Mercurial > projects > dwt-win
view dwt/internal/image/PngHuffmanTables.d @ 2:57151e2793a2
More common modules from dwt-linux
author | Frank Benoit <benoit@tionex.de> |
---|---|
date | Wed, 23 Jan 2008 12:01:46 +0100 |
parents | |
children |
line wrap: on
line source
/******************************************************************************* * Copyright (c) 2000, 2006 IBM Corporation and others. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * IBM Corporation - initial API and implementation * Port to the D programming language: * Frank Benoit <benoit@tionex.de> *******************************************************************************/ module dwt.internal.image.PngHuffmanTables; import dwt.internal.image.PngHuffmanTable; import dwt.internal.image.PngDecodingDataStream; import dwt.internal.image.PngLzBlockReader; 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) { return new PngHuffmanTables(stream); } static PngHuffmanTables getFixedTables() { return new PngHuffmanTables(); } private PngHuffmanTable getFixedLiteralTable() { if (FixedLiteralTable is null) { FixedLiteralTable = new PngHuffmanTable(FixedLiteralLengths); } return FixedLiteralTable; } private PngHuffmanTable getFixedDistanceTable() { if (FixedDistanceTable is null) { FixedDistanceTable = new PngHuffmanTable(FixedDistanceLengths); } return FixedDistanceTable; } private this () { literalTable = getFixedLiteralTable(); distanceTable = getFixedDistanceTable(); } private this (PngDecodingDataStream stream) { 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) { 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 is 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 is 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 is 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) { return literalTable.getNextValue(stream); } int getNextDistanceValue(PngDecodingDataStream stream) { return distanceTable.getNextValue(stream); } }