Jdialog paint

Question

How does the painting work on a JDialog window ? I am opening a JDialog on clicking a button and on that Jdialog has 2 jpanels. one with a jbutton and other panel for just painting a image. on the top of the image the user can draw rectangles. where should i put the code for mousedragged event ??

Answer 1

here is my code. please run after replacing the image URL. I ned to draw rectangles on top of the image...it draws but something is not right
import java.net.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
class MapDialog extends JDialog implements MouseMotionListener{
     JButton btnMap,btnCancel;
     JLabel lblImage;
     JPanel pnlButtons,pnlImage;
     Image  im;
     int locationx,locationy;
     int startx,starty;
     boolean bIsMouseDragged;
     int counter;
     int rectPoints[];
     int iRectCounter;
     String[] strCoords;
     public MapDialog() {
          rectPoints = new int[200];
          strCoords = new String[200];
          addMouseMotionListener(this);
               MyMouseListener mml = new MyMouseListener();
               addMouseListener(mml);
               pnlButtons = new JPanel();
               pnlImage = new JPanel();
               btnMap = new JButton("Save");
               btnCancel = new JButton("Cancel");
               pnlButtons.add(btnMap);
               pnlButtons.add(btnCancel);
               getContentPane().add(pnlImage, BorderLayout.CENTER);
               getContentPane().add(pnlButtons, BorderLayout.SOUTH);
               pack();
               Toolkit tk = Toolkit.getDefaultToolkit();
               Dimension d = tk.getScreenSize();
               setLocation(((int)d.getWidth() /2 ) - getWidth() / 2  , ((int)d.getHeight() / 2) - getHeight() / 2);
          public void paint(Graphics g) {
                         System.out.println("paint called");
                         validate();
                         super.paint(g);
     public void paintComponents(Graphics g) {
          System.out.println("pc called");
          Graphics g2 = pnlImage.getGraphics();
          try {
                         URL url = new URL("http://localhost/java/mapedit2/images/leftart.jpg");
                         im = Toolkit.getDefaultToolkit().getImage(url);
                         MediaTracker mt = new MediaTracker(this);
                         mt.addImage(im, 0);
                         try {
                              mt.waitForAll();
                         } catch (InterruptedException e) {}
                    } catch(MalformedURLException ure) {System.out.println("exception");}
          g2.drawImage(im,0,0,this);
          if( bIsMouseDragged) {
                              g2.drawLine(startx,starty,locationx,starty);
                              g2.drawLine(startx,starty,startx,locationy);
                              g2.drawLine(startx,locationy,locationx,locationy);
                              g2.drawLine(locationx,starty,locationx,locationy);
     //     g2.dispose();
     public void mouseDragged(MouseEvent me) {
                         locationx = me.getX();
                         locationy = me.getY();
                         bIsMouseDragged = true;
                         repaint();
                    public void mouseMoved(MouseEvent me) {
                                   //System.out.println(me.getX());
          class MyMouseListener extends MouseAdapter {
                         public void mousePressed(MouseEvent me) {
                                        startx = 0;
                                        starty = 0;
                                        locationx = 0;
                                        locationy = 0;
                                        System.out.println("start X : " + me.getX());
                                        System.out.println("start Y : " + me.getX());
                                        startx = me.getX();
                                        starty = me.getY();
                                        //repaint();
                         public void mouseReleased(MouseEvent me) {
                              int rectWidth = (int) Math.sqrt( (locationx - startx) * (locationx - startx));
                              int rectHeight = (int) Math.sqrt( (locationy - starty) * (locationy - starty));
                              System.out.println("iRectCounter " + iRectCounter);
                              rectPoints[iRectCounter] = startx;
                              rectPoints[iRectCounter+1] = starty;
                              rectPoints[iRectCounter+2] = rectWidth;
                              rectPoints[iRectCounter+3] = rectHeight;
                              iRectCounter += 4;
                              System.out.println("end X : " + me.getX());
                              System.out.println("end Y : " + me.getX());
                              bIsMouseDragged = false;
                              // THIS IS THE LINE THAT POPS UP THE HTTP ENTERING VALUE
                              //AddlinkDialog2 aldialog = new AddlinkDialog2(ImagePanel.this, true);
     public static void main(String[] args) {
          //JFrame frame = new JFrame();
          //frame.add(
          MapDialog md = new MapDialog();
          md.pack();
          md.setVisible(true);
          md.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
     }