package examples;

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

/**
 * CS401 Example 36
 * 
 * Demonstrates the use of JCheckBox GUI components. The program displays a
 * JLabel containing some text and provides two JCheckBox buttons to allow the
 * user to dynamically make the text bold, italics, bold and italics, or plain.
 * 
 * Note that JCheckBoxes fire a different kind of event when the user clicks on
 * them, an ItemEvent. This then requires a different kind of Listener, which
 * the program now implements. The ItemListener interface defines only a single
 * method, itemStateChanged(ItemEvent e), which is called when an ItemEvent
 * object is generated by the GUI.
 * 
 * @author PJ Dillon
 */
public class ex36 implements ItemListener
{
	private JLabel label;
	private JCheckBox bold, italic;
	private Font font;
	
	public ex36()
	{
		JFrame window = new JFrame("Example 36");
		window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		Container c = window.getContentPane();
		c.setLayout(new FlowLayout());
		
		font = new Font("TimesRoman", Font.PLAIN, 72);
		label = new JLabel("Text To Change");
		label.setFont(font);
		c.add(label);
		
		/*
		 * Declare the JCheckBoxes
		 */
		bold = new JCheckBox("Bold");
		c.add(bold);
		
		italic = new JCheckBox("Italics");
		c.add(italic);
		
		//Register this object to listen for ItemEvents
		bold.addItemListener(this);
		italic.addItemListener(this);
		
		window.setSize(520, 200);
		window.setVisible(true);
	}
	
	public void itemStateChanged(ItemEvent e)
	{
		/*
		 * The constants for setting a font's style are defined in such a way so as 
		 * to allow each kind of style to be added or subtracted from an overall
		 * 'style' value. Thus, with each change in the state of a JCheckBox, we
		 * want to add or subject the proper style from the current one. 
		 */
		
		//get the current style
		int style = font.getStyle();
		
		/*
		 * The ItemEvent class defines the getStateChange() method, which acesses
		 * the new state of the object that generated the ItemEvent. The return
		 * value can be compared with one of two constants defined in the ItemEvent
		 * class, SELECTED and DESELECTED. If the JCheckBox has become SELECTED, the
		 * user wishes to make the text either bold or italic. Otherwise, we need to
		 * remove the bold or italics style from the font. We can know which style
		 * the user wants to change by knowing which JCheckBox generated the event.
		 */
		if(e.getStateChange() == ItemEvent.SELECTED)
		{
			if(e.getSource() == bold)
				style += Font.BOLD;
			else if(e.getSource() == italic)
				style += Font.ITALIC;
		}
		else
		{
			if(e.getSource() == bold)
				style -= Font.BOLD;
			else if(e.getSource() == italic)
				style -= Font.ITALIC;
		}
		
		font = new Font("TimesRoman", style, 72);
		label.setFont(font);
		label.repaint();
	}
	
	public static void main(String[] args)
	{
		new ex36();
	}
}