Notes
-
The chess board complete with columns on the left and above it is provided by a 9×9
GridLayout. The first cell of the grid layout is a label with no text. -
To simplify the game logic though, we maintain a separate 8×8 array of buttons.
-
To allow keyboard functionality we use buttons for the chess board places. This also provides inbuilt focus indication. The margin of the button is removed to allow them to shrink to the size of the icon. We can add an
ActionListenerto the button and it will respond to both keyboard and mouse events. -
To maintain a square board, we employ a little trickery. The chess board is added to a
GridBagLayoutas the only component with noGridBagContraintsspecified. That way it is always centered. To get the resizing behavior required, the chess board queries the actual size of the parent component, and returns a preferred size that is the maximum it can, while still square and not exceeding the smaller size of the width or height of the parent. -
The chess piece image was obtained from Example images for code and mark-up Q&As, which was in turn developed out of ‘Fill’ Unicode characters in labels.
Using images is simpler, whereas filling Unicode characters is more versatile as well as being ‘lighter’. I.E. to support 4 different colors in 3 separate sizes of 3 different chess piece styles would require 36 separate sprite sheets!
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";
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
};
public static final int BLACK = 0, WHITE = 1;
ChessGUI() {
initializeGui();
}
public final void initializeGui() {
// create the images for the chess pieces
createImages();
// set up the main GUI
gui.setBorder(new EmptyBorder(5, 5, 5, 5));
JToolBar tools = new JToolBar();
tools.setFloatable(false);
gui.add(tools, BorderLayout.PAGE_START);
Action newGameAction = new AbstractAction("New") {
@Override
public void actionPerformed(ActionEvent e) {
setupNewGame();
}
};
tools.add(newGameAction);
tools.add(new JButton("Save")); // TODO - add functionality!
tools.add(new JButton("Restore")); // TODO - add functionality!
tools.addSeparator();
tools.add(new JButton("Resign")); // TODO - add functionality!
tools.addSeparator();
tools.add(message);
gui.add(new JLabel("?"), BorderLayout.LINE_START);
chessBoard = new JPanel(new GridLayout(0, 9)) {
/**
* Override the preferred size to return the largest it can, in
* a square shape. Must (must, must) be added to a GridBagLayout
* as the only component (it uses the parent as a guide to size)
* with no GridBagConstaint (so it is centered).
*/
@Override
public final Dimension getPreferredSize() {
Dimension d = super.getPreferredSize();
Dimension prefSize = null;
Component c = getParent();
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();
// the smaller of the two sizes
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)
));
// Set the BG to be ochre
Color ochre = new Color(204,119,34);
chessBoard.setBackground(ochre);
JPanel boardConstrain = new JPanel(new GridBagLayout());
boardConstrain.setBackground(ochre);
boardConstrain.add(chessBoard);
gui.add(boardConstrain);
// create the 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);
// our chess pieces are 64x64 px in size, so we'll
// 'fill this in' using a transparent icon..
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;
}
}
/*
* fill the chess board
*/
chessBoard.add(new JLabel(""));
// fill the top row
for (int ii = 0; ii < 8; ii++) {
chessBoard.add(
new JLabel(COLS.substring(ii, ii + 1),
SwingConstants.CENTER));
}
// fill the black non-pawn piece row
for (int ii = 0; ii < 8; ii++) {
for (int jj = 0; jj < 8; jj++) {
switch (jj) {
case 0:
chessBoard.add(new JLabel("" + (9-(ii + 1)),
SwingConstants.CENTER));
default:
chessBoard.add(chessBoardSquares[jj][ii]);
}
}
}
}
public final JComponent getGui() {
return gui;
}
private final void createImages() {
try {
URL url = new URL("http://i.stack.imgur.com/memI0.png");
BufferedImage bi = ImageIO.read(url);
for (int ii = 0; ii < 2; ii++) {
for (int jj = 0; jj < 6; jj++) {
chessPieceImages[ii][jj] = bi.getSubimage(
jj * 64, ii * 64, 64, 64);
}
}
} catch (Exception e) {
e.printStackTrace();
System.exit(1);
}
}
/**
* Initializes the icons of the initial chess board piece places
*/
private final void setupNewGame() {
message.setText("Make your move!");
// set up the black pieces
for (int ii = 0; ii < STARTING_ROW.length; ii++) {
chessBoardSquares[ii][0].setIcon(new ImageIcon(
chessPieceImages[BLACK][STARTING_ROW[ii]]));
}
for (int ii = 0; ii < STARTING_ROW.length; ii++) {
chessBoardSquares[ii][1].setIcon(new ImageIcon(
chessPieceImages[BLACK][PAWN]));
}
// set up the white pieces
for (int ii = 0; ii < STARTING_ROW.length; ii++) {
chessBoardSquares[ii][6].setIcon(new ImageIcon(
chessPieceImages[WHITE][PAWN]));
}
for (int ii = 0; ii < STARTING_ROW.length; ii++) {
chessBoardSquares[ii][7].setIcon(new ImageIcon(
chessPieceImages[WHITE][STARTING_ROW[ii]]));
}
}
public static void main(String[] args) {
Runnable r = new Runnable() {
@Override
public void run() {
ChessGUI cg = new ChessGUI();
JFrame f = new JFrame("ChessChamp");
f.add(cg.getGui());
// Ensures JVM closes after frame(s) closed and
// all non-daemon threads are finished
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
// See https://stackoverflow.com/a/7143398/418556 for demo.
f.setLocationByPlatform(true);
// ensures the frame is the minimum size it needs to be
// in order display the components within it
f.pack();
// ensures the minimum size is enforced.
f.setMinimumSize(f.getSize());
f.setVisible(true);
}
};
// Swing GUIs should be created and updated on the EDT
// http://docs.oracle.com/javase/tutorial/uiswing/concurrency
SwingUtilities.invokeLater(r);
}
}