 119, 34)); // Ochre color
        JPanel boardConstrain = new JPanel(new GridBagLayout());
        boardConstrain.setBackground(new Color(204, 119, 34)); // Ochre color
        boardConstrain.add(chessBoard);
        gui.add(boardConstrain);

        // Chess board squares
        Insets buttonMargin = new Insets(0, 0, 0, 0);
        for (int ii = 0; ii < chessBoardSquares.length; ii++) {
            for (int jj = 0; jj < chessBoardSquares[ii].length; jj++) {
                JButton b = new JButton();
                b.setMargin(buttonMargin);
                ImageIcon icon = new ImageIcon(new BufferedImage(64, 64, BufferedImage.TYPE_INT_ARGB));
                b.setIcon(icon);
                if ((jj % 2 == 1 && ii % 2 == 1) || (jj % 2 == 0 && ii % 2 == 0)) {
                    b.setBackground(Color.WHITE);
                } else {
                    b.setBackground(Color.BLACK);
                }
                chessBoardSquares[jj][ii] = b;
            }
        }

        // Initial chess board setup
        chessBoard.add(new JLabel(""));

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