Java: Example - Raise.java

This program program was inspired by a Gore-Bush ballots in Florida. The paintComponent method looks too complicated and should be improved. Also, there's no need to redraw all the fixed elements; these should be drawn only once. So many programs, so little time.

// Raise.java - Ask employee if they want a raise.
//   Example of mouse listeners.
//    2000-12-01 ... 2002-02-19
// Fred Swartz

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

////////////////////////////////////////////////////////////////////// Raise
public class Raise {
    //================================================================= main
    public static void main(String[] args) {
        JFrame w = new RaiseWindow();
        w.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        w.setVisible(true);
    }//end main
}//endclass Raise


//////////////////////////////////////////////////////////////// RaiseWindow
class RaiseWindow extends JFrame {
    private SurveyForm survey;   // "component" of the survey form.

    //========================================================== constructor
    public RaiseWindow() {
        // Create components
        survey = new SurveyForm();
        JButton resetButton = new JButton("Reset");
        resetButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                survey.reset(false);
            }
        });
        
        // Build title
        JLabel title = new JLabel("Want a Raise?", JLabel.CENTER);
        title.setFont(new Font("Serif", Font.BOLD, 48));
        title.setForeground(Color.white);
        JPanel titlePanel = new JPanel();
        titlePanel.setBackground(Color.blue);
        titlePanel.add(title);
        
        // Layout components
        Container content = this.getContentPane();
        content.setLayout(new BoxLayout(content, BoxLayout.Y_AXIS));
        content.add(titlePanel);
        content.add(survey);
        content.add(resetButton);
        
        this.setTitle("Employee Survey");
        this.setResizable(false);
        this.pack();
    }//end constructor
}//endclass RaiseWindow


/////////////////////////////////////////////////////////// class SurveyForm
class SurveyForm extends JPanel implements MouseMotionListener {

    private boolean finished = false; // set true after button selected
    private int     buttonX;
    private int     buttonY;

    // The mouse coordinates are set by the mouse listeners.
    // They must be instance variables so that paintComponent can
    // use them in calculating the button position if necessary.
    private int mouseX = 0;
    private int mouseY = 0;

    //========================================================== constructor
    public SurveyForm() {
        this.setBackground(Color.white);
        this.setPreferredSize(new Dimension(300, 230));
        this.setFont(new Font("Serif", Font.BOLD, 48));
        this.addMouseMotionListener(this);
    }//end constructor
    
    //================================================================ reset
    public void reset(boolean fin) {
        // Called whenever the status of the form should be reset.
        finished = fin;
        this.repaint();  // repaint after any change that might show
    }//end 

    //======================================================= paintComponent
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        
        final int NAME_X    = 20;  // x coord of names
        final int NORAISE_Y = 80;  // y coord of NoRaise button
        final int RAISE_Y   = NORAISE_Y + 100;
        final int MARK_X    = 240; // x coord of buttons
        final int RADIUS    = 16;  // button radius
        final int CRITICAL_DIST = 3 * RADIUS;
        final int CENTER_X   = MARK_X; // x coord of buttons
        final int CENTER_Y   = RAISE_Y - 16; // default y coord of noraise
        final int leftEdge   = CENTER_X - CRITICAL_DIST;
        final int rightEdge  = CENTER_X + CRITICAL_DIST;
        final int topEdge    = CENTER_Y - CRITICAL_DIST;
        final int bottomEdge = CENTER_Y + CRITICAL_DIST;
        
        // Draw choices
        g.setColor(Color.black);
        g.drawString("No Raise", NAME_X, NORAISE_Y);
        g.drawString("Raise"   , NAME_X, RAISE_Y);

        // Check to see if near "No Raise" button, and "select" it if so.
        if (mouseY > (NORAISE_Y-CRITICAL_DIST) && mouseY < (NORAISE_Y+CRITICAL_DIST)
                && mouseX > leftEdge && mouseX < rightEdge) {
            finished = true; // Cause No Raise radio button to be "selected"
        }
        
        if (finished) { // Draw selected No Raise button and fixed Raise button
            g.fillOval(MARK_X-RADIUS, NORAISE_Y-16-RADIUS, 2*RADIUS, 2*RADIUS);
            g.drawOval(CENTER_X-RADIUS, CENTER_Y-RADIUS, 2*RADIUS, 2*RADIUS);
            
        } else {
            // Draw empty No Raise button (doesn't depend on mouse position)
            g.drawOval(MARK_X-RADIUS, NORAISE_Y-16-RADIUS, 2*RADIUS, 2*RADIUS);

            // Draw Raise button (depends on mouse position)
            buttonX = CENTER_X;// Assume normal position; change if mouse is near
            buttonY = CENTER_Y;
            if (mouseX > leftEdge && mouseX < rightEdge
                    && mouseY > topEdge && mouseY < bottomEdge) {
                // mouse is near the Raise button, so we may move it
                int mdx = CENTER_X - mouseX;
                int mdy = CENTER_Y - mouseY;
                if (mdx == 0)
                    mdx = 1;  // don't let mouse appear at center
                if (mdy == 0)
                    mdy = 1;  // don't let mouse appear at center
                // compute distance of mouse from center.
                double mouseDist = Math.sqrt(mdx*mdx + mdy*mdy);
                if (mouseDist < CRITICAL_DIST) {
                    // It's within the critical radius.
                    double bdist = CRITICAL_DIST - mouseDist;// button to center
                    double ratio = bdist / mouseDist;

                    buttonX = CENTER_X + (int)(ratio * mdx);
                    buttonY = CENTER_Y + (int)(ratio * mdy);
                }
            }
            g.drawOval(buttonX-RADIUS, buttonY-RADIUS, 2*RADIUS, 2*RADIUS);
        }
    }//end paintComponent

    //================================================== mouseMoved listener
    public void mouseMoved(MouseEvent e) {
        this.mouseX = e.getX();
        this.mouseY = e.getY();
        this.repaint();
    }//end mouseMoved   
    
    //================================================== mouseMoved listener
    public void mouseDragged(MouseEvent e) {
        this.mouseX = e.getX();
        this.mouseY = e.getY();
        this.repaint();
    }//end mouseDragged

}//end class SurveyForm