opencv · asmorkalov · Feb 1, 2024 · Nov 27, 2023 · Jan 26, 2024 · Jan 26, 2024
diff --git a/modules/objdetect/include/opencv2/objdetect/graphical_code_detector.hpp b/modules/objdetect/include/opencv2/objdetect/graphical_code_detector.hpp
@@ -66,6 +66,10 @@ class CV_EXPORTS_W_SIMPLE GraphicalCodeDetector {
     @param decoded_info UTF8-encoded output vector of string or empty vector of string if the codes cannot be decoded.
     @param points optional output vector of vertices of the found graphical code quadrangles. Will be empty if not found.
     @param straight_code The optional vector of images containing binarized codes
+
+    - If there are QR codes encoded with a Structured Append mode on the image and all of them detected and decoded correctly,
+    method writes a full message to position corresponds to 0-th code in a sequence. The rest of QR codes from the same sequence
+    have empty string.
     */
     CV_WRAP bool detectAndDecodeMulti(InputArray img, CV_OUT std::vector<std::string>& decoded_info, OutputArray points = noArray(),
                                       OutputArrayOfArrays straight_code = noArray()) const;
@@ -78,4 +82,4 @@ class CV_EXPORTS_W_SIMPLE GraphicalCodeDetector {
 
 }
 
-#endif
+#endif
diff --git a/modules/objdetect/src/graphical_code_detector_impl.hpp b/modules/objdetect/src/graphical_code_detector_impl.hpp
@@ -30,6 +30,9 @@ class QRCodeDecoder {
 
     QRCodeEncoder::EncodeMode mode;
     QRCodeEncoder::ECIEncodings eci;
+    uint8_t parity = 0;
+    uint8_t sequence_num = 0;
+    uint8_t total_num = 1;
 };
 
 }

diff --git a/modules/objdetect/src/qrcode.cpp b/modules/objdetect/src/qrcode.cpp
@@ -1016,6 +1016,17 @@ class QRDecode
     float coeff_expansion = 1.f;
     vector<Point2f> getOriginalPoints() {return original_points;}
     bool useAlignmentMarkers;
+
+    // Structured Append mode generates a sequence of QR codes.
+    // Final message is restored according to the index of the code in sequence.
+    // Different QR codes are grouped by a parity value.
+    bool isStructured() { return mode == QRCodeEncoder::EncodeMode::MODE_STRUCTURED_APPEND; }
+    struct {
+        uint8_t parity = 0;
+        uint8_t sequence_num = 0;
+        uint8_t total_num = 1;
+    } structure_info;
+
 protected:
     double getNumModules();
     Mat getHomography() {
@@ -1068,6 +1079,8 @@ class QRDecode
     std::string result_info;
     uint8_t version, version_size;
     float test_perspective_size;
+    QRCodeEncoder::EncodeMode mode;
+
     struct sortPairAsc
     {
         bool operator()(const std::pair<size_t, double> &a,
@@ -2781,7 +2794,6 @@ static std::string encodeUTF8_bytesarray(const uint8_t* str, const size_t size)
 
 bool QRDecode::decodingProcess()
 {
-    QRCodeEncoder::EncodeMode mode;
     QRCodeEncoder::ECIEncodings eci;
     const uint8_t* payload;
     size_t payload_len;
@@ -2826,6 +2838,9 @@ bool QRDecode::decodingProcess()
     eci = decoder->eci;
     payload = reinterpret_cast<const uint8_t*>(result_info.c_str());
     payload_len = result_info.size();
+    structure_info.parity = decoder->parity;
+    structure_info.sequence_num = decoder->sequence_num;
+    structure_info.total_num = decoder->total_num;
 #endif
 
