Java/J2ME/Clip

Clipping Region

   <source lang="java">

//jad file (please verify the jar size) /* MIDlet-Name: ClippingRegion MIDlet-Version: 1.0 MIDlet-Vendor: MyCompany MIDlet-Jar-URL: ClippingRegion.jar MIDlet-1: ClippingRegion, , ClippingRegion MicroEdition-Configuration: CLDC-1.0 MicroEdition-Profile: MIDP-1.0 MIDlet-JAR-SIZE: 100

• /

import javax.microedition.lcdui.Alert; import javax.microedition.lcdui.Canvas; import javax.microedition.lcdui.rumand; import javax.microedition.lcdui.rumandListener; import javax.microedition.lcdui.Display; import javax.microedition.lcdui.Displayable; import javax.microedition.lcdui.Graphics; import javax.microedition.lcdui.Image; import javax.microedition.midlet.MIDlet; public class ClippingRegion extends MIDlet {

 private Display display;
 private MyCanvas canvas;
 public ClippingRegion() {
   display = Display.getDisplay(this);
   canvas = new MyCanvas(this);
 }
 protected void startApp() {
   display.setCurrent(canvas);
 }
 protected void pauseApp() {
 }
 protected void destroyApp(boolean unconditional) {
 }
 public void exitMIDlet() {
   destroyApp(true);
   notifyDestroyed();
 }
 public Display getDisplay() {
   return display;
 }

} class MyCanvas extends Canvas implements CommandListener {

 private Command exit = new Command("Exit", Command.EXIT, 1);
 private ClippingRegion clippingRegion;
 private Image image = null;
 public MyCanvas(ClippingRegion clippingRegion) {
   this.clippingRegion = clippingRegion;
   
   addCommand(exit);
   setCommandListener(this);
   try {
     image = Image.createImage(70, 70);
     Graphics graphics = image.getGraphics();
     graphics.setColor(255, 0, 0);
     graphics.fillArc(10, 10, 60, 50, 180, 180);
   } catch (Exception error) {
     Alert alert = new Alert("Failure", "Creating Image", null, null);
     alert.setTimeout(Alert.FOREVER);
     this.clippingRegion.getDisplay().setCurrent(alert);
   }
 }
 protected void paint(Graphics graphics) {
   if (image != null) {
     graphics.setColor(255, 255, 255);
     graphics.fillRect(0, 0, getWidth(), getHeight());
     graphics.setClip(35, 35, 40, 40);
     graphics.drawImage(image, 30, 30, Graphics.VCENTER | Graphics.HCENTER);
   }
 }
 public void commandAction(Command command, Displayable display) {
   if (command == exit) {
     clippingRegion.exitMIDlet();
   }
 }

}

      </source>
   
  
 
  

Move a clipping region around a Canvas

   <source lang="java">

/*--------------------------------------------------

• Clip.java
• Move a clipping region around a Canvas
• Example from the book: Core J2ME Technology
• Copyright John W. Muchow http://www.CoreJ2ME.ru
• You may use/modify for any non-commercial purpose
• -------------------------------------------------*/

import javax.microedition.midlet.*; import javax.microedition.lcdui.*; import java.util.*; public class Clip extends MIDlet {

 private Display  display;     // The display
 private ClipCanvas canvas;    // Canvas 

 public Clip()
 {
   display = Display.getDisplay(this);
   canvas  = new ClipCanvas(this);
 }

 protected void startApp()
 {
   display.setCurrent( canvas );
 }

 protected void pauseApp()
 { }
 protected void destroyApp( boolean unconditional )
 { }

 public void exitMIDlet()
 {
   destroyApp(true);
   notifyDestroyed();
 }

} /*--------------------------------------------------

• Class ClipCanvas
• Display the clipping region
• -------------------------------------------------*/

class ClipCanvas extends Canvas implements CommandListener {

 private Command cmExit;  // Exit
 private Clip midlet;      // Main midlet
 private Image im = null; // Image to display
 private Random random;    // Get random number
 
 private int clipx = 0,  clipy = 0,  // View port 
 
             clipw = 45, cliph = 45; // (clipping region)
             
 private int old_clipx = 0, old_clipy = 0; // Last clipping region
 

 public ClipCanvas(Clip midlet)
 {
   this.midlet = midlet;
   
   // Create exit command & listen for events
   cmExit = new Command("Exit", Command.EXIT, 1);
   addCommand(cmExit);
   setCommandListener(this);
   // Get random values for starting point
   random = new java.util.Random();

   // Make sure the entire clipping region is 
   // visible on the display  
   clipx = Math.min((getWidth() - clipw),
                    (random.nextInt() >>> 1) % getWidth());
   clipy = Math.min((getHeight() - cliph),
                    (random.nextInt() >>> 1) % getHeight());
   try
   {
     // Create immutable image
     im = Image.createImage("/house.png");
   }
   catch (java.io.IOException e)
   {
     System.err.println("Unable to locate or read .png file");
   }    
 } 
 protected void paint(Graphics g)
 {
   if (im != null)
   {
     // Clear only the previous clipping region
     g.setColor(255, 255, 255);
     g.fillRect(old_clipx, old_clipy, clipw, cliph);      
     // Set the new clipping region
     g.setClip(clipx, clipy, clipw, cliph);
     // Draw image  
     g.drawImage(im, 0, 0, Graphics.LEFT | Graphics.TOP);
   }
 }
 public void commandAction(Command c, Displayable d)
 {
   if (c == cmExit)
     midlet.exitMIDlet();
 }
 
 protected void keyPressed(int keyCode)
 {
   // Save the last clipping region
   old_clipx = clipx;
   old_clipy = clipy;
   
   switch (getGameAction(keyCode))
   {
     case UP: 
       // Move clipping region up 3 pixels
       if (clipy > 0)
         clipy = Math.max(0, clipy - 3);
       break;
     
     case DOWN:
       // Move clipping region down 3 pixels      
       if (clipy + cliph < getHeight())
         clipy = Math.min(getHeight(), clipy + 3);
       break;
       
     case LEFT:
      // Move clipping region left 3 pixels
      if (clipx > 0)
         clipx = Math.max(0, clipx - 3);
       break;
     case RIGHT:
       // Move clipping region right 3 pixels      
       if (clipx + clipw < getWidth())
         clipx = Math.min(getWidth(), clipx + 3);
      break;
      
     case FIRE:
       // Show the whole screen by reseting 
       // the clipping region to the entire display
       clipx = clipy = 0;
       clipw = getWidth();
       cliph = getHeight();       
  }        
   repaint();
 }

}

      </source>