I found that if QR-Code was generated with non standard charSet (and the message language is not English) than decoded QString contains wrong characters. So we must use QTextCodec to make it readable.

Now tagFound signal emits decoded string. If you want to know  what code was detected and what charSet is used, use tagFoundAdvanced(QString tag, QString format, QString charSet) signal or functions foundedFormat() and charSet().

source/CameraImageWrapper.cpp

@@ -114,7 +114,7 @@ ArrayRef<char> CameraImageWrapper::getMatrix() const
         ArrayRef<char> tmpRow;
         tmpRow = getRow(y, ArrayRef<char>(width));
 #if __cplusplus > 199711L
-        memcpy(m, tmpRow->values()..data(), width);
+        memcpy(m, tmpRow->values().data(), width);
 #else
 		memcpy(m, &tmpRow->values()[0], width);
 #endif

source/QZXing.h

@@ -75,6 +75,10 @@ public:
     }
 #endif
 
+    QString decoderFormatToString(int fmt);
+    QString foundedFormat() const;
+    QString charSet() const;
+
 public slots:
     /**
       * The decoding function. Will try to decode the given image based on the enabled decoders.
@@ -123,6 +127,7 @@ public slots:
     QString decodeSubImageQML(const QUrl &imageUrl,
                               const double offsetX = 0, const double offsetY = 0,
                               const double width = 0, const double height = 0);
+
     /**
       * Get the prossecing time in millisecond of the last decode operation.
       * Added mainly as a statistic measure.
@@ -153,6 +158,8 @@ private:
     DecoderFormatType enabledDecoders;
     ImageHandler *imageHandler;
     int processingTime;
+    QString foundedFmt;
+    QString charSet_;
 
     /**
       * If true, the decoding operation will take place at a different thread.

source/qzxing.cpp

@@ -44,6 +44,73 @@ QZXing::QZXing(QZXing::DecoderFormat decodeHints, QObject *parent) : QObject(par
     setDecoder(decodeHints);
 }
 
+QString QZXing::decoderFormatToString(int fmt)
+{
+    switch (fmt) {
+      case 1:
+          return "AZTEC";
+
+      case 2:
+          return "CODABAR";
+
+      case 3:
+          return "CODE_39";
+
+      case 4:
+          return "CODE_93";
+
+      case 5:
+          return "CODE_128";
+
+      case 6:
+          return "DATA_MATRIX";
+
+      case 7:
+          return "EAN_8";
+
+      case 8:
+          return "EAN_13";
+
+      case 9:
+          return "ITF";
+
+      case 10:
+          return "MAXICODE";
+
+      case 11:
+          return "PDF_417";
+
+      case 12:
+          return "QR_CODE";
+
+      case 13:
+          return "RSS_14";
+
+      case 14:
+          return "RSS_EXPANDED";
+
+      case 15:
+          return "UPC_A";
+
+      case 16:
+          return "UPC_E";
+
+      case 17:
+          return "UPC_EAN_EXTENSION";
+    } // switch
+    return QString();
+}
+
+QString QZXing::foundedFormat() const
+{
+    return foundedFmt;
+}
+
+QString QZXing::charSet() const
+{
+    return charSet_;
+}
+
 void QZXing::setDecoder(const uint &hint)
 {
     unsigned int newHints = 0;
@@ -113,16 +180,15 @@ QString QZXing::decodeImage(QImage &image, int maxWidth, int maxHeight, bool smo
 
     if(image.isNull())
     {
-        qDebug() << "Image Null";
+        qDebug() << "Image is Null";
         emit decodingFinished(false);
-        processingTime = -1;
+        processingTime = t.elapsed();
         return "";
     }
 
-    CameraImageWrapper* ciw;
+    CameraImageWrapper *ciw = NULL;
-
     try {
-        if(maxWidth > 0 || maxHeight > 0)
+        if ((maxWidth > 0) || (maxHeight > 0))
             ciw = CameraImageWrapper::Factory(image, maxWidth, maxHeight, smoothTransformation);
         else
             ciw = new CameraImageWrapper(image);
@@ -138,17 +204,27 @@ QString QZXing::decodeImage(QImage &image, int maxWidth, int maxHeight, bool smo
         res = decoder->decode(ref, DecodeHints((int)enabledDecoders));
 