     // Check output string format
@@ -2879,6 +2894,9 @@ bool QRDecode::decodingProcess()
             CV_LOG_WARNING(NULL, "QR: ECI is not supported properly");
             result_info.assign((const char*)payload, payload_len);
             return true;
+        case QRCodeEncoder::EncodeMode::MODE_STRUCTURED_APPEND:
+            result_info.assign((const char*)payload, payload_len);
+            return true;
         default:
             CV_LOG_WARNING(NULL, "QR: unsupported QR data type");
             return false;
@@ -4076,11 +4094,44 @@ bool ImplContour::decodeMulti(
         }
         straight_qrcode.assign(tmp_straight_qrcodes);
     }
+
     decoded_info.clear();
     for (size_t i = 0; i < info.size(); i++)
     {
-       decoded_info.push_back(info[i]);
+        auto& decoder = qrdec[i];
+        if (!decoder.isStructured())
+        {
+            decoded_info.push_back(info[i]);
+            continue;
+        }
+
+        // Store final message corresponding to 0-th code in a sequence.
+        if (decoder.structure_info.sequence_num != 0)
+        {
+            decoded_info.push_back("");
+            continue;
+        }
+
+        cv::String decoded = info[i];
+        for (size_t idx = 1; idx < decoder.structure_info.total_num; ++idx)
+        {
+            auto it = std::find_if(qrdec.begin(), qrdec.end(), [&](QRDecode& dec) {
+                return dec.structure_info.parity == decoder.structure_info.parity &&
+                       dec.structure_info.sequence_num == idx;
+            });
+            if (it != qrdec.end())
+            {
+                decoded += info[it - qrdec.begin()];
+            }
+            else
+            {
+                decoded = "";
+                break;
+            }
+        }
+        decoded_info.push_back(decoded);
     }
+
     alignmentMarkers.resize(src_points.size());
     updateQrCorners.resize(src_points.size()*4ull);
     for (size_t i = 0ull; i < src_points.size(); i++) {

diff --git a/modules/objdetect/src/qrcode_encoder.cpp b/modules/objdetect/src/qrcode_encoder.cpp
@@ -342,7 +342,13 @@ int QRCodeEncoderImpl::versionAuto(const std::string& input_str)
         return -1;
     }
 
-    const auto tmp_version = findVersionCapacity((int)payload_tmp.size(), ecc_level, possible_version);
+    int nbits = static_cast<int>(payload_tmp.size());
+
+    // Extra info for structure's position, total and parity + mode of final message
+    if (mode_type == MODE_STRUCTURED_APPEND)
+        nbits += 4 + 4 + 8 + 4;
+
+    const auto tmp_version = findVersionCapacity(nbits, ecc_level, possible_version);
 
     return tmp_version;
 }
@@ -365,7 +371,7 @@ void QRCodeEncoderImpl::generateQR(const std::string &input)
     auto string_itr = input.begin();
     for (int i = struct_num; i > 0; --i)
     {
-        sequence_num = (uint8_t) i;
+        sequence_num = (uint8_t) (struct_num - i);
         size_t segment_begin = string_itr - input.begin();
         size_t segment_end = (input.end() - string_itr) / i;
 
@@ -1356,6 +1362,7 @@ class QRCodeDecoderImpl : public QRCodeDecoder {
     void decodeByte(String& result);
     void decodeECI(String& result);
     void decodeKanji(String& result);
+    void decodeStructuredAppend(String& result);
 };
 
 QRCodeDecoder::~QRCodeDecoder()
@@ -1746,6 +1753,11 @@ void QRCodeDecoderImpl::decodeSymbols(String& result) {
             decodeECI(result);
         else if (currMode == QRCodeEncoder::EncodeMode::MODE_KANJI)
             decodeKanji(result);
+        else if (currMode == QRCodeEncoder::EncodeMode::MODE_STRUCTURED_APPEND) {
+            sequence_num = static_cast<uint8_t>(bitstream.next(4));
+            total_num = static_cast<uint8_t>(1 + bitstream.next(4));
+            parity = static_cast<uint8_t>(bitstream.next(8));
+        }
         else
             CV_Error(Error::StsNotImplemented, format("mode %d", currMode));
     }

diff --git a/modules/objdetect/test/test_qrcode_encode.cpp b/modules/objdetect/test/test_qrcode_encode.cpp
@@ -349,7 +349,7 @@ TEST(Objdetect_QRCode_Encode_Kanji, regression)
     }
 }
 
