Jsp实现动态验证码(由5个类组成的gif动验证码)

import java.awt.*;
import java.io.*;
import java.util.Date;
import java.util.*;
import java.awt.image.*;

public class GifValidateCode {
//定义验证码字符。去除了O和I等容易混淆的字母（也可写成）
String[] s = {"A", "B", "C", "D", "E", "F", "G", "H", "G", "K","M", "N", "P", "Q", "R", "S",
"T", "U", "V", "W","X", "Y", "Z", "a", "b", "c", "d", "e", "f", "g","h", "i", "j",
"k", "m", "n", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "1", "2", "3",
"4", "5", "6", "7", "8", "9", "地", "在", "要", "工", "上", "是", "中", "国", "不", "这"};

//定义生成的验证码的宽度和高度
int width = 160;
int height = 35;

/**
* 获得(生成)GIF验证码
* @param os
* @return String 系统自动生成的验证码的内容
*/
public String getValidateCode(OutputStream os) {
BufferedImage frame = null;
@SuppressWarnings("unused")
Graphics2D teg = null;
@SuppressWarnings("unused")
AlphaComposite ac = AlphaComposite.getInstance(AlphaComposite.SRC_OVER,1);
AnimatedGifEncoder agf = new AnimatedGifEncoder();
agf.start(os);
agf.setQuality(10);
agf.setDelay(100);
agf.setRepeat(0);

// 生成6个随机字符
String rands[] = new String[6];
for (int i = 0; i < 6; i++) {
rands[i] = s[this.randomInt(0, s.length)];
}

//分别使用6种字体
Font[] font = new Font[6];
font[0] = new Font("Gungsuh", Font.BOLD, 24);
font[1] = new Font("宋体", Font.BOLD, 24);
font[2] = new Font("Times New Roman", Font.BOLD, 24);
font[3] = new Font("隶书", Font.BOLD, 24);
font[4] = new Font("Arial Unicode MS", Font.BOLD, 24);
font[5] = new Font("方正舒体", Font.BOLD, 24);

//生成各种颜色
Color bgcolor = new Color(255,255,255);
Color linecolor = getRandColor(200, 250);
Color fontcolor[] = new Color[6];
Random random = new Random();
for (int i = 0; i < 6; i++) {
fontcolor[i] = new Color(20 + random.nextInt(110),
20 + random.nextInt(110), 20 + random.nextInt(110));
}
//生成Gif信息类
for (int i = 0; i < font.length; i++) {
frame = this.getImage(bgcolor, linecolor, fontcolor, rands, font, i);
agf.addFrame(frame);
frame.flush();
}
agf.finish();
String fonts = rands[0] + rands[1]+rands[2]+rands[3]+rands[4]+rands[5];
return fonts;
}
/*
* // 随机产生150个干扰点
g.setColor(Color.gray);
Random rand = new Random();
for (int i = 0; i < 150; i++) {
g.setColor(new Color(0x123456));//设置干扰点的颜色
int x = rand.nextInt(width);
int y = rand.nextInt(height);
g.drawOval(x, y, 1, 1); //可以使用干扰线等其他的方式只是调用不同的方法而已
}
Random rnd = new Random(new Date().getTime());
for(int i=0;i<10;i++){
// g.setColor(getRandomColor(100, 155));    //随机线条的颜色
int x1 = rnd.nextInt(width);    //线条两端坐标值
int y1 = rnd.nextInt(height);
int x2 = rnd.nextInt(width);
int y2 = rnd.nextInt(height);
g.drawLine(x1, y1, x2, y2); //画线条
}
* */

//out.clear();
//out = pageContext.pushBody();

/**
* 获得图片缓冲
* @param bgcolor  背景颜色
* @param linecolor 背景线的颜色
* @param fontcolor  字体颜色
* @param str
* @param font 字体
* @param flag
* @return BufferedImage
*/
private BufferedImage getImage(Color bgcolor, Color linecolor,Color[] fontcolor,
String[] str, Font[] font,int flag) {
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
//或得图形上下文
Graphics2D g2d = image.createGraphics();
//利用指定颜色填充背景
g2d.setColor(bgcolor);
g2d.fillRect(0, 0, width, height);
//画背景线 3*3  (数字越大格子越密)
g2d.setColor(linecolor);
for (int i = 0; i < height / 3; i++)
g2d.drawLine(0, i * 3, width, i * 3);
for (int i = 0; i < width / 3; i++)
g2d.drawLine(i * 3, 0, i * 3, height);
// 画背景LOGO
/*AlphaComposite ac = AlphaComposite.getInstance(AlphaComposite.SRC_OVER,
0.2f);
g2d.setComposite(ac);
g2d.setFont(new Font("隶书", Font.ITALIC + Font.BOLD, 26));
g2d.setColor(Color.red);
g2d.drawString("HAHA小组", 19, 25);*/

//以下生成验证码
//透明度从0 循环到1 步长为0.2 。一共6个字母
//int[] height ={23,31,27,22,25,29};

int[] height = new int[6];

Random rand = new Random();

for(int i=0; i<6; i++){
height[i] = rand.nextInt(15) + 20;
}
AlphaComposite ac3 = null;
for (int i = 0; i < str.length; i++) {
g2d.setFont(font[i]);
ac3 = AlphaComposite.getInstance(AlphaComposite.SRC_OVER,
getAlpha(flag, i));
g2d.setComposite(ac3);
g2d.setColor(fontcolor[i]);
g2d.drawString(str[i], 25 * i + 8, height[i]);
}

// 随机产生20个干扰点
for (int i = 0; i < 200; i++) {
g2d.setColor(new Color(0x123456));//设置干扰点的随机颜色
int x = rand.nextInt(width);
int y = rand.nextInt(this.height);

g2d.drawOval(x, y, 1, 1); //可以使用干扰线等其他的方式只是调用不同的方法而已
}

// 画15条干扰线
Random rnd = new Random(new Date().getTime());
for(int i=0;i<15;i++){

g2d.setColor(getRandColor(100, 155));  //设置干扰线的随机颜色
int x1 = rnd.nextInt(width);    //线条两端坐标值
int y1 = rnd.nextInt(this.height);
int x2 = rnd.nextInt(width);
int y2 = rnd.nextInt(this.height);
g2d.drawLine(x1, y1, x2, y2); //画线条
}

g2d.dispose();
return image;
}

/**
* 获得循环透明度，从0到1 步长为0.2
* @param i
* @param j
* @return float
*/
private float getAlpha(int i, int j) {
if ((i + j) > 5)
return ((i + j) * 0.2f - 1.2f);
else
return (i + j) * 0.2f;
}

/**
* 获得随机颜色
* @param fc 给定范围获得随机颜色
* @param bc 给定范围获得随机颜色
* @return Color
*/
private Color getRandColor(int fc, int bc) {
Random random = new Random();
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}

/**
* 产生随机数
* 返回[from,to)之间的一个随机整数
* @param from 起始值
* @param to 结束值
* @return  [from,to)之间的一个随机整数
*/
Random r = new Random();
private int randomInt(int from, int to) {
return from + r.nextInt(to - from);
}
}

