Class PackBitsDecoder
- java.lang.Object
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- com.twelvemonkeys.io.enc.PackBitsDecoder
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- All Implemented Interfaces:
Decoder
public final class PackBitsDecoder extends java.lang.Object implements Decoder
Decoder implementation for Apple PackBits run-length encoding.From Wikipedia, the free encyclopedia
PackBits is a fast, simple compression scheme for run-length encoding of data.Apple introduced the PackBits format with the release of MacPaint on the Macintosh computer. This compression scheme is one of the types of compression that can be used in TIFF-files.
A PackBits data stream consists of packets of one byte of header followed by data. The header is a signed byte; the data can be signed, unsigned, or packed (such as MacPaint pixels).
PackBits Header byte Data 0 to 127 1 + n literal bytes of data 0 to -127 One byte of data, repeated 1 - n times in the decompressed output -128 No operation Note that interpreting 0 as positive or negative makes no difference in the output. Runs of two bytes adjacent to non-runs are typically written as literal data.
- Version:
- $Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/io/enc/PackBitsDecoder.java#1 $
- Author:
- Harald Kuhr
- See Also:
- Understanding PackBits
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Constructor Summary
Constructors Constructor Description PackBitsDecoder()
Creates aPackBitsDecoder
.PackBitsDecoder(boolean disableNoOp)
Creates aPackBitsDecoder
, with optional compatibility mode.PackBitsDecoder(int sampleSize, boolean disableNoOp)
Creates aPackBitsDecoder
, with optional compatibility mode.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
decode(java.io.InputStream stream, java.nio.ByteBuffer buffer)
Decodes bytes from the given input stream, to the given buffer.
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Constructor Detail
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PackBitsDecoder
public PackBitsDecoder()
Creates aPackBitsDecoder
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PackBitsDecoder
public PackBitsDecoder(boolean disableNoOp)
Creates aPackBitsDecoder
, with optional compatibility mode.As some implementations of PackBits-like encoders treat
-128
as length of a compressed run, instead of a no-op, it's possible to disable no-ops for compatibility. Should be used with caution, even though, most known encoders never write no-ops in the compressed streams.- Parameters:
disableNoOp
-true
if-128
should be treated as a compressed run, and not a no-op
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PackBitsDecoder
public PackBitsDecoder(int sampleSize, boolean disableNoOp)
Creates aPackBitsDecoder
, with optional compatibility mode.As some implementations of PackBits-like encoders treat
-128
as length of a compressed run, instead of a no-op, it's possible to disable no-ops for compatibility. Should be used with caution, even though, most known encoders never write no-ops in the compressed streams.- Parameters:
disableNoOp
-true
if-128
should be treated as a compressed run, and not a no-op
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