Return bytes array if UTF-8 decoding failed

modules/objdetect/include/opencv2/objdetect.hpp

@@ -808,6 +808,13 @@ public:
      */
     CV_WRAP std::string detectAndDecodeCurved(InputArray img, OutputArray points=noArray(),
                                               OutputArray straight_qrcode = noArray());
+
+    /** @brief Returns a kid of encoding for the decoded info from the latest QR codes
+    @param codeIdx an index of the previously decoded QR code.
+                   When @ref decode or @ref detectAndDecode is used, valid value is zero.
+                   For @ref decodeMulti or @ref detectAndDecodeMulti use indices corresponding to the output order.
+    */
+    CV_WRAP QRCodeEncoder::ECIEncodings getEncoding(size_t codeIdx = 0);
 };
 
 class CV_EXPORTS_W_SIMPLE QRCodeDetectorAruco : public GraphicalCodeDetector {

modules/objdetect/misc/python/pyopencv_objdetect.hpp

@@ -7,4 +7,31 @@ typedef QRCodeEncoder::Params QRCodeEncoder_Params;
 typedef HOGDescriptor::HistogramNormType HOGDescriptor_HistogramNormType;
 typedef HOGDescriptor::DescriptorStorageFormat HOGDescriptor_DescriptorStorageFormat;
 
+static PyObject* pyopencv_cv_GraphicalCodeDetector_detectAndDecode(PyObject* self, PyObject* py_args, PyObject* kw);
+
+static PyObject* pyopencv_cv_GraphicalCodeDetector_detectAndDecodeECI(PyObject* self, PyObject* py_args, PyObject* kw) {
+    // Run original method
+    PyObject* retval = pyopencv_cv_GraphicalCodeDetector_detectAndDecode(self, py_args, kw);
+
+    if (PyErr_Occurred()) {
+        PyObject *type = nullptr, *value = nullptr, *traceback = nullptr;
+        PyErr_Fetch(&type, &value, &traceback);
+
+        PyObject* object = PyUnicodeDecodeError_GetObject(value);
+        if (object && PyBytes_Check(object)) {
+            // TODO: use getEncoding. For now return just bytes array.
+            PyTuple_SetItem(retval, 0, object);
+            // PyObject* decoded = PyUnicode_FromEncodedObject(object, "ISO-8859-1", NULL);
+            // PyTuple_SetItem(retval, 0, decoded);
+        } else {
+            PyErr_Restore(type, value, traceback);
+        }
+    }
+    return retval;
+}
+
+// TODO: copy docstring somehow
+#define PYOPENCV_EXTRA_METHODS_GraphicalCodeDetector \
+    {"detectAndDecode", CV_PY_FN_WITH_KW_(pyopencv_cv_GraphicalCodeDetector_detectAndDecodeECI, 0), "detectAndDecode(img[, points[, straight_code]]) -> retval, points, straight_code\n.   @brief Both detects and decodes graphical code\n.   \n.        @param img grayscale or color (BGR) image containing graphical code.\n.        @param points optional output array of vertices of the found graphical code quadrangle, will be empty if not found.\n.        @param straight_code The optional output image containing binarized code"},
+
 #endif

modules/objdetect/src/qrcode.cpp

@@ -963,6 +963,7 @@ public:
     double epsX, epsY;
     mutable vector<vector<Point2f>> alignmentMarkers;
     mutable vector<Point2f> updateQrCorners;
+    mutable vector<QRