This Is What I Know About: February 2012

Thursday, 9 February 2012

How to close child windows when closing parent window in javascript?

In many instances we want to close all child windows when main parent window is closed. This can be easily achieved using javascript.

To achieve this we need to do three thing

1) Create an array. This array is required for storing references of all child windows.

var childwindows = new Array();

2) Open child window using window.open and then store references of child window into an array

function openPopup(){
 try{
  var d = new Date();
  var win = window.open("Test.html",'test'+d.getMilliseconds(),'width=200,height=100')
  childwindows[childwindows.length] = win;
  win.focus();
 }catch(e){
  alert(e);
 }
}

3) Finally close all child windows on window.onunload event.

window.onunload = function closeChildWin(){
 for(var i=0; i<childwindows.length; i++){
  try{
     childwindows[i].close()
  }catch(e){
   alert(e);
  }
 }
}

To test this you can copy and paste following code into the file and save it as a Test.html. Let me know if it has helped you.

<html>
 <body>
        <input type="submit" onclick="openPopup()" value="Open new Window">
 </body>
</html>

<script>

var childwindows = new Array();

function openPopup(){
 try{
  var d = new Date();
  var win = window.open("Test.html",'test'+d.getMilliseconds(),'width=200,height=100')
  childwindows[childwindows.length] = win;
  win.focus();
 }catch(e){
  alert(e);
 }
}

window.onunload = function closeChildWin(){
 for(var i=0; i<childwindows.length; i++){
  try{
     childwindows[i].close()
  }catch(e){
   alert(e);
  }
 }
}

</script>

Friday, 3 February 2012

JBox2D with JavaFX 2.0 Tutorial: Attaching an image to body

In Write your first JBox2D with JavaFX 2 program posts we have seen how to create a ball and its GUI representation using JavaFX Circle shape. We can also use images for GUI representation. Following code snippet shows how to attach an image to the body.

import javafx.scene.Parent;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import org.jbox2d.collision.shapes.CircleShape;
import org.jbox2d.dynamics.Body;
import org.jbox2d.dynamics.BodyDef;
import org.jbox2d.dynamics.BodyType;
import org.jbox2d.dynamics.FixtureDef;

/**
 *
 * @author dilip
 */
public class Ball extends Parent{

    
    //X and Y position of the ball in JBox2D world
    private float posX;
    private float posY;
    
    //Ball radius in pixels
    private int radius;
    
    public Ball(float posX, float posY, int radius){
        this.posX = posX;
        this.posY = posY;
        this.radius = radius;
        create();
    }

    
    private void create(){
        
        /**
         * Set ball position on JavaFX scene. We need to convert JBox2D coordinates 
         * to JavaFX coordinates which are in pixels.
         */
        this.setLayoutX(Utils.toPixelPosX(posX)); 
        this.setLayoutY(Utils.toPixelPosY(posY));
        
        //Create an JBox2D body defination for ball.
        BodyDef bd = new BodyDef();
        bd.type = BodyType.DYNAMIC;;
        bd.position.set(posX, posY);
        
        CircleShape cs = new CircleShape();
        cs.m_radius = radius * 0.1f;  //We need to convert radius to JBox2D equivalent
        
        // Create a fixture for ball
        FixtureDef fd = new FixtureDef();
        fd.shape = cs;
        fd.density = 0.5f;
        fd.friction = 0.3f;        
        fd.restitution = 0.5f;

        /**
        * Virtual invisible JBox2D body of ball. Bodies have velocity and position. 
        * Forces, torques, and impulses can be applied to these bodies.
        */
        Body body = Utils.world.createBody(bd);
        body.createFixture(fd);
        this.setUserData(body);

        //Attach an image.
        ImageView iv = new ImageView();
        iv.setSmooth(true);
        iv.setImage(new Image(Ball.class.getResourceAsStream("images/ball.png")));
        getChildren().add(iv);
    }
}