public class RunLengthDecodeFilter extends Object implements Filter
The RunLengthDecode filter decodes data that has been encoded in a simple byte-oriented format based on run length. The encoded data is a sequence of runs, where each run consists of a length byte followed by 1 to 128 bytes of data. If the length byte is in the range 0 to 127, the following length + 1 (1 to 128) bytes are copied literally during decompression. If length is in the range 129 to 255, the following single byte is to be copied 257 ? length (2 to 128) times during decompression. A length value of 128 denotes EOD. The compression achieved by run-length encoding depends on the input data. In the best case (all zeros), a compression of approximately 64:1 is achieved for long files. The worst case (the hexadecimal sequence 00 alternating with FF) results in an expansion of 127:128.
Constructor and Description |
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RunLengthDecodeFilter()
Constructor.
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Modifier and Type | Method and Description |
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void |
decode(InputStream compressedData,
OutputStream result,
COSDictionary options,
int filterIndex)
This will decode some compressed data.
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void |
encode(InputStream rawData,
OutputStream result,
COSDictionary options,
int filterIndex)
This will encode some data.
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public void decode(InputStream compressedData, OutputStream result, COSDictionary options, int filterIndex) throws IOException
decode
in interface Filter
compressedData
- The compressed byte stream.result
- The place to write the uncompressed byte stream.options
- The options to use to encode the data.filterIndex
- The index to the filter being decoded.IOException
- If there is an error decompressing the stream.public void encode(InputStream rawData, OutputStream result, COSDictionary options, int filterIndex) throws IOException
encode
in interface Filter
rawData
- The raw data to encode.result
- The place to write to encoded results to.options
- The options to use to encode the data.filterIndex
- The index to the filter being encoded.IOException
- If there is an error compressing the stream.Copyright © 2002-2014 The Apache Software Foundation. All Rights Reserved.