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Diffstat (limited to 'src/main/java/org/pdfbox/filter/LZWFilter.java')
| -rw-r--r-- | src/main/java/org/pdfbox/filter/LZWFilter.java | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/src/main/java/org/pdfbox/filter/LZWFilter.java b/src/main/java/org/pdfbox/filter/LZWFilter.java new file mode 100644 index 0000000..e8ba003 --- /dev/null +++ b/src/main/java/org/pdfbox/filter/LZWFilter.java @@ -0,0 +1,235 @@ +/**
+ * Copyright (c) 2003-2005, 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.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.PushbackInputStream;
+import java.io.StreamCorruptedException;
+
+import org.pdfbox.cos.COSDictionary;
+
+import org.pdfbox.io.NBitInputStream;
+import org.pdfbox.io.NBitOutputStream;
+
+/**
+ * This is the used for the LZWDecode filter.
+ *
+ * @author Ben Litchfield (ben@benlitchfield.com)
+ * @version $Revision: 1.13 $
+ */
+public class LZWFilter implements Filter
+{
+
+ /**
+ * The LZW clear table code.
+ */
+ public static final long CLEAR_TABLE = 256;
+ /**
+ * The LZW end of data code.
+ */
+ public static final long EOD = 257;
+
+ /**
+ * 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
+ {
+ //log.debug("decode( )");
+ NBitInputStream in = null;
+ in = new NBitInputStream( compressedData );
+ in.setBitsInChunk( 9 );
+ LZWDictionary dic = new LZWDictionary();
+ byte firstByte = 0;
+ long nextCommand = 0;
+ while( (nextCommand = in.read() ) != EOD )
+ {
+ // log.debug( "decode - nextCommand=" + nextCommand + ", bitsInChunk: " + in.getBitsInChunk());
+
+ if( nextCommand == CLEAR_TABLE )
+ {
+ in.setBitsInChunk( 9 );
+ dic = new LZWDictionary();
+ }
+ else
+ {
+ byte[] data = dic.getData( nextCommand );
+ if( data == null )
+ {
+ dic.visit( firstByte );
+ data = dic.getData( nextCommand );
+ dic.clear();
+ }
+ if( data == null )
+ {
+ throw new StreamCorruptedException( "Error: data is null" );
+ }
+ dic.visit(data);
+
+ //log.debug( "decode - dic.getNextCode(): " + dic.getNextCode());
+
+ if( dic.getNextCode() >= 2047 )
+ {
+ in.setBitsInChunk( 12 );
+ }
+ else if( dic.getNextCode() >= 1023 )
+ {
+ in.setBitsInChunk( 11 );
+ }
+ else if( dic.getNextCode() >= 511 )
+ {
+ in.setBitsInChunk( 10 );
+ }
+ else
+ {
+ in.setBitsInChunk( 9 );
+ }
+ /**
+ if( in.getBitsInChunk() != dic.getCodeSize() )
+ {
+ in.unread( nextCommand );
+ in.setBitsInChunk( dic.getCodeSize() );
+ System.out.print( "Switching " + nextCommand + " to " );
+ nextCommand = in.read();
+ System.out.println( "" + nextCommand );
+ data = dic.getData( nextCommand );
+ }**/
+ firstByte = data[0];
+ result.write( data );
+ }
+ }
+ result.flush();
+ }
+
+
+ /**
+ * 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.debug("encode( )");
+ PushbackInputStream input = new PushbackInputStream( rawData, 4096 );
+ LZWDictionary dic = new LZWDictionary();
+ NBitOutputStream out = new NBitOutputStream( result );
+ out.setBitsInChunk( 9 ); //initially nine
+ out.write( CLEAR_TABLE );
+ ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+ int byteRead = 0;
+ for( int i=0; (byteRead = input.read()) != -1; i++ )
+ {
+ //log.debug( "byteRead = '" + (char)byteRead + "' (0x" + Integer.toHexString(byteRead) + "), i=" + i);
+ buffer.write( byteRead );
+ dic.visit( (byte)byteRead );
+ out.setBitsInChunk( dic.getCodeSize() );
+
+ //log.debug( "Getting node '" + new String( buffer.toByteArray() ) + "', buffer.size = " + buffer.size() );
+ LZWNode node = dic.getNode( buffer.toByteArray() );
+ int nextByte = input.read();
+ if( nextByte != -1 )
+ {
+ //log.debug( "nextByte = '" + (char)nextByte + "' (0x" + Integer.toHexString(nextByte) + ")");
+ LZWNode next = node.getNode( (byte)nextByte );
+ if( next == null )
+ {
+ //log.debug("encode - No next node, writing node and resetting buffer (" +
+ // " node.getCode: " + node.getCode() + ")" +
+ // " bitsInChunk: " + out.getBitsInChunk() +
+ // ")");
+ out.write( node.getCode() );
+ buffer.reset();
+ }
+
+ input.unread( nextByte );
+ }
+ else
+ {
+ //log.debug("encode - EOF on lookahead: writing node, resetting buffer, and terminating read loop (" +
+ // " node.getCode: " + node.getCode() + ")" +
+ // " bitsInChunk: " + out.getBitsInChunk() +
+ // ")");
+ out.write( node.getCode() );
+ buffer.reset();
+ break;
+ }
+
+ if( dic.getNextCode() == 4096 )
+ {
+ //log.debug("encode - Clearing dictionary and unreading pending buffer data (" +
+ // " bitsInChunk: " + out.getBitsInChunk() +
+ // ")");
+ out.write( CLEAR_TABLE );
+ dic = new LZWDictionary();
+ input.unread( buffer.toByteArray() );
+ buffer.reset();
+ }
+ }
+
+ // Fix the code size based on the fact that we are writing the EOD
+ //
+ if( dic.getNextCode() >= 2047 )
+ {
+ out.setBitsInChunk( 12 );
+ }
+ else if( dic.getNextCode() >= 1023 )
+ {
+ out.setBitsInChunk( 11 );
+ }
+ else if( dic.getNextCode() >= 511 )
+ {
+ out.setBitsInChunk( 10 );
+ }
+ else
+ {
+ out.setBitsInChunk( 9 );
+ }
+
+ //log.debug("encode - Writing EOD (" +
+ // " bitsInChunk: " + out.getBitsInChunk() +
+ // ")");
+ out.write( EOD );
+ out.close();
+ result.flush();
+ }
+}
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