/* Copyright 2012 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'use strict';
(function (root, factory) {
if (typeof define === 'function' && define.amd) {
define('pdfjs/core/jbig2', ['exports', 'pdfjs/shared/util',
'pdfjs/core/arithmetic_decoder'], factory);
} else if (typeof exports !== 'undefined') {
factory(exports, require('../shared/util.js'),
require('./arithmetic_decoder.js'));
} else {
factory((root.pdfjsCoreJbig2 = {}), root.pdfjsSharedUtil,
root.pdfjsCoreArithmeticDecoder);
}
}(this, function (exports, sharedUtil, coreArithmeticDecoder) {
var error = sharedUtil.error;
var log2 = sharedUtil.log2;
var readInt8 = sharedUtil.readInt8;
var readUint16 = sharedUtil.readUint16;
var readUint32 = sharedUtil.readUint32;
var shadow = sharedUtil.shadow;
var ArithmeticDecoder = coreArithmeticDecoder.ArithmeticDecoder;
var Jbig2Image = (function Jbig2ImageClosure() {
// Utility data structures
function ContextCache() {}
ContextCache.prototype = {
getContexts: function(id) {
if (id in this) {
return this[id];
}
return (this[id] = new Int8Array(1 << 16));
}
};
function DecodingContext(data, start, end) {
this.data = data;
this.start = start;
this.end = end;
}
DecodingContext.prototype = {
get decoder() {
var decoder = new ArithmeticDecoder(this.data, this.start, this.end);
return shadow(this, 'decoder', decoder);
},
get contextCache() {
var cache = new ContextCache();
return shadow(this, 'contextCache', cache);
}
};
// Annex A. Arithmetic Integer Decoding Procedure
// A.2 Procedure for decoding values
function decodeInteger(contextCache, procedure, decoder) {
var contexts = contextCache.getContexts(procedure);
var prev = 1;
function readBits(length) {
var v = 0;
for (var i = 0; i < length; i++) {
var bit = decoder.readBit(contexts, prev);
prev = (prev < 256 ? (prev << 1) | bit :
(((prev << 1) | bit) & 511) | 256);
v = (v << 1) | bit;
}
return v >>> 0;
}
var sign = readBits(1);
var value = readBits(1) ?
(readBits(1) ?
(readBits(1) ?
(readBits(1) ?
(readBits(1) ?
(readBits(32) + 4436) :
readBits(12) + 340) :
readBits(8) + 84) :
readBits(6) + 20) :
readBits(4) + 4) :
readBits(2);
return (sign === 0 ? value : (value > 0 ? -value : null));
}
// A.3 The IAID decoding procedure
function decodeIAID(contextCache, decoder, codeLength) {
var contexts = contextCache.getContexts('IAID');
var prev = 1;
for (var i = 0; i < codeLength; i++) {
var bit = decoder.readBit(contexts, prev);
prev = (prev << 1) | bit;
}
if (codeLength < 31) {
return prev & ((1 << codeLength) - 1);
}
return prev & 0x7FFFFFFF;
}
// 7.3 Segment types
var SegmentTypes = [
'SymbolDictionary', null, null, null, 'IntermediateTextRegion', null,
'ImmediateTextRegion', 'ImmediateLosslessTextRegion', null, null, null,
null, null, null, null, null, 'patternDictionary', null, null, null,
'IntermediateHalftoneRegion', null, 'ImmediateHalftoneRegion',
'ImmediateLosslessHalftoneRegion', null, null, null, null, null, null, null,
null, null, null, null, null, 'IntermediateGenericRegion', null,
'ImmediateGenericRegion', 'ImmediateLosslessGenericRegion',
'IntermediateGenericRefinementRegion', null,
'ImmediateGenericRefinementRegion',
'ImmediateLosslessGenericRefinementRegion', null, null, null, null,
'PageInformation', 'EndOfPage', 'EndOfStripe', 'EndOfFile', 'Profiles',
'Tables', null, null, null, null, null, null, null, null,
'Extension'
];
var CodingTemplates = [
[{x: -1, y: -2}, {x: 0, y: -2}, {x: 1, y: -2}, {x: -2, y: -1},
{x: -1, y: -1}, {x: 0, y: -1}, {x: 1, y: -1}, {x: 2, y: -1},
{x: -4, y: 0}, {x: -3, y: 0}, {x: -2, y: 0}, {x: -1, y: 0}],
[{x: -1, y: -2}, {x: 0, y: -2}, {x: 1, y: -2}, {x: 2, y: -2},
{x: -2, y: -1}, {x: -1, y: -1}, {x: 0, y: -1}, {x: 1, y: -1},
{x: 2, y: -1}, {x: -3, y: 0}, {x: -2, y: 0}, {x: -1, y: 0}],
[{x: -1, y: -2}, {x: 0, y: -2}, {x: 1, y: -2}, {x: -2, y: -1},
{x: -1, y: -1}, {x: 0, y: -1}, {x: 1, y: -1}, {x: -2, y: 0},
{x: -1, y: 0}],
[{x: -3, y: -1}, {x: -2, y: -1}, {x: -1, y: -1}, {x: 0, y: -1},
{x: 1, y: -1}, {x: -4, y: 0}, {x: -3, y: 0}, {x: -2, y: 0}, {x: -1, y: 0}]
];
var RefinementTemplates = [
{
coding: [{x: 0, y: -1}, {x: 1, y: -1}, {x: -1, y: 0}],
reference: [{x: 0, y: -1}, {x: 1, y: -1}, {x: -1, y: 0}, {x: 0, y: 0},
{x: 1, y: 0}, {x: -1, y: 1}, {x: 0, y: 1}, {x: 1, y: 1}]
},
{
coding: [{x: -1, y: -1}, {x: 0, y: -1}, {x: 1, y: -1}, {x: -1, y: 0}],
reference: [{x: 0, y: -1}, {x: -1, y: 0}, {x: 0, y: 0}, {x: 1, y: 0},
{x: 0, y: 1}, {x: 1, y: 1}]
}
];
// See 6.2.5.7 Decoding the bitmap.