<%@ page contentType="text/html" pageEncoding="GBK"
import="java.util.*,javax.imageio.*,java.io.*,java.awt.*,
java.awt.image.*,com.accp.shi.validatecode.*"%>
<%
GifValidateCode gvc = new GifValidateCode();
OutputStream stream = response.getOutputStream();  // 获得输出流
String code = gvc.getValidateCode(stream);
out.clear();  //释放在jsp中使用的对象
out = pageContext.pushBody();  //释放在jsp中使用的对象
%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<mce:script type="text/javascript"><!--
function changeValidateCode()
{
var imgCode = document.getElementById("imgCode");
imgCode.src = "code.jsp?s="+new Date().getTime(); //当点击换一张时可清空缓存中的原有页面，所以添加了一个时间作为参数传过去
}
// --></mce:script>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="">
用户名：<input type="text" name="txtName"><br>
密　码：<input type="password" name="txtPassword"><br>
<img alt="验证码" src="code.jsp" mce_src="code.jsp" id="imgCode"><a href="javascript:changeValidateCode()" mce_href="javascript:changeValidateCode()">看不清，换一张</a><br>
<input type="submit" value="注 册">
</form>
</body>
</html>

package com.accp.bookshop.util;

import java.io.*;
import java.awt.*;
import java.awt.image.*;

/**
* Class AnimatedGifEncoder - Encodes a GIF file consisting of one or
* more frames.
* <pre>
* Example:
*    AnimatedGifEncoder e = new AnimatedGifEncoder();
*    e.start(outputFileName);
*    e.setDelay(1000);   // 1 frame per sec
*    e.addFrame(image1);
*    e.addFrame(image2);
*    e.finish();
* </pre>
* No copyright asserted on the source code of this class.  May be used
* for any purpose, however, refer to the Unisys LZW patent for restrictions
* on use of the associated LZWEncoder class.  Please forward any corrections
* to kweiner@fmsware.com.
*
* @author Kevin Weiner, FM Software
* @version 1.03 November 2003
*
*/

public class AnimatedGifEncoder {

protected int width; // image size
protected int height;
protected Color transparent = null; // transparent color if given
protected int transIndex; // transparent index in color table
protected int repeat = -1; // no repeat
protected int delay = 0; // frame delay (hundredths)
protected boolean started = false; // ready to output frames
protected OutputStream out;
protected BufferedImage image; // current frame
protected byte[] pixels; // BGR byte array from frame
protected byte[] indexedPixels; // converted frame indexed to palette
protected int colorDepth; // number of bit planes
protected byte[] colorTab; // RGB palette
protected boolean[] usedEntry = new boolean[256]; // active palette entries
protected int palSize = 7; // color table size (bits-1)
protected int dispose = -1; // disposal code (-1 = use default)
protected boolean closeStream = false; // close stream when finished
protected boolean firstFrame = true;
protected boolean sizeSet = false; // if false, get size from first frame
protected int sample = 10; // default sample interval for quantizer

/**
* Sets the delay time between each frame, or changes it
* for subsequent frames (applies to last frame added).
*
* @param ms int delay time in milliseconds
*/
public void setDelay(int ms) {
delay = Math.round(ms / 10.0f);
}

/**
* Sets the GIF frame disposal code for the last added frame
* and any subsequent frames.  Default is 0 if no transparent
* color has been set, otherwise 2.
* @param code int disposal code.
*/
public void setDispose(int code) {
if (code >= 0) {
dispose = code;
}
}

/**
* Sets the number of times the set of GIF frames
* should be played.  Default is 1; 0 means play
* indefinitely.  Must be invoked before the first
* image is added.
*
* @param iter int number of iterations.
* @return
*/
public void setRepeat(int iter) {
if (iter >= 0) {
repeat = iter;
}
}

/**
* Sets the transparent color for the last added frame
* and any subsequent frames.
* Since all colors are subject to modification
* in the quantization process, the color in the final
* palette for each frame closest to the given color
* becomes the transparent color for that frame.
* May be set to null to indicate no transparent color.
*
* @param c Color to be treated as transparent on display.
*/
public void setTransparent(Color c) {
transparent = c;
}

/**
* Adds next GIF frame.  The frame is not written immediately, but is
* actually deferred until the next frame is received so that timing
* data can be inserted.  Invoking <code>finish()</code> flushes all
* frames.  If <code>setSize</code> was not invoked, the size of the
* first image is used for all subsequent frames.
*
* @param im BufferedImage containing frame to write.
* @return true if successful.
*/
public boolean addFrame(BufferedImage im) {
if ((im == null) || !started) {
return false;
}
boolean ok = true;
try {
if (!sizeSet) {
// use first frame's size
setSize(im.getWidth(), im.getHeight());
}
image = im;
getImagePixels(); // convert to correct format if necessary
analyzePixels(); // build color table & map pixels
if (firstFrame) {
writeLSD(); // logical screen descriptior
writePalette(); // global color table
if (repeat >= 0) {
// use NS app extension to indicate reps
writeNetscapeExt();
}
}
writeGraphicCtrlExt(); // write graphic control extension
writeImageDesc(); // image descriptor
if (!firstFrame) {
writePalette(); // local color table
}
writePixels(); // encode and write pixel data
firstFrame = false;
} catch (IOException e) {
ok = false;
}

return ok;
}

/**
* Flushes any pending data and closes output file.
* If writing to an OutputStream, the stream is not
* closed.
*/
public boolean finish() {
if (!started) return false;
boolean ok = true;
started = false;
try {
out.write(0x3b); // gif trailer
out.flush();
if (closeStream) {
out.close();
}
} catch (IOException e) {
ok = false;
}

// reset for subsequent use
transIndex = 0;
out = null;
image = null;
pixels = null;
indexedPixels = null;
colorTab = null;
closeStream = false;
firstFrame = true;

return ok;
}

/**
* Sets frame rate in frames per second.  Equivalent to
* <code>setDelay(1000/fps)</code>.
*
* @param fps float frame rate (frames per second)
*/
public void setFrameRate(float fps) {
if (fps != 0f) {
delay = Math.round(100f / fps);
}
}

/**
* Sets quality of color quantization (conversion of images
* to the maximum 256 colors allowed by the GIF specification).
* Lower values (minimum = 1) produce better colors, but slow
* processing significantly.  10 is the default, and produces
* good color mapping at reasonable speeds.  Values greater
* than 20 do not yield significant improvements in speed.
*
* @param quality int greater than 0.
* @return
*/
public void setQuality(int quality) {
if (quality < 1) quality = 1;
sample = quality;
}

/**
* Sets the GIF frame size.  The default size is the
* size of the first frame added if this method is
* not invoked.
*
* @param w int frame width.
* @param h int frame width.
*/
public void setSize(int w, int h) {
if (started && !firstFrame) return;
width = w;
height = h;
if (width < 1) width = 320;
if (height < 1) height = 240;
sizeSet = true;
}

/**
* Initiates GIF file creation on the given stream.  The stream
* is not closed automatically.
*
* @param os OutputStream on which GIF images are written.
* @return false if initial write failed.
*/
public boolean start(OutputStream os) {
if (os == null) return false;
boolean ok = true;
closeStream = false;
out = os;
try {
writeString("GIF89a"); // header
} catch (IOException e) {
ok = false;
}
return started = ok;
}

