Panel refreshing and double buffering

Question

Hi all swing experts
Could any one solve the problem.I have an application,which is having a JSplit pane.
On the left of the JSplit pane , there is a tree. When u click a node from the tree
that will be selected and you can place that node into the right side panel.
And the same way you can click an another node (redirection or sink) and drop into the
panel.you can draw a line by clicking the source and the sink / or redirection.
The line is getting drawn dynamically by getting the x,y coordinates of the node.
once the line is drawn am storing the line into vector, since this is getting drawn
dynamically once if i minimize and maxmize it will disappear.
For avoiding this am trying to redraw the old line from the vector when the window
is getting activated, here the problem starts it draws the line but the line
is getting disappeared immly.
HOW DO I SOLVE THIS?
is it possible to solve this problem with double buffering tech? if so how?
PL HELP.
Software - Visual Tool
Last Modified -7/23/01
sami
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
import javax.swing.border.TitledBorder;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.plaf.FontUIResource;
import javax.swing.tree.*;
import java.lang.System;
import java.net.*;
import java.awt.image.*;
import javax.swing.event.*;
public class CompTree extends JFrame implements TreeSelectionListener,WindowListener{      
// Swing components declarations     
     public JSplitPane jSplitPane1,jSplitPaneTop;
     public JScrollPane treeScrollPane,splitScrollPane;     
public JTree mainTree,jtree ;
public static DefaultMutableTreeNode topchildnode1, topchildnode2, topchildnode3,toptreenode;
DrawPanel dp = new DrawPanel();
     public int i=0;
     public int j=0;
     public int flag = 1 ;
     public String var,S,R,D;
Frame fr = new Frame("GUI TOOL");
public CompTree()
     File nFile = null ;     
     mainTree = DrawTree(nFile,"N") ;
     mainTree.updateUI();
     mainTree.setBackground(new Color(105,205,159));     
          // Tree is getting added into scroll pane
     treeScrollPane = new JScrollPane(mainTree);
          treeScrollPane.setVerticalScrollBarPolicy(javax.swing.JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
treeScrollPane.setHorizontalScrollBarPolicy(javax.swing.JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
          splitScrollPane = new JScrollPane();
          splitScrollPane.setViewportView(dp.panel1);          
          splitScrollPane.setVerticalScrollBarPolicy(javax.swing.JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
splitScrollPane.setHorizontalScrollBarPolicy(javax.swing.JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
jSplitPane1 = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,treeScrollPane,splitScrollPane);          
     jSplitPane1.setOneTouchExpandable(true);
     jSplitPane1.setContinuousLayout(true);
jSplitPane1.addComponentListener(new ComponentAdapter(){
          public void componentResized(ComponentEvent e) {      
               System.out.println("Componenet resized");
          flag = 1;
          paint(dp.panel1.getGraphics());          
//Provide minimum sizes for the two components in the split pane
Dimension minimumSize = new Dimension(150,75);
          splitScrollPane.setMinimumSize(minimumSize);
//Provide a preferred size for the split pane
jSplitPane1.setPreferredSize(new Dimension(700, 500));
          //setContentPane(jSplitPane1);
          fr.add(jSplitPane1);
          fr.setSize(700,500);
          fr.setVisible(true);          
          fr.addWindowListener(this);     
public void windowActivated(WindowEvent we){
     System.out.println("activated");
     dp.draw();
public void windowClosed(WindowEvent we){System.out.println("closed");}
public void windowIconified(WindowEvent we){System.out.println("iconified");}
public void windowDeiconified(WindowEvent we){
     dp.draw();
     System.out.println("deiconified");
public void windowDeactivated(WindowEvent we){System.out.println("deactivated");}
public void windowOpened(WindowEvent we){
     dp.repaint();
     System.out.println("opened");
public void windowClosing(WindowEvent we){
     System.exit(0);
     System.out.println("closing");
     public void valueChanged(TreeSelectionEvent e) {
          DefaultMutableTreeNode node = (DefaultMutableTreeNode)
          mainTree.getLastSelectedPathComponent();     
          String strRootNode = "" ;
          try{
               Object rootNode = node.getRoot();          
               strRootNode = rootNode.toString() ;
          catch(Exception eRoot)
               System.out.println("Error in geting Root Node");
          if (node == null) return;
          Object nodeInfo = node.getUserObject();          
