Correct this code for event handling.

[Akshay Kumar]

hi,

i've two classes called MyApplet extends Applet and MyComponent extends Component, and written separate mouselisteners for each.

i hav created an instance of MyComponent in MyApplet and now i want to handle the mouse events in MyComponent say, i've a OK button in MyComponent and after clicking on that only i should come back to MyApplet.

the problem i'm facing is could not able to handle mouse events in MyComponent but i could in MyApplet.

for more info plz, look into this code below, and suggest me in how to handle it properly.

thanx.

note: after creation of the instance, it returns immediately without listening to mouse events.

--------MyApplet.java-------------
import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class MyApplet extends Applet implements MouseListener{

MyComponent comp;

public void init(){
addMouseListener(this);
}

public void paint(Graphics g){
comp = new MyComponent(g);
}

public void mousePressed(MouseEvent me){System.out.println("Mouse Pressed in MyApplet");}
public void mouseEntered(MouseEvent me){System.out.println("Mouse Entered in MyApplet");}
public void mouseReleased(MouseEvent me){System.out.println("Mouse Released in MyApplet");}
public void mouseExited(MouseEvent me){System.out.println("Mouse Exited in MyApplet");}
public void mouseClicked(MouseEvent me){System.out.println("Mouse Clicked in MyApplet");}

}


----------MyComponent.java-----------
import java.awt.*;
import java.awt.event.*;

public class MyComponent extends Component implements MouseListener{

MyComponent(Graphics g){
g.setColor(Color.RED);
g.fillRect(100, 100, 300, 200);
g.setColor(Color.WHITE);
g.drawString("This is My Component", 150, 150);

enableEvents(AWTEvent.MOUSE_EVENT_MASK);
addMouseListener(this);
MouseListener[] mls = (MouseListener[])(getListeners(MouseListener.class));
System.out.println("Registered Listeners are :: " + mls);
}

protected void processMouseEvent(MouseEvent e){
System.out.println("processMouseEvent called");
super.processMouseEvent(e);
}

public void mousePressed(MouseEvent me){System.out.println("Mouse Pressed in MyComponent");}
public void mouseEntered(MouseEvent me){System.out.println("Mouse Entered in MyComponent");}
public void mouseReleased(MouseEvent me){System.out.println("Mouse Released in MyComponent");}
public void mouseExited(MouseEvent me){System.out.println("Mouse Exited in MyComponent");}
public void mouseClicked(MouseEvent me){System.out.println("Mouse Clicked in MyComponent");}

}

[Maysam Sorkhabi]

I don't know why would you want to extend the component class and then initialize it in your applet. I think its a better idea to just create an instance of whatever component you need inside your init() method (in the applet class). For example JButton some_button = new JButton(). (This is a swing component).

Consult the swing API for more info.

[Akshay Kumar]

fine. how to add a swing component to an applet when the total applet is displayed as single image, means all the controls been drawn on a image and finally this image is drawn to the applet using Graphics object.

pour comments on this.

thanx.

[Craig Wood]

Here's a demo in AWT. You mentioned swing which would be a little different.

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
 
public class ImageInAnApplet extends Applet
{
    public void init()
    {
        CustomImagePanel imagePanel = new CustomImagePanel();
        ScrollPane scrollPane = new ScrollPane();
        scrollPane.add(imagePanel);
        ImagePointer pointer = imagePanel.pointer;
        setLayout(new BorderLayout());
        add(scrollPane);
        add(pointer.getOutputPanel(), "South");
    }
 
    public static void main(String[] args)
    {
        Applet applet = new ImageInAnApplet();
        Frame f = new Frame();
        f.addWindowListener(new WindowAdapter()
        {
            public void windowClosing(WindowEvent e)
            {
                System.exit(0);
            }
        });
        f.add(applet);
        f.setSize(400,400);
        f.setLocation(200,200);
        applet.init();
        f.setVisible(true);
    }
}
 
class CustomImagePanel extends Panel
{
    ImagePointer pointer;
    Image image;
 
    public CustomImagePanel()
    {
        loadImage();
        pointer = new ImagePointer(this);
        addMouseMotionListener(pointer);
    }
 
    public void paint(Graphics g)
    {
        super.paint(g);
        int w = getWidth();
        int h = getHeight();
        int imageWidth = image.getWidth(this);
        int imageHeight = image.getHeight(this);
        int x = (w - imageWidth)/2;
        int y = (h - imageHeight)/2;
        g.drawImage(image, x, y, this);
    }
 
    public Dimension getPreferredSize()
    {
        return new Dimension(image.getWidth(this), image.getHeight(this));
    }
 
    private void loadImage()
    {
        String fileName = "images/heron.jpg";
        Toolkit toolkit = Toolkit.getDefaultToolkit();
        MediaTracker tracker = new MediaTracker(this);
        URL url = getClass().getResource(fileName);
        image = toolkit.getImage(url);
        tracker.addImage(image, 0);
        try
        {
            tracker.waitForID(0);
        }
        catch(InterruptedException ie)
        {
            System.out.println("interrupt: " + ie.getMessage());
        }
    }
}
 
class ImagePointer extends MouseMotionAdapter
{
    CustomImagePanel imagePanel;
    Label pointerLabel;
 
    public ImagePointer(CustomImagePanel cip)
    {
        imagePanel = cip;
    }
 
    public void mouseMoved(MouseEvent e)
    {
        int x = e.getX();
        int y = e.getY();
        pointerLabel.setText("x = " + x + ",  y = " + y);
    }
 
    public Panel getOutputPanel()
    {
        pointerLabel = new Label();
        pointerLabel.setAlignment(Label.CENTER);
        Panel panel = new Panel(new GridLayout(1,0));
        panel.add(pointerLabel);
        return panel;
    }
}

[Akshay Kumar]

thanx. now, 'm clear in my stands.