import javax.swing.*;
import java.util.*;

public class CheckMouse{
  public static void main(String args[]){
     JFrame frame=new JFrame("CheckMouse");
     frame.setSize(600,600);
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

     JCanvas canvas=new JCanvas();
     frame.add(canvas);
     frame.setVisible(true);

     JEventQueue events=new JEventQueue();
     events.listenTo(canvas,"canvas");
     int x0=0,y0=0;
     while(true){
       EventObject event=events.waitEvent();
       if(events.isMouseEvent(event)){
         int x=events.getMouseX(event); 
         int y=events.getMouseY(event); 
         if(events.isMousePressed(event)){x0=x;y0=y;}
         if(events.isMouseClicked(event))
           canvas.drawOval(x0-5,y0-5,10,10);
         if(events.isMouseReleased(event))
           canvas.drawLine(x0,y0,x,y);
       }
     }
  }
}