org.pdfbox.filter
Class RunLengthDecodeFilter
java.lang.Object
org.pdfbox.filter.RunLengthDecodeFilter
- Filter
public class RunLengthDecodeFilter
extends java.lang.Object
This is a filter for the RunLength Decoder.
From the PDF Reference
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.
void | decode(InputStream compressedData, OutputStream result, COSDictionary options) - This will decode some compressed data.
|
void | encode(InputStream rawData, OutputStream result, COSDictionary options) - This will encode some data.
|
RunLengthDecodeFilter
public RunLengthDecodeFilter()
Constructor.
decode
public void decode(InputStream compressedData,
OutputStream result,
COSDictionary options)
throws IOException
This will decode some compressed data.
- 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.
encode
public void encode(InputStream rawData,
OutputStream result,
COSDictionary options)
throws IOException
This will encode some data.
- 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.