org.gridfour.compress

Class CodecFloat

java.lang.Object

org.gridfour.compress.CodecFloat

All Implemented Interfaces:

ICompressionDecoder, ICompressionEncoder

public class CodecFloat
extends Object
implements ICompressionEncoder, ICompressionDecoder

Provides data compression and decompression for floating-point values. Integer values are not supported.

Constructor Summary

Constructors

Constructor and Description
CodecFloat()

Method Summary

Modifier and Type	Method and Description
void	analyze(int nRows, int nColumns, byte[] packing) Analyzes the content of the packing to collect statistics on the compression.
void	clearAnalysisData() Clears all accumulated analysis data.
int[]	decode(int nRows, int nColumns, byte[] packing) Decodes the content of the packing and populates an integer array to store the data.
float[]	decodeFloats(int nRows, int nColumns, byte[] packing) Decodes the content of the packing and populates an integer array to store the data.
byte[]	encode(int codecIndex, int nRows, int nCols, int[] values) Encodes the specified tile data in a compressed form.
byte[]	encodeFloats(int codecIndex, int nRows, int nColumns, float[] values) Encodes the specified tile data in a compressed form.
boolean	implementsFloatingPointEncoding() Indicates whether the implementation can encode floating-point values
boolean	implementsIntegerEncoding() Indicates whether the implementation can encode integral data types
void	reportAnalysisData(PrintStream ps, int nTilesInRaster) Prints analysis results (if any) to specified print stream

Methods inherited from class java.lang.Object

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

Constructor Detail

CodecFloat

public CodecFloat()

Method Detail

decode

public int[] decode(int nRows,
                    int nColumns,
                    byte[] packing)
             throws IOException

Description copied from interface: ICompressionDecoder

Decodes the content of the packing and populates an integer array to store the data.

Specified by:

decode in interface ICompressionDecoder

Parameters:

nRows - a value of 1 or greater giving the number of rows in the tile

nColumns - a value of 1 or greater giving the number of columns in the

packing - an array of bytes containing the encoded data to be decompressed

Returns:

if successful, a valid integer array giving content for the tile in row-major order

Throws:

IOException - in the event of an incompatible packing

encode

public byte[] encode(int codecIndex,
                     int nRows,
                     int nCols,
                     int[] values)

Description copied from interface: ICompressionEncoder

Encodes the specified tile data in a compressed form.

Specified by:

encode in interface ICompressionEncoder

Parameters:

codecIndex - the index assigned by the application to associate a codec with an entry in the raster file.

nRows - a value of 1 or greater giving the number of rows in the tile

nCols - a value of 1 or greater giving the number of columns in the tile

values - the values of the tile in row-major order

Returns:

if successful, an array of bytes of length greater than 1; if unsuccessful, a null.

analyze

public void analyze(int nRows,
                    int nColumns,
                    byte[] packing)
             throws IOException

Description copied from interface: ICompressionDecoder

Analyzes the content of the packing to collect statistics on the compression.

This method is intended to be used when assessing the results of data compression. It may be used for a single tile or for a collection of multiple tiles. When used for multiple tiles, the results are assumed to be cumulative. Thus an implementation is expected to maintain statistics as state data (class member data).

Specified by:

analyze in interface ICompressionDecoder

Parameters:

nRows - the number of rows in the tile to be analyzed.

nColumns - the number of columns in the tile to be analyzed.

packing - a valid packing for the associated codec implementation

Throws:

IOException - in the event of an incompatible packing

reportAnalysisData

public void reportAnalysisData(PrintStream ps,
                               int nTilesInRaster)

Description copied from interface: ICompressionDecoder

Prints analysis results (if any) to specified print stream

Specified by:

reportAnalysisData in interface ICompressionDecoder

Parameters:

ps - a valid print stream.

nTilesInRaster - the number of tiles in the raster

clearAnalysisData

public void clearAnalysisData()

Description copied from interface: ICompressionDecoder

Clears all accumulated analysis data.

Specified by:

clearAnalysisData in interface ICompressionDecoder

encodeFloats

public byte[] encodeFloats(int codecIndex,
                           int nRows,
                           int nColumns,
                           float[] values)

Description copied from interface: ICompressionEncoder

Encodes the specified tile data in a compressed form.

Specified by:

encodeFloats in interface ICompressionEncoder

Parameters:

codecIndex - the index assigned by the application to associate a codec with an entry in the raster file.

nRows - a value of 1 or greater giving the number of rows in the tile

nColumns - a value of 1 or greater giving the number of columns in the tile

values - the values of the tile in row-major order

Returns:

if successful, an array of bytes of length greater than 1; if unsuccessful, a null.

decodeFloats

public float[] decodeFloats(int nRows,
                            int nColumns,
                            byte[] packing)
                     throws IOException

Description copied from interface: ICompressionDecoder

Decodes the content of the packing and populates an integer array to store the data.

Specified by:

decodeFloats in interface ICompressionDecoder

Parameters:

nRows - a value of 1 or greater giving the number of rows in the tile

nColumns - a value of 1 or greater giving the number of columns in the

packing - an array of bytes containing the encoded data to be decompressed

Returns:

if successful, a valid integer array giving content for the tile in row-major order

Throws:

IOException - in the event of an incompatible packing

implementsFloatingPointEncoding

public boolean implementsFloatingPointEncoding()

Description copied from interface: ICompressionEncoder

Indicates whether the implementation can encode floating-point values

Specified by:

implementsFloatingPointEncoding in interface ICompressionEncoder

Returns:

true if direct encoding of floats is supported, otherwise false.

implementsIntegerEncoding

public boolean implementsIntegerEncoding()

Description copied from interface: ICompressionEncoder

Indicates whether the implementation can encode integral data types

Specified by:

implementsIntegerEncoding in interface ICompressionEncoder

Returns:

true if the encoding of integral data types is supported, otherwise false.