pdfjs-dist/lib/core/jbig2.js

/* Copyright 2017 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';

var sharedUtil = require('../shared/util.js');
var coreArithmeticDecoder = require('./arithmetic_decoder.js');
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() {
  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);
    }
  };
  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;
  }
  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;
  }
  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
    }]
  }];
  var ReusedContexts = [0x9B25, 0x0795, 0x00E5, 0x0195];
  var RefinementReusedContexts = [0x0020, 0x0008];
  function decodeBitmapTemplate0(width, height, decodingContext) {
    var decoder = decodingContext.decoder;
    var contexts = decodingContext.contextCache.getContexts('GB');
    var contextLabel,
        i,
        j,
        pixel,
        row,
        row1,
        row2,
        bitmap = [];
    var OLD_PIXEL_MASK = 0x7BF7;
    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];
      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);
        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;
  }
  function decodeBitmap(mmr, width, height, templateIndex, prediction, skip, at, decodingContext) {
    if (mmr) {
      error('JBIG2 error: MMR encoding is not supported');
    }
    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);
    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);
      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;
    }
    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);
          continue;
        }
      }
      row = new Uint8Array(row);
      bitmap.push(row);
      for (j = 0; j < width; j++) {
        if (useskip && skip[i][j]) {
          row[j] = 0;
          continue;
        }
        if (j >= sbb_left && j < sbb_right && i >= sbb_top) {
          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 {
          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;
  }
  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;
          } 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;
          } else {
            contextLabel = contextLabel << 1 | referenceBitmap[i0][j0];
          }
        }
        var pixel = decoder.readBit(contexts, contextLabel);
        row[j] = pixel;
      }
    }
    return bitmap;
  }
  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);
      currentHeight += deltaHeight;
      var currentWidth = 0;
      while (true) {
        var deltaWidth = decodeInteger(contextCache, 'IADW', decoder);
        if (deltaWidth === null) {
          break;
        }
        currentWidth += deltaWidth;
        var bitmap;
        if (refinement) {
          var numberOfInstances = decodeInteger(contextCache, 'IAAI', decoder);
          if (numberOfInstances > 1) {
            bitmap = decodeTextRegion(huffman, refinement, currentWidth, currentHeight, 0, numberOfInstances, 1, symbols.concat(newSymbols), symbolCodeLength, 0, 0, 1, 0, huffmanTables, refinementTemplateIndex, refinementAt, decodingContext);
          } else {
            var symbolId = decodeIAID(contextCache, decoder, symbolCodeLength);
            var rdx = decodeInteger(contextCache, 'IARDX', decoder);
            var rdy = decodeInteger(contextCache, 'IARDY', decoder);
            var symbol = symbolId < symbols.length ? symbols[symbolId] : newSymbols[symbolId - symbols.length];
            bitmap = decodeRefinement(currentWidth, currentHeight, refinementTemplateIndex, symbol, rdx, rdy, false, refinementAt, decodingContext);
          }
        } else {
          bitmap = decodeBitmap(false, currentWidth, currentHeight, templateIndex, false, null, at, decodingContext);
        }
        newSymbols.push(bitmap);
      }
    }
    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');
    }
    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);
    var firstS = 0;
    i = 0;
    while (i < numberOfSymbolInstances) {
      var deltaT = decodeInteger(contextCache, 'IADT', decoder);
      stripT += deltaT;
      var deltaFirstS = decodeInteger(contextCache, 'IAFS', decoder);
      firstS += deltaFirstS;
      var currentS = firstS;
      do {
        var currentT = stripSize === 1 ? 0 : decodeInteger(contextCache, 'IAIT', decoder);
        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);
          var rdh = decodeInteger(contextCache, 'IARDH', decoder);
          var rdx = decodeInteger(contextCache, 'IARDX', decoder);
          var rdy = decodeInteger(contextCache, 'IARDY', decoder);
          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) {
          for (s2 = 0; s2 < symbolHeight; s2++) {
            row = bitmap[offsetS + s2];
            if (!row) {
              continue;
            }
            symbolRow = symbolBitmap[s2];
            var maxWidth = Math.min(width - offsetT, symbolWidth);
            switch (combinationOperator) {
              case 0:
                for (t2 = 0; t2 < maxWidth; t2++) {
                  row[offsetT + t2] |= symbolRow[t2];
                }
                break;
              case 2:
                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:
                for (s2 = 0; s2 < symbolWidth; s2++) {
                  row[offsetS + s2] |= symbolRow[s2];
                }
                break;
              case 2:
                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);
        if (deltaS === null) {
          break;
        }
        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) {
      if (segmentType === 38) {
        var genericRegionInfo = readRegionSegmentInformation(data, position);
        var genericRegionSegmentFlags = data[position + RegionSegmentInformationFieldLength];
        var genericRegionMmr = !!(genericRegionSegmentFlags & 1);
        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;
      }
    }
    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;
  }
  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:
        var dictionary = {};
        var dictionaryFlags = readUint16(data, position);
        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:
      case 7:
        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;
        if (textRegion.huffman) {
          error('JBIG2 error: huffman is not supported');
        }
        args = [textRegion, header.referredTo, data, position, end];
        break;
      case 38:
      case 39:
        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:
        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];
        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:
        break;
      case 50:
        break;
      case 51:
        break;
      case 62:
        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;
    }
    readSegments(header, data, position, end);
    error('Not implemented');
  }
  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);
      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:
          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:
          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');
      }
      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;
      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;