/**
* Initiates writing of a GIF file with the specified name.
*
* @param file String containing output file name.
* @return false if open or initial write failed.
*/
public boolean start(String file) {
boolean ok = true;
try {
out = new BufferedOutputStream(new FileOutputStream(file));
ok = start(out);
closeStream = true;
} catch (IOException e) {
ok = false;
}
return started = ok;
}

/**
* Analyzes image colors and creates color map.
*/
protected void analyzePixels() {
int len = pixels.length;
int nPix = len / 3;
indexedPixels = new byte[nPix];
NeuQuant nq = new NeuQuant(pixels, len, sample);
// initialize quantizer
colorTab = nq.process(); // create reduced palette
// convert map from BGR to RGB
for (int i = 0; i < colorTab.length; i += 3) {
byte temp = colorTab[i];
colorTab[i] = colorTab[i + 2];
colorTab[i + 2] = temp;
usedEntry[i / 3] = false;
}
// map image pixels to new palette
int k = 0;
for (int i = 0; i < nPix; i++) {
int index =
nq.map(pixels[k++] & 0xff,
pixels[k++] & 0xff,
pixels[k++] & 0xff);
usedEntry[index] = true;
indexedPixels[i] = (byte) index;
}
pixels = null;
colorDepth = 8;
palSize = 7;
// get closest match to transparent color if specified
if (transparent != null) {
transIndex = findClosest(transparent);
}
}

/**
* Returns index of palette color closest to c
*
*/
protected int findClosest(Color c) {
if (colorTab == null) return -1;
int r = c.getRed();
int g = c.getGreen();
int b = c.getBlue();
int minpos = 0;
int dmin = 256 * 256 * 256;
int len = colorTab.length;
for (int i = 0; i < len;) {
int dr = r - (colorTab[i++] & 0xff);
int dg = g - (colorTab[i++] & 0xff);
int db = b - (colorTab[i] & 0xff);
int d = dr * dr + dg * dg + db * db;
int index = i / 3;
if (usedEntry[index] && (d < dmin)) {
dmin = d;
minpos = index;
}
i++;
}
return minpos;
}

/**
* Extracts image pixels into byte array "pixels"
*/
protected void getImagePixels() {
int w = image.getWidth();
int h = image.getHeight();
int type = image.getType();
if ((w != width)
|| (h != height)
|| (type != BufferedImage.TYPE_3BYTE_BGR)) {
// create new image with right size/format
BufferedImage temp =
new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
Graphics2D g = temp.createGraphics();
g.drawImage(image, 0, 0, null);
image = temp;
}
pixels = ((DataBufferByte) image.getRaster().getDataBuffer()).getData();
}

/**
* Writes Graphic Control Extension
*/
protected void writeGraphicCtrlExt() throws IOException {
out.write(0x21); // extension introducer
out.write(0xf9); // GCE label
out.write(4); // data block size
int transp, disp;
if (transparent == null) {
transp = 0;
disp = 0; // dispose = no action
} else {
transp = 1;
disp = 2; // force clear if using transparent color
}
if (dispose >= 0) {
disp = dispose & 7; // user override
}
disp <<= 2;

// packed fields
out.write(0 | // 1:3 reserved
disp | // 4:6 disposal
0 | // 7   user input - 0 = none
transp); // 8   transparency flag

writeShort(delay); // delay x 1/100 sec
out.write(transIndex); // transparent color index
out.write(0); // block terminator
}

/**
* Writes Image Descriptor
*/
protected void writeImageDesc() throws IOException {
out.write(0x2c); // image separator
writeShort(0); // image position x,y = 0,0
writeShort(0);
writeShort(width); // image size
writeShort(height);
// packed fields
if (firstFrame) {
// no LCT  - GCT is used for first (or only) frame
out.write(0);
} else {
// specify normal LCT
out.write(0x80 | // 1 local color table  1=yes
0 | // 2 interlace - 0=no
0 | // 3 sorted - 0=no
0 | // 4-5 reserved
palSize); // 6-8 size of color table
}
}

/**
* Writes Logical Screen Descriptor
*/
protected void writeLSD() throws IOException {
// logical screen size
writeShort(width);
writeShort(height);
// packed fields
out.write((0x80 | // 1   : global color table flag = 1 (gct used)
0x70 | // 2-4 : color resolution = 7
0x00 | // 5   : gct sort flag = 0
palSize)); // 6-8 : gct size

out.write(0); // background color index
out.write(0); // pixel aspect ratio - assume 1:1
}

/**
* Writes Netscape application extension to define
* repeat count.
*/
protected void writeNetscapeExt() throws IOException {
out.write(0x21); // extension introducer
out.write(0xff); // app extension label
out.write(11); // block size
writeString("NETSCAPE" + "2.0"); // app id + auth code
out.write(3); // sub-block size
out.write(1); // loop sub-block id
writeShort(repeat); // loop count (extra iterations, 0=repeat forever)
out.write(0); // block terminator
}

/**
* Writes color table
*/
protected void writePalette() throws IOException {
out.write(colorTab, 0, colorTab.length);
int n = (3 * 256) - colorTab.length;
for (int i = 0; i < n; i++) {
out.write(0);
}
}

/**
* Encodes and writes pixel data
*/
protected void writePixels() throws IOException {
LZWEncoder encoder =
new LZWEncoder(width, height, indexedPixels, colorDepth);
encoder.encode(out);
}

/**
*    Write 16-bit value to output stream, LSB first
*/
protected void writeShort(int value) throws IOException {
out.write(value & 0xff);
out.write((value >> 8) & 0xff);
}

/**
* Writes string to output stream
*/
protected void writeString(String s) throws IOException {
for (int i = 0; i < s.length(); i++) {
out.write((byte) s.charAt(i));
}
}
}

package com.accp.bookshop.util;

import java.net.*;
import java.io.*;
import java.util.*;
import java.awt.*;
import java.awt.image.*;

/**
* Class GifDecoder - Decodes a GIF file into one or more frames.
* <br><pre>
* Example:
*    GifDecoder d = new GifDecoder();
*    d.read("sample.gif");
*    int n = d.getFrameCount();
*    for (int i = 0; i < n; i++) {
*       BufferedImage frame = d.getFrame(i);  // frame i
*       int t = d.getDelay(i);  // display duration of frame in milliseconds
*       // do something with frame
*    }
* </pre>
* No copyright asserted on the source code of this class.  May be used for
* any purpose, however, refer to the Unisys LZW patent for any additional
* restrictions.  Please forward any corrections to kweiner@fmsware.com.
*
* @author Kevin Weiner, FM Software; LZW decoder adapted from John Cristy's ImageMagick.
* @version 1.03 November 2003
*
*/

public class GifDecoder {

/**
* File read status: No errors.
*/
public static final int STATUS_OK = 0;

/**
* File read status: Error decoding file (may be partially decoded)
*/
public static final int STATUS_FORMAT_ERROR = 1;