          TreeNode ParentNode = node.getParent();               
          final String strParentName = node.toString() ;
               if (strParentName.equals("Source"))
          System.out.println("Before source");     
          var = "S";
          System.out.println("This is source");
          else if (strParentName.equals("Redirection"))
var ="R";
          else if (strParentName.equals("Sink") )
               var ="D";
          else
               if ( strRootNode != strParentName){
     public JTree DrawTree( File file, String strIsValid)
               jtree = new JTree();
               toptreenode = new DefaultMutableTreeNode("Start");
               topchildnode1 = new DefaultMutableTreeNode("Source");
               topchildnode2 = new DefaultMutableTreeNode("Sink");
               topchildnode3 = new DefaultMutableTreeNode("Redirection");
               toptreenode.add(topchildnode1);
               toptreenode.add(topchildnode2);
               toptreenode.add(topchildnode3);
               jtree.putClientProperty("JTree.lineStyle", "Angled");
               DefaultTreeModel defaulttreemodel = new DefaultTreeModel(toptreenode);
               jtree.setModel(defaulttreemodel);
               DefaultTreeSelectionModel defaulttreeselectionmodel = new DefaultTreeSelectionModel();
               defaulttreeselectionmodel.setSelectionMode(1);
               jtree.setSelectionModel(defaulttreeselectionmodel);
               jtree.addTreeSelectionListener(this);
               jtree.setEditable(true);
               return jtree;      
public static void main(String args[]){
     CompTree ct = new CompTree();
     * This class contains all the component related to panel 1
     * this can be used for .....
public class DrawPanel extends JPanel implements ActionListener,
     ComponentListener,MouseListener,KeyListener{
     public JRadioButton uniRadio,multiRadio,show;
     public JButton sBut,rBut,dBut;
     public int flag = 1 ;
     public int Radio = 1;
     public boolean sIndicator = true;
     public boolean rIndicator = true;
     public boolean isDestSelected = false;
     public boolean isDestFirstTime = true;
public int x1 = 0 ;
     public int y1 = 0 ;
     public int x2 = 0 ;
     public int y2 = 0;
     public int x3 = 0;
     public int y3 = 0;
     public int k=0;
     public int l = 40;
public int b = 40;     
     public String connection1,connection2,connection3,destination1,destination2;
     public int locX;
     public int locY;
public JPanel panel1 = new JPanel ();      
public JPanel panel2 = new JPanel ();     
     Vector lines = new Vector();
     Vector colors = new Vector();
     Vector obj = new Vector();
Vector source = new Vector();
     Vector loc = new Vector();
     BasicStroke stroke = new BasicStroke(2.0f);
Icon compImage = new ImageIcon("network1.gif"); //new
Icon workImage = new ImageIcon("tconnect02.gif");
Icon lapImage = new ImageIcon("server02.gif");
     public DrawPanel(){
     am adding radio button for checking the mode unicast and broad cast mode -- new
uniRadio = new JRadioButton("Unicast Mode");
uniRadio.setMnemonic(KeyEvent.VK_B);
uniRadio.setSelected(true);
multiRadio = new JRadioButton("Broadcast Mode");
multiRadio.setMnemonic(KeyEvent.VK_C);
show = new JRadioButton("show Panel");
show.setMnemonic(KeyEvent.VK_C);
     ButtonGroup group = new ButtonGroup();
group.add(uniRadio);
group.add(multiRadio);
          group.add(show);
     /*     Border border = ButtonGroup.getBorder();
          Border margin = new EmptyBorder(10,10,10,10);
          ButtonGroup.setBorder(new CompoundBorder(border,margin)); */
          uniRadio.addActionListener(this);
     multiRadio.addActionListener(this);
          show.addActionListener(this);
panel1.add(uniRadio);
          panel1.add(multiRadio);
          panel1.add(show);
          uniRadio.setBounds(150,15,100,40);
          multiRadio.setBounds(260,15,120,40);
          show.setBounds(390,15,100,40);
          uniRadio.setBackground(new Color(105,200,205));
          multiRadio.setBackground(new Color(105,200,205));
          show.setBackground(new Color(105,200,205));
          /*****************PANEL 1*********************/
          panel1.setLayout(null);
panel1.setBounds(new Rectangle(0,0,400,400));
          panel1.setBackground(new Color(105,100,205));
          panel1.addComponentListener(this);
          panel1.addMouseListener(this);      
     public void sourceObject(String name)
sBut = new JButton(compImage);
     panel1.add(sBut);     
     sBut.setMnemonic(KeyEvent.VK_F);
     sBut.setBounds(new Rectangle(locX,locY,l,b));     
     sBut.addActionListener(this);
     sBut.addMouseListener(this);
     sBut.addKeyListener(this);
System.out.println("am inside the source object") ;
     sBut.setBackground(new Color(105,100,205));
