org.icepdf.core.pobjects.filters

Class PredictorDecode

java.lang.Object

java.io.InputStream

org.icepdf.core.pobjects.filters.ChunkingInputStream

org.icepdf.core.pobjects.filters.PredictorDecode

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class PredictorDecode
extends ChunkingInputStream

Predictor decoder for LZW and Flate data streams. Uses the same streaming as our other Filters but simplifies how the bytes are read in as we treat the parent (LZW or Flate) stream as a regular ChunkingInputStream.

Since:

5.0.6

Field Summary

Fields

Modifier and Type	Field and Description
protected byte[]	aboveBuffer
protected static Name	BITS_PER_COMPONENT_VALUE
protected int	bitsPerComponent
protected int	bytesPerPixel
protected static Name	COLORS_VALUE
protected static Name	COLUMNS_VALUE
protected static Name	DECODE_PARMS_VALUE
protected static Name	EARLY_CHANGE_VALUE
protected int	numComponents
protected int	predictor
protected static int	PREDICTOR_NONE No predictor function is used
protected static int	PREDICTOR_PNG_AVG For current row, derive each byte from average of byte left-by-bytesPerPixel and byte above
protected static int	PREDICTOR_PNG_NONE For current row, PNG predictor to do nothing
protected static int	PREDICTOR_PNG_OPTIMUM When given in DecodeParms dict, in stream dict, means first byte of each row is row's predictor
protected static int	PREDICTOR_PNG_PAETH For current row, derive each byte from non-linear function of byte left-by-bytesPerPixel and byte above and byte left-by-bytesPerPixel of above
protected static int	PREDICTOR_PNG_SUB For current row, derive each byte from byte left-by-bytesPerPixel
protected static int	PREDICTOR_PNG_UP For current row, derive each byte from byte above
protected static int	PREDICTOR_TIFF_2 For every row, each component is derived from corresponding component in entry to left
protected static Name	PREDICTOR_VALUE
protected int	width
protected static Name	WIDTH_VALUE

Fields inherited from class org.icepdf.core.pobjects.filters.ChunkingInputStream

buffer, in

Constructor Summary

Constructors

Constructor and Description
PredictorDecode(java.io.InputStream input, Library library, java.util.HashMap entries)

Method Summary

Modifier and Type	Method and Description
protected void	applyPredictor(int numRead, int currPredictor) Apply predictor logic to buffer[] using aboveBuffer[] from previous pass.
protected int	fillInternalBuffer() This is only called if bufferAvailable is 0.
static boolean	isPredictor(Library library, java.util.HashMap entries)

Methods inherited from class org.icepdf.core.pobjects.filters.ChunkingInputStream

available, close, fillBufferFromInputStream, fillBufferFromInputStream, mark, markSupported, read, read, read, reset, setBufferSize, setInputStream, skip, toString

Methods inherited from class java.lang.Object

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

Field Detail

PREDICTOR_NONE

protected static final int PREDICTOR_NONE

No predictor function is used

See Also:

Constant Field Values

PREDICTOR_TIFF_2

protected static final int PREDICTOR_TIFF_2

For every row, each component is derived from corresponding component in entry to left

See Also:

Constant Field Values

PREDICTOR_PNG_NONE

protected static final int PREDICTOR_PNG_NONE

For current row, PNG predictor to do nothing

See Also:

Constant Field Values

PREDICTOR_PNG_SUB

protected static final int PREDICTOR_PNG_SUB

For current row, derive each byte from byte left-by-bytesPerPixel

See Also:

Constant Field Values

PREDICTOR_PNG_UP

protected static final int PREDICTOR_PNG_UP

For current row, derive each byte from byte above

See Also:

Constant Field Values

PREDICTOR_PNG_AVG

protected static final int PREDICTOR_PNG_AVG

For current row, derive each byte from average of byte left-by-bytesPerPixel and byte above

See Also:

Constant Field Values

PREDICTOR_PNG_PAETH

protected static final int PREDICTOR_PNG_PAETH

For current row, derive each byte from non-linear function of byte left-by-bytesPerPixel and byte above and byte left-by-bytesPerPixel of above

See Also:

Constant Field Values

PREDICTOR_PNG_OPTIMUM

protected static final int PREDICTOR_PNG_OPTIMUM

When given in DecodeParms dict, in stream dict, means first byte of each row is row's predictor

See Also:

Constant Field Values

DECODE_PARMS_VALUE

protected static final Name DECODE_PARMS_VALUE

PREDICTOR_VALUE

protected static final Name PREDICTOR_VALUE

WIDTH_VALUE

protected static final Name WIDTH_VALUE

COLUMNS_VALUE

protected static final Name COLUMNS_VALUE

COLORS_VALUE

protected static final Name COLORS_VALUE

BITS_PER_COMPONENT_VALUE

protected static final Name BITS_PER_COMPONENT_VALUE

EARLY_CHANGE_VALUE

protected static final Name EARLY_CHANGE_VALUE

predictor

protected int predictor

numComponents

protected int numComponents

bitsPerComponent

protected int bitsPerComponent

width

protected int width

bytesPerPixel

protected int bytesPerPixel

aboveBuffer

protected byte[] aboveBuffer

Constructor Detail

PredictorDecode

public PredictorDecode(java.io.InputStream input,
                       Library library,
                       java.util.HashMap entries)

Method Detail

fillInternalBuffer

protected int fillInternalBuffer()
                          throws java.io.IOException

Description copied from class: ChunkingInputStream

This is only called if bufferAvailable is 0. Implementations should read in more data, and return how many bytes are now available

Specified by:

fillInternalBuffer in class ChunkingInputStream

Throws:

java.io.IOException

applyPredictor

protected void applyPredictor(int numRead,
                              int currPredictor)

Apply predictor logic to buffer[] using aboveBuffer[] from previous pass.

Parameters:

numRead - number of bytes read in last pass.

currPredictor - predictor to apply to buffer data.

isPredictor

public static boolean isPredictor(Library library,
                                  java.util.HashMap entries)