Source Code Cross Referenced for CaptchaReader.java in  » Content-Management-System » apache-lenya-2.0 » org » apache » cocoon » reading » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Content Management System » apache lenya 2.0 » org.apache.cocoon.reading 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * Licensed to the Apache Software Foundation (ASF) under one or more
003:         * contributor license agreements.  See the NOTICE file distributed with
004:         * this work for additional information regarding copyright ownership.
005:         * The ASF licenses this file to You under the Apache License, Version 2.0
006:         * (the "License"); you may not use this file except in compliance with
007:         * the License.  You may obtain a copy of the License at
008:         *
009:         *      http://www.apache.org/licenses/LICENSE-2.0
010:         *
011:         * Unless required by applicable law or agreed to in writing, software
012:         * distributed under the License is distributed on an "AS IS" BASIS,
013:         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014:         * See the License for the specific language governing permissions and
015:         * limitations under the License.
016:         */
017:        package org.apache.cocoon.reading;
018:
019:        import java.awt.Color;
020:        import java.awt.Font;
021:        import java.awt.FontMetrics;
022:        import java.awt.Graphics2D;
023:        import java.awt.Image;
024:        import java.awt.RenderingHints;
025:        import java.awt.geom.Rectangle2D;
026:        import java.awt.image.BufferedImage;
027:        import java.awt.image.WritableRaster;
028:        import java.io.ByteArrayOutputStream;
029:        import java.io.IOException;
030:        import java.lang.reflect.Field;
031:        import java.util.Random;
032:
033:        import com.sun.image.codec.jpeg.JPEGCodec;
034:        import com.sun.image.codec.jpeg.JPEGEncodeParam;
035:        import com.sun.image.codec.jpeg.JPEGImageEncoder;
036:
037:        /**
038:         * <p>The {@link CaptchaReader} is a simple tool generating JPEG images for the text
039:         * supplied as its source in a way so that it's hard to parse automatically.</p>
040:         * 
041:         * <p><i>CAPTCHA</i> means quite literally <i>Completely Automated Public Turing
042:         * Test to Tell Computers and Humans Apart</i> and one of the best resources on
043:         * this can be found at the <a href="http://www.captcha.net/">Carnegie Mellon
044:         * School of Computer Science CAPTCHA project.</a>.
045:         * 
046:         * <p>This reader creates very simple <i>CAPTCHAs</i> from within a Cocoon pipeline,
047:         * enabling quick and safe end-user presence identificat. As an example, look at the
048:         * following pipeline snippet:</p>
049:         * 
050:         * <pre>
051:         * &lt;map:match pattern="*"&gt;
052:         *   &lt;map:read type="captcha" src="{1}"/&gt;
053:         * &lt;/map:match&gt;
054:         * </pre>
055:         * 
056:         * <p>The example will produce an image containing the text in <code>{1}</code>
057:         * "warped" or "bent" in a way similar to the Adobe&reg; Photoshop&reg; "Wave"
058:         * filter plugin.</p>
059:         * 
060:         * <p>Few pipeline parameters control the operation of the {@link CaptchaReader}
061:         * (this component is not configurable):</p>
062:         * 
063:         * <ul>
064:         *   <li><code>width</code>: the width of the image to generate (default: 100).</li>
065:         *   <li><code>height</code>: the height of the image to generate (default: 50).</li>
066:         *   <li><code>foreground</code>: the text foreground color (default: random).</li>
067:         *   <li><code>background</code>: the image background color (default: white).</li>
068:         *   <li><code>font</code>: the font to use for the text (default: serif).</li>
069:         *   <li><code>scale</code>: the scaling factor for interim images (default: 5).</li>
070:         *   <li><code>amount</code>: the amount of text warping to apply (default: 1).</li>