     System.out.println("key number" +sBut.getMnemonic());
     System.out.println("MY LOCATION : SBUT : "+ sBut.getLocation());
     public void redirectionObject(String name)
     rBut = new JButton(workImage);
     panel1.add(rBut);
     rBut.setBounds(new Rectangle(locX,locY,l,b));     
rBut.addActionListener(this);
     rBut.addMouseListener(this);
     rBut.addKeyListener(this);
     rBut.setBackground(new Color(105,100,205));
System.out.println("am inside the redirection :" + j) ;
System.out.println("MY LOCATION : RBUT : "+ rBut.getLocation());          
public void destinationObject(String name){     
     dBut = new JButton(lapImage);
     panel1.add(dBut);     
     dBut.setBackground(new Color(105,100,205));
System.out.println("am inside the destination object") ;     
dBut.setBounds(new Rectangle(locX,locY,l,b));                    
     System.out.println("am inside the destination:" + j) ;
     dBut.addActionListener(this);
     dBut.addMouseListener(this);
     dBut.addKeyListener(this);
     System.out.println("MY LOCATION : DBUT : "+ dBut.getLocation());           
public void paintComponent(Graphics g){
super.paintComponent(g);
     System.out.println("inside paint");
     Graphics2D g2 = (Graphics2D) g;
g2.setStroke(stroke);
if(flag == 1){
     /* this is for drawing current line, this will be drawn when component event happens */
          g.setColor(getForeground());
System.out.println("inside flag");
int np = lines.size();
                    System.out.println("Total number of lines present the buffer to draw :" + np);
                         for (int I=0; I < np; I++) {                       
     Rectangle p = (Rectangle)lines.elementAt(I);
                    g2.setColor((Color)colors.elementAt(I));
                         System.out.println("width" + p.width);
                         g2.setColor(Color.red);
                    //     g2.setPaint(p.x,p.y,p.width,p.height);
                         g2.drawLine(p.x,p.y,p.width,p.height);                         
                         System.out.println("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");
                         System.out.println(obj.elementAt(I));
                         System.out.println("$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");
                         System.out.println(p.x +"," +","+ p.y + ","+ ","+ p.width+ "," + ","+ p.height);
flag = -1;
}else if(flag == -1){
     if(x1 != 0 && y1 != 0 && x2 != 0 && y2 != 0 ){
connection1 = "source to redirection";
g2.setColor(Color.red);
     g2.drawLine(x1,y1,x2,y2);          
     lines.addElement(new Rectangle(x1,y1,x2,y2));
     colors.addElement(getForeground());
     obj.addElement(connection1);
     x1 = 0 ;y1 = 0 ;
     x2 = 0 ;y2 = 0 ;
else if (x2 != 0 && y2 != 0 && x3 != 0 && y3 != 0 )
          connection2 = "Redirection to Destination";
          g2.setColor(Color.green);
               g2.drawLine(x2,y2,x3,y3);                    
colors.addElement(getForeground());
               lines.addElement(new Rectangle(x2,y2,x3,y3));               
               obj.addElement(connection2);
               x2 = 0; y2 = 0 ;
               x3 = 0 ; y3 = 0 ;                    
else if (x1 != 0 && y1 != 0 && x3 != 0 && y3 != 0)
               connection3 = "Source to Destination";
               g2.setColor(Color.red);
               g2.drawLine(x1,y1,x3,y3);                    
colors.addElement(getForeground());
               lines.addElement(new Rectangle(x1,y1,x3,y3));                              
               obj.addElement(connection3);
                    x1 = 0; y1 = 0 ;
                    x3 = 0 ; y3 = 0 ;                    
                    /*     Image offscreen = panel1.createImage(400,400);
          Graphics og = offscreen.getGraphics();
     og.drawLine(200,200,500,500);
          g.drawImage(offscreen,0,0,null); */
// Component Listener's method
public void componentHidden(ComponentEvent e) { 
if(e.getSource().equals(panel1)){System.out.println("Componenet Hidden");}
          System.out.println("Componenet Hidden");
public void componentMoved(ComponentEvent e) {
          System.out.println("Componenet moved");
          draw();
public void componentResized(ComponentEvent e) {      
          System.out.println("Componenet resized");
          flag = 1;
          paintComponent(panel1.getGraphics());
public void componentShown(ComponentEvent e) {     
          System.out.println("Componenet Shown");
// Mouse Listerner's Method
     public void mouseClicked(MouseEvent me){
if (me.getSource().equals(panel1))
          System.out.println("inside mouse clicked");
                    if(var == "S"){
the boolean sIndicator will allow the usage of source object only once
     This is the case for both unicast and multi cast.It has been restricted
     to single use.