         QString string = QString(res->getText()->getText().c_str());
-        processingTime = t.elapsed();
+        if (!string.isEmpty() && (string.length() > 0)) {
-        qDebug() << "Deconding succeeded: " << string;
+            int fmt = res->getBarcodeFormat().value;
+            foundedFmt = decoderFormatToString(fmt);
+            charSet_ = QString::fromStdString(res->getCharSet());
+            if (!charSet_.isEmpty()) {
+                QTextCodec *codec = QTextCodec::codecForName(res->getCharSet().c_str());
+                if (codec)
+                    string = codec->toUnicode(res->getText()->getText().c_str());
+            }
             emit tagFound(string);
+            emit tagFoundAdvanced(string, foundedFmt, charSet_);
+        }
+        processingTime = t.elapsed();
         emit decodingFinished(true);
         return string;
     }
-    catch(zxing::Exception& /*e*/)
+    catch(zxing::Exception &e)
     {
-        qDebug() << "Deconding failed";
+        emit error(QString(e.what()));
         emit decodingFinished(false);
-        processingTime = -1;
+        processingTime = t.elapsed();
         return "";
     }
 }
@@ -173,6 +249,7 @@ QString QZXing::decodeSubImageQML(QObject* item,
 {
     if(item  == NULL)
     {
+        processingTime = 0;
         emit decodingFinished(false);
         return "";
     }
@@ -186,6 +263,7 @@ QString QZXing::decodeImageQML(const QUrl &imageUrl)
 {
     return decodeSubImageQML(imageUrl);
 }
+
 QString QZXing::decodeSubImageQML(const QUrl &imageUrl,
                                   const double offsetX, const double offsetY,
                                   const double width, const double height)
@@ -214,7 +292,3 @@ uint QZXing::getEnabledFormats() const
 {
     return enabledDecoders;
 }
-
-
-
-

source/zxing/zxing/Result.cpp

@@ -33,8 +33,8 @@ using zxing::BarcodeFormat;
 Result::Result(Ref<String> text,
                ArrayRef<char> rawBytes,
                ArrayRef< Ref<ResultPoint> > resultPoints,
-               BarcodeFormat format) :
+               BarcodeFormat format, std::string charSet) :
-  text_(text), rawBytes_(rawBytes), resultPoints_(resultPoints), format_(format) {
+  text_(text), rawBytes_(rawBytes), resultPoints_(resultPoints), format_(format), charSet_(charSet) {
 }
 
 Result::~Result() {
@@ -59,3 +59,8 @@ ArrayRef< Ref<ResultPoint> >& Result::getResultPoints() {
 zxing::BarcodeFormat Result::getBarcodeFormat() const {
     return format_;
 }
+
+std::string Result::getCharSet() const
+{
+    return charSet_;
+}

source/zxing/zxing/Result.h

@@ -35,18 +35,21 @@ private:
   ArrayRef<char> rawBytes_;
   ArrayRef< Ref<ResultPoint> > resultPoints_;
   BarcodeFormat format_;
+  //NOTE: My
+  std::string charSet_;
 
 public:
   Result(Ref<String> text,
          ArrayRef<char> rawBytes,
          ArrayRef< Ref<ResultPoint> > resultPoints,
-         BarcodeFormat format);
+         BarcodeFormat format, std::string charSet = "");
   ~Result();
   Ref<String> getText();
   ArrayRef<char> getRawBytes();
   ArrayRef< Ref<ResultPoint> > const& getResultPoints() const;
   ArrayRef< Ref<ResultPoint> >& getResultPoints();
   BarcodeFormat getBarcodeFormat() const;
+  std::string getCharSet() const;
 
   friend std::ostream& operator<<(std::ostream &out, Result& result);
 };

source/zxing/zxing/common/DecoderResult.cpp

@@ -27,15 +27,15 @@ using namespace zxing;
 DecoderResult::DecoderResult(ArrayRef<char> rawBytes,
                              Ref<String> text,
                              ArrayRef< ArrayRef<char> >& byteSegments,
-                             string const& ecLevel) :
+                             string const& ecLevel, string charSet) :
   rawBytes_(rawBytes),
   text_(text),
   byteSegments_(byteSegments),
-  ecLevel_(ecLevel) {}
+  ecLevel_(ecLevel), charSet_(charSet) {}
 
 DecoderResult::DecoderResult(ArrayRef<char> rawBytes,
                              Ref<String> text)
-  : rawBytes_(rawBytes), text_(text) {}
+  : rawBytes_(rawBytes), text_(text),charSet_("") {}
 
 ArrayRef<char> DecoderResult::getRawBytes() {
   return rawBytes_;
@@ -44,3 +44,8 @@ ArrayRef<char> DecoderResult::getRawBytes() {
 Ref<String> DecoderResult::getText() {
     return text_;
 }
+
+string DecoderResult::charSet()
+{
+    return charSet_;
+}

source/zxing/zxing/common/DecoderResult.h

@@ -33,17 +33,21 @@ private:
   Ref<String> text_;
   ArrayRef< ArrayRef<char> > byteSegments_;
   std::string ecLevel_;
+  std::string charSet_;
 
 public:
   DecoderResult(ArrayRef<char> rawBytes,
                 Ref<String> text,
                 ArrayRef< ArrayRef<char> >& byteSegments,
-                std::string const& ecLevel);
+                std::string const& ecLevel,
+                std::string charSet = "");
 
