QRFormatInformation.cpp Example File

 /*
  *  FormatInformation.cpp
  *  zxing
  *
  *  Created by Christian Brunschen on 18/05/2008.
  *  Copyright 2008 ZXing authors All rights reserved.
  *
  * 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.
  */

 #include <zxing/qrcode/FormatInformation.h>
 #include <limits>
 #include <zxing/common/Types.h>

 namespace zxing {
 namespace qrcode {

 using namespace std;

 int FormatInformation::FORMAT_INFO_MASK_QR = 0x5412;
 int FormatInformation::FORMAT_INFO_DECODE_LOOKUP[][2] = { { 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 },
 };
 int FormatInformation::N_FORMAT_INFO_DECODE_LOOKUPS = 32;

 int FormatInformation::BITS_SET_IN_HALF_BYTE[] = { 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4 };

 FormatInformation::FormatInformation(int formatInfo) :
     errorCorrectionLevel_(ErrorCorrectionLevel::forBits((formatInfo >> 3) & 0x03)), dataMask_((byte)(formatInfo & 0x07)) {
 }

 ErrorCorrectionLevel& FormatInformation::getErrorCorrectionLevel() {
   return errorCorrectionLevel_;
 }

 char FormatInformation::getDataMask() {
   return dataMask_;
 }

 int FormatInformation::numBitsDiffering(int a, int b) {
   a ^= b;
   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)];
 }

 Ref<FormatInformation> FormatInformation::decodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
   Ref<FormatInformation> result(doDecodeFormatInformation(maskedFormatInfo1, maskedFormatInfo2));
   if (result != 0) {
     return result;
   }
   // 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);
 }
 Ref<FormatInformation> FormatInformation::doDecodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
   // Find the int in FORMAT_INFO_DECODE_LOOKUP with fewest bits differing
   int bestDifference = numeric_limits<int>::max();
   int bestFormatInfo = 0;
   for (int i = 0; i < N_FORMAT_INFO_DECODE_LOOKUPS; i++) {
     int* decodeInfo = FORMAT_INFO_DECODE_LOOKUP[i];
     int targetInfo = decodeInfo[0];
     if (targetInfo == maskedFormatInfo1 || targetInfo == maskedFormatInfo2) {
       // Found an exact match
       Ref<FormatInformation> result(new FormatInformation(decodeInfo[1]));
       return result;
     }
     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;
         }
       }
   }
   if (bestDifference <= 3) {
     Ref<FormatInformation> result(new FormatInformation(bestFormatInfo));
     return result;
   }
   Ref<FormatInformation> result;
   return result;
 }

 bool operator==(const FormatInformation &a, const FormatInformation &b) {
   return &(a.errorCorrectionLevel_) == &(b.errorCorrectionLevel_) && a.dataMask_ == b.dataMask_;
 }

 ostream& operator<<(ostream& out, const FormatInformation& fi) {
   const FormatInformation *fip = &fi;
   out << "FormatInformation @ " << fip;
   return out;
 }

 }
 }