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Issue 820 second format info was read incorrectly

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Semantically, this is just C++ version of the changes from Java. I also did
some minor renaming of variables to match the current Java source to aide
in keeping the two trees in sync.


git-svn-id: https://zxing.googlecode.com/svn/trunk@1754 59b500cc-1b3d-0410-9834-0bbf25fbcc57
This commit is contained in:
smparkes@smparkes.net 2011-04-29 18:01:46 +00:00
parent 9afb71c862
commit d65d3e0d4b
3 changed files with 36 additions and 31 deletions
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26
cpp/core/src/zxing/qrcode/FormatInformation.cpp
View file

@ -59,32 +59,42 @@ int FormatInformation::numBitsDiffering(unsigned int a, unsigned int b) {
+ BITS_SET_IN_HALF_BYTE[(a >> 28 & 0x0F)];
}
Ref<FormatInformation> FormatInformation::decodeFormatInformation(int rawFormatInfo) {
Ref<FormatInformation> result(doDecodeFormatInformation(rawFormatInfo));
Ref<FormatInformation> FormatInformation::decodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2) {
Ref<FormatInformation> result(doDecodeFormatInformation(maskedFormatInfo1, maskedFormatInfo2));
if (result != 0) {
return result;
}
return doDecodeFormatInformation(rawFormatInfo ^ FORMAT_INFO_MASK_QR);
// 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 rawFormatInfo) {
// Unmask:
int unmaskedFormatInfo = rawFormatInfo ^ 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 == unmaskedFormatInfo) {
if (targetInfo == maskedFormatInfo1 || targetInfo == maskedFormatInfo2) {
// Found an exact match
Ref<FormatInformation> result(new FormatInformation(decodeInfo[1]));
return result;
}
int bitsDifference = numBitsDiffering(unmaskedFormatInfo, targetInfo);
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));

4
cpp/core/src/zxing/qrcode/FormatInformation.h
View file

@ -41,8 +41,8 @@ private:
public:
static int numBitsDiffering(unsigned int a, unsigned int b);
static Ref<FormatInformation> decodeFormatInformation(int rawFormatInfo);
static Ref<FormatInformation> doDecodeFormatInformation(int rawFormatInfo);
static Ref<FormatInformation> decodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2);
static Ref<FormatInformation> doDecodeFormatInformation(int maskedFormatInfo1, int maskedFormatInfo2);
ErrorCorrectionLevel &getErrorCorrectionLevel();
unsigned char getDataMask();
friend bool operator==(const FormatInformation &a, const FormatInformation &b);

37
cpp/core/src/zxing/qrcode/decoder/BitMatrixParser.cpp
View file

@ -43,36 +43,31 @@ Ref<FormatInformation> BitMatrixParser::readFormatInformation() {
}
// Read top-left format info bits
int formatInfoBits = 0;
for (int x = 0; x < 6; x++) {
formatInfoBits = copyBit(x, 8, formatInfoBits);
int formatInfoBits1 = 0;
for (int i = 0; i < 6; i++) {
formatInfoBits1 = copyBit(i, 8, formatInfoBits1);
}
// .. and skip a bit in the timing pattern ...
formatInfoBits = copyBit(7, 8, formatInfoBits);
formatInfoBits = copyBit(8, 8, formatInfoBits);
formatInfoBits = copyBit(8, 7, formatInfoBits);
formatInfoBits1 = copyBit(7, 8, formatInfoBits1);
formatInfoBits1 = copyBit(8, 8, formatInfoBits1);
formatInfoBits1 = copyBit(8, 7, formatInfoBits1);
// .. and skip a bit in the timing pattern ...
for (int y = 5; y >= 0; y--) {
formatInfoBits = copyBit(8, y, formatInfoBits);
for (int j = 5; j >= 0; j--) {
formatInfoBits1 = copyBit(8, j, formatInfoBits1);
}
parsedFormatInfo_ = FormatInformation::decodeFormatInformation(formatInfoBits);
if (parsedFormatInfo_ != 0) {
return parsedFormatInfo_;
}
// Hmm, failed. Try the top-right/bottom-left pattern
// Read the top-right/bottom-left pattern
int dimension = bitMatrix_->getDimension();
formatInfoBits = 0;
int yMin = dimension - 8;
for (int y = dimension - 1; y >= yMin; y--) {
formatInfoBits = copyBit(8, y, formatInfoBits);
int formatInfoBits2 = 0;
int jMin = dimension - 7;
for (int j = dimension - 1; j >= jMin; j--) {
formatInfoBits2 = copyBit(8, j, formatInfoBits2);
}
for (int x = dimension - 7; x < dimension; x++) {
formatInfoBits = copyBit(x, 8, formatInfoBits);
for (int i = dimension - 8; i < dimension; i++) {
formatInfoBits2 = copyBit(i, 8, formatInfoBits2);
}
parsedFormatInfo_ = FormatInformation::decodeFormatInformation(formatInfoBits);
parsedFormatInfo_ = FormatInformation::decodeFormatInformation(formatInfoBits1,formatInfoBits2);
if (parsedFormatInfo_ != 0) {
return parsedFormatInfo_;
}