Canvas for processing game actions

<strong>/*————————————————–</strong>
<strong>* GameActions.java</strong>
<strong>*</strong>
<strong>* Canvas for processing game actions</strong>
<strong>*</strong>
<strong>* Example from the book: Core J2ME Technology</strong>
<strong>* Copyright John W. Muchow http://www.CoreJ2ME.com</strong&gt;
<strong>* You may use/modify for any non-commercial purpose</strong>
<strong>*————————————————-*/ </strong>
<strong>import javax.microedition.midlet.*;</strong>
<strong>import javax.microedition.lcdui.*;</strong>

<strong>public class GameActions extends MIDlet</strong>
<strong>{</strong>
<strong> private Display display; // The display</strong>
<strong> private GameActionCanvas canvas; // Canvas</strong>

<strong>public GameActions()</strong>
<strong> {</strong>
<strong> display = Display.getDisplay(this);</strong>
<strong> canvas = new GameActionCanvas(this);</strong>
<strong> }</strong>

<strong>protected void startApp()</strong>
<strong> {</strong>
<strong> display.setCurrent( canvas );</strong>
<strong> }</strong>

<strong>protected void pauseApp()</strong>
<strong> { }</strong>

<strong>protected void destroyApp( boolean unconditional )</strong>
<strong> { }</strong>

<strong>public void exitMIDlet()</strong>
<strong> {</strong>
<strong> destroyApp(true);</strong>
<strong> notifyDestroyed();</strong>
<strong> }</strong>
<strong>}</strong>

<strong>/*————————————————–</strong>
<strong>* GameActionCanvas.java</strong>
<strong>*</strong>
<strong>* Game action event handling</strong>
<strong>*————————————————-*/</strong>
<strong>class GameActionCanvas extends Canvas implements CommandListener</strong>
<strong>{</strong>
<strong> private Command cmExit; // Exit midlet</strong>
<strong> private String keyText = null; // Key code text</strong>
<strong> private GameActions midlet;</strong>

<strong>/*————————————————–</strong>
<strong> * Constructor</strong>
<strong> *————————————————-*/</strong>
<strong> public GameActionCanvas(GameActions midlet)</strong>
<strong> {</strong>
<strong> this.midlet = midlet;</strong>

<strong>// Create exit command &amp; listen for events</strong>
<strong> cmExit = new Command(”Exit”, Command.EXIT, 1);</strong>
<strong> addCommand(cmExit);</strong>
<strong> setCommandListener(this);</strong>
<strong> }</strong>

<strong>/*————————————————–</strong>
<strong> * Paint the text representing the key code </strong>
<strong> *————————————————-*/</strong>
<strong> protected void paint(Graphics g)</strong>
<strong> {</strong>
<strong> // Clear the background (to white)</strong>
<strong> g.setColor(255, 255, 255);</strong>
<strong> g.fillRect(0, 0, getWidth(), getHeight());</strong>

<strong>// Set color and draw text</strong>
<strong> if (keyText != null)</strong>
<strong> {</strong>
<strong> // Draw with black pen</strong>
<strong> g.setColor(0, 0, 0);</strong>
<strong> // Center the text</strong>
<strong> g.drawString(keyText, getWidth()/2, getHeight()/2, Graphics.TOP | Graphics.HCENTER);</strong>
<strong> }</strong>
<strong> }</strong>

<strong>/*————————————————–</strong>
<strong> * Command event handling</strong>
<strong> *————————————————-*/ </strong>
<strong> public void commandAction(Command c, Displayable d)</strong>
<strong> {</strong>
<strong> if (c == cmExit)</strong>
<strong> midlet.exitMIDlet();</strong>
<strong> }</strong>

<strong>/*————————————————–</strong>
<strong> * Game action event handling</strong>
<strong> * A game action will be converted into a key code </strong>
<strong> * and handed off to this method</strong>
<strong> *————————————————-*/ </strong>
<strong> protected void keyPressed(int keyCode)</strong>
<strong> {</strong>
<strong> switch (getGameAction(keyCode))</strong>
<strong> {</strong>
<strong> // Place logic of each action inside the case</strong>
<strong> case FIRE:</strong>
<strong> case UP: </strong>
<strong> case DOWN:</strong>
<strong> case LEFT:</strong>
<strong> case RIGHT:</strong>
<strong> case GAME_A:</strong>
<strong> case GAME_B:</strong>
<strong> case GAME_C:</strong>
<strong> case GAME_D:</strong>
<strong> default:</strong>
<strong> // Print the text of the game action</strong>
<strong> keyText = getKeyName(keyCode);</strong>
<strong> } </strong>
<strong> repaint();</strong>
<strong> }</strong>
<strong>}</strong>