itextpdf.jar is a component in iText 5 Java library to provide core functionalities. iText Java library allows you to generate and manage PDF documents.

The Source Code files are provided at iText GitHub site.

You can compile it to generate your JAR file, using pom.xml as the build configuration file.

The source code of itextpdf-5.5.14.jar is provided below:

⏎ com/itextpdf/text/pdf/qrcode/FormatInformation.java

/*
 * Copyright 2007 ZXing authors
 *
 * 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.
 */

package com.itextpdf.text.pdf.qrcode;

/**
 * <p>Encapsulates a QR Code's format information, including the data mask used and
 * error correction level.</p>
 *
 * @author Sean Owen
 * @see ErrorCorrectionLevel
 * @since 5.0.2
 */
final class FormatInformation {

  private static final int FORMAT_INFO_MASK_QR = 0x5412;

  /**
   * See ISO 18004:2006, Annex C, Table C.1
   */
  private static final int[][] FORMAT_INFO_DECODE_LOOKUP = {
      {0x5412, 0x00},
      {0x5125, 0x01},
      {0x5E7C, 0x02},
      {0x5B4B, 0x03},
      {0x45F9, 0x04},
      {0x40CE, 0x05},
      {0x4F97, 0x06},
      {0x4AA0, 0x07},
      {0x77C4, 0x08},
      {0x72F3, 0x09},
      {0x7DAA, 0x0A},
      {0x789D, 0x0B},
      {0x662F, 0x0C},
      {0x6318, 0x0D},
      {0x6C41, 0x0E},
      {0x6976, 0x0F},
      {0x1689, 0x10},
      {0x13BE, 0x11},
      {0x1CE7, 0x12},
      {0x19D0, 0x13},
      {0x0762, 0x14},
      {0x0255, 0x15},
      {0x0D0C, 0x16},
      {0x083B, 0x17},
      {0x355F, 0x18},
      {0x3068, 0x19},
      {0x3F31, 0x1A},
      {0x3A06, 0x1B},
      {0x24B4, 0x1C},
      {0x2183, 0x1D},
      {0x2EDA, 0x1E},
      {0x2BED, 0x1F},
  };

  /**
   * Offset i holds the number of 1 bits in the binary representation of i
   */
  private static final int[] BITS_SET_IN_HALF_BYTE =
      {0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4};

  private final ErrorCorrectionLevel errorCorrectionLevel;
  private final byte dataMask;

  private FormatInformation(int formatInfo) {
    // Bits 3,4
    errorCorrectionLevel = ErrorCorrectionLevel.forBits((formatInfo >> 3) & 0x03);
    // Bottom 3 bits
    dataMask = (byte) (formatInfo & 0x07);
  }

  static int numBitsDiffering(int a, int b) {
    a ^= b; // a now has a 1 bit exactly where its bit differs with b's
    // Count bits set quickly with a series of lookups:
    return BITS_SET_IN_HALF_BYTE[a & 0x0F] +
        BITS_SET_IN_HALF_BYTE[(a >>> 4 & 0x0F)] +
        BITS_SET_IN_HALF_BYTE[(a >>> 8 & 0x0F)] +
        BITS_SET_IN_HALF_BYTE[(a >>> 12 & 0x0F)] +
        BITS_SET_IN_HALF_BYTE[(a >>> 16 & 0x0F)] +
        BITS_SET_IN_HALF_BYTE[(a >>> 20 & 0x0F)] +
        BITS_SET_IN_HALF_BYTE[(a >>> 24 & 0x0F)] +
        BITS_SET_IN_HALF_BYTE[(a >>> 28 & 0x0F)];
  }

  /**
   * @param maskedFormatInfo1 format info indicator, with mask still applied
   * @param maskedFormatInfo2 second copy of same info; both are checked at the same time
   *  to establish best match
   * @return information about the format it specifies, or <code>null</code>
   *  if doesn't seem to match any known pattern
   */
  static FormatInformation decodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
    FormatInformation formatInfo = doDecodeFormatInformation(maskedFormatInfo1, maskedFormatInfo2);
    if (formatInfo != null) {
      return formatInfo;
    }
    // Should return null, but, some QR codes apparently
    // do not mask this info. Try again by actually masking the pattern
    // first
    return doDecodeFormatInformation(maskedFormatInfo1 ^ FORMAT_INFO_MASK_QR,
                                     maskedFormatInfo2 ^ FORMAT_INFO_MASK_QR);
  }

  private static FormatInformation doDecodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
    // Find the int in FORMAT_INFO_DECODE_LOOKUP with fewest bits differing
    int bestDifference = Integer.MAX_VALUE;
    int bestFormatInfo = 0;
    for (int i = 0; i < FORMAT_INFO_DECODE_LOOKUP.length; i++) {
      int[] decodeInfo = FORMAT_INFO_DECODE_LOOKUP[i];
      int targetInfo = decodeInfo[0];
      if (targetInfo == maskedFormatInfo1 || targetInfo == maskedFormatInfo2) {
        // Found an exact match
        return new FormatInformation(decodeInfo[1]);
      }
      int bitsDifference = numBitsDiffering(maskedFormatInfo1, targetInfo);
      if (bitsDifference < bestDifference) {
        bestFormatInfo = decodeInfo[1];
        bestDifference = bitsDifference;
      }
      if (maskedFormatInfo1 != maskedFormatInfo2) {
        // also try the other option
        bitsDifference = numBitsDiffering(maskedFormatInfo2, targetInfo);
        if (bitsDifference < bestDifference) {
          bestFormatInfo = decodeInfo[1];
          bestDifference = bitsDifference;
        }
      }
    }
    // Hamming distance of the 32 masked codes is 7, by construction, so <= 3 bits
    // differing means we found a match
    if (bestDifference <= 3) {
      return new FormatInformation(bestFormatInfo);
    }
    return null;
  }

  ErrorCorrectionLevel getErrorCorrectionLevel() {
    return errorCorrectionLevel;
  }

  byte getDataMask() {
    return dataMask;
  }

  public int hashCode() {
    return (errorCorrectionLevel.ordinal() << 3) | (int) dataMask;
  }

  public boolean equals(Object o) {
    if (!(o instanceof FormatInformation)) {
      return false;
    }
    FormatInformation other = (FormatInformation) o;
    return this.errorCorrectionLevel == other.errorCorrectionLevel &&
        this.dataMask == other.dataMask;
  }

}

⏎ com/itextpdf/text/pdf/qrcode/FormatInformation.java

Or download all of them as a single archive file:

File name: itextpdf-5.5.14-fyi.zip
File size: 2163839 bytes
Release date: 2009-10-09
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