                         if (sIndicator){
                         System.out.println("inside mouse clicked");
                    System.out.println("locX" + locX);
                    locX = me.getX();
locY = me.getY();
               sourceObject("Source");
                         sIndicator = false;
                    }else{}
          }else if (var == "R")
if(rIndicator){
if(!isDestSelected){
System.out.println("redirection" + locX);
locX = me.getX();
locY = me.getY();
               redirectionObject("Redirection");
               rIndicator = false;
               }else{}
} else{}
          }else if(var == "D"){
          if(Radio == 1 && isDestSelected == false){
          System.out.println("Destination -- uni cast mode" + locX);
locX = me.getX();
locY = me.getY();
               destinationObject("Sink");
          isDestSelected = true;
          } else if (Radio == 2)
                              System.out.println("Destination -- Multicast mode" + locX);
                              locX = me.getX();
                              locY = me.getY();
                              destinationObject("Sink");
                              isDestSelected = true;                    
     public void mousePressed(MouseEvent me){System.out.println("am inside mouse pressed"); }
     public void mouseReleased(MouseEvent me){
          System.out.println("am inside mouse released");
          paintComponent(panel1.getGraphics());
     public void mouseEntered(MouseEvent me){}
     public void mouseExited(MouseEvent me){}
// key Listener
public void keyReleased(KeyEvent e) {        
                    Component compo =(JButton)e.getSource();                               
                         if (e.getKeyChar() == e.VK_DELETE){                         
                         remove(compo);
          public void keyTyped(KeyEvent e) {}
          public void keyPressed(KeyEvent e){}
public void remove(Component comp){          
System.out.println("inside delete key" );                         
     panel1.remove(comp);
     panel1.repaint();     
     public void draw(){
          super.paint(panel1.getGraphics());
          System.out.println("inside draw");
          flag = 1;
          paintComponent(panel1.getGraphics());     
     public void actionPerformed(ActionEvent e)
                         if(e.getSource().equals(sBut)){
                              System.out.println("am s button");                
                              x1 = sBut.getX() + l;
                              y1 = sBut.getY() + (b/2);
                         else if(e.getSource().equals(rBut)){
                              System.out.println("am r button");               
                              x2 = rBut.getX() ;
                              y2 = rBut.getY()+ b/2;
                              System.out.println("x2 : " + x2 + "y2 :" +y2 );
                         else if(e.getSource().equals(dBut)){
                              System.out.println("am d button");                
                              x3 = dBut.getX();
                              y3 = dBut.getY()+ b/2;
                         else if (e.getSource().equals(uniRadio)){
                              System.out.println("uni radio");
                              Radio = 1 ;
                         } else if (e.getSource().equals(multiRadio)){
                                   System.out.println("multi radio");
                                   Radio = 2;
                         } else if (e.getSource().equals(show)){            
                              System.out.println("inside show");
*********************************************

Answer 1

ok
i don't take a long time tracing your code, but i think u have to overwrite the repaint methode so it 's call the methode which will paint the line each time.
hope this will help!