var ReusedContexts = [
0x9B25, // 10011 0110010 0101
0x0795, // 0011 110010 101
0x00E5, // 001 11001 01
0x0195 // 011001 0101
];
var RefinementReusedContexts = [
0x0020, // '000' + '0' (coding) + '00010000' + '0' (reference)
0x0008 // '0000' + '001000'
];
function decodeBitmapTemplate0(width, height, decodingContext) {
var decoder = decodingContext.decoder;
var contexts = decodingContext.contextCache.getContexts('GB');
var contextLabel, i, j, pixel, row, row1, row2, bitmap = [];
// ...ooooo....
// ..ooooooo... Context template for current pixel (X)
// .ooooX...... (concatenate values of 'o'-pixels to get contextLabel)
var OLD_PIXEL_MASK = 0x7BF7; // 01111 0111111 0111
for (i = 0; i < height; i++) {
row = bitmap[i] = new Uint8Array(width);
row1 = (i < 1) ? row : bitmap[i - 1];
row2 = (i < 2) ? row : bitmap[i - 2];
// At the beginning of each row:
// Fill contextLabel with pixels that are above/right of (X)
contextLabel = (row2[0] << 13) | (row2[1] << 12) | (row2[2] << 11) |
(row1[0] << 7) | (row1[1] << 6) | (row1[2] << 5) |
(row1[3] << 4);
for (j = 0; j < width; j++) {
row[j] = pixel = decoder.readBit(contexts, contextLabel);
// At each pixel: Clear contextLabel pixels that are shifted
// out of the context, then add new ones.
contextLabel = ((contextLabel & OLD_PIXEL_MASK) << 1) |
(j + 3 < width ? row2[j + 3] << 11 : 0) |
(j + 4 < width ? row1[j + 4] << 4 : 0) | pixel;
}
}
return bitmap;
}
// 6.2 Generic Region Decoding Procedure
function decodeBitmap(mmr, width, height, templateIndex, prediction, skip, at,
decodingContext) {
if (mmr) {
error('JBIG2 error: MMR encoding is not supported');
}
// Use optimized version for the most common case
if (templateIndex === 0 && !skip && !prediction && at.length === 4 &&
at[0].x === 3 && at[0].y === -1 && at[1].x === -3 && at[1].y === -1 &&
at[2].x === 2 && at[2].y === -2 && at[3].x === -2 && at[3].y === -2) {
return decodeBitmapTemplate0(width, height, decodingContext);
}
var useskip = !!skip;
var template = CodingTemplates[templateIndex].concat(at);
// Sorting is non-standard, and it is not required. But sorting increases
// the number of template bits that can be reused from the previous
// contextLabel in the main loop.
template.sort(function (a, b) {
return (a.y - b.y) || (a.x - b.x);
});
var templateLength = template.length;
var templateX = new Int8Array(templateLength);
var templateY = new Int8Array(templateLength);
var changingTemplateEntries = [];
var reuseMask = 0, minX = 0, maxX = 0, minY = 0;
var c, k;
for (k = 0; k < templateLength; k++) {
templateX[k] = template[k].x;
templateY[k] = template[k].y;
minX = Math.min(minX, template[k].x);
maxX = Math.max(maxX, template[k].x);
minY = Math.min(minY, template[k].y);
// Check if the template pixel appears in two consecutive context labels,
// so it can be reused. Otherwise, we add it to the list of changing
// template entries.
