package nl.captcha;import java.awt.AlphaComposite;import java.awt.Color;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.io.Serializable;import javax.imageio.ImageIO;import nl.captcha.backgrounds.BackgroundProducer;import nl.captcha.backgrounds.TransparentBackgroundProducer;import nl.captcha.gimpy.GimpyRenderer;import nl.captcha.gimpy.RippleGimpyRenderer;import nl.captcha.noise.CurvedLineNoiseProducer;import nl.captcha.noise.NoiseProducer;import nl.captcha.text.producer.DefaultTextProducer;import nl.captcha.text.producer.TextProducer;import nl.captcha.text.renderer.DefaultWordRenderer;import nl.captcha.text.renderer.WordRenderer;/** * A builder for generating a CAPTCHA image/answer pair. *  * <p> * Example for generating a new CAPTCHA: * </p> * <pre>Captcha captcha = new Captcha.Builder(200, 50) * 	.addText() * 	.addBackground() * 	.build();</pre> * <p>Note that the <code>build()</code> must always be called last. Other methods are optional, * and can sometimes be repeated. For example:</p> * <pre>Captcha captcha = new Captcha.Builder(200, 50) * 	.addText() * 	.addNoise() * 	.addNoise() * 	.addNoise() * 	.addBackground() * 	.build();</pre> * <p>Adding multiple backgrounds has no affect; the last background added will simply be the * one that is eventually rendered.</p> * <p>To validate that <code>answerStr</code> is a correct answer to the CAPTCHA:</p> *  * <code>captcha.isCorrect(answerStr);</code> *  * @author <a href="mailto:james.childers@gmail.com">James Childers</a> * v */public final class Captcha implements Serializable {    private static final long serialVersionUID = 617511236L;    public static final String NAME = "simpleCaptcha";    private Builder _builder;    private Captcha(Builder builder) {        _builder = builder;    }    public static class Builder implements Serializable {        private static final long serialVersionUID = 1L;        /**         * @serial         */        private String _answer = "";        /**         * @serial         */        private BufferedImage _img;        /**         * @serial         */        private BufferedImage _bg;        private boolean _addBorder = false;        public Builder(int width, int height) {            _img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);        }        /**         * Add a background using the default BackgroundProducer.         *          * @return         */        public Builder addBackground() {            return addBackground(new TransparentBackgroundProducer());        }        /**         * Add a background using the given BackgroundProducer.         *          * @param bgProd         * @return         */        public Builder addBackground(BackgroundProducer bgProd) {        	_bg = bgProd.getBackground(_img.getWidth(), _img.getHeight());                        return this;        }        /**         * Add text to the image using the default TextProducer         *          * @return         */        public Builder addText() {            return addText(new DefaultTextProducer());        }        /**         * Add text to the image using the given TextProducer         *          * @param txtProd         * @return         */        public Builder addText(TextProducer txtProd) {            return addText(txtProd, new DefaultWordRenderer());        }                /**         * Display the answer on the image using the given WordRenderer.         *           * @param wRenderer         * @return         */        public Builder addText(WordRenderer wRenderer) {        	return addText(new DefaultTextProducer(), wRenderer);        }                public Builder addText(TextProducer txtProd, WordRenderer wRenderer) {        	_answer += txtProd.getText();        	wRenderer.render(_answer, _img);        	        	return this;        }        /**         * Add noise using the default NoiseProducer.         *          * @return         */        public Builder addNoise() {            return this.addNoise(new CurvedLineNoiseProducer());        }        /**         * Add noise using the given NoiseProducer.         *          * @param nProd         * @return         */        public Builder addNoise(NoiseProducer nProd) {            nProd.makeNoise(_img);            return this;        }        /**         * Gimp the image using the default GimpyRenderer.         *          * @return         */        public Builder gimp() {            return gimp(new RippleGimpyRenderer());        }        /**         * Gimp the image using the given GimpyRenderer.         *          * @param gimpy         * @return         */        public Builder gimp(GimpyRenderer gimpy) {            gimpy.gimp(_img);            return this;        }        /**         * Draw a single-pixel wide black border around the image.         *          * @return         */        public Builder addBorder() {        	_addBorder = true;            return this;        }        /**         * Build the CAPTCHA. This method should always be called, and should always         * be called last.         *          * @return         */        public Captcha build() {        	if (_bg == null) {        		_bg = new TransparentBackgroundProducer().getBackground(_img.getWidth(), _img.getHeight());        	}        	// Paint the main image over the background        	Graphics2D g = _bg.createGraphics();        	g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1.0f));        	g.drawImage(_img, null, null);        	        	// Add the border, if necessary        	if (_addBorder) {        		int width = _img.getWidth();        		int height = _img.getHeight();        			            g.setColor(Color.BLACK);	            g.drawLine(0, 0, 0, width);	            g.drawLine(0, 0, width, 0);	            g.drawLine(0, height - 1, width, height - 1);	            g.drawLine(width - 1, height - 1, width - 1, 0);        	}        	_img = _bg;        	            return new Captcha(this);        }        @Override        public String toString() {            StringBuffer sb = new StringBuffer();            sb.append("[Answer: ");            sb.append(_answer);            sb.append("][Image: ");            sb.append(_img);            sb.append("]");            return sb.toString();        }                private void writeObject(ObjectOutputStream out) throws IOException {            out.writeObject(_answer);            ImageIO.write(_img, "png", ImageIO.createImageOutputStream(out));        }        private void readObject(ObjectInputStream in) throws IOException,                ClassNotFoundException {            _answer = (String) in.readObject();            _img = ImageIO.read(ImageIO.createImageInputStream(in));        }    }    public boolean isCorrect(String answer) {        return _builder._answer.equals(answer);    }        public String getAnswer() {    	return _builder._answer;    }    public BufferedImage getImage() {        return _builder._img;    }    @Override    public String toString() {        return _builder.toString();    }}