/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.myfaces.custom.captcha.util;
import java.awt.Color;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.font.TextLayout;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import org.apache.batik.ext.awt.image.codec.PNGEncodeParam;
import org.apache.batik.ext.awt.image.codec.PNGImageEncoder;
/**
* This class is responsible for generating the CAPTCHA image.
*
* @since 1.1.7
*/
public class CAPTCHAImageGenerator
{
//private static final Color startingColor = new Color(150, 50, 150);
//private static final Color endingColor = new Color(255, 255, 255);
/*
* A helper method to draw the captcha text on the generated image.
*/
private void drawTextOnImage(Graphics2D graphics, String captchaText)
{
Font font;
TextLayout textLayout;
double currentFontStatus = Math.random();
// Generate random font status.
if (currentFontStatus >= 0.5)
{
font = new Font("Arial", Font.PLAIN, 60);
}
else
{
font = new Font("Arial", Font.BOLD, 60);
}
graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
textLayout = new TextLayout(captchaText, font, graphics
.getFontRenderContext());
textLayout.draw(graphics, CAPTCHAConstants.TEXT_X_COORDINATE,
CAPTCHAConstants.TEXT_Y_COORDINATE);
}
/*
* A helper method to apply noise on the generated image.
*/
private void applyNoiseOnImage(Graphics2D graphics, int bufferedImageWidth,
int bufferedImageHeight, Color startingColor, Color endingColor)
{
// Applying shear.
applyShear(graphics, bufferedImageWidth, bufferedImageHeight,
startingColor, endingColor);
// Drawing a broken line on the image.
drawBrokenLineOnImage(graphics);
}
/*
* This helper method is used for applying current gradient paint to the
* Graphics2D object.
*/
private static void applyCurrentGradientPaint(Graphics2D graphics,
int width, int height, Color startingColor, Color endingColor)
{
GradientPaint gradientPaint = new GradientPaint(0, 0, startingColor,
width, height, endingColor);
graphics.setPaint(gradientPaint);
}
/**
* This method generates the CAPTCHA image.
* @param response
* @param captchaText
* @param startingColor
* @param endingColor
* @throws IOException
*/
public void generateImage(OutputStream out, String captchaText,
Color startingColor, Color endingColor) throws IOException
{
BufferedImage bufferedImage;
Graphics2D graphics;
PNGEncodeParam param;
PNGImageEncoder captchaPNGImage;
// Create the CAPTCHA Image.
bufferedImage = new BufferedImage(
CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH,
CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT,
BufferedImage.TYPE_BYTE_INDEXED);
// Setup the graphics object.
graphics = bufferedImage.createGraphics();
applyCurrentGradientPaint(graphics, bufferedImage.getWidth(),
bufferedImage.getHeight(), startingColor, endingColor);
graphics.fillRect(0, 0, bufferedImage.getWidth(), bufferedImage
.getHeight());
graphics.setColor(Color.black);
// Draw text on the CAPTCHA image.
drawTextOnImage(graphics, captchaText);
// Apply noise on the CAPTCHA image.
applyNoiseOnImage(graphics, bufferedImage.getWidth(), bufferedImage
.getHeight(), startingColor, endingColor);
// Draw the image border.
drawBorders(graphics, bufferedImage.getWidth(), bufferedImage
.getHeight());
param = PNGEncodeParam.getDefaultEncodeParam(bufferedImage);
captchaPNGImage = new PNGImageEncoder(out, param);
captchaPNGImage.encode(bufferedImage);
}
/*
* This helper method is used for drawing a thick line on the image.
*/
private void drawThickLineOnImage(Graphics graphics, int x1, int y1,
int x2, int y2)
{
int dX = x2 - x1;
int dY = y2 - y1;
int xPoints[] = new int[4];
int yPoints[] = new int[4];
int thickness = 2;
double lineLength = Math.sqrt(dX * dX + dY * dY);
double scale = (double) (thickness) / (2 * lineLength);
double ddx = -scale * (double) dY;
double ddy = scale * (double) dX;
graphics.setColor(Color.black);
ddx += (ddx > 0) ? 0.5 : -0.5;
ddy += (ddy > 0) ? 0.5 : -0.5;
dX = (int) ddx;
dY = (int) ddy;
xPoints[0] = x1 + dX;
yPoints[0] = y1 + dY;
xPoints[1] = x1 - dX;
yPoints[1] = y1 - dY;
xPoints[2] = x2 - dX;
yPoints[2] = y2 - dY;
xPoints[3] = x2 + dX;
yPoints[3] = y2 + dY;
graphics.fillPolygon(xPoints, yPoints, 4);
}
/*
* This helper method is used for drawing a broken line on the image.
*/
private void drawBrokenLineOnImage(Graphics2D graphics)
{
int yPoint1;
int yPoint2;
int yPoint3;
int yPoint4;
int yPoint5;
Random random = new Random();
// Random Y Points.
yPoint1 = random.nextInt(CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT);
yPoint2 = random.nextInt(CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT);
yPoint3 = CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT / 2;
yPoint4 = random.nextInt(CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT);
yPoint5 = random.nextInt(CAPTCHAConstants.DEFAULT_CAPTCHA_HEIGHT);
// Draw the random broken line.
drawThickLineOnImage(graphics, 0, yPoint1,
CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 4, yPoint2);
drawThickLineOnImage(graphics,
CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 4, yPoint2,
CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 2, yPoint3);
drawThickLineOnImage(graphics,
CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 2, yPoint3,
3 * CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 4, yPoint4);
drawThickLineOnImage(graphics,
3 * CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH / 4, yPoint4,
CAPTCHAConstants.DEFAULT_CAPTCHA_WIDTH, yPoint5);
}
/*
* This helper method is used for calculating the delta of the shearing
* equation.
*/
private double getDelta(int period, double i, double phase, double frames)
{
return (double) (period / 2)
* Math.sin(i / (double) period
+ (2 * CAPTCHAConstants.PI * phase) / frames);
}
/*
* This helper method is used for applying shear on the image.
*/
private void applyShear(Graphics2D graphics, int bufferedImageWidth,
int bufferedImageHeight, Color startingColor, Color endingColor)
{
int periodValue = 20;
int numberOfFrames = 15;
int phaseNumber = 7;
double deltaX;
double deltaY;
applyCurrentGradientPaint(graphics, bufferedImageWidth,
bufferedImageHeight, startingColor, endingColor);
for (int i = 0; i < bufferedImageWidth; ++i)
{
deltaX = getDelta(periodValue, i, phaseNumber, numberOfFrames);
graphics.copyArea(i, 0, 1, bufferedImageHeight, 0, (int) deltaX);
graphics.drawLine(i, (int) deltaX, i, 0);
graphics.drawLine(i, (int) deltaX + bufferedImageHeight, i,
bufferedImageHeight);
}
for (int i = 0; i < bufferedImageHeight; ++i)
{
deltaY = getDelta(periodValue, i, phaseNumber, numberOfFrames);
graphics.copyArea(0, i, bufferedImageWidth, 1, (int) deltaY, 0);
graphics.drawLine((int) deltaY, i, 0, i);
graphics.drawLine((int) deltaY + bufferedImageWidth, i,
bufferedImageWidth, i);
}
}
/*
* This helper method is used for drawing the borders the image.
*/
private void drawBorders(Graphics2D graphics, int width, int height)
{
graphics.setColor(Color.black);
graphics.drawLine(0, 0, 0, width - 1);
graphics.drawLine(0, 0, width - 1, 0);
graphics.drawLine(0, height - 1, width, height - 1);
graphics.drawLine(width - 1, height - 1, width - 1, 0);
}
}