Hi,

Can someone tell me how i can implement a mouselistener interface on a frame.

I have a program that loads an image on a canvas. now i want to get the screen coordinate where user clicks on the image. I can do this using an applet but i want to do it with awt frame.

Can someone tell me?

Regards

It's no different...

This is not a private message !!

I tried the applet code on frame but it didn't work. That's why asked if someone could help.

What exactly didn't work? Code should be the same.

public class MyFrame extends Frame implements MouseListener

//include methods found in the MouseListener interface

What exactly didn't work? Code should be the same.

public class MyFrame extends Frame implements MouseListener

//include methods found in the MouseListener interface

Yes i did the same. But the program did not respond to the mouse events. Nothing happened.

This is not a private message !!

If it had been you'd not have gotten a response at all...

I tried the applet code on frame but it didn't work. That's why asked if someone could help.

It does work the same, but you may be confused about the way it works in applets and not realise it...

Post your code then. (in code tags)

Its a long code but i hope u can easilt find the mouse events.

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
class ImgMod3 extends Frame implements MouseListener {
  String msg = "";
 int mX = 0;
 int mY = 0;
  Image rawImg;
  int imgCols;//Number of horizontal pixels
  int imgRows;//Number of rows of pixels
  Image modImg;//Reference to modified image
  //Inset values for the Frame
  int inTop;
  int inLeft;
 //To add only one picture at a time
 int ig = 1;
  //This program will be executed to process the
  // if the name of another program is not
  // entered on the command line.  
  static String theProcessingClass = "PrintMouse";
  // This image file will be processed if another file name is
  // not entered on the command line.  
  static String theImgFile = "white.gif";
  MediaTracker tracker;
  Display display = new Display();//A Canvas
  Button replotButton = new Button("Replot");
  //References to arrays that store pixel data.
  int[][][] threeDPix;
  int[][][] threeDPixMod;
  int[] oneDPix;
  //Reference to the image-processing object.
  ImgIntfc02 imageProcessingObject;
  //-------------------------------------------//
  public static void main(String[] args){
    // Program supports gif files and jpg files
    // and possibly some other file types as well.
    if(args.length == 0){
      //Use default processing class and default image file.  No code required here.
      // Class and file names were specified above. 
    }else if(args.length == 1){
      theProcessingClass = args[0];
      //Use default image file
    }else if(args.length == 2){
      theProcessingClass = args[0];
      theImgFile = args[1];
    }else{
      System.out.println("Invalid args");
      System.exit(1);
    }//end else
    //Display name of processing program and
    // image file.
    System.out.println("Processing program: " + theProcessingClass);
    System.out.println("Image file: " + theImgFile);
    //Instantiate an object of this class
    ImgMod3 obj = new ImgMod3();
  }//end main
  //-------------------------------------------//
  public ImgMod3(){//constructor
    //Get an image from the specified file.  Can
    // be in a different directory if the path
    // was entered with the file name on the command line.
    rawImg = Toolkit.getDefaultToolkit().getImage(theImgFile);
    //Use a MediaTracker object to block until
    // the image is loaded or ten seconds has elapsed.
    tracker = new MediaTracker(this);
    tracker.addImage(rawImg,1);
    try{
      if(!tracker.waitForID(1,10000)){
        System.out.println("Load error.");
        System.exit(1);
      }//end if
    }catch(InterruptedException e){
      e.printStackTrace();
      System.exit(1);
    }//end catch
    //Make certain that the file was successfully
    // loaded.
    if((tracker.statusAll(false) & MediaTracker.ERRORED & MediaTracker.ABORTED) != 0){
      System.out.println("Load errored or aborted");
      System.exit(1);
    }//end if
    //Raw image has been loaded.  Get width and
    // height of the raw image.
    imgCols = rawImg.getWidth(this);
    imgRows = rawImg.getHeight(this);
    this.setTitle("Copyright 2004, Baldwin");
    this.setBackground(Color.YELLOW);
    this.add(display);
    this.add(replotButton,BorderLayout.SOUTH);
    //Make it possible to get insets and the
    // height of the button.
    setVisible(true);
    //Get and store inset data for the Frame and
    // the height of the button.
    inTop = this.getInsets().top;
    inLeft = this.getInsets().left;
    int buttonHeight = replotButton.getSize().height;
    //Size the frame so that a small amount of
    // yellow background will show on the right
    // and on the bottom when both images are
    // displayed, one above the other.  Also, the
    // placement of the images on the Canvas
    // causes a small amount of background to
    // show between the images.
    this.setSize(inLeft+imgCols + 1,inTop + buttonHeight + imgRows + 7);
 addMouseListener(this);
    //=========================================//
    //Anonymous inner class listener for replot
    // button.  This actionPerformed method is
    // invoked when the user clicks the Replot
    // button.  It is also invoked at startup
    // when this program posts an ActionEvent to
    // the system event queue attributing the
    // event to the Replot button.
    replotButton.addActionListener(
      new ActionListener(){
