From 6025b6016517c6d898d8957d1d7e03ba71431912 Mon Sep 17 00:00:00 2001 From: tknall Date: Fri, 1 Dec 2006 12:20:24 +0000 Subject: Initial import of release 2.2. git-svn-id: https://joinup.ec.europa.eu/svn/pdf-as/trunk@4 7b5415b0-85f9-ee4d-85bd-d5d0c3b42d1c --- .../org/pdfbox/filter/RunLengthDecodeFilter.java | 126 +++++++++++++++++++++ 1 file changed, 126 insertions(+) create mode 100644 src/main/java/org/pdfbox/filter/RunLengthDecodeFilter.java (limited to 'src/main/java/org/pdfbox/filter/RunLengthDecodeFilter.java') diff --git a/src/main/java/org/pdfbox/filter/RunLengthDecodeFilter.java b/src/main/java/org/pdfbox/filter/RunLengthDecodeFilter.java new file mode 100644 index 0000000..d1fe1c1 --- /dev/null +++ b/src/main/java/org/pdfbox/filter/RunLengthDecodeFilter.java @@ -0,0 +1,126 @@ +/** + * Copyright (c) 2004, www.pdfbox.org + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + * 3. Neither the name of pdfbox; nor the names of its + * contributors may be used to endorse or promote products derived from this + * software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON + * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * http://www.pdfbox.org + * + */ +package org.pdfbox.filter; + +import java.io.IOException; +import java.io.InputStream; +import java.io.OutputStream; + +import org.apache.log4j.Logger; +import org.pdfbox.cos.COSDictionary; + +/** + * 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.
+ *
+ * + * @author Ben Litchfield + * @version $Revision: 1.3 $ + */ +public class RunLengthDecodeFilter implements Filter +{ + private static Logger log = Logger.getLogger( RunLengthDecodeFilter.class ); + + private static final int RUN_LENGTH_EOD = 128; + + /** + * Constructor. + */ + public RunLengthDecodeFilter() + { + //default constructor + } + + /** + * This will decode some compressed data. + * + * @param compressedData The compressed byte stream. + * @param result The place to write the uncompressed byte stream. + * @param options The options to use to encode the data. + * + * @throws IOException If there is an error decompressing the stream. + */ + public void decode( InputStream compressedData, OutputStream result, COSDictionary options ) throws IOException + { + int dupAmount = -1; + byte[] buffer = new byte[128]; + while( (dupAmount = compressedData.read()) != -1 && dupAmount != RUN_LENGTH_EOD ) + { + if( dupAmount <= 127 ) + { + int amountToCopy = dupAmount+1; + int compressedRead = 0; + while( amountToCopy > 0 ) + { + compressedRead = compressedData.read( buffer, 0, amountToCopy ); + result.write( buffer, 0, compressedRead ); + amountToCopy -= compressedRead; + } + } + else + { + int dupByte = compressedData.read(); + for( int i=0; i<257-dupAmount; i++ ) + { + result.write( dupByte ); + } + } + } + } + + /** + * This will encode some data. + * + * @param rawData The raw data to encode. + * @param result The place to write to encoded results to. + * @param options The options to use to encode the data. + * + * @throws IOException If there is an error compressing the stream. + */ + public void encode( InputStream rawData, OutputStream result, COSDictionary options ) throws IOException + { + log.warn( "Warning: RunLengthDecodeFilter.encode is not implemented yet, skipping this stream." ); + } +} \ No newline at end of file -- cgit v1.2.3