if (k < templateLength - 1 &&
template[k].y === template[k + 1].y &&
template[k].x === template[k + 1].x - 1) {
reuseMask |= 1 << (templateLength - 1 - k);
} else {
changingTemplateEntries.push(k);
}
}
var changingEntriesLength = changingTemplateEntries.length;
var changingTemplateX = new Int8Array(changingEntriesLength);
var changingTemplateY = new Int8Array(changingEntriesLength);
var changingTemplateBit = new Uint16Array(changingEntriesLength);
for (c = 0; c < changingEntriesLength; c++) {
k = changingTemplateEntries[c];
changingTemplateX[c] = template[k].x;
changingTemplateY[c] = template[k].y;
changingTemplateBit[c] = 1 << (templateLength - 1 - k);
}
// Get the safe bounding box edges from the width, height, minX, maxX, minY
var sbb_left = -minX;
var sbb_top = -minY;
var sbb_right = width - maxX;
var pseudoPixelContext = ReusedContexts[templateIndex];
var row = new Uint8Array(width);
var bitmap = [];
var decoder = decodingContext.decoder;
var contexts = decodingContext.contextCache.getContexts('GB');
var ltp = 0, j, i0, j0, contextLabel = 0, bit, shift;
for (var i = 0; i < height; i++) {
if (prediction) {
var sltp = decoder.readBit(contexts, pseudoPixelContext);
ltp ^= sltp;
if (ltp) {
bitmap.push(row); // duplicate previous row
continue;
}
}
row = new Uint8Array(row);
bitmap.push(row);
for (j = 0; j < width; j++) {
if (useskip && skip[i][j]) {
row[j] = 0;
continue;
}
// Are we in the middle of a scanline, so we can reuse contextLabel
// bits?
if (j >= sbb_left && j < sbb_right && i >= sbb_top) {
// If yes, we can just shift the bits that are reusable and only
// fetch the remaining ones.
contextLabel = (contextLabel << 1) & reuseMask;
for (k = 0; k < changingEntriesLength; k++) {
i0 = i + changingTemplateY[k];
j0 = j + changingTemplateX[k];
bit = bitmap[i0][j0];
if (bit) {
bit = changingTemplateBit[k];
contextLabel |= bit;
}
}
} else {
// compute the contextLabel from scratch
contextLabel = 0;
shift = templateLength - 1;
for (k = 0; k < templateLength; k++, shift--) {
j0 = j + templateX[k];
if (j0 >= 0 && j0 < width) {
i0 = i + templateY[k];
if (i0 >= 0) {
bit = bitmap[i0][j0];
if (bit) {
contextLabel |= bit << shift;
}
}
}
}
}
var pixel = decoder.readBit(contexts, contextLabel);
row[j] = pixel;
}
}
return bitmap;
}
// 6.3.2 Generic Refinement Region Decoding Procedure
function decodeRefinement(width, height, templateIndex, referenceBitmap,
offsetX, offsetY, prediction, at,
decodingContext) {
var codingTemplate = RefinementTemplates[templateIndex].coding;
if (templateIndex === 0) {
codingTemplate = codingTemplate.concat([at[0]]);
}
var codingTemplateLength = codingTemplate.length;
var codingTemplateX = new Int32Array(codingTemplateLength);
var codingTemplateY = new Int32Array(codingTemplateLength);
var k;
for (k = 0; k < codingTemplateLength; k++) {
codingTemplateX[k] = codingTemplate[k].x;
codingTemplateY[k] = codingTemplate[k].y;
}
var referenceTemplate = RefinementTemplates[templateIndex].reference;
if (templateIndex === 0) {
referenceTemplate = referenceTemplate.concat([at[1]]);
}
var referenceTemplateLength = referenceTemplate.length;
var referenceTemplateX = new Int32Array(referenceTemplateLength);
var referenceTemplateY = new Int32Array(referenceTemplateLength);
for (k = 0; k < referenceTemplateLength; k++) {
referenceTemplateX[k] = referenceTemplate[k].x;
referenceTemplateY[k] = referenceTemplate[k].y;
}
var referenceWidth = referenceBitmap[0].length;
var referenceHeight = referenceBitmap.length;
var pseudoPixelContext = RefinementReusedContexts[templateIndex];
var bitmap = [];
var decoder = decodingContext.decoder;
var contexts = decodingContext.contextCache.getContexts('GR');
var ltp = 0;
for (var i = 0; i < height; i++) {
if (prediction) {
var sltp = decoder.readBit(contexts, pseudoPixelContext);
ltp ^= sltp;
if (ltp) {
error('JBIG2 error: prediction is not supported');
}
}
var row = new Uint8Array(width);
bitmap.push(row);
for (var j = 0; j < width; j++) {
var i0, j0;
var contextLabel = 0;
for (k = 0; k < codingTemplateLength; k++) {
i0 = i + codingTemplateY[k];
j0 = j + codingTemplateX[k];
if (i0 < 0 || j0 < 0 || j0 >= width) {
contextLabel <<= 1; // out of bound pixel
} else {
contextLabel = (contextLabel << 1) | bitmap[i0][j0];
}
}
for (k = 0; k < referenceTemplateLength; k++) {
