The Java Programming Language

Description

This program demonstrates and power of Java graphics along with their ease of use.

Source Code

import java.awt.*;
import java.awt.event.*;
import java.applet.*;


public class canvasboard extends Applet implements 
	MouseMotionListener, ItemListener {

	Canvas picture;
	Point spot;
	Choice Colors = null;

	public void init() {
		setLayout(new BorderLayout());
		
		//add canvas
		picture = new Canvas();
		addMouseMotionListener(this);
		setBackground(Color.black);

		//adds canvas to north region
		add("North", picture);
		
			
		//add color choices for foreground
		Colors = new Choice();
		Colors.addItem("white");
		Colors.addItem("gray");
		Colors.addItem("red");
		Colors.addItem("green");
		Colors.addItem("blue");
		Colors.addItem("yellow");
		Colors.addItem("magenta");
		Colors.addItem("cyan");
		Colors.addItem("pink");
		Colors.addItem("orange");
		Colors.addItemListener(this);
		add("West", Colors);
	}

	public void update(Graphics g) {
		// wont clear screen when mouse moves.
		paint(g);
	}
	
	public void mouseDragged(MouseEvent e) {
		spot = e.getPoint();
		repaint();
	}

	public void mouseMoved(MouseEvent e) {
		//must be implemented
	}

	public void itemStateChanged(ItemEvent e) {
		ItemSelectable is = e.getItemSelectable();
		String s = is.getSelectedObjects() [0].toString();
		
		if ("white".equals(s))
			setForeground(Color.white);
		else if ("gray".equals(s))
			setForeground(Color.gray);
		else if ("red".equals(s))
			setForeground(Color.red);
		else if ("green".equals(s))
			setForeground(Color.green);
		else if ("blue".equals(s))
			setForeground(Color.blue);
		else if ("yellow".equals(s))
			setForeground(Color.yellow);
		else if("magenta".equals(s))
			setForeground(Color.magenta);
		else if("cyan".equals(s))
			setForeground(Color.cyan);
		else if("pink".equals(s))
			setForeground(Color.pink);
		else if("orange".equals(s))
			setForeground(Color.orange);
	
		repaint();
	}
				
	public void paint(Graphics g) {
		if (spot !=null)
			g.fillOval(spot.x - 2, spot.y - 2, 4, 4);
	}
			

		
}

Sample Run Coose a color and start drawing, you may change colors at anytime, to clear the screen hit your browsers refresh button

Program Notes

This program was compiled and run using the Java Developers Kit, Version 1.2.1 for Win32 on x86 from Sun Microsystems running under Windows 98.