PaintApp Listing

PaintApp.java

/*	PaintApp.java - Paint Applet.

	Java Resources
	http://geocities.datacellar.net/SiliconValley/Bay/4050/

	Color Parameters:
		bgcolor     = background
		fgcolor     = foreground (drawing color)
		bordercolor = border

	Each color value is a hexadecimal number of the form
		"rrggbb"
	where rr, gg, bb specify the amount of red, green, and blue,
	respectively, and can range from 00 to FF.

	Example:
	<PARAM NAME="bgcolor" VALUE="FFFFFF">
*/

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

//
// PaintApp
//

public class PaintApp extends Applet {
	//
	// Attributes
	//

	private Dimension size;
	private Color backColor, foreColor, borderColor;

	private Image drawImage;
	private Graphics gDraw;

	private Point prevPoint;
	private boolean isDrawing = false;

	//
	// Operations
	//

	public void init() {
		size = size();

		backColor = initColor("bgcolor", getBackground());
		foreColor = initColor("fgcolor", Color.black);
		borderColor = initColor("bordercolor", Color.black);

		clearImage();
	}

	// Get the color from the applet parameters
	private Color initColor(String param, Color defColor) {
		try {
			String s;

			if((s = getParameter(param)) != null)
				defColor = new Color(Integer.parseInt(s, 16));
		}
		catch(Exception e) { }

		return defColor;
	}

	public void paint(Graphics g) {
		g.drawImage(drawImage, 0, 0, null);
	}

	public void update(Graphics g) { // Override-don't erase background
		paint(g);
	}

	public boolean mouseDown(Event evt, int x, int y) {
		if(evt.modifiers == Event.META_MASK) {
			clearImage();
			repaint();
		} else {
			prevPoint = new Point(x, y);
			isDrawing = true;
		}

		return true;
	}

	public boolean mouseDrag(Event evt, int x, int y) {
		if(isDrawing) {
			gDraw.drawLine(prevPoint.x, prevPoint.y, x, y);
			prevPoint.move(x, y);
			repaint();
		}

		return true;
	}

	public boolean mouseUp(Event evt, int x, int y) {
		isDrawing = false;
		return true;
	}

	private void clearImage() {
		drawImage = createImage(size.width, size.height);
		gDraw = drawImage.getGraphics();
		gDraw.setColor(backColor);
		gDraw.fillRect(0, 0, size.width, size.height);
		gDraw.setColor(borderColor);
		gDraw.drawRect(0, 0, size.width - 1, size.height - 1);
		gDraw.setColor(foreColor);
	}

	//
	// Information functions
	//

	public String getAppletInfo() {
		return "Paint Applet. Copyright © 1998 Java Resources.";
	}

	public String[][] getParameterInfo() {
		String info[][] = {
			{ "bgcolor",     "rrggbb", "Background" },
			{ "fgcolor",     "rrggbb", "Foreground" },
			{ "bordercolor", "rrggbb", "Border" }
		};

		return info;
	}
}

PaintApp.html

<title>PaintApp Java Applet</title>

<div align=center>

<h1>PaintApp</h1>
Scribble in the box below.<br>
Right-click to erase.<p>

<applet code=PaintApp width=200 height=200>
<param name="bgcolor" value="ffffff">
<param name="fgcolor" value="ff">
<param name="bordercolor" value="808080">
This scribble applet requires a Java-enabled browser.
</applet>

</div>