i0 = i + referenceTemplateY[k] + offsetY;
j0 = j + referenceTemplateX[k] + offsetX;
if (i0 < 0 || i0 >= referenceHeight || j0 < 0 ||
j0 >= referenceWidth) {
contextLabel <<= 1; // out of bound pixel
} else {
contextLabel = (contextLabel << 1) | referenceBitmap[i0][j0];
}
}
var pixel = decoder.readBit(contexts, contextLabel);
row[j] = pixel;
}
}
return bitmap;
}
// 6.5.5 Decoding the symbol dictionary
function decodeSymbolDictionary(huffman, refinement, symbols,
numberOfNewSymbols, numberOfExportedSymbols,
huffmanTables, templateIndex, at,
refinementTemplateIndex, refinementAt,
decodingContext) {
if (huffman) {
error('JBIG2 error: huffman is not supported');
}
var newSymbols = [];
var currentHeight = 0;
var symbolCodeLength = log2(symbols.length + numberOfNewSymbols);
var decoder = decodingContext.decoder;
var contextCache = decodingContext.contextCache;
while (newSymbols.length < numberOfNewSymbols) {
var deltaHeight = decodeInteger(contextCache, 'IADH', decoder); // 6.5.6
currentHeight += deltaHeight;
var currentWidth = 0;
var totalWidth = 0;
while (true) {
var deltaWidth = decodeInteger(contextCache, 'IADW', decoder); // 6.5.7
if (deltaWidth === null) {
break; // OOB
}
currentWidth += deltaWidth;
totalWidth += currentWidth;
var bitmap;
if (refinement) {
// 6.5.8.2 Refinement/aggregate-coded symbol bitmap
var numberOfInstances = decodeInteger(contextCache, 'IAAI', decoder);
if (numberOfInstances > 1) {
bitmap = decodeTextRegion(huffman, refinement,
currentWidth, currentHeight, 0,
numberOfInstances, 1, //strip size
symbols.concat(newSymbols),
symbolCodeLength,
0, //transposed
0, //ds offset
1, //top left 7.4.3.1.1
0, //OR operator
huffmanTables,
refinementTemplateIndex, refinementAt,
decodingContext);
} else {
var symbolId = decodeIAID(contextCache, decoder, symbolCodeLength);
var rdx = decodeInteger(contextCache, 'IARDX', decoder); // 6.4.11.3
var rdy = decodeInteger(contextCache, 'IARDY', decoder); // 6.4.11.4
var symbol = (symbolId < symbols.length ? symbols[symbolId] :
newSymbols[symbolId - symbols.length]);
bitmap = decodeRefinement(currentWidth, currentHeight,
refinementTemplateIndex, symbol, rdx, rdy, false, refinementAt,
decodingContext);
}
} else {
// 6.5.8.1 Direct-coded symbol bitmap
bitmap = decodeBitmap(false, currentWidth, currentHeight,
templateIndex, false, null, at, decodingContext);
}
newSymbols.push(bitmap);
}
}
// 6.5.10 Exported symbols
var exportedSymbols = [];
var flags = [], currentFlag = false;
var totalSymbolsLength = symbols.length + numberOfNewSymbols;
while (flags.length < totalSymbolsLength) {
var runLength = decodeInteger(contextCache, 'IAEX', decoder);
while (runLength--) {
flags.push(currentFlag);
}
currentFlag = !currentFlag;
}
for (var i = 0, ii = symbols.length; i < ii; i++) {
if (flags[i]) {
exportedSymbols.push(symbols[i]);
}
}
for (var j = 0; j < numberOfNewSymbols; i++, j++) {
if (flags[i]) {
exportedSymbols.push(newSymbols[j]);
}
}
return exportedSymbols;
}
function decodeTextRegion(huffman, refinement, width, height,
defaultPixelValue, numberOfSymbolInstances,
stripSize, inputSymbols, symbolCodeLength,
transposed, dsOffset, referenceCorner,
combinationOperator, huffmanTables,
refinementTemplateIndex, refinementAt,
decodingContext) {
if (huffman) {
error('JBIG2 error: huffman is not supported');
}
// Prepare bitmap
var bitmap = [];
var i, row;
for (i = 0; i < height; i++) {
row = new Uint8Array(width);
if (defaultPixelValue) {
for (var j = 0; j < width; j++) {
row[j] = defaultPixelValue;
}
}
bitmap.push(row);
}
var decoder = decodingContext.decoder;
var contextCache = decodingContext.contextCache;
var stripT = -decodeInteger(contextCache, 'IADT', decoder); // 6.4.6
var firstS = 0;
i = 0;
while (i < numberOfSymbolInstances) {
var deltaT = decodeInteger(contextCache, 'IADT', decoder); // 6.4.6
stripT += deltaT;
var deltaFirstS = decodeInteger(contextCache, 'IAFS', decoder); // 6.4.7
firstS += deltaFirstS;
var currentS = firstS;
do {
var currentT = (stripSize === 1 ? 0 :
decodeInteger(contextCache, 'IAIT', decoder)); // 6.4.9
var t = stripSize * stripT + currentT;
var symbolId = decodeIAID(contextCache, decoder, symbolCodeLength);
var applyRefinement = (refinement &&
decodeInteger(contextCache, 'IARI', decoder));
var symbolBitmap = inputSymbols[symbolId];
