Package com.twelvemonkeys.io.enc
Class PackBitsEncoder
java.lang.Object
com.twelvemonkeys.io.enc.PackBitsEncoder
- All Implemented Interfaces:
Encoder
Encoder 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).
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/PackBitsEncoder.java#1 $
- Author:
- Harald Kuhr
- See Also:
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
encode
(OutputStream stream, ByteBuffer buffer) Encodes up tobuffer.remaining()
bytes into the given input stream, from the given buffer.
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Constructor Details
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PackBitsEncoder
public PackBitsEncoder()Creates aPackBitsEncoder
.
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Method Details
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encode
Description copied from interface:Encoder
Encodes up tobuffer.remaining()
bytes into the given input stream, from the given buffer.- Specified by:
encode
in interfaceEncoder
- Parameters:
stream
- the output stream to encode data tobuffer
- buffer to read data from- Throws:
IOException
- if an I/O error occurs
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