/**
* File read status: Unable to open source.
*/
public static final int STATUS_OPEN_ERROR = 2;

protected BufferedInputStream in;
protected int status;

protected int width; // full image width
protected int height; // full image height
protected boolean gctFlag; // global color table used
protected int gctSize; // size of global color table
protected int loopCount = 1; // iterations; 0 = repeat forever

protected int[] gct; // global color table
protected int[] lct; // local color table
protected int[] act; // active color table

protected int bgIndex; // background color index
protected int bgColor; // background color
protected int lastBgColor; // previous bg color
protected int pixelAspect; // pixel aspect ratio

protected boolean lctFlag; // local color table flag
protected boolean interlace; // interlace flag
protected int lctSize; // local color table size

protected int ix, iy, iw, ih; // current image rectangle
protected Rectangle lastRect; // last image rect
protected BufferedImage image; // current frame
protected BufferedImage lastImage; // previous frame

protected byte[] block = new byte[256]; // current data block
protected int blockSize = 0; // block size

// last graphic control extension info
protected int dispose = 0;
// 0=no action; 1=leave in place; 2=restore to bg; 3=restore to prev
protected int lastDispose = 0;
protected boolean transparency = false; // use transparent color
protected int delay = 0; // delay in milliseconds
protected int transIndex; // transparent color index

protected static final int MaxStackSize = 4096;
// max decoder pixel stack size

// LZW decoder working arrays
protected short[] prefix;
protected byte[] suffix;
protected byte[] pixelStack;
protected byte[] pixels;

protected ArrayList frames; // frames read from current file
protected int frameCount;

static class GifFrame {
public GifFrame(BufferedImage im, int del) {
image = im;
delay = del;
}
public BufferedImage image;
public int delay;
}

/**
* Gets display duration for specified frame.
*
* @param n int index of frame
* @return delay in milliseconds
*/
public int getDelay(int n) {
//
delay = -1;
if ((n >= 0) && (n < frameCount)) {
delay = ((GifFrame) frames.get(n)).delay;
}
return delay;
}

/**
* Gets the number of frames read from file.
* @return frame count
*/
public int getFrameCount() {
return frameCount;
}

/**
* Gets the first (or only) image read.
*
* @return BufferedImage containing first frame, or null if none.
*/
public BufferedImage getImage() {
return getFrame(0);
}

/**
* Gets the "Netscape" iteration count, if any.
* A count of 0 means repeat indefinitiely.
*
* @return iteration count if one was specified, else 1.
*/
public int getLoopCount() {
return loopCount;
}

/**
* Creates new frame image from current data (and previous
* frames as specified by their disposition codes).
*/
protected void setPixels() {
// expose destination image's pixels as int array
int[] dest =
((DataBufferInt) image.getRaster().getDataBuffer()).getData();

// fill in starting image contents based on last image's dispose code
if (lastDispose > 0) {
if (lastDispose == 3) {
// use image before last
int n = frameCount - 2;
if (n > 0) {
lastImage = getFrame(n - 1);
} else {
lastImage = null;
}
}

if (lastImage != null) {
int[] prev =
((DataBufferInt) lastImage.getRaster().getDataBuffer()).getData();
System.arraycopy(prev, 0, dest, 0, width * height);
// copy pixels

if (lastDispose == 2) {
// fill last image rect area with background color
Graphics2D g = image.createGraphics();
Color c = null;
if (transparency) {
c = new Color(0, 0, 0, 0); 	// assume background is transparent
} else {
c = new Color(lastBgColor); // use given background color
}
g.setColor(c);
g.setComposite(AlphaComposite.Src); // replace area
g.fill(lastRect);
g.dispose();
}
}
}

// copy each source line to the appropriate place in the destination
int pass = 1;
int inc = 8;
int iline = 0;
for (int i = 0; i < ih; i++) {
int line = i;
if (interlace) {
if (iline >= ih) {
pass++;
switch (pass) {
case 2 :
iline = 4;
break;
case 3 :
iline = 2;
inc = 4;
break;
case 4 :
iline = 1;
inc = 2;
}
}
line = iline;
iline += inc;
}
line += iy;
if (line < height) {
int k = line * width;
int dx = k + ix; // start of line in dest
int dlim = dx + iw; // end of dest line
if ((k + width) < dlim) {
dlim = k + width; // past dest edge
}
int sx = i * iw; // start of line in source
while (dx < dlim) {
// map color and insert in destination
int index = ((int) pixels[sx++]) & 0xff;
int c = act[index];
if (c != 0) {
dest[dx] = c;
}
dx++;
}
}
}
}

/**
* Gets the image contents of frame n.
*
* @return BufferedImage representation of frame, or null if n is invalid.
*/
public BufferedImage getFrame(int n) {
BufferedImage im = null;
if ((n >= 0) && (n < frameCount)) {
im = ((GifFrame) frames.get(n)).image;
}
return im;
}

/**
* Gets image size.
*
* @return GIF image dimensions
*/
public Dimension getFrameSize() {
return new Dimension(width, height);
}

/**
* Reads GIF image from stream
*
* @param BufferedInputStream containing GIF file.
* @return read status code (0 = no errors)
*/
public int read(BufferedInputStream is) {
init();
if (is != null) {
in = is;
readHeader();
if (!err()) {
readContents();
if (frameCount < 0) {
status = STATUS_FORMAT_ERROR;
}
}
} else {
status = STATUS_OPEN_ERROR;
}
try {
is.close();
} catch (IOException e) {
}
return status;
}

/**
* Reads GIF image from stream
*
* @param InputStream containing GIF file.
* @return read status code (0 = no errors)
*/
public int read(InputStream is) {
init();
if (is != null) {
if (!(is instanceof BufferedInputStream))
is = new BufferedInputStream(is);
in = (BufferedInputStream) is;
readHeader();
if (!err()) {
readContents();
if (frameCount < 0) {
status = STATUS_FORMAT_ERROR;
}
}
} else {
status = STATUS_OPEN_ERROR;
}
try {
is.close();
} catch (IOException e) {
}
return status;
}

/**
* Reads GIF file from specified file/URL source
* (URL assumed if name contains ":/" or "file:")
*
* @param name String containing source
* @return read status code (0 = no errors)
*/
public int read(String name) {
status = STATUS_OK;
try {
name = name.trim().toLowerCase();
if ((name.indexOf("file:") >= 0) ||
(name.indexOf(":/") > 0)) {
URL url = new URL(name);
in = new BufferedInputStream(url.openStream());
} else {
in = new BufferedInputStream(new FileInputStream(name));
}
status = read(in);
} catch (IOException e) {
status = STATUS_OPEN_ERROR;
}

return status;
}

/**
* Decodes LZW image data into pixel array.
* Adapted from John Cristy's ImageMagick.
*/
protected void decodeImageData() {
int NullCode = -1;
int npix = iw * ih;
int available,
clear,
code_mask,
code_size,
end_of_information,
in_code,
old_code,
bits,
code,
count,
i,
datum,
data_size,
first,
top,
bi,
pi;

if ((pixels == null) || (pixels.length < npix)) {
pixels = new byte[npix]; // allocate new pixel array
}
if (prefix == null) prefix = new short[MaxStackSize];
if (suffix == null) suffix = new byte[MaxStackSize];
if (pixelStack == null) pixelStack = new byte[MaxStackSize + 1];

//  Initialize GIF data stream decoder.

data_size = read();
clear = 1 << data_size;
end_of_information = clear + 1;
available = clear + 2;
old_code = NullCode;
code_size = data_size + 1;
code_mask = (1 << code_size) - 1;
for (code = 0; code < clear; code++) {
prefix[code] = 0;
suffix[code] = (byte) code;
}