        public void actionPerformed(ActionEvent e){
          //Pass a 3D array of pixel data to the
          // processing object and get a modified 3D array of pixel data back. 
          threeDPixMod = imageProcessingObject.processImg(threeDPix,imgRows,imgCols);
          //Convert the modified pixel data to a
          // 1D array of pixel data.
          oneDPix = convertToOneDim(threeDPixMod,imgCols,imgRows);
          //Use the createImage() method to
          // create a new image from the 1D array of pixel data.
          modImg = createImage(new MemoryImageSource(imgCols,imgRows,oneDPix,0,imgCols));
          //Repaint the image display frame with
          // the original image at the top and
          // the modified pixel data at the bottom.
          display.repaint();
        }//end actionPerformed
      }//end ActionListener
    );//end addActionListener
    //End anonymous inner class.
    //=========================================//
    //Create a 1D array object to receive the
    // pixel representation of the image
    oneDPix = new int[imgCols * imgRows];
    //Convert the rawImg to numeric pixel
    // representation.  Note that grapPixels()
    // throws InterruptedException
    try{
      //Instantiate a PixelGrabber object
      // specifying oneDPix as the array in which
      // to put the numeric pixel data. 
      PixelGrabber pgObj = new PixelGrabber(rawImg,0,0,imgCols,imgRows, oneDPix,0,imgCols);
      //Invoke the grabPixels() method on the
      // PixelGrabber object to extract the pixel
      // data from the image into an array of
      // numeric pixel data stored in oneDPix.
      if(pgObj.grabPixels() && ((pgObj.getStatus() & ImageObserver.ALLBITS)!= 0)){
        //Convert the pixel byte data in the 1D
        // array to int data in a 3D array to
        // make it easier to work with the pixel
        // data later.  Recall that pixel data is
        // unsigned byte data and Java does not
        // support unsigned arithmetic.
        threeDPix = convertToThreeDim(oneDPix,imgCols,imgRows);
        //Instantiate a new object of the image
        // processing class.  Note that this
        // object is instantiated using the
        // newInstance method of the class named
        // Class.  This approach does not support
        // the use of a parameterized
        // constructor.
        try{
          imageProcessingObject = (ImgIntfc02)Class.forName(theProcessingClass).newInstance();
           //Post counterfeit ActionEvent to the
           // system event queue and attribute it
           // to the Replot button.  Posting this event causes
           // the image-processing method to be
           // invoked, passing the 3D array of pixel data to the method, and receiving a 3D array of modified
           // pixel data back from the method.
          Toolkit.getDefaultToolkit().
                getSystemEventQueue().postEvent(new ActionEvent(replotButton, ActionEvent.ACTION_PERFORMED, "Replot"));
          //At this point, the modified image
          // have been displayed.  
        }catch(Exception e){
          System.out.println(e);
        }//end catch
      }//end if statement on grabPixels
      else System.out.println("Pixel grab not successful");
    }catch(InterruptedException e){
      e.printStackTrace();
    }//end catch
    //Cause the composite of the frame, the
    // canvas, and the button to become visible.
    this.setVisible(true);
    //=========================================//
    //Anonymous inner class listener to terminate
    // program.
    this.addWindowListener(
      new WindowAdapter(){
        public void windowClosing(WindowEvent e){
          System.exit(0);//terminate the program
        }//end windowClosing()
      }//end WindowAdapter
    );//end addWindowListener
    //=========================================//
  }//end constructor
  //===========================================//
 public void mouseClicked(MouseEvent me) {
  mX = 0;
  mY = 10;
  msg = "Mouse clicked";
  //repaint();
  System.out.println("mY = " + mY);
 }
 public void mouseEntered(MouseEvent me) {
  mX = 0;
  mY = 10;
  msg = "Mouse entered";
  repaint();
 }
 public void mouseExited(MouseEvent me) { 
  mX = 0;
  mY = 10;
  msg = "Mouse exited";
  repaint();
 }
 public void mousePressed(MouseEvent me) {
  mX = me.getX();
  mY = me.getY();
  msg = "Down";
  repaint();
 }
 public void mouseReleased(MouseEvent me) {
  mX = me.getX();
  mY = me.getY();
  msg = "Up";
  repaint();
 }
 public void paint(Graphics g) {
  g.drawString(msg + " " + mX + " " + mY, mX, mY);
 }
  ///Inner class for canvas object on which to
  // display the two images.
  class Display extends Canvas
  {
   //Override the paint method to display both
   // the rawImg and the modImg on the same
   // Canvas object, separated by one row of
   // pixels in the background color.
   public void paint(Graphics g)
   {
    //First confirm that the image has been
    // completely loaded and neither image
    // reference is null.
    if (tracker.statusID(1, false) == MediaTracker.COMPLETE)
    {
     if ((rawImg != null) && ig==1)
     {
      g.drawImage(rawImg, 0, 0, this);
      ig = 2;
      //g.drawImage(modImg, 0, imgRows + 1, this);
     }//end if
     else if((modImg!=null) && ig==2)
     {
      g.drawImage(modImg, 0, 0, this);
     }
    }//end if
   }//end paint()
  }//end class myCanvas
//=============================================//
  //Save pixel values as type int to make
  // arithmetic easier later.
  //The purpose of this method is to convert the
  // data in the int oneDPix array into a 3D
  // array of ints.
  
