EventQueuePanel.java Source code

Introduction

Here is the source code for EventQueuePanel.java

Source

import java.awt.AWTEvent;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class EventQueuePanel extends JPanel implements ActionListener {
    EventQueuePanel() {
        JButton button = new JButton("Draw line");
        add(button);
        button.addActionListener(this);
    }

    public void actionPerformed(ActionEvent evt) {
        Graphics g = getGraphics();

        displayPrompt(g, "Click to chooose the first point");
        Point p = getClick();
        g.drawOval(p.x - 2, p.y - 2, 4, 4);
        displayPrompt(g, "Click to choose the second point");
        Point q = getClick();
        g.drawOval(q.x - 2, q.y - 2, 4, 4);
        g.drawLine(p.x, p.y, q.x, q.y);
        displayPrompt(g, "Done! Press button the start again.");
        g.dispose();
    }

    public void displayPrompt(Graphics g, String s) {
        y += 20;
        g.drawString(s, 0, y);
    }

    public Point getClick() {
        EventQueue eq = Toolkit.getDefaultToolkit().getSystemEventQueue();
        while (true) {
            try {
                AWTEvent evt = eq.getNextEvent();
                if (evt.getID() == MouseEvent.MOUSE_PRESSED) {
                    MouseEvent mevt = (MouseEvent) evt;
                    Point p = mevt.getPoint();
                    Point top = getRootPane().getLocation();
                    p.x -= top.x;
                    p.y -= top.y;
                    return p;
                }
            } catch (InterruptedException e) {
            }
        }
    }

    private int y = 60;

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setTitle("EventQueueTest");
        frame.setSize(300, 200);
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

        Container contentPane = frame.getContentPane();
        contentPane.add(new EventQueuePanel());

        frame.show();
    }

}