//  Decode GIF pixel stream.

datum = bits = count = first = top = pi = bi = 0;

for (i = 0; i < npix;) {
if (top == 0) {
if (bits < code_size) {
//  Load bytes until there are enough bits for a code.
if (count == 0) {
// Read a new data block.
count = readBlock();
if (count <= 0)
break;
bi = 0;
}
datum += (((int) block[bi]) & 0xff) << bits;
bits += 8;
bi++;
count--;
continue;
}

//  Get the next code.

code = datum & code_mask;
datum >>= code_size;
bits -= code_size;

//  Interpret the code

if ((code > available) || (code == end_of_information))
break;
if (code == clear) {
//  Reset decoder.
code_size = data_size + 1;
code_mask = (1 << code_size) - 1;
available = clear + 2;
old_code = NullCode;
continue;
}
if (old_code == NullCode) {
pixelStack[top++] = suffix[code];
old_code = code;
first = code;
continue;
}
in_code = code;
if (code == available) {
pixelStack[top++] = (byte) first;
code = old_code;
}
while (code > clear) {
pixelStack[top++] = suffix[code];
code = prefix[code];
}
first = ((int) suffix[code]) & 0xff;

//  Add a new string to the string table,

if (available >= MaxStackSize)
break;
pixelStack[top++] = (byte) first;
prefix[available] = (short) old_code;
suffix[available] = (byte) first;
available++;
if (((available & code_mask) == 0)
&& (available < MaxStackSize)) {
code_size++;
code_mask += available;
}
old_code = in_code;
}

//  Pop a pixel off the pixel stack.

top--;
pixels[pi++] = pixelStack[top];
i++;
}

for (i = pi; i < npix; i++) {
pixels[i] = 0; // clear missing pixels
}

}

/**
* Returns true if an error was encountered during reading/decoding
*/
protected boolean err() {
return status != STATUS_OK;
}

/**
* Initializes or re-initializes reader
*/
protected void init() {
status = STATUS_OK;
frameCount = 0;
frames = new ArrayList();
gct = null;
lct = null;
}

/**
* Reads a single byte from the input stream.
*/
protected int read() {
int curByte = 0;
try {
curByte = in.read();
} catch (IOException e) {
status = STATUS_FORMAT_ERROR;
}
return curByte;
}

/**
* Reads next variable length block from input.
*
* @return number of bytes stored in "buffer"
*/
protected int readBlock() {
blockSize = read();
int n = 0;
if (blockSize > 0) {
try {
int count = 0;
while (n < blockSize) {
count = in.read(block, n, blockSize - n);
if (count == -1)
break;
n += count;
}
} catch (IOException e) {
}

if (n < blockSize) {
status = STATUS_FORMAT_ERROR;
}
}
return n;
}

/**
* Reads color table as 256 RGB integer values
*
* @param ncolors int number of colors to read
* @return int array containing 256 colors (packed ARGB with full alpha)
*/
protected int[] readColorTable(int ncolors) {
int nbytes = 3 * ncolors;
int[] tab = null;
byte[] c = new byte[nbytes];
int n = 0;
try {
n = in.read(c);
} catch (IOException e) {
}
if (n < nbytes) {
status = STATUS_FORMAT_ERROR;
} else {
tab = new int[256]; // max size to avoid bounds checks
int i = 0;
int j = 0;
while (i < ncolors) {
int r = ((int) c[j++]) & 0xff;
int g = ((int) c[j++]) & 0xff;
int b = ((int) c[j++]) & 0xff;
tab[i++] = 0xff000000 | (r << 16) | (g << 8) | b;
}
}
return tab;
}

/**
* Main file parser.  Reads GIF content blocks.
*/
protected void readContents() {
// read GIF file content blocks
boolean done = false;
while (!(done || err())) {
int code = read();
switch (code) {

case 0x2C : // image separator
readImage();
break;

case 0x21 : // extension
code = read();
switch (code) {
case 0xf9 : // graphics control extension
readGraphicControlExt();
break;

case 0xff : // application extension
readBlock();
String app = "";
for (int i = 0; i < 11; i++) {
app += (char) block[i];
}
if (app.equals("NETSCAPE2.0")) {
readNetscapeExt();
}
else
skip(); // don't care
break;

default : // uninteresting extension
skip();
}
break;

case 0x3b : // terminator
done = true;
break;

case 0x00 : // bad byte, but keep going and see what happens
break;

default :
status = STATUS_FORMAT_ERROR;
}
}
}

/**
* Reads Graphics Control Extension values
*/
protected void readGraphicControlExt() {
read(); // block size
int packed = read(); // packed fields
dispose = (packed & 0x1c) >> 2; // disposal method
if (dispose == 0) {
dispose = 1; // elect to keep old image if discretionary
}
transparency = (packed & 1) != 0;
delay = readShort() * 10; // delay in milliseconds
transIndex = read(); // transparent color index
read(); // block terminator
}

/**
* Reads GIF file header information.
*/
protected void readHeader() {
String id = "";
for (int i = 0; i < 6; i++) {
id += (char) read();
}
if (!id.startsWith("GIF")) {
status = STATUS_FORMAT_ERROR;
return;
}

readLSD();
if (gctFlag && !err()) {
gct = readColorTable(gctSize);
bgColor = gct[bgIndex];
}
}

/**
* Reads next frame image
*/
protected void readImage() {
ix = readShort(); // (sub)image position & size
iy = readShort();
iw = readShort();
ih = readShort();

int packed = read();
lctFlag = (packed & 0x80) != 0; // 1 - local color table flag
interlace = (packed & 0x40) != 0; // 2 - interlace flag
// 3 - sort flag
// 4-5 - reserved
lctSize = 2 << (packed & 7); // 6-8 - local color table size

if (lctFlag) {
lct = readColorTable(lctSize); // read table
act = lct; // make local table active
} else {
act = gct; // make global table active
if (bgIndex == transIndex)
bgColor = 0;
}
int save = 0;
if (transparency) {
save = act[transIndex];
act[transIndex] = 0; // set transparent color if specified
}

if (act == null) {
status = STATUS_FORMAT_ERROR; // no color table defined
}

if (err()) return;

decodeImageData(); // decode pixel data
skip();

if (err()) return;

frameCount++;

// create new image to receive frame data
image =
new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB_PRE);

setPixels(); // transfer pixel data to image

frames.add(new GifFrame(image, delay)); // add image to frame list

if (transparency) {
act[transIndex] = save;
}
resetFrame();

}

/**
* Reads Logical Screen Descriptor
*/
protected void readLSD() {

// logical screen size
width = readShort();
height = readShort();

// packed fields
int packed = read();
gctFlag = (packed & 0x80) != 0; // 1   : global color table flag
// 2-4 : color resolution
// 5   : gct sort flag
gctSize = 2 << (packed & 7); // 6-8 : gct size

bgIndex = read(); // background color index
pixelAspect = read(); // pixel aspect ratio
}

/**
* Reads Netscape extenstion to obtain iteration count
*/
protected void readNetscapeExt() {
do {
readBlock();
if (block[0] == 1) {
// loop count sub-block
int b1 = ((int) block[1]) & 0xff;
int b2 = ((int) block[2]) & 0xff;
loopCount = (b2 << 8) | b1;
}
} while ((blockSize > 0) && !err());
}