071:         *   <li><code>quality</code>: the JPEG encoding quality (default: 0.75).</li>
072:         * </ul>
073:         * 
074:         * <p>Note that when the <code>foreground</code> parameter is not specified, the
075:         * color used to write the text will be randomly chosen in a way that it contrasts
076:         * well with the background color to avoid problems of illegible text.</p>
077:         * 
078:         * <p>Both the <code>foreground</code> and <code>background</code> parameters accept
079:         * strings in the format specified by {@link Color#decode(String)} (for example
080:         * <code>fff</code>, or <code>0099CC</code>) or one of the field names of the
081:         * {@link Color} class (for example {@link Color#BLACK BLACK} or {@link Color#cyan
082:         * cyan} ...).</p>
083:         * 
084:         * <p>The <code>scale</code> parameter controls how much the specified size should
085:         * be scaled while processing the interim images: the bigger the scaling factor, the
086:         * better the image quality, but also the memory used while generating the final
087:         * image will be bigger. In other words, use with care.</p>
088:         * 
089:         * <p>The <code>amount</code> parameter is interpreted as a floating point number
090:         * and must be greater than zero. This controls how much text should be warped, and
091:         * normally a value of <code>1</code> produce quite-good warping. Increasing (or
092:         * decreasing) this value will produce more (ore less) warping.</p>
093:         *
094:         * <p>Remember that in no way the {@link CaptchaReader} claims to be able to
095:         * generate "unbreakable" text (that will be impossible), and improvements to the
096:         * algorithm are welcome.</p>
097:         *
098:         */
099:        public class CaptchaReader extends AbstractReader {
100:
101:            /** <p>A unique {@link Random} instance to use.</p> */
102:            private static final Random RANDOM = new Random();
103:
104:            /**
105:             * <p>The content type of the generated content: <code>image/jpeg</code>.</p>
106:             *
107:             * @return Always <code>image/jpeg</code>.
108:             */
109:            public String getMimeType() {
110:                return "image/jpeg";
111:            }
112:
113:            /**
114:             * <p>Return a {@link Color} instance from a specified parameter.</p>
115:             *
116:             * @param parameterName The name of the parameter whose to use as the color.
117:             * @param defaultColor The default {@link Color} to return.
118:             * @return the interpreted color or the default color specified.
119:             */
120:            private Color getColor(String parameterName, Color defaultColor) {
121:                String colorString = this .parameters.getParameter(
122:                        parameterName, null);
123:                if (colorString == null)
124:                    return defaultColor;
125:                try {
126:                    return Color.decode(colorString);
127:                } catch (Exception e1) {
128:                    try {
129:                        Field colorField = Color.class
130:                                .getDeclaredField(colorString);
131:                        return (Color) colorField.get(Color.class);
132:                    } catch (Exception e2) {
133:                        return defaultColor;
134:                    }
135:                }
136:            }
137:
138:            private Graphics2D antialiasedGraphics(BufferedImage image) {
139:                Graphics2D graphics = image.createGraphics();
140:                graphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
141:                        RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
142:                return graphics;
143:            }
144:
145:            /**
146:             * <p>Create an image containing the text specified as this reader source
147:             * warped to avoid automatic interpretation.</p>
148:             *
149:             * @throws IOException if an I/O error occurred generating the image.