   DecoderResult(ArrayRef<char> rawBytes, Ref<String> text);
 
   ArrayRef<char> getRawBytes();
   Ref<String> getText();
+  // NOTE: my
+  std::string charSet();
 };
 
 }

source/zxing/zxing/qrcode/QRCodeReader.cpp

@@ -38,7 +38,7 @@ namespace zxing {
 			ArrayRef< Ref<ResultPoint> > points (detectorResult->getPoints());
 			Ref<DecoderResult> decoderResult(decoder_.decode(detectorResult->getBits()));
 			Ref<Result> result(
-							   new Result(decoderResult->getText(), decoderResult->getRawBytes(), points, BarcodeFormat::QR_CODE));
+                               new Result(decoderResult->getText(), decoderResult->getRawBytes(), points, BarcodeFormat::QR_CODE, decoderResult->charSet()));
 			return result;
 		}
 		

source/zxing/zxing/qrcode/decoder/DecodedBitStreamParser.h

@@ -47,7 +47,7 @@ private:
   static void decodeHanziSegment(Ref<BitSource> bits, std::string &result, int count);
   static void decodeKanjiSegment(Ref<BitSource> bits, std::string &result, int count);
   static void decodeByteSegment(Ref<BitSource> bits, std::string &result, int count);
-  static void decodeByteSegment(Ref<BitSource> bits_,
+  static std::string decodeByteSegment(Ref<BitSource> bits_,
                                 std::string& result,
                                 int count,
                                 zxing::common::CharacterSetECI* currentCharacterSetECI,

source/zxing/zxing/qrcode/decoder/QRDecodedBitStreamParser.cpp

@@ -102,6 +102,7 @@ void DecodedBitStreamParser::append(std::string &result,
     result.append((const char *)bufOut);
     delete[] bufOut;
 #else
+    Q_UNUSED(src);
     result.append((const char *)bufIn, nIn);
 #endif
 }
@@ -181,7 +182,7 @@ void DecodedBitStreamParser::decodeKanjiSegment(Ref<BitSource> bits, std::string
     delete[] buffer;
 }
 
-void DecodedBitStreamParser::decodeByteSegment(Ref<BitSource> bits_,
+std::string DecodedBitStreamParser::decodeByteSegment(Ref<BitSource> bits_,
                                                       string& result,
                                                       int count,
                                                       CharacterSetECI* currentCharacterSetECI,
@@ -217,6 +218,7 @@ void DecodedBitStreamParser::decodeByteSegment(Ref<BitSource> bits_,
         throw FormatException();
     }
     byteSegments->values().push_back(bytes_);
+    return encoding;
 }
 
 void DecodedBitStreamParser::decodeNumericSegment(Ref<BitSource> bits, std::string &result, int count) {
@@ -357,8 +359,9 @@ DecodedBitStreamParser::decode(ArrayRef<char> bytes,
     string result;
     result.reserve(50);
     ArrayRef< ArrayRef<char> > byteSegments (0);
-  try {
     CharacterSetECI* currentCharacterSetECI = 0;
+    string charSet = "";
+    try {
         bool fc1InEffect = false;
         Mode* mode = 0;
         do {
@@ -410,7 +413,7 @@ DecodedBitStreamParser::decode(ArrayRef<char> bytes,
                         } else if (mode == &Mode::ALPHANUMERIC) {
                             decodeAlphanumericSegment(bits_, result, count, fc1InEffect);
                         } else if (mode == &Mode::BYTE) {
-              decodeByteSegment(bits_, result, count, currentCharacterSetECI, byteSegments, hints);
+                            charSet = decodeByteSegment(bits_, result, count, currentCharacterSetECI, byteSegments, hints);
                         } else if (mode == &Mode::KANJI) {
                             decodeKanjiSegment(bits_, result, count);
                         } else {
@@ -425,7 +428,6 @@ DecodedBitStreamParser::decode(ArrayRef<char> bytes,
         // from readBits() calls
         throw FormatException();
     }
-  
+    return Ref<DecoderResult>(new DecoderResult(bytes, Ref<String>(new String(result)), byteSegments, (string)ecLevel, charSet));
-  return Ref<DecoderResult>(new DecoderResult(bytes, Ref<String>(new String(result)), byteSegments, (string)ecLevel));
 }