Event Handlers:Mouse over "circles"

[Sanjit Singh]

Hi Everyone,
I am a beginner with Swing and I have to complete a project that is due soon. So I would be grateful if somebody could help me out.
I basically have a JFrame and a JPanel inside it to draw a few lines and circles. I am making a time graph inside the JPanel using raw x and y coordinates. I want to achieve the following:
1.I want to draw a small circle at the point where two lines meet.
2.I would also like to have a small pop up box with a message inside it when the user brings his mouse over this circle. I would not like to have a JOptionPane but instead a small window as I have lots of text (multiple lines)to display. When the user moves his mouse away from this circle, then the message box should close automatically.
I have already done point 1. by having a
public void paintComponent(Graphics g)
method in which I am using the graphics object to draw lines and circles.
PROBLEM: My main problem is in point 2, where I would like to add mouse listeners to this circle and somehow to implement this pop box. How can I achieve this? Can I have event handlers on a "circle" and that also inside the paintComponent method? Which swing component should I use for the popup window and how can I use it for my purpose?
Any help in this regard (sample code)would be highly appreciated. Thanks in advance!
Sanjit

[Nathan Pruett]

Here's a short example of how to use multiple tooltips on components that generate graphics... enjoy!

import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.Iterator;
import javax.swing.*;
 
public class CircleToolTip extends JFrame {
    
    private CirclePanel p;
    
    public CircleToolTip() {
        super( "Circle Tool Tip" );
        p = new CirclePanel();
        Circle c = new Circle( 100, 100, 50 );
        c.setColor( Color.blue );
        c.setToolTipText( "This is a blue circle" );
        p.addCircle( c );
        Circle c2 = new Circle( 200, 200, 25 );
        c2.setToolTipText( "This is a red circle" );
        c2.setColor( Color.red );
        p.addCircle( c2 );
        getContentPane().add( p );
        setDefaultCloseOperation( EXIT_ON_CLOSE );
        setSize( 400, 400 );
        setVisible( true );
    }
    
    public static void main( String[] arg ) {
        new CircleToolTip();
    }
    
    private class CirclePanel extends JPanel {
        
        private ArrayList circles;
        
        public CirclePanel() {
            circles = new ArrayList();
            setToolTipText( "" );
        }
        
        public void addCircle( Circle c ) {
            circles.add( c );
        }
        
        public void remove( Circle c ) {
            int i = circles.indexOf( c );
            if ( i != -1 ) {
                circles.remove( i );
            }
        }
        
        public void paintComponent( Graphics g ) {
            super.paintComponent( g );
            Iterator iter = circles.iterator();
            Color oldColor = g.getColor();
            while ( iter.hasNext() ) {
                Circle c = (Circle)iter.next();
                g.setColor( c.getColor() );
                g.fillOval( c.getX(), c.getY(), c.getRadius(),  c.getRadius() );
            }
            g.setColor( oldColor );
        }
        
        public String getToolTipText( MouseEvent evt ) {
            Iterator iter = circles.iterator();
            while ( iter.hasNext() ) {
                Circle c = (Circle)iter.next();
                Rectangle bounds = new Rectangle( c.getX(),
                        c.getY(), c.getRadius(), c.getRadius() );
                if ( bounds.contains( evt.getPoint() ) ) {
                    return c.getToolTipText();
                }
            }
            return (String)null;
        }
        
    }
    
    private class Circle {
        
        private int x;
        private int y;
        private int radius;
        private String toolTip;
        private Color color;
        
        public Circle() {
            this( 0, 0, 1 );
        }
        
        public Circle( int radius ) {
            this( 0, 0, radius );
        }
        
        public Circle( int x, int y ) {
            this( x, y, 1 );
        }
        
        public Circle( int x, int y, int radius ) {
            this.x = x;
            this.y = y;
            this.radius = radius;
            toolTip = "";
            color = Color.black;
        }
        
        public void setX( int x ) {
            this.x = x;
        }
        
        public int getX() {
            return x;
        }
        
        public void setY( int y ) {
            this.y = y;
        }
        
        public int getY() {
            return y;
        }
        
        public void setRadius( int radius ) {
            this.radius = radius;
        }
        
        public int getRadius() {
            return radius;
        }
        
        public void setToolTipText( String text ) { 
            this.toolTip = text;
        }
        
        public String getToolTipText() {
            return toolTip;
        }
        
        public void setColor( Color color ) {
            this.color = color;
        }
        
        public Color getColor() {
            return color;
        }
        
        public boolean equals( Object obj ) {
            if ( obj instanceof Circle ) {
                Circle c = (Circle)obj;
                if ( c.getX() == getX() ) {
                    if ( c.getY() == getY() ) {
                        if ( c.getColor().equals( getColor() ) ) {
                            if ( c.getToolTipText().equals( getToolTipText() ) ) {
                                return true;
                            }
                        }
                    }
                }
            }
            return false;
        }
        
    }
    
}