--- /dev/null
+/*******************************************************************************
+ * Copyright (c) 2000, 2011 IBM Corporation and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ * IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.swt.internal.image;
+
+import java.io.*;
+
+public class PngHuffmanTables {
+ PngHuffmanTable literalTable;
+ PngHuffmanTable distanceTable;
+
+ static PngHuffmanTable FixedLiteralTable;
+ static PngHuffmanTable FixedDistanceTable;
+
+ static final int LiteralTableSize = 288;
+ static final int[] FixedLiteralLengths = {
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,
+ 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 7, 7, 7, 7, 7, 7, 7, 7,
+ 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8,
+ };
+
+ static final int DistanceTableSize = 32;
+ static final int[] FixedDistanceLengths = {
+ 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+ 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+ };
+
+ static final int LengthCodeTableSize = 19;
+ static final int[] LengthCodeOrder = {
+ 16, 17, 18, 0, 8, 7, 9, 6, 10, 5,
+ 11, 4, 12, 3, 13, 2, 14, 1, 15
+ };
+
+static PngHuffmanTables getDynamicTables(PngDecodingDataStream stream) throws IOException {
+ return new PngHuffmanTables(stream);
+}
+static PngHuffmanTables getFixedTables() {
+ return new PngHuffmanTables();
+}
+
+private PngHuffmanTable getFixedLiteralTable() {
+ if (FixedLiteralTable == null) {
+ FixedLiteralTable = new PngHuffmanTable(FixedLiteralLengths);
+ }
+ return FixedLiteralTable;
+}
+
+private PngHuffmanTable getFixedDistanceTable() {
+ if (FixedDistanceTable == null) {
+ FixedDistanceTable = new PngHuffmanTable(FixedDistanceLengths);
+ }
+ return FixedDistanceTable;
+}
+
+private PngHuffmanTables () {
+ literalTable = getFixedLiteralTable();
+ distanceTable = getFixedDistanceTable();
+}
+
+private PngHuffmanTables (PngDecodingDataStream stream) throws IOException {
+ int literals = PngLzBlockReader.FIRST_LENGTH_CODE
+ + stream.getNextIdatBits(5);
+ int distances = PngLzBlockReader.FIRST_DISTANCE_CODE
+ + stream.getNextIdatBits(5);
+ int codeLengthCodes = PngLzBlockReader.FIRST_CODE_LENGTH_CODE
+ + stream.getNextIdatBits(4);
+
+ if (codeLengthCodes > PngLzBlockReader.LAST_CODE_LENGTH_CODE) {
+ stream.error();
+ }
+
+ /* Tricky, tricky, tricky. The length codes are stored in
+ * a very odd order. (For the order, see the definition of
+ * the static field lengthCodeOrder.) Also, the data may
+ * not contain values for all the codes. It may just contain
+ * values for the first X number of codes. The table should
+ * be of size <LengthCodeTableSize> regardless of the number
+ * of values actually given in the table.
+ */
+ int[] lengthCodes = new int[LengthCodeTableSize];
+ for (int i = 0; i < codeLengthCodes; i++) {
+ lengthCodes[LengthCodeOrder[i]] = stream.getNextIdatBits(3);
+ }
+ PngHuffmanTable codeLengthsTable = new PngHuffmanTable(lengthCodes);
+
+ int[] literalLengths = readLengths(
+ stream, literals, codeLengthsTable, LiteralTableSize);
+ int[] distanceLengths = readLengths(
+ stream, distances, codeLengthsTable, DistanceTableSize);
+
+ literalTable = new PngHuffmanTable(literalLengths);
+ distanceTable = new PngHuffmanTable(distanceLengths);
+}
+
+private int [] readLengths (PngDecodingDataStream stream,
+ int numLengths,
+ PngHuffmanTable lengthsTable,
+ int tableSize) throws IOException
+{
+ int[] lengths = new int[tableSize];
+
+ for (int index = 0; index < numLengths;) {
+ int value = lengthsTable.getNextValue(stream);
+ if (value < 16) {
+ // Literal value
+ lengths[index] = value;
+ index++;
+ } else if (value == 16) {
+ // Repeat the previous code 3-6 times.
+ int count = stream.getNextIdatBits(2) + 3;
+ for (int i = 0; i < count; i++) {
+ lengths[index] = lengths [index - 1];
+ index++;
+ }
+ } else if (value == 17) {
+ // Repeat 0 3-10 times.
+ int count = stream.getNextIdatBits(3) + 3;
+ for (int i = 0; i < count; i++) {
+ lengths[index] = 0;
+ index++;
+ }
+ } else if (value == 18) {
+ // Repeat 0 11-138 times.
+ int count = stream.getNextIdatBits(7) + 11;
+ for (int i = 0; i < count; i++) {
+ lengths[index] = 0;
+ index++;
+ }
+ } else {
+ stream.error();
+ }
+ }
+ return lengths;
+}
+
+int getNextLiteralValue(PngDecodingDataStream stream) throws IOException {
+ return literalTable.getNextValue(stream);
+}
+
+int getNextDistanceValue(PngDecodingDataStream stream) throws IOException {
+ return distanceTable.getNextValue(stream);
+}
+
+}
Code Review / simantics / platform.git / blobdiff