var symbolWidth = symbolBitmap[0].length;
var symbolHeight = symbolBitmap.length;
if (applyRefinement) {
var rdw = decodeInteger(contextCache, 'IARDW', decoder); // 6.4.11.1
var rdh = decodeInteger(contextCache, 'IARDH', decoder); // 6.4.11.2
var rdx = decodeInteger(contextCache, 'IARDX', decoder); // 6.4.11.3
var rdy = decodeInteger(contextCache, 'IARDY', decoder); // 6.4.11.4
symbolWidth += rdw;
symbolHeight += rdh;
symbolBitmap = decodeRefinement(symbolWidth, symbolHeight,
refinementTemplateIndex, symbolBitmap, (rdw >> 1) + rdx,
(rdh >> 1) + rdy, false, refinementAt,
decodingContext);
}
var offsetT = t - ((referenceCorner & 1) ? 0 : symbolHeight);
var offsetS = currentS - ((referenceCorner & 2) ? symbolWidth : 0);
var s2, t2, symbolRow;
if (transposed) {
// Place Symbol Bitmap from T1,S1
for (s2 = 0; s2 < symbolHeight; s2++) {
row = bitmap[offsetS + s2];
if (!row) {
continue;
}
symbolRow = symbolBitmap[s2];
// To ignore Parts of Symbol bitmap which goes
// outside bitmap region
var maxWidth = Math.min(width - offsetT, symbolWidth);
switch (combinationOperator) {
case 0: // OR
for (t2 = 0; t2 < maxWidth; t2++) {
row[offsetT + t2] |= symbolRow[t2];
}
break;
case 2: // XOR
for (t2 = 0; t2 < maxWidth; t2++) {
row[offsetT + t2] ^= symbolRow[t2];
}
break;
default:
error('JBIG2 error: operator ' + combinationOperator +
' is not supported');
}
}
currentS += symbolHeight - 1;
} else {
for (t2 = 0; t2 < symbolHeight; t2++) {
row = bitmap[offsetT + t2];
if (!row) {
continue;
}
symbolRow = symbolBitmap[t2];
switch (combinationOperator) {
case 0: // OR
for (s2 = 0; s2 < symbolWidth; s2++) {
row[offsetS + s2] |= symbolRow[s2];
}
break;
case 2: // XOR
for (s2 = 0; s2 < symbolWidth; s2++) {
row[offsetS + s2] ^= symbolRow[s2];
}
break;
default:
error('JBIG2 error: operator ' + combinationOperator +
' is not supported');
}
}
currentS += symbolWidth - 1;
}
i++;
var deltaS = decodeInteger(contextCache, 'IADS', decoder); // 6.4.8
if (deltaS === null) {
break; // OOB
}
currentS += deltaS + dsOffset;
} while (true);
}
return bitmap;
}
function readSegmentHeader(data, start) {
var segmentHeader = {};
segmentHeader.number = readUint32(data, start);
var flags = data[start + 4];
var segmentType = flags & 0x3F;
if (!SegmentTypes[segmentType]) {
error('JBIG2 error: invalid segment type: ' + segmentType);
}
segmentHeader.type = segmentType;
segmentHeader.typeName = SegmentTypes[segmentType];
segmentHeader.deferredNonRetain = !!(flags & 0x80);
var pageAssociationFieldSize = !!(flags & 0x40);
var referredFlags = data[start + 5];
var referredToCount = (referredFlags >> 5) & 7;
var retainBits = [referredFlags & 31];
var position = start + 6;
if (referredFlags === 7) {
referredToCount = readUint32(data, position - 1) & 0x1FFFFFFF;
position += 3;
var bytes = (referredToCount + 7) >> 3;
retainBits[0] = data[position++];
while (--bytes > 0) {
retainBits.push(data[position++]);
}
} else if (referredFlags === 5 || referredFlags === 6) {
error('JBIG2 error: invalid referred-to flags');
}
segmentHeader.retainBits = retainBits;
var referredToSegmentNumberSize = (segmentHeader.number <= 256 ? 1 :
(segmentHeader.number <= 65536 ? 2 : 4));
var referredTo = [];
var i, ii;
for (i = 0; i < referredToCount; i++) {
var number = (referredToSegmentNumberSize === 1 ? data[position] :
(referredToSegmentNumberSize === 2 ? readUint16(data, position) :
readUint32(data, position)));
referredTo.push(number);
position += referredToSegmentNumberSize;
}
segmentHeader.referredTo = referredTo;
if (!pageAssociationFieldSize) {
segmentHeader.pageAssociation = data[position++];
} else {
segmentHeader.pageAssociation = readUint32(data, position);
position += 4;
}
segmentHeader.length = readUint32(data, position);
position += 4;
if (segmentHeader.length === 0xFFFFFFFF) {
// 7.2.7 Segment data length, unknown segment length
if (segmentType === 38) { // ImmediateGenericRegion
var genericRegionInfo = readRegionSegmentInformation(data, position);
var genericRegionSegmentFlags = data[position +
RegionSegmentInformationFieldLength];
var genericRegionMmr = !!(genericRegionSegmentFlags & 1);
// searching for the segment end
var searchPatternLength = 6;
var searchPattern = new Uint8Array(searchPatternLength);
if (!genericRegionMmr) {
searchPattern[0] = 0xFF;
searchPattern[1] = 0xAC;
}