/**
* Reads next 16-bit value, LSB first
*/
protected int readShort() {
// read 16-bit value, LSB first
return read() | (read() << 8);
}

/**
* Resets frame state for reading next image.
*/
protected void resetFrame() {
lastDispose = dispose;
lastRect = new Rectangle(ix, iy, iw, ih);
lastImage = image;
lastBgColor = bgColor;
int dispose = 0;
boolean transparency = false;
int delay = 0;
lct = null;
}

/**
* Skips variable length blocks up to and including
* next zero length block.
*/
protected void skip() {
do {
readBlock();
} while ((blockSize > 0) && !err());
}
}

package com.accp.bookshop.util;

import java.io.OutputStream;
import java.io.IOException;

//==============================================================================
//  Adapted from Jef Poskanzer's Java port by way of J. M. G. Elliott.
//  K Weiner 12/00

class LZWEncoder {

private static final int EOF = -1;

private int imgW, imgH;
private byte[] pixAry;
private int initCodeSize;
private int remaining;
private int curPixel;

// GIFCOMPR.C       - GIF Image compression routines
//
// Lempel-Ziv compression based on 'compress'.  GIF modifications by
// David Rowley (mgardi@watdcsu.waterloo.edu)

// General DEFINEs

static final int BITS = 12;

static final int HSIZE = 5003; // 80% occupancy

// GIF Image compression - modified 'compress'
//
// Based on: compress.c - File compression ala IEEE Computer, June 1984.
//
// By Authors:  Spencer W. Thomas      (decvax!harpo!utah-cs!utah-gr!thomas)
//              Jim McKie              (decvax!mcvax!jim)
//              Steve Davies           (decvax!vax135!petsd!peora!srd)
//              Ken Turkowski          (decvax!decwrl!turtlevax!ken)
//              James A. Woods         (decvax!ihnp4!ames!jaw)
//              Joe Orost              (decvax!vax135!petsd!joe)

int n_bits; // number of bits/code
int maxbits = BITS; // user settable max # bits/code
int maxcode; // maximum code, given n_bits
int maxmaxcode = 1 << BITS; // should NEVER generate this code

int[] htab = new int[HSIZE];
int[] codetab = new int[HSIZE];

int hsize = HSIZE; // for dynamic table sizing

int free_ent = 0; // first unused entry

// block compression parameters -- after all codes are used up,
// and compression rate changes, start over.
boolean clear_flg = false;

// Algorithm:  use open addressing double hashing (no chaining) on the
// prefix code / next character combination.  We do a variant of Knuth's
// algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
// secondary probe.  Here, the modular division first probe is gives way
// to a faster exclusive-or manipulation.  Also do block compression with
// an adaptive reset, whereby the code table is cleared when the compression
// ratio decreases, but after the table fills.  The variable-length output
// codes are re-sized at this point, and a special CLEAR code is generated
// for the decompressor.  Late addition:  construct the table according to
// file size for noticeable speed improvement on small files.  Please direct
// questions about this implementation to ames!jaw.

int g_init_bits;

int ClearCode;
int EOFCode;

// output
//
// Output the given code.
// Inputs:
//      code:   A n_bits-bit integer.  If == -1, then EOF.  This assumes
//              that n_bits =< wordsize - 1.
// Outputs:
//      Outputs code to the file.
// Assumptions:
//      Chars are 8 bits long.
// Algorithm:
//      Maintain a BITS character long buffer (so that 8 codes will
// fit in it exactly).  Use the VAX insv instruction to insert each
// code in turn.  When the buffer fills up empty it and start over.

int cur_accum = 0;
int cur_bits = 0;

int masks[] =
{
0x0000,
0x0001,
0x0003,
0x0007,
0x000F,
0x001F,
0x003F,
0x007F,
0x00FF,
0x01FF,
0x03FF,
0x07FF,
0x0FFF,
0x1FFF,
0x3FFF,
0x7FFF,
0xFFFF };

// Number of characters so far in this 'packet'
int a_count;

// Define the storage for the packet accumulator
byte[] accum = new byte[256];

//----------------------------------------------------------------------------
LZWEncoder(int width, int height, byte[] pixels, int color_depth) {
imgW = width;
imgH = height;
pixAry = pixels;
initCodeSize = Math.max(2, color_depth);
}

// Add a character to the end of the current packet, and if it is 254
// characters, flush the packet to disk.
void char_out(byte c, OutputStream outs) throws IOException {
accum[a_count++] = c;
if (a_count >= 254)
flush_char(outs);
}

// Clear out the hash table

// table clear for block compress
void cl_block(OutputStream outs) throws IOException {
cl_hash(hsize);
free_ent = ClearCode + 2;
clear_flg = true;

output(ClearCode, outs);
}

// reset code table
void cl_hash(int hsize) {
for (int i = 0; i < hsize; ++i)
htab[i] = -1;
}

void compress(int init_bits, OutputStream outs) throws IOException {
int fcode;
int i /* = 0 */;
int c;
int ent;
int disp;
int hsize_reg;
int hshift;

// Set up the globals:  g_init_bits - initial number of bits
g_init_bits = init_bits;

// Set up the necessary values
clear_flg = false;
n_bits = g_init_bits;
maxcode = MAXCODE(n_bits);

ClearCode = 1 << (init_bits - 1);
EOFCode = ClearCode + 1;
free_ent = ClearCode + 2;

a_count = 0; // clear packet

ent = nextPixel();

hshift = 0;
for (fcode = hsize; fcode < 65536; fcode *= 2)
++hshift;
hshift = 8 - hshift; // set hash code range bound

hsize_reg = hsize;
cl_hash(hsize_reg); // clear hash table

output(ClearCode, outs);

outer_loop : while ((c = nextPixel()) != EOF) {
fcode = (c << maxbits) + ent;
i = (c << hshift) ^ ent; // xor hashing

if (htab[i] == fcode) {
ent = codetab[i];
continue;
} else if (htab[i] >= 0) // non-empty slot
{
disp = hsize_reg - i; // secondary hash (after G. Knott)
if (i == 0)
disp = 1;
do {
if ((i -= disp) < 0)
i += hsize_reg;

if (htab[i] == fcode) {
ent = codetab[i];
continue outer_loop;
}
} while (htab[i] >= 0);
}
output(ent, outs);
ent = c;
if (free_ent < maxmaxcode) {
codetab[i] = free_ent++; // code -> hashtable
htab[i] = fcode;
} else
cl_block(outs);
}
// Put out the final code.
output(ent, outs);
output(EOFCode, outs);
}

//----------------------------------------------------------------------------
void encode(OutputStream os) throws IOException {
os.write(initCodeSize); // write "initial code size" byte

remaining = imgW * imgH; // reset navigation variables
curPixel = 0;

compress(initCodeSize + 1, os); // compress and write the pixel data

os.write(0); // write block terminator
}

// Flush the packet to disk, and reset the accumulator
void flush_char(OutputStream outs) throws IOException {
if (a_count > 0) {
outs.write(a_count);
outs.write(accum, 0, a_count);
a_count = 0;
}
}

final int MAXCODE(int n_bits) {
return (1 << n_bits) - 1;
}

//----------------------------------------------------------------------------
// Return the next pixel from the image
//----------------------------------------------------------------------------
private int nextPixel() {
if (remaining == 0)
return EOF;

