diff options
Diffstat (limited to 'src/main/java/com/lowagie/text/pdf/LZWDecoder.java')
| -rw-r--r-- | src/main/java/com/lowagie/text/pdf/LZWDecoder.java | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/src/main/java/com/lowagie/text/pdf/LZWDecoder.java b/src/main/java/com/lowagie/text/pdf/LZWDecoder.java new file mode 100644 index 0000000..b8bedcf --- /dev/null +++ b/src/main/java/com/lowagie/text/pdf/LZWDecoder.java @@ -0,0 +1,231 @@ +/*
+ * Copyright (c) 2001 Sun Microsystems, Inc. All Rights Reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * -Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * -Redistribution in binary form must reproduct the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of Sun Microsystems, Inc. or the names of contributors may
+ * be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * This software is provided "AS IS," without a warranty of any kind. ALL
+ * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
+ * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
+ * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
+ * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
+ * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
+ * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
+ * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
+ * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
+ * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGES.
+ *
+ * You acknowledge that Software is not designed,licensed or intended for use in
+ * the design, construction, operation or maintenance of any nuclear facility.
+ *
+ * Adapted from the JAI codecs TIFFLZWDecoder.
+ */
+package com.lowagie.text.pdf;
+import java.io.OutputStream;
+import java.io.IOException;
+import com.lowagie.text.ExceptionConverter;
+/**
+ * A class for performing LZW decoding.
+ *
+ *
+ */
+public class LZWDecoder {
+
+ byte stringTable[][];
+ byte data[] = null;
+ OutputStream uncompData;
+ int tableIndex, bitsToGet = 9;
+ int bytePointer, bitPointer;
+ int nextData = 0;
+ int nextBits = 0;
+
+ int andTable[] = {
+ 511,
+ 1023,
+ 2047,
+ 4095
+ };
+
+ public LZWDecoder() {
+ }
+
+ /**
+ * Method to decode LZW compressed data.
+ *
+ * @param data The compressed data.
+ * @param uncompData Array to return the uncompressed data in.
+ */
+ public void decode(byte data[], OutputStream uncompData) {
+
+ if(data[0] == (byte)0x00 && data[1] == (byte)0x01) {
+ throw new RuntimeException("LZW flavour not supported.");
+ }
+
+ initializeStringTable();
+
+ this.data = data;
+ this.uncompData = uncompData;
+
+ // Initialize pointers
+ bytePointer = 0;
+ bitPointer = 0;
+
+ nextData = 0;
+ nextBits = 0;
+
+ int code, oldCode = 0;
+ byte string[];
+
+ while ((code = getNextCode()) != 257) {
+
+ if (code == 256) {
+
+ initializeStringTable();
+ code = getNextCode();
+
+ if (code == 257) {
+ break;
+ }
+
+ writeString(stringTable[code]);
+ oldCode = code;
+
+ } else {
+
+ if (code < tableIndex) {
+
+ string = stringTable[code];
+
+ writeString(string);
+ addStringToTable(stringTable[oldCode], string[0]);
+ oldCode = code;
+
+ } else {
+
+ string = stringTable[oldCode];
+ string = composeString(string, string[0]);
+ writeString(string);
+ addStringToTable(string);
+ oldCode = code;
+ }
+ }
+ }
+ }
+
+
+ /**
+ * Initialize the string table.
+ */
+ public void initializeStringTable() {
+
+ stringTable = new byte[8192][];
+
+ for (int i=0; i<256; i++) {
+ stringTable[i] = new byte[1];
+ stringTable[i][0] = (byte)i;
+ }
+
+ tableIndex = 258;
+ bitsToGet = 9;
+ }
+
+ /**
+ * Write out the string just uncompressed.
+ */
+ public void writeString(byte string[]) {
+ try {
+ uncompData.write(string);
+ }
+ catch (IOException e) {
+ throw new ExceptionConverter(e);
+ }
+ }
+
+ /**
+ * Add a new string to the string table.
+ */
+ public void addStringToTable(byte oldString[], byte newString) {
+ int length = oldString.length;
+ byte string[] = new byte[length + 1];
+ System.arraycopy(oldString, 0, string, 0, length);
+ string[length] = newString;
+
+ // Add this new String to the table
+ stringTable[tableIndex++] = string;
+
+ if (tableIndex == 511) {
+ bitsToGet = 10;
+ } else if (tableIndex == 1023) {
+ bitsToGet = 11;
+ } else if (tableIndex == 2047) {
+ bitsToGet = 12;
+ }
+ }
+
+ /**
+ * Add a new string to the string table.
+ */
+ public void addStringToTable(byte string[]) {
+
+ // Add this new String to the table
+ stringTable[tableIndex++] = string;
+
+ if (tableIndex == 511) {
+ bitsToGet = 10;
+ } else if (tableIndex == 1023) {
+ bitsToGet = 11;
+ } else if (tableIndex == 2047) {
+ bitsToGet = 12;
+ }
+ }
+
+ /**
+ * Append <code>newString</code> to the end of <code>oldString</code>.
+ */
+ public byte[] composeString(byte oldString[], byte newString) {
+ int length = oldString.length;
+ byte string[] = new byte[length + 1];
+ System.arraycopy(oldString, 0, string, 0, length);
+ string[length] = newString;
+
+ return string;
+ }
+
+ // Returns the next 9, 10, 11 or 12 bits
+ public int getNextCode() {
+ // Attempt to get the next code. The exception is caught to make
+ // this robust to cases wherein the EndOfInformation code has been
+ // omitted from a strip. Examples of such cases have been observed
+ // in practice.
+ try {
+ nextData = (nextData << 8) | (data[bytePointer++] & 0xff);
+ nextBits += 8;
+
+ if (nextBits < bitsToGet) {
+ nextData = (nextData << 8) | (data[bytePointer++] & 0xff);
+ nextBits += 8;
+ }
+
+ int code =
+ (nextData >> (nextBits - bitsToGet)) & andTable[bitsToGet-9];
+ nextBits -= bitsToGet;
+
+ return code;
+ } catch(ArrayIndexOutOfBoundsException e) {
+ // Strip not terminated as expected: return EndOfInformation code.
+ return 257;
+ }
+ }
+}
|