150:             */
151:            public void generate() throws IOException {
152:
153:                /* Retrieve the current operational parameters from Cocoon's sitemap */
154:                final int width = this .parameters.getParameterAsInteger(
155:                        "width", 100);
156:                final int height = this .parameters.getParameterAsInteger(
157:                        "height", 50);
158:                Color background = this .getColor("background", Color.white);
159:                Color foreground = this .getColor("foreground", null);
160:                if (foreground == null) {
161:                    int r = (RANDOM.nextInt(64) + 96 + background.getRed()) & 0x0ff;
162:                    int g = (RANDOM.nextInt(64) + 96 + background.getGreen()) & 0x0ff;
163:                    int b = (RANDOM.nextInt(64) + 96 + background.getBlue()) & 0x0ff;
164:                    foreground = new Color(r, g, b);
165:                }
166:                final String fontName = this .parameters.getParameter("font",
167:                        "serif");
168:                final int scale = this .parameters.getParameterAsInteger(
169:                        "scale", 5);
170:                final float amount = this .parameters.getParameterAsFloat(
171:                        "amount", 2);
172:                final float quality = this .parameters.getParameterAsFloat(
173:                        "quality", 0.75F);
174:                final String text = this .source;
175:
176:                /* Create the final buffered image we will be writing to at the bottom */
177:                final BufferedImage result = new BufferedImage(width, height,
178:                        BufferedImage.TYPE_INT_RGB);
179:
180:                /* Starting with a size of 100, evaluate how big the real font should be */
181:                final Font baseFont = new Font(fontName, Font.PLAIN, 100);
182:                final Graphics2D graphics = this .antialiasedGraphics(result);
183:                final FontMetrics metrics = graphics.getFontMetrics(baseFont);
184:                final Rectangle2D tempSize = metrics.getStringBounds(text,
185:                        graphics);
186:
187:                /* Evaluate the image size of the resulting image and prepare a ratio */
188:                final double tempWidth = tempSize.getWidth()
189:                        + (2 * tempSize.getHeight());
190:                final double tempHeight = (tempSize.getHeight() * (1 + amount));
191:                final double ratioWidth = width * scale / tempWidth;
192:                final double ratioHeight = height * scale / tempHeight;
193:                final double ratio = ratioWidth < ratioHeight ? ratioWidth
194:                        : ratioHeight;
195:                final Font font = baseFont.deriveFont((float) (100 * ratio));
196:
197:                /* Evaluate the final size of the text to write */
198:                final FontMetrics sourceMetrics = graphics.getFontMetrics(font);
199:                final Rectangle2D size = sourceMetrics.getStringBounds(text,
200:                        graphics);
201:                final double textWidth = size.getWidth();
202:                final double textHeight = size.getHeight();
203:
204:                /* Evaluate the final size of the interim images */
205:                int scaledWidth = (int) (tempWidth * ratio);
206:                int scaledHeight = (int) (tempHeight * ratio);
207:
208:                /* Create a couple of images to write the plain string and the warped one */
209:                BufferedImage source = new BufferedImage(scaledWidth,
210:                        scaledHeight, BufferedImage.TYPE_BYTE_GRAY);
211:                BufferedImage warped = new BufferedImage(scaledWidth,
212:                        scaledHeight, BufferedImage.TYPE_INT_ARGB);
213:
214:                /* Prepare the background and the font of the source image */
215:                final Graphics2D sourceGraphics = this 
216:                        .antialiasedGraphics(source);
217:                sourceGraphics.setColor(Color.black);
218:                sourceGraphics.fillRect(0, 0, scaledWidth, scaledHeight);
219:                sourceGraphics.setFont(font);
220:
221:                /* Write the string exactly in the middle of the source image */
222:                float textX = (float) ((scaledWidth - textWidth) / 2);
223:                float textY = (float) ((scaledHeight - textHeight) / 2);
224:                sourceGraphics.setColor(Color.white);
225:                sourceGraphics.drawString(text, textX, textY
226:                        + sourceMetrics.getAscent());
227:
228:                /* Randomize displacement factors for sine-waves */
229:                final int displaceTop = RANDOM.nextInt(scaledWidth);
230:                final int displaceBtm = RANDOM.nextInt(scaledWidth);
231:                final int displaceVer = RANDOM.nextInt(scaledHeight);
232:
233:                /* Calculate the horizontal and vertical amplitude and wavelength of sines */
234:                final double amplitHor = textHeight * amount / 4;
235:                final double amplitVer = textHeight / 8;
236:                final double t = (RANDOM.nextDouble() * textWidth / 2)
237:                        + (textWidth * 0.75);
