import javax.swing.*; import java.awt.*; import java.awt.event.*; /** * This class is a starter file for a "Tron LightCycle" game in which two players drive lightcycles in * an arena, leaving trails behind them as they go. If a player bumps into one of these trails or * into a wall, the other player wins. This game does not try to show the lightcycles themselves, * only the trails that are left. In this starter program, there is just one lightcycle that leaves a * trail of random colors, and crossing a trail or hitting a wall has no effect. */ public class TronPanel extends JPanel implements FocusListener, KeyListener, ActionListener, MouseListener { private MosaicPanel arena; // The arena in which the "lightcycles" move. It consists of squares arranged // into rows and columns. private JLabel message; // This label appears under the arena and holds a message for the user. private Timer timer; // Whenever the arena has the input focus, this timer emits a stream of ActionEvents // that drive the action. Everytime an ActionEvent occurs, the actionPerformed method // in this class is called. private final static int ROWS = 60; // Number of rows in the arena. private final static int COLUMNS = 80; // Number of columns in the arena. private final static int BLOCKSIZE = 10; // Size of each square in the arena-- used only in creating the arena object. private final static int BORDER_WIDTH = 5; // The width of the colored border around the arena. private final static int UP = 0, LEFT = 1, DOWN = 2, RIGHT = 3, NOT_MOVING = 4; // Constants representing possible directions. private int direction; // The direction that the "lightcycle" is currently heading, one of the above constants. private int currentColumn, currentRow; // The current row number and column number where the "lightcycle" is located. /** * The "constructor" for the TronPanel class creates all the components that are * displayed in the panel and adds them to the panel. It also sets up listening * for events. The panel listens for mouse events from the label and from the * arena, for focus events from the arena, for action events from the timer, and * for key events from the arena. (Thus, key events are only processed when the * arena has the input focus.) */ public TronPanel() { arena = new MosaicPanel(ROWS, COLUMNS, BLOCKSIZE, BLOCKSIZE, Color.GRAY, BORDER_WIDTH); message = new JLabel("To Start, Click the Arena", JLabel.CENTER); message.setBackground(Color.LIGHT_GRAY); message.setBorder(BorderFactory.createEmptyBorder(5,0,5,0)); JPanel bottom = new JPanel(); bottom.setLayout(new BorderLayout()); bottom.setBackground(Color.LIGHT_GRAY); setBackground(Color.DARK_GRAY); setLayout(new BorderLayout(3,3)); bottom.add(message,BorderLayout.CENTER); add(bottom, BorderLayout.SOUTH); add(arena, BorderLayout.CENTER); setBorder(BorderFactory.createLineBorder(Color.DARK_GRAY,3)); arena.setGroutingColor(null); arena.addFocusListener(this); arena.addKeyListener(this); arena.addMouseListener(this); message.addMouseListener(this); } /** * This method responds to the action events that are generated by the timer as * long as the game is in progress. It simply moves the "lightcycle" one square * in the curretnly selected direction. (It gets "stuck" in the same position * when it hits one of the walls of the arena.) The square containing the * "lightcycle" is colored with a random color. Note that if the current * direction is NOT_MOVING, then the light cycle does not move. */ public void actionPerformed(ActionEvent e) { switch (direction) { case UP: if (currentRow > 0) currentRow--; // Move up one row, unless already in the top row, number 0. break; case DOWN: if (currentRow < ROWS-1) currentRow++; // Move down one row, unless already in the bottom row, number ROWS-1. break; case RIGHT: if (currentColumn < COLUMNS-1) currentColumn++; // Move right one column, unless already in the rightmost column, number COLUMNS-1. break; case LEFT: if (currentColumn > 0) currentColumn--; // Move left one column, unless already in the leftmost column, number 0. break; } arena.setHSBColor(currentRow,currentColumn,Math.random(),1,1); } /** * This method is called when the user presses a key on the keyboard (but only if the * arena has the input focus). If the user presses an arrow key, the current direction * of motion of the light cycle is set to the direction that corresponds to the arrow * (up, down, left, or right). If the "P" key is pressed, the game is paused (by giving * the input focus to the message component, which indirectly stops the game from running). s */ public void keyPressed(KeyEvent e) { int code = e.getKeyCode(); // This code tells which key was pressed. The value is one of the // virtual keyboard ("VK") constants in the KeyEvent class. if (code == KeyEvent.VK_LEFT) direction = LEFT; else if (code == KeyEvent.VK_RIGHT) direction = RIGHT; else if (code == KeyEvent.VK_UP) direction = UP; else if (code == KeyEvent.VK_DOWN) direction = DOWN; else if (code == KeyEvent.VK_P) message.requestFocus(); } /** * This method is called when the arena gains focus, which means that it will start * receiving Key events. When this happens, the game action is turned on (by creating * a timer to drive the game), the color of the arena's border is changed to cyan, * and the text of the message is changed. */ public void focusGained(FocusEvent e) { arena.setBorder(BorderFactory.createLineBorder(Color.CYAN, BORDER_WIDTH)); arena.fill(null); // This resets all the squares to black to erase the picture from the previous run. currentColumn = COLUMNS/4*3; // Starting column, 3/4 of the way across the scree. currentRow = ROWS/2; // Starting row, halfway down the screen direction = UP; // Starting direction of motion. arena.setColor(currentRow,currentColumn,255,0,0); // color first square red direction = NOT_MOVING; // No motion until a direction key is pressed message.setText("To PAUSE, Click this Message or Press \"P\""); timer = new Timer(50,this); // timer generates an ActionEvent every 50 milliseconds timer.start(); } /** * This method is called when the arena loses focus, which means that it will not * receive Key events. When this happens, the game is suspended (by turning off * the timer that drives the game), the color of the arena's border is changed to * gray, and the text of the message is changed. */ public void focusLost(FocusEvent e) { arena.setBorder(BorderFactory.createLineBorder(Color.GRAY, BORDER_WIDTH)); if (timer != null) timer.stop(); timer = null; message.setText("To START, Click the Arena"); } /** * Mouse clicks on the arena and on the message are simply used to move the focus to * the component that was clicked. (The point of giving the focus to the message is * simply to make the arena lose focus, which causes the game to be paused.) */ public void mousePressed(MouseEvent e) { if (e.getSource() == arena) arena.requestFocus(); else message.requestFocus(); } // The following subroutines are required by the "KeyListener" and "MouseListener" interfaces, // but are not used in this program. They are defined as subrotines with empty bodies, which // means that they do nothing. public void mouseClicked(MouseEvent e) {} public void mouseEntered(MouseEvent e) {} public void mouseExited(MouseEvent e) {} public void mouseReleased(MouseEvent e) {} public void keyReleased(KeyEvent e) {} public void keyTyped(KeyEvent e) {} } // end class TronPanel