--remaining;

byte pix = pixAry[curPixel++];

return pix & 0xff;
}

void output(int code, OutputStream outs) throws IOException {
cur_accum &= masks[cur_bits];

if (cur_bits > 0)
cur_accum |= (code << cur_bits);
else
cur_accum = code;

cur_bits += n_bits;

while (cur_bits >= 8) {
char_out((byte) (cur_accum & 0xff), outs);
cur_accum >>= 8;
cur_bits -= 8;
}

// If the next entry is going to be too big for the code size,
// then increase it, if possible.
if (free_ent > maxcode || clear_flg) {
if (clear_flg) {
maxcode = MAXCODE(n_bits = g_init_bits);
clear_flg = false;
} else {
++n_bits;
if (n_bits == maxbits)
maxcode = maxmaxcode;
else
maxcode = MAXCODE(n_bits);
}
}

if (code == EOFCode) {
// At EOF, write the rest of the buffer.
while (cur_bits > 0) {
char_out((byte) (cur_accum & 0xff), outs);
cur_accum >>= 8;
cur_bits -= 8;
}

flush_char(outs);
}
}
}

package com.accp.bookshop.util;

/* NeuQuant Neural-Net Quantization Algorithm
* ------------------------------------------
*
* Copyright (c) 1994 Anthony Dekker
*
* NEUQUANT Neural-Net quantization algorithm by Anthony Dekker, 1994.
* See "Kohonen neural networks for optimal colour quantization"
* in "Network: Computation in Neural Systems" Vol. 5 (1994) pp 351-367.
* for a discussion of the algorithm.
*
* Any party obtaining a copy of these files from the author, directly or
* indirectly, is granted, free of charge, a full and unrestricted irrevocable,
* world-wide, paid up, royalty-free, nonexclusive right and license to deal
* in this software and documentation files (the "Software"), including without
* limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons who receive
* copies from any such party to do so, with the only requirement being
* that this copyright notice remain intact.
*/

// Ported to Java 12/00 K Weiner

public class NeuQuant {

protected static final int netsize = 256; /* number of colours used */

/* four primes near 500 - assume no image has a length so large */
/* that it is divisible by all four primes */
protected static final int prime1 = 499;
protected static final int prime2 = 491;
protected static final int prime3 = 487;
protected static final int prime4 = 503;

protected static final int minpicturebytes = (3 * prime4);
/* minimum size for input image */

/* Program Skeleton
----------------
[select samplefac in range 1..30]
[read image from input file]
pic = (unsigned char*) malloc(3*width*height);
initnet(pic,3*width*height,samplefac);
learn();
unbiasnet();
[write output image header, using writecolourmap(f)]
inxbuild();
write output image using inxsearch(b,g,r)      */

/* Network Definitions
------------------- */

protected static final int maxnetpos = (netsize - 1);
protected static final int netbiasshift = 4; /* bias for colour values */
protected static final int ncycles = 100; /* no. of learning cycles */

/* defs for freq and bias */
protected static final int intbiasshift = 16; /* bias for fractions */
protected static final int intbias = (((int) 1) << intbiasshift);
protected static final int gammashift = 10; /* gamma = 1024 */
protected static final int gamma = (((int) 1) << gammashift);
protected static final int betashift = 10;
protected static final int beta = (intbias >> betashift); /* beta = 1/1024 */
protected static final int betagamma =
(intbias << (gammashift - betashift));

/* defs for decreasing radius factor */
protected static final int initrad = (netsize >> 3); /* for 256 cols, radius starts */
protected static final int radiusbiasshift = 6; /* at 32.0 biased by 6 bits */
protected static final int radiusbias = (((int) 1) << radiusbiasshift);
protected static final int initradius = (initrad * radiusbias); /* and decreases by a */
protected static final int radiusdec = 30; /* factor of 1/30 each cycle */

/* defs for decreasing alpha factor */
protected static final int alphabiasshift = 10; /* alpha starts at 1.0 */
protected static final int initalpha = (((int) 1) << alphabiasshift);

protected int alphadec; /* biased by 10 bits */

/* radbias and alpharadbias used for radpower calculation */
protected static final int radbiasshift = 8;
protected static final int radbias = (((int) 1) << radbiasshift);
protected static final int alpharadbshift = (alphabiasshift + radbiasshift);
protected static final int alpharadbias = (((int) 1) << alpharadbshift);

/* Types and Global Variables
-------------------------- */

protected byte[] thepicture; /* the input image itself */
protected int lengthcount; /* lengthcount = H*W*3 */

protected int samplefac; /* sampling factor 1..30 */

//   typedef int pixel[4];                /* BGRc */
protected int[][] network; /* the network itself - [netsize][4] */

protected int[] netindex = new int[256];
/* for network lookup - really 256 */

protected int[] bias = new int[netsize];
/* bias and freq arrays for learning */
protected int[] freq = new int[netsize];
protected int[] radpower = new int[initrad];
/* radpower for precomputation */

/* Initialise network in range (0,0,0) to (255,255,255) and set parameters
----------------------------------------------------------------------- */
public NeuQuant(byte[] thepic, int len, int sample) {

int i;
int[] p;

thepicture = thepic;
lengthcount = len;
samplefac = sample;

network = new int[netsize][];
for (i = 0; i < netsize; i++) {
network[i] = new int[4];
p = network[i];
p[0] = p[1] = p[2] = (i << (netbiasshift + 8)) / netsize;
freq[i] = intbias / netsize; /* 1/netsize */
bias[i] = 0;
}
}

public byte[] colorMap() {
byte[] map = new byte[3 * netsize];
int[] index = new int[netsize];
for (int i = 0; i < netsize; i++)
index[network[i][3]] = i;
int k = 0;
for (int i = 0; i < netsize; i++) {
int j = index[i];
map[k++] = (byte) (network[j][0]);
map[k++] = (byte) (network[j][1]);
map[k++] = (byte) (network[j][2]);
}
return map;
}

/* Insertion sort of network and building of netindex[0..255] (to do after unbias)
------------------------------------------------------------------------------- */
public void inxbuild() {

int i, j, smallpos, smallval;
int[] p;
int[] q;
int previouscol, startpos;

previouscol = 0;
startpos = 0;
for (i = 0; i < netsize; i++) {
p = network[i];
smallpos = i;
smallval = p[1]; /* index on g */
/* find smallest in i..netsize-1 */
for (j = i + 1; j < netsize; j++) {
q = network[j];
if (q[1] < smallval) { /* index on g */
smallpos = j;
smallval = q[1]; /* index on g */
}
}
q = network[smallpos];
/* swap p (i) and q (smallpos) entries */
if (i != smallpos) {
j = q[0];
q[0] = p[0];
p[0] = j;
j = q[1];
q[1] = p[1];
p[1] = j;
j = q[2];
q[2] = p[2];
p[2] = j;
j = q[3];
q[3] = p[3];
p[3] = j;
}
/* smallval entry is now in position i */
if (smallval != previouscol) {
netindex[previouscol] = (startpos + i) >> 1;
for (j = previouscol + 1; j < smallval; j++)
netindex[j] = i;
previouscol = smallval;
startpos = i;
}
}
netindex[previouscol] = (startpos + maxnetpos) >> 1;
for (j = previouscol + 1; j < 256; j++)
netindex[j] = maxnetpos; /* really 256 */
}