-TEST(Objdetect_QRCode_Encode_Decode_Structured_Append, DISABLED_regression)
+TEST(Objdetect_QRCode_Encode_Decode_Structured_Append, regression)
 {
     // disabled since QR decoder probably doesn't support structured append mode qr codes
     const std::string root = "qrcode/decode_encode";
@@ -385,35 +385,43 @@ TEST(Objdetect_QRCode_Encode_Decode_Structured_Append, DISABLED_regression)
             vector<Mat> qrcodes;
             encoder->encodeStructuredAppend(input_info, qrcodes);
             EXPECT_TRUE(!qrcodes.empty()) << "Can't generate this QR images";
+            CV_CheckEQ(qrcodes.size(), (size_t)j, "Number of QR codes");
 
-            std::string output_info = "";
+            std::vector<Point2f> corners(4 * qrcodes.size());
             for (size_t k = 0; k < qrcodes.size(); k++)
             {
                 Mat qrcode = qrcodes[k];
+                corners[4 * k] = Point2f(border_width, border_width);
+                corners[4 * k + 1] = Point2f(qrcode.cols * 1.0f - border_width, border_width);
+                corners[4 * k + 2] = Point2f(qrcode.cols * 1.0f - border_width, qrcode.rows * 1.0f - border_width);
+                corners[4 * k + 3] = Point2f(border_width, qrcode.rows * 1.0f - border_width);
 
-                std::vector<Point2f> corners(4);
-                corners[0] = Point2f(border_width, border_width);
-                corners[1] = Point2f(qrcode.cols * 1.0f - border_width, border_width);
-                corners[2] = Point2f(qrcode.cols * 1.0f - border_width, qrcode.rows * 1.0f - border_width);
-                corners[3] = Point2f(border_width, qrcode.rows * 1.0f - border_width);
+                float width_ratio = fixed_size.width * 1.0f / qrcode.cols;
+                float height_ratio = fixed_size.height * 1.0f / qrcode.rows;
+                resize(qrcode, qrcodes[k], fixed_size, 0, 0, INTER_AREA);
 
-                Mat resized_src;
-                resize(qrcode, resized_src, fixed_size, 0, 0, INTER_AREA);
-                float width_ratio =  resized_src.cols * 1.0f / qrcode.cols;
-                float height_ratio = resized_src.rows * 1.0f / qrcode.rows;
-                for(size_t m = 0; m < corners.size(); m++)
+                for (size_t ki = 0; ki < 4; ki++)
                 {
-                    corners[m].x = corners[m].x * width_ratio;
-                    corners[m].y = corners[m].y * height_ratio;
+                    corners[4 * k + ki].x = corners[4 * k + ki].x * width_ratio + fixed_size.width * k;
+                    corners[4 * k + ki].y = corners[4 * k + ki].y * height_ratio;
                 }
+            }
 
-                Mat straight_barcode;
-                std::string decoded_info = QRCodeDetector().decode(resized_src, corners, straight_barcode);
-                EXPECT_FALSE(decoded_info.empty())
-                    << "The generated QRcode cannot be decoded." << " Mode: " << modes[i]
-                    << " structures number: " << k << "/" << j;
-                output_info += decoded_info;
+            Mat resized_src;
+            hconcat(qrcodes, resized_src);
+
+            std::vector<cv::String> decoded_info;
+            cv::String output_info;
+            EXPECT_TRUE(QRCodeDetector().decodeMulti(resized_src, corners, decoded_info));
+            for (size_t k = 0; k < decoded_info.size(); ++k)
+            {
+                if (!decoded_info[k].empty())
+                    output_info = decoded_info[k];
             }
+            EXPECT_FALSE(output_info.empty())
+                << "The generated QRcode cannot be decoded." << " Mode: " << modes[i]
+                << " structures number: " << j;
+
             EXPECT_EQ(input_info, output_info) << "The generated QRcode is not same as test data." << " Mode: " << mode <<
                                                   " structures number: " << j;
         }