  int[][][] convertToThreeDim(
          int[] oneDPix,int imgCols,int imgRows){
    //Create the new 3D array to be populated
    // with color data.
    int[][][] data = new int[imgRows][imgCols][4];
    for(int row = 0;row < imgRows;row++){
      //Extract a row of pixel data into a
      // temporary array of ints
      int[] aRow = new int[imgCols];
      for(int col = 0; col < imgCols;col++){
        int element = row * imgCols + col;
        aRow[col] = oneDPix[element];
      }//end for loop on col
      //Move the data into the 3D array.  Note
      // the use of bitwise AND and bitwise right
      // shift operations to mask all but the
      // correct set of eight bits.
      for(int col = 0;col < imgCols;col++){
        //Alpha data
        data[row][col][0] = (aRow[col] >> 24) & 0xFF;
        //Red data
        data[row][col][1] = (aRow[col] >> 16) & 0xFF;
        //Green data
        data[row][col][2] = (aRow[col] >> 8) & 0xFF;
        //Blue data
        data[row][col][3] = (aRow[col]) & 0xFF;
      }//end for loop on col
    }//end for loop on row
    return data;
  }//end convertToThreeDim
  //-------------------------------------------//
  //The purpose of this method is to convert the
  // data in the 3D array of ints back into the
  // 1d array of type int.  This is the reverse
  // of the method named convertToThreeDim.
  int[] convertToOneDim(int[][][] data,int imgCols,int imgRows){
    //Create the 1D array of type int to be
    // populated with pixel data, one int value
    // per pixel, with four color and alpha bytes
    // per int value.
    int[] oneDPix = new int[imgCols * imgRows * 4];
    //Move the data into the 1D array.  Note the
    // use of the bitwise OR operator and the
    // bitwise left-shift operators to put the
    // four 8-bit bytes into each int.
    for(int row = 0,cnt = 0;row < imgRows;row++){
      for(int col = 0;col < imgCols;col++){
        oneDPix[cnt] = ((data[row][col][0] << 24) & 0xFF000000) | ((data[row][col][1] << 16)
                                   & 0x00FF0000) | ((data[row][col][2] << 8) & 0x0000FF00)
                           | ((data[row][col][3]) & 0x000000FF);
        cnt++;
      }//end for loop on col
    }//end for loop on row
    return oneDPix;
  }//end convertToOneDim
}//end ImgMod3.java class
//=============================================//

Hi,

I have implemented the MouseListener on Canvas class and it worked that way too. But i still can't understand why is it not working on Frame.

Regards.

Here's a little example that should demonstrate what is probably going on in your code.

import java.awt.*;
import java.awt.event.*;

class ImgMod3 extends Frame implements MouseListener
{
    public ImgMod3()
    {
        this.addMouseListener(this);
        //this.add(new Panel());
        
        this.addWindowListener(new WindowAdapter()
        {
            public void windowClosing(WindowEvent e)
            {
                System.exit(0);
            }
        });
    }
    
    
    public void mouseClicked(MouseEvent e)
    {
        javax.swing.JOptionPane.showMessageDialog(this, "Mouse button clicked");
    }
    
    public void mouseEntered(MouseEvent e){}
    
    public void mouseExited(MouseEvent e){}
    
    public void mousePressed(MouseEvent e){}
    
    public void mouseReleased(MouseEvent e){}
    
    public static void main(String[] args)
    {
        ImgMod3 frame = new ImgMod3();
        frame.pack();
        frame.setSize(300,300);
        frame.setVisible(true);
    }
}

If you uncomment the line in the constructor then run the program, you'll notice that the events are no longer triggered. It's because the Frame is covered up by another component, so technically it'd be like trying to click on a window that's behind another window.

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