238:                final double b = (RANDOM.nextDouble() * textWidth / 2)
239:                        + (textWidth * 0.75);
240:                final double wlenTop = textHeight > t ? textHeight : t;
241:                final double wlenBtm = textHeight > b ? textHeight : b;
242:
243:                /* Calculate the offsets for horizontal (top and bottom) sine waves */
244:                final double offsetTop = amplitHor;
245:                final double offsetBtm = scaledHeight - amplitHor;
246:
247:                /* Prepare an array for vertical displacement sine wave */
248:                final double vert[] = new double[scaledHeight];
249:                for (int v = 0; v < scaledHeight; v++) {
250:                    vert[v] = Math.sin((Math.PI * (v + displaceVer))
251:                            / textHeight)
252:                            * amplitVer;
253:                }
254:
255:                /* Iterate all the target image pixels and render the distortion */
256:                int x1 = Integer.MAX_VALUE;
257:                int x2 = Integer.MIN_VALUE;
258:                int y1 = Integer.MAX_VALUE;
259:                int y2 = Integer.MIN_VALUE;
260:                final WritableRaster sourceRaster = source.getRaster();
261:                final WritableRaster warpedRaster = warped.getRaster();
262:                final double src[] = new double[9];
263:                final double col[] = new double[] { foreground.getRed(),
264:                        foreground.getGreen(), foreground.getBlue(), 0 };
265:                for (int h = 0; h < scaledWidth; h++) {
266:                    final double baseTop = (Math.PI * (h + displaceTop))
267:                            / wlenTop;
268:                    final double baseBtm = (Math.PI * (h + displaceBtm))
269:                            / wlenBtm;
270:                    final double top = offsetTop + Math.sin(baseTop)
271:                            * amplitHor;
272:                    final double btm = offsetBtm - Math.sin(baseBtm)
273:                            * amplitHor;
274:
275:                    for (int v = 0; v < scaledHeight; v++) {
276:                        final double x = (h + vert[v]);
277:                        final double y = (v * ((btm - top) / scaledHeight))
278:                                + top;
279:
280:                        if ((y > 0) && (y < scaledHeight - 1) && (x > 0)
281:                                && (x < scaledWidth - 1)) {
282:
283:                            /* Retrieve the nine pixels around the source one */
284:                            sourceRaster.getPixels((int) (x - 1),
285:                                    (int) (y - 1), 3, 3, src);
286:
287:                            /* Average their value (it's grayscale) to have a better warp */
288:                            double alpha = ((src[1] + src[3] + src[5] + src[7]) * 0.1)
289:                                    + ((src[0] + src[2] + src[6] + src[8]) * 0.025)
290:                                    + (src[4] * 0.5);
291:
292:                            /* Write the resultin pixel in the target image if necessary */
293:                            if (alpha > 0) {
294:                                col[3] = alpha;
295:                                warpedRaster.setPixel(h, v, col);
296:                                if (h < x1)
297:                                    x1 = h;
298:                                if (h > x2)
299:                                    x2 = h;
300:                                if (v < y1)
301:                                    y1 = v;
302:                                if (v > y2)
303:                                    y2 = v;
304:                            }
305:                        }
306:                    }
307:                }
308:
309:                /* Crop the image to the maximum extent of the warped text (if visible) */
310:                source = null;
311:                int xd = x2 - x1 + 1;
312:                int yd = y2 - y1 + 1;
313:                if ((xd > 1) && (yd > 1)) {
314:                    warped = warped.getSubimage(x1, y1, xd, yd);
315:                }
316:
317:                /* Rescale the cropped image to the required size */
318:                Image image = warped.getScaledInstance(width, height,
319:                        Image.SCALE_SMOOTH);
320:                graphics.setBackground(background);
321:                graphics.setColor(background);
322:                graphics.fillRect(0, 0, width, height);
323:                graphics.setColor(foreground);
324:                graphics.drawImage(image, 0, 0, null);
325:                warped = null;
326:
327:                /* Write the processed image as a JPEG image */
328:                ByteArrayOutputStream buffer = new ByteArrayOutputStream();
329:                JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(buffer);
330:                JPEGEncodeParam param = encoder
331:                        .getDefaultJPEGEncodeParam(result);
332:                param.setQuality(quality, true);
333:                encoder.encode(result, param);
334:                buffer.flush();
335:                buffer.close();
336:                this.out.write(buffer.toByteArray());
337:                this.out.flush();
338:            }
339:        }
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