WikiCaptcha.java

package org.jboss.seam.wiki.core.captcha;

import org.jboss.seam.ScopeType;
import org.jboss.seam.annotations.Install;
import org.jboss.seam.annotations.Name;
import org.jboss.seam.annotations.Scope;
import org.jboss.seam.annotations.intercept.BypassInterceptors;
import org.jboss.seam.captcha.Captcha;
import org.jboss.seam.log.Log;
import org.jboss.seam.log.Logging;

import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.Serializable;

/**
 * Some code borrowed here: http://www.jroller.com/mlconnor/entry/simple_captcha_jsp
 *
 * @author Christian Bauer
 */
@Name("org.jboss.seam.captcha.captcha")
@Scope(ScopeType.SESSION)
@Install(precedence = Install.APPLICATION)
@BypassInterceptors
public class WikiCaptcha extends Captcha implements Serializable {

    Log log = Logging.getLog(WikiCaptcha.class);

    Color backgroundColor = new Color(0xf5, 0xf5, 0xf5);
    Font textFont = new Font("Arial", Font.PLAIN, 25);
    int charsToPrint = 6;
    int width = 120;
    int height = 25;
    int circlesToDraw = 4;
    float horizMargin = 20.0f;
    double rotationRange = 0.2;
    String elegibleChars = "ABDEFGHJKLMRSTUVWXYabdefhkmnrstuvwx245679";
    char[] chars = elegibleChars.toCharArray();

    @Override
    public void init() {
        StringBuffer challengeString = new StringBuffer();
        for (int i = 0; i < charsToPrint; i++) {
            double randomValue = Math.random();
            int randomIndex = (int) Math.round(randomValue * (chars.length - 1));
            char characterToShow = chars[randomIndex];
            challengeString.append(characterToShow);
        }

        setChallenge(challengeString.toString());
        log.debug("setting captcha challenge: " + getChallenge());
    }

    @Override
    public BufferedImage renderChallenge() {

        // Background
        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = (Graphics2D) bufferedImage.getGraphics();
        g.setColor(backgroundColor);
        g.fillRect(0, 0, width, height);

        // Some obfuscation circles
        for (int i = 0; i < circlesToDraw; i++) {
            int circleColor = 80 + (int) (Math.random() * 70);
            float circleLinewidth = 0.3f + (float) (Math.random());
            g.setColor(new Color(circleColor, circleColor, circleColor));
            g.setStroke(new BasicStroke(circleLinewidth));
            int circleRadius = (int) (Math.random() * height / 2.0);
            int circleX = (int) (Math.random() * width - circleRadius);
            int circleY = (int) (Math.random() * height - circleRadius);
            g.drawOval(circleX, circleY, circleRadius * 2, circleRadius * 2);
        }

        // Text
        g.setFont(textFont);
        FontMetrics fontMetrics = g.getFontMetrics();
        int maxAdvance = fontMetrics.getMaxAdvance();
        int fontHeight = fontMetrics.getHeight();
        float spaceForLetters = -horizMargin * 2 + width;
        float spacePerChar = spaceForLetters / (charsToPrint - 1.0f);

        char[] allChars = getChallenge().toCharArray();
        for (int i = 0; i < allChars.length; i++) {
            char charToPrint = allChars[i];
            int charWidth = fontMetrics.charWidth(charToPrint);
            int charDim = Math.max(maxAdvance, fontHeight);
            int halfCharDim = (charDim / 2);
            BufferedImage charImage = new BufferedImage(charDim, charDim, BufferedImage.TYPE_INT_ARGB);
            Graphics2D charGraphics = charImage.createGraphics();
            charGraphics.translate(halfCharDim, halfCharDim);
            double angle = (Math.random() - 0.5) * rotationRange;
            charGraphics.transform(AffineTransform.getRotateInstance(angle));
            charGraphics.translate(-halfCharDim, -halfCharDim);
            int charColor = 60 + (int) (Math.random() * 90);
            charGraphics.setColor(new Color(charColor, charColor, charColor));
            charGraphics.setFont(textFont);
            int charX = (int) (0.5 * charDim - 0.5 * charWidth);
            charGraphics.drawString("" + charToPrint, charX, ((charDim - fontMetrics.getAscent()) / 2 + fontMetrics.getAscent()));
            float x = horizMargin + spacePerChar * (i) - charDim / 2.0f;
            int y = ((height - charDim) / 2);
            g.drawImage(charImage, (int) x, y, charDim, charDim, null, null);

            charGraphics.dispose();
        }
        g.dispose();

        return bufferedImage;
    }

    @Override
    // Remove this: @CaptchaResponse so we can use our own validator, even if someone by accident uses s:validate/All
    public String getResponse() {
        return super.getResponse();
    }

    public String getProtectedChallenge() {
        return getChallenge();
    }

}