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WhiteboardUser.javaAPI DocExample3816Tue Jan 20 22:33:38 GMT 1998dcj.examples.Collaborative

WhiteboardUser

public class WhiteboardUser extends RMICollaboratorImpl implements MouseMotionListener, MouseListener
Source code from "Java Distributed Computing", by Jim Farley. Class: WhiteboardUser Example: 10-2 Description: A collaborator in an RMI-based shared whiteboard.

Fields Summary
protected Hashtable
lastPts
protected Component
whiteboard
protected Image
buffer
Constructors Summary
public WhiteboardUser(String name, Color color, String host, String mname)


      
                           
        
    super(name, host, mname);
    getIdentity().setProperty("color", color);
    buildUI();
Methods Summary
protected voidbuildUI()

    Frame f = new Frame();
    GridBagLayout gridbag = new GridBagLayout();
    GridBagConstraints c = new GridBagConstraints();
    f.setLayout(gridbag);
    f.addNotify();
    c.fill = GridBagConstraints.BOTH;
    c.gridwidth = GridBagConstraints.REMAINDER;
    Canvas canvas1 = new java.awt.Canvas();
    canvas1.setSize(240,180);
    canvas1.setBackground(Color.white);
    gridbag.setConstraints(canvas1, c);
    f.add(canvas1);
    String name = null;
    try {
      name = getIdentity().getName();
    }
    catch (Exception e) {
      name = "unknown";
    }
    Label label1 = new java.awt.Label("Your name: " + name);
    label1.setSize(100,30);
    gridbag.setConstraints(label1, c);
    f.add(label1);
    f.setSize(240,210);
    f.show();
    whiteboard = canvas1;
    whiteboard.addMouseListener(this);
    whiteboard.addMouseMotionListener(this);
    buffer = whiteboard.createImage(f.getSize().width,
                                    f.getSize().height);
public voidmouseClicked(java.awt.event.MouseEvent ev)

public voidmouseDragged(java.awt.event.MouseEvent ev)
    //System.out.println("Got mouse drag");
    Point evPt = ev.getPoint();
    try {
      broadcast("drag", evPt);
    }
    catch (Exception e) {
      //System.out.println("exception");
    }
    //System.out.println("Finished drag.");
  
public voidmouseEntered(java.awt.event.MouseEvent ev)
public voidmouseExited(java.awt.event.MouseEvent ev)
public voidmouseMoved(java.awt.event.MouseEvent ev)
public voidmousePressed(java.awt.event.MouseEvent ev)
    //System.out.println("Got mouse pressed");
    Point evPt = ev.getPoint();
    try {
      broadcast("start", evPt);
    }
    catch (Exception e) {}
  
public voidmouseReleased(java.awt.event.MouseEvent ev)
    Point evPt = ev.getPoint();
    try {
      broadcast("end", evPt);
    }
    catch (Exception e) {}
  
protected voidnextLine(java.lang.String agent, java.awt.Point pt, java.awt.Color c)
    Graphics g = buffer.getGraphics();
    if (c != null)
      g.setColor(c);
    Point lastPt = (Point)lastPts.get(agent);
    g.drawLine(lastPt.x, lastPt.y, pt.x, pt.y);
    whiteboard.getGraphics().drawImage(buffer, 0, 0, whiteboard);
  
public booleannotify(java.lang.String tag, java.lang.Object data, Identity src)

    Color agentColor = null;
    try {
      agentColor = (Color)src.getProperty("color");
    }
    catch (Exception exc) {}

    if (tag.compareTo("start") == 0) {
      lastPts.put(src.getName(), data);
    }
    else if (tag.compareTo("drag") == 0) {
      nextLine(src.getName(), (Point)data, agentColor);
      lastPts.put(src.getName(), data);
    }
    else if (tag.compareTo("end") == 0) {
      nextLine(src.getName(), (Point)data, agentColor);
      lastPts.remove(src.getName());
    }

    return true;