/* Main Learning Loop
------------------ */
public void learn() {

int i, j, b, g, r;
int radius, rad, alpha, step, delta, samplepixels;
byte[] p;
int pix, lim;

if (lengthcount < minpicturebytes)
samplefac = 1;
alphadec = 30 + ((samplefac - 1) / 3);
p = thepicture;
pix = 0;
lim = lengthcount;
samplepixels = lengthcount / (3 * samplefac);
delta = samplepixels / ncycles;
alpha = initalpha;
radius = initradius;

rad = radius >> radiusbiasshift;
if (rad <= 1)
rad = 0;
for (i = 0; i < rad; i++)
radpower[i] =
alpha * (((rad * rad - i * i) * radbias) / (rad * rad));

//fprintf(stderr,"beginning 1D learning: initial radius=%d/n", rad);

if (lengthcount < minpicturebytes)
step = 3;
else if ((lengthcount % prime1) != 0)
step = 3 * prime1;
else {
if ((lengthcount % prime2) != 0)
step = 3 * prime2;
else {
if ((lengthcount % prime3) != 0)
step = 3 * prime3;
else
step = 3 * prime4;
}
}

i = 0;
while (i < samplepixels) {
b = (p[pix + 0] & 0xff) << netbiasshift;
g = (p[pix + 1] & 0xff) << netbiasshift;
r = (p[pix + 2] & 0xff) << netbiasshift;
j = contest(b, g, r);

altersingle(alpha, j, b, g, r);
if (rad != 0)
alterneigh(rad, j, b, g, r); /* alter neighbours */

pix += step;
if (pix >= lim)
pix -= lengthcount;

i++;
if (delta == 0)
delta = 1;
if (i % delta == 0) {
alpha -= alpha / alphadec;
radius -= radius / radiusdec;
rad = radius >> radiusbiasshift;
if (rad <= 1)
rad = 0;
for (j = 0; j < rad; j++)
radpower[j] =
alpha * (((rad * rad - j * j) * radbias) / (rad * rad));
}
}
//fprintf(stderr,"finished 1D learning: final alpha=%f !/n",((float)alpha)/initalpha);
}

/* Search for BGR values 0..255 (after net is unbiased) and return colour index
---------------------------------------------------------------------------- */
public int map(int b, int g, int r) {

int i, j, dist, a, bestd;
int[] p;
int best;

bestd = 1000; /* biggest possible dist is 256*3 */
best = -1;
i = netindex[g]; /* index on g */
j = i - 1; /* start at netindex[g] and work outwards */

while ((i < netsize) || (j >= 0)) {
if (i < netsize) {
p = network[i];
dist = p[1] - g; /* inx key */
if (dist >= bestd)
i = netsize; /* stop iter */
else {
i++;
if (dist < 0)
dist = -dist;
a = p[0] - b;
if (a < 0)
a = -a;
dist += a;
if (dist < bestd) {
a = p[2] - r;
if (a < 0)
a = -a;
dist += a;
if (dist < bestd) {
bestd = dist;
best = p[3];
}
}
}
}
if (j >= 0) {
p = network[j];
dist = g - p[1]; /* inx key - reverse dif */
if (dist >= bestd)
j = -1; /* stop iter */
else {
j--;
if (dist < 0)
dist = -dist;
a = p[0] - b;
if (a < 0)
a = -a;
dist += a;
if (dist < bestd) {
a = p[2] - r;
if (a < 0)
a = -a;
dist += a;
if (dist < bestd) {
bestd = dist;
best = p[3];
}
}
}
}
}
return (best);
}
public byte[] process() {
learn();
unbiasnet();
inxbuild();
return colorMap();
}

/* Unbias network to give byte values 0..255 and record position i to prepare for sort
----------------------------------------------------------------------------------- */
public void unbiasnet() {

int i, j;

for (i = 0; i < netsize; i++) {
network[i][0] >>= netbiasshift;
network[i][1] >>= netbiasshift;
network[i][2] >>= netbiasshift;
network[i][3] = i; /* record colour no */
}
}

/* Move adjacent neurons by precomputed alpha*(1-((i-j)^2/[r]^2)) in radpower[|i-j|]
--------------------------------------------------------------------------------- */
protected void alterneigh(int rad, int i, int b, int g, int r) {

int j, k, lo, hi, a, m;
int[] p;

lo = i - rad;
if (lo < -1)
lo = -1;
hi = i + rad;
if (hi > netsize)
hi = netsize;

j = i + 1;
k = i - 1;
m = 1;
while ((j < hi) || (k > lo)) {
a = radpower[m++];
if (j < hi) {
p = network[j++];
try {
p[0] -= (a * (p[0] - b)) / alpharadbias;
p[1] -= (a * (p[1] - g)) / alpharadbias;
p[2] -= (a * (p[2] - r)) / alpharadbias;
} catch (Exception e) {
} // prevents 1.3 miscompilation
}
if (k > lo) {
p = network[k--];
try {
p[0] -= (a * (p[0] - b)) / alpharadbias;
p[1] -= (a * (p[1] - g)) / alpharadbias;
p[2] -= (a * (p[2] - r)) / alpharadbias;
} catch (Exception e) {
}
}
}
}

/* Move neuron i towards biased (b,g,r) by factor alpha
---------------------------------------------------- */
protected void altersingle(int alpha, int i, int b, int g, int r) {

/* alter hit neuron */
int[] n = network[i];
n[0] -= (alpha * (n[0] - b)) / initalpha;
n[1] -= (alpha * (n[1] - g)) / initalpha;
n[2] -= (alpha * (n[2] - r)) / initalpha;
}

/* Search for biased BGR values
---------------------------- */
protected int contest(int b, int g, int r) {

/* finds closest neuron (min dist) and updates freq */
/* finds best neuron (min dist-bias) and returns position */
/* for frequently chosen neurons, freq[i] is high and bias[i] is negative */
/* bias[i] = gamma*((1/netsize)-freq[i]) */

int i, dist, a, biasdist, betafreq;
int bestpos, bestbiaspos, bestd, bestbiasd;
int[] n;

bestd = ~(((int) 1) << 31);
bestbiasd = bestd;
bestpos = -1;
bestbiaspos = bestpos;

for (i = 0; i < netsize; i++) {
n = network[i];
dist = n[0] - b;
if (dist < 0)
dist = -dist;
a = n[1] - g;
if (a < 0)
a = -a;
dist += a;
a = n[2] - r;
if (a < 0)
a = -a;
dist += a;
if (dist < bestd) {
bestd = dist;
bestpos = i;
}
biasdist = dist - ((bias[i]) >> (intbiasshift - netbiasshift));
if (biasdist < bestbiasd) {
bestbiasd = biasdist;
bestbiaspos = i;
}
betafreq = (freq[i] >> betashift);
freq[i] -= betafreq;
bias[i] += (betafreq << gammashift);
}
freq[bestpos] += beta;
bias[bestpos] -= betagamma;
return (bestbiaspos);
}
}