Class LZWEncoder

java.lang.Object
  LZWEncoder

public class LZWEncoder
extends java.lang.Object

Adapted from Jef Poskanzer's Java port by way of J. M. G. Elliott.

Field Summary

(package private) int	a_count Number of characters so far in this 'packet'.
(package private) byte[]	accum Define the storage for the packet accumulator.
(package private) static int	BITS DEFINE BITS AS 12.
(package private) boolean	clear_flg block compression parameters -- after all codes are used up, and compression rate changes, start over.
(package private) int	ClearCode Integer representing the clear code.
(package private) int[]	codetab Integer Array of size HSIZE.
(package private) int	cur_accum Integer representing the Current Accumulation.
(package private) int	cur_bits Integer representing the Current Bits.
int	curPixel Integer representing current pixel.
static int	EOF Integer representing End Of File value.
(package private) int	EOFCode Integer representing the EOF code.
(package private) int	free_ent first unused entry.
(package private) int	g_init_bits Integer.
(package private) int	hsize for dynamic table sizing.
(package private) static int	HSIZE DEFINE HSIZE AS 5003.
(package private) int[]	htab Integer Array of size HSIZE.
int	imgH Integer representing image Height.
int	imgW Integer representing image Width.
private int	initCodeSize Integer representing initial Code Size.
(package private) int[]	masks An array of hex masks.
(package private) int	maxbits user settable max # bits/code.
(package private) int	maxcode maximum code, given n_bits.
(package private) int	maxmaxcode should NEVER generate this code.
(package private) int	n_bits number of bits/code.
private byte[]	pixAry Byte array representing the pixel color values.
int	remaining Integer representing remaining pixels.

Constructor Summary

LZWEncoder(int width, int height, byte[] pixels, int color_depth)
This is the constructor for the LZWEncoder class.

Method Summary

(package private) void	char_out(byte c, java.io.OutputStream outs) Add a character to the end of the current packet, and if it is 254 characters, flush the packet to disk.
(package private) void	cl_block(java.io.OutputStream outs) Clear out the hash table table clear for block compress.
(package private) void	cl_hash(int hsize) Reset code table.
(package private) void	compress(int init_bits, java.io.OutputStream outs) Compress code table.
(package private) void	encode(java.io.OutputStream os) This method does the encoding and sends to an output stream.
(package private) void	flush_char(java.io.OutputStream outs) Flush the packet to disk, and reset the accumulator.
(package private) int	MAXCODE(int n_bits) This method returns the Max Code given the number of bits.
int	nextPixel() Return the next pixel from the image.
(package private) void	output(int code, java.io.OutputStream outs) This method produces the output.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

EOF

public static final int EOF

Integer representing End Of File value.

See Also:

Constant Field Values

imgW

public int imgW

Integer representing image Width.

imgH

public int imgH

Integer representing image Height.

pixAry

private byte[] pixAry

Byte array representing the pixel color values.

initCodeSize

private int initCodeSize

Integer representing initial Code Size.

remaining

public int remaining

Integer representing remaining pixels.

curPixel

public int curPixel

Integer representing current pixel.

BITS

static final int BITS

DEFINE BITS AS 12.

See Also:

Constant Field Values

HSIZE

static final int HSIZE

DEFINE HSIZE AS 5003.

See Also:

Constant Field Values

n_bits

int n_bits

number of bits/code.

maxbits

int maxbits

user settable max # bits/code.

maxcode

int maxcode

maximum code, given n_bits.

maxmaxcode

int maxmaxcode

should NEVER generate this code.

htab

int[] htab

Integer Array of size HSIZE.

codetab

int[] codetab

Integer Array of size HSIZE.

hsize

int hsize

for dynamic table sizing.

free_ent

int free_ent

first unused entry.

clear_flg

boolean clear_flg

block compression parameters -- after all codes are used up, and compression rate changes, start over.

g_init_bits

int g_init_bits

Integer.

ClearCode

int ClearCode

Integer representing the clear code.

EOFCode

int EOFCode

Integer representing the EOF code.

cur_accum

int cur_accum

Integer representing the Current Accumulation.

cur_bits

int cur_bits

Integer representing the Current Bits.

masks

int[] masks

An array of hex masks.

a_count

int a_count

Number of characters so far in this 'packet'.

accum

byte[] accum

Define the storage for the packet accumulator.

Constructor Detail

LZWEncoder

LZWEncoder(int width,
           int height,
           byte[] pixels,
           int color_depth)

This is the constructor for the LZWEncoder class.

Parameters:

width - int representing width

height - int representing height

pixels - byte array representing the picture color codes

color_depth - int representing color depth

Method Detail

char_out

void char_out(byte c,
              java.io.OutputStream outs)
        throws java.io.IOException

Add a character to the end of the current packet, and if it is 254 characters, flush the packet to disk.

Parameters:

c - a single byte

outs - output stream

Throws:

java.io.IOException

cl_block

void cl_block(java.io.OutputStream outs)
        throws java.io.IOException

Clear out the hash table table clear for block compress.

Parameters:

outs - OutputStream object

Throws:

java.io.IOException

cl_hash

void cl_hash(int hsize)

Reset code table.

Parameters:

hsize - an int representing the hash table size

compress

void compress(int init_bits,
              java.io.OutputStream outs)
        throws java.io.IOException

Compress code table.

Parameters:

outs - OutputStream object

init_bits - int representing the init bits

Throws:

java.io.IOException

encode

void encode(java.io.OutputStream os)
      throws java.io.IOException

This method does the encoding and sends to an output stream.

Parameters:

os - OutputStream object

Throws:

java.io.IOException

flush_char

void flush_char(java.io.OutputStream outs)
          throws java.io.IOException

Flush the packet to disk, and reset the accumulator.

Parameters:

outs - OutputStream object

Throws:

java.io.IOException

MAXCODE

final int MAXCODE(int n_bits)

This method returns the Max Code given the number of bits.

Parameters:

n_bits - integer representing the number of bits

Returns:

the maxcode as an integer

nextPixel

public int nextPixel()

Return the next pixel from the image.

Returns:

the next pixel from the image

output

void output(int code,
            java.io.OutputStream outs)
      throws java.io.IOException

This method produces the output.

Parameters:

code - an integer representing the code

outs - OutputStream object

Throws:

java.io.IOException