searchPattern[2] = (genericRegionInfo.height >>> 24) & 0xFF;
searchPattern[3] = (genericRegionInfo.height >> 16) & 0xFF;
searchPattern[4] = (genericRegionInfo.height >> 8) & 0xFF;
searchPattern[5] = genericRegionInfo.height & 0xFF;
for (i = position, ii = data.length; i < ii; i++) {
var j = 0;
while (j < searchPatternLength && searchPattern[j] === data[i + j]) {
j++;
}
if (j === searchPatternLength) {
segmentHeader.length = i + searchPatternLength;
break;
}
}
if (segmentHeader.length === 0xFFFFFFFF) {
error('JBIG2 error: segment end was not found');
}
} else {
error('JBIG2 error: invalid unknown segment length');
}
}
segmentHeader.headerEnd = position;
return segmentHeader;
}
function readSegments(header, data, start, end) {
var segments = [];
var position = start;
while (position < end) {
var segmentHeader = readSegmentHeader(data, position);
position = segmentHeader.headerEnd;
var segment = {
header: segmentHeader,
data: data
};
if (!header.randomAccess) {
segment.start = position;
position += segmentHeader.length;
segment.end = position;
}
segments.push(segment);
if (segmentHeader.type === 51) {
break; // end of file is found
}
}
if (header.randomAccess) {
for (var i = 0, ii = segments.length; i < ii; i++) {
segments[i].start = position;
position += segments[i].header.length;
segments[i].end = position;
}
}
return segments;
}
// 7.4.1 Region segment information field
function readRegionSegmentInformation(data, start) {
return {
width: readUint32(data, start),
height: readUint32(data, start + 4),
x: readUint32(data, start + 8),
y: readUint32(data, start + 12),
combinationOperator: data[start + 16] & 7
};
}
var RegionSegmentInformationFieldLength = 17;
function processSegment(segment, visitor) {
var header = segment.header;
var data = segment.data, position = segment.start, end = segment.end;
var args, at, i, atLength;
switch (header.type) {
case 0: // SymbolDictionary
// 7.4.2 Symbol dictionary segment syntax
var dictionary = {};
var dictionaryFlags = readUint16(data, position); // 7.4.2.1.1
dictionary.huffman = !!(dictionaryFlags & 1);
dictionary.refinement = !!(dictionaryFlags & 2);
dictionary.huffmanDHSelector = (dictionaryFlags >> 2) & 3;
dictionary.huffmanDWSelector = (dictionaryFlags >> 4) & 3;
dictionary.bitmapSizeSelector = (dictionaryFlags >> 6) & 1;
dictionary.aggregationInstancesSelector = (dictionaryFlags >> 7) & 1;
dictionary.bitmapCodingContextUsed = !!(dictionaryFlags & 256);
dictionary.bitmapCodingContextRetained = !!(dictionaryFlags & 512);
dictionary.template = (dictionaryFlags >> 10) & 3;
dictionary.refinementTemplate = (dictionaryFlags >> 12) & 1;
position += 2;
if (!dictionary.huffman) {
atLength = dictionary.template === 0 ? 4 : 1;
at = [];
for (i = 0; i < atLength; i++) {
at.push({
x: readInt8(data, position),
y: readInt8(data, position + 1)
});
position += 2;
}
dictionary.at = at;
}
if (dictionary.refinement && !dictionary.refinementTemplate) {
at = [];
for (i = 0; i < 2; i++) {
at.push({
x: readInt8(data, position),
y: readInt8(data, position + 1)
});
position += 2;
}
dictionary.refinementAt = at;
}
dictionary.numberOfExportedSymbols = readUint32(data, position);
position += 4;
dictionary.numberOfNewSymbols = readUint32(data, position);
position += 4;
args = [dictionary, header.number, header.referredTo,
data, position, end];
break;
case 6: // ImmediateTextRegion
case 7: // ImmediateLosslessTextRegion
var textRegion = {};
textRegion.info = readRegionSegmentInformation(data, position);
position += RegionSegmentInformationFieldLength;
var textRegionSegmentFlags = readUint16(data, position);
position += 2;
textRegion.huffman = !!(textRegionSegmentFlags & 1);
textRegion.refinement = !!(textRegionSegmentFlags & 2);
textRegion.stripSize = 1 << ((textRegionSegmentFlags >> 2) & 3);
textRegion.referenceCorner = (textRegionSegmentFlags >> 4) & 3;
textRegion.transposed = !!(textRegionSegmentFlags & 64);
textRegion.combinationOperator = (textRegionSegmentFlags >> 7) & 3;
textRegion.defaultPixelValue = (textRegionSegmentFlags >> 9) & 1;
textRegion.dsOffset = (textRegionSegmentFlags << 17) >> 27;
textRegion.refinementTemplate = (textRegionSegmentFlags >> 15) & 1;
if (textRegion.huffman) {
var textRegionHuffmanFlags = readUint16(data, position);
position += 2;
textRegion.huffmanFS = (textRegionHuffmanFlags) & 3;
