import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTabbedPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;

public class SnapBug extends JPanel implements ComponentListener {
    private static final long serialVersionUID = 1L;
    private final JFrame frm;
    // for displaying output in frame
    private final JTextArea consoleText = new JTextArea();
    private int width;
    private int height;
    private static final int SIZE = 10;// it is for the grid

    public SnapBug(JFrame frm) {
        this.frm = frm;
        width = frm.getSize().width;
        height = frm.getSize().height;

        JTabbedPane tab = new JTabbedPane();
        tab.addTab("consoleText", new JScrollPane(this.consoleText));
        tab.addTab("paint", this);

        initializeConsoleText();
        addComponentListener(this);
        frm.add(tab);
    }

    private void initializeConsoleText() {
        consoleText.setEditable(false);
        consoleText.setFont(new Font("Monospaced", Font.PLAIN, 12));
        consoleText.setTabSize(4);
    }

    // so that you can see what effect to paint method
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        for (int i = 0; i < width; i += SIZE) {
            g.drawLine(i, 0, i, height);
        }
        for (int j = 0; j < height; j += SIZE) {
            g.drawLine(0, j, width, j);
        }
    }

    public void componentResized(ComponentEvent ce) {
        width = frm.getSize().width;
        height = frm.getSize().height;
        println("width: " + width + "\t height: " + height);
    }

    public void componentMoved(ComponentEvent ce) {
    }

    public void componentHidden(ComponentEvent ce) {
    }

    public void componentShown(ComponentEvent ce) {
    }

    public void println(String message) {
        consoleText.append(message + "\n");
        System.out.println(message);
        consoleText.setCaretPosition(consoleText.getDocument().getLength());
    }

    public static void main(String args[]) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame obj = new JFrame("SnapBug");
                obj.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                int base = 350;
                double ratio = (Math.pow(5, 0.5) + 1) / 2;
                obj.setSize((int) (base * ratio), base);
                obj.setLocationRelativeTo(null);
                new SnapBug(obj);
                obj.setVisible(true);
            }
        });
    }
}