textRegion.huffmanDS = (textRegionHuffmanFlags >> 2) & 3;
textRegion.huffmanDT = (textRegionHuffmanFlags >> 4) & 3;
textRegion.huffmanRefinementDW = (textRegionHuffmanFlags >> 6) & 3;
textRegion.huffmanRefinementDH = (textRegionHuffmanFlags >> 8) & 3;
textRegion.huffmanRefinementDX = (textRegionHuffmanFlags >> 10) & 3;
textRegion.huffmanRefinementDY = (textRegionHuffmanFlags >> 12) & 3;
textRegion.huffmanRefinementSizeSelector =
!!(textRegionHuffmanFlags & 14);
}
if (textRegion.refinement && !textRegion.refinementTemplate) {
at = [];
for (i = 0; i < 2; i++) {
at.push({
x: readInt8(data, position),
y: readInt8(data, position + 1)
});
position += 2;
}
textRegion.refinementAt = at;
}
textRegion.numberOfSymbolInstances = readUint32(data, position);
position += 4;
// TODO 7.4.3.1.7 Symbol ID Huffman table decoding
if (textRegion.huffman) {
error('JBIG2 error: huffman is not supported');
}
args = [textRegion, header.referredTo, data, position, end];
break;
case 38: // ImmediateGenericRegion
case 39: // ImmediateLosslessGenericRegion
var genericRegion = {};
genericRegion.info = readRegionSegmentInformation(data, position);
position += RegionSegmentInformationFieldLength;
var genericRegionSegmentFlags = data[position++];
genericRegion.mmr = !!(genericRegionSegmentFlags & 1);
genericRegion.template = (genericRegionSegmentFlags >> 1) & 3;
genericRegion.prediction = !!(genericRegionSegmentFlags & 8);
if (!genericRegion.mmr) {
atLength = genericRegion.template === 0 ? 4 : 1;
at = [];
for (i = 0; i < atLength; i++) {
at.push({
x: readInt8(data, position),
y: readInt8(data, position + 1)
});
position += 2;
}
genericRegion.at = at;
}
args = [genericRegion, data, position, end];
break;
case 48: // PageInformation
var pageInfo = {
width: readUint32(data, position),
height: readUint32(data, position + 4),
resolutionX: readUint32(data, position + 8),
resolutionY: readUint32(data, position + 12)
};
if (pageInfo.height === 0xFFFFFFFF) {
delete pageInfo.height;
}
var pageSegmentFlags = data[position + 16];
var pageStripingInformation = readUint16(data, position + 17);
pageInfo.lossless = !!(pageSegmentFlags & 1);
pageInfo.refinement = !!(pageSegmentFlags & 2);
pageInfo.defaultPixelValue = (pageSegmentFlags >> 2) & 1;
pageInfo.combinationOperator = (pageSegmentFlags >> 3) & 3;
pageInfo.requiresBuffer = !!(pageSegmentFlags & 32);
pageInfo.combinationOperatorOverride = !!(pageSegmentFlags & 64);
args = [pageInfo];
break;
case 49: // EndOfPage
break;
case 50: // EndOfStripe
break;
case 51: // EndOfFile
break;
case 62: // 7.4.15 defines 2 extension types which
// are comments and can be ignored.
break;
default:
error('JBIG2 error: segment type ' + header.typeName + '(' +
header.type + ') is not implemented');
}
var callbackName = 'on' + header.typeName;
if (callbackName in visitor) {
visitor[callbackName].apply(visitor, args);
}
}
function processSegments(segments, visitor) {
for (var i = 0, ii = segments.length; i < ii; i++) {
processSegment(segments[i], visitor);
}
}
function parseJbig2(data, start, end) {
var position = start;
if (data[position] !== 0x97 || data[position + 1] !== 0x4A ||
data[position + 2] !== 0x42 || data[position + 3] !== 0x32 ||
data[position + 4] !== 0x0D || data[position + 5] !== 0x0A ||
data[position + 6] !== 0x1A || data[position + 7] !== 0x0A) {
error('JBIG2 error: invalid header');
}
var header = {};
position += 8;
var flags = data[position++];
header.randomAccess = !(flags & 1);
if (!(flags & 2)) {
header.numberOfPages = readUint32(data, position);
position += 4;
}
var segments = readSegments(header, data, position, end);
error('Not implemented');
// processSegments(segments, new SimpleSegmentVisitor());
}
function parseJbig2Chunks(chunks) {
var visitor = new SimpleSegmentVisitor();
for (var i = 0, ii = chunks.length; i < ii; i++) {
var chunk = chunks[i];
var segments = readSegments({}, chunk.data, chunk.start, chunk.end);
processSegments(segments, visitor);
}
return visitor.buffer;
}
function SimpleSegmentVisitor() {}
SimpleSegmentVisitor.prototype = {
onPageInformation: function SimpleSegmentVisitor_onPageInformation(info) {
this.currentPageInfo = info;
var rowSize = (info.width + 7) >> 3;
var buffer = new Uint8Array(rowSize * info.height);
// The contents of ArrayBuffers are initialized to 0.
// Fill the buffer with 0xFF only if info.defaultPixelValue is set
if (info.defaultPixelValue) {
for (var i = 0, ii = buffer.length; i < ii; i++) {
buffer[i] = 0xFF;
}
}
this.buffer = buffer;
},
drawBitmap: function SimpleSegmentVisitor_drawBitmap(regionInfo, bitmap) {
var pageInfo = this.currentPageInfo;
var width = regionInfo.width, height = regionInfo.height;
var rowSize = (pageInfo.width + 7) >> 3;
var combinationOperator = pageInfo.combinationOperatorOverride ?
regionInfo.combinationOperator : pageInfo.combinationOperator;
var buffer = this.buffer;
var mask0 = 128 >> (regionInfo.x & 7);
var offset0 = regionInfo.y * rowSize + (regionInfo.x >> 3);
var i, j, mask, offset;
switch (combinationOperator) {
case 0: // OR
for (i = 0; i < height; i++) {
mask = mask0;
offset = offset0;
for (j = 0; j < width; j++) {
if (bitmap[i][j]) {
buffer[offset] |= mask;
}
mask >>= 1;
if (!mask) {
mask = 128;
offset++;
}
}
offset0 += rowSize;
}
break;
case 2: // XOR
for (i = 0; i < height; i++) {
mask = mask0;
offset = offset0;
for (j = 0; j < width; j++) {
if (bitmap[i][j]) {
buffer[offset] ^= mask;
}
mask >>= 1;
if (!mask) {
mask = 128;
offset++;
}
}
offset0 += rowSize;
}
break;
default:
error('JBIG2 error: operator ' + combinationOperator +
' is not supported');
}
},
onImmediateGenericRegion:
function SimpleSegmentVisitor_onImmediateGenericRegion(region, data,
start, end) {
var regionInfo = region.info;
var decodingContext = new DecodingContext(data, start, end);
var bitmap = decodeBitmap(region.mmr, regionInfo.width, regionInfo.height,
region.template, region.prediction, null,
region.at, decodingContext);
this.drawBitmap(regionInfo, bitmap);
},
onImmediateLosslessGenericRegion:
function SimpleSegmentVisitor_onImmediateLosslessGenericRegion() {
this.onImmediateGenericRegion.apply(this, arguments);
},
onSymbolDictionary:
function SimpleSegmentVisitor_onSymbolDictionary(dictionary,
currentSegment,
referredSegments,
data, start, end) {
var huffmanTables;
if (dictionary.huffman) {
error('JBIG2 error: huffman is not supported');
}
// Combines exported symbols from all referred segments
var symbols = this.symbols;
if (!symbols) {
this.symbols = symbols = {};
}
var inputSymbols = [];
for (var i = 0, ii = referredSegments.length; i < ii; i++) {
inputSymbols = inputSymbols.concat(symbols[referredSegments[i]]);
}
var decodingContext = new DecodingContext(data, start, end);
symbols[currentSegment] = decodeSymbolDictionary(dictionary.huffman,
dictionary.refinement, inputSymbols, dictionary.numberOfNewSymbols,
dictionary.numberOfExportedSymbols, huffmanTables,
dictionary.template, dictionary.at,
dictionary.refinementTemplate, dictionary.refinementAt,
decodingContext);
},
onImmediateTextRegion:
function SimpleSegmentVisitor_onImmediateTextRegion(region,
referredSegments,
data, start, end) {
var regionInfo = region.info;
var huffmanTables;
// Combines exported symbols from all referred segments
var symbols = this.symbols;
var inputSymbols = [];
for (var i = 0, ii = referredSegments.length; i < ii; i++) {
inputSymbols = inputSymbols.concat(symbols[referredSegments[i]]);
}
var symbolCodeLength = log2(inputSymbols.length);
var decodingContext = new DecodingContext(data, start, end);
var bitmap = decodeTextRegion(region.huffman, region.refinement,
regionInfo.width, regionInfo.height, region.defaultPixelValue,
region.numberOfSymbolInstances, region.stripSize, inputSymbols,
symbolCodeLength, region.transposed, region.dsOffset,
region.referenceCorner, region.combinationOperator, huffmanTables,
region.refinementTemplate, region.refinementAt, decodingContext);
this.drawBitmap(regionInfo, bitmap);
},
onImmediateLosslessTextRegion:
function SimpleSegmentVisitor_onImmediateLosslessTextRegion() {
this.onImmediateTextRegion.apply(this, arguments);
}
};
function Jbig2Image() {}
Jbig2Image.prototype = {
parseChunks: function Jbig2Image_parseChunks(chunks) {
return parseJbig2Chunks(chunks);
}
};
return Jbig2Image;
})();
exports.Jbig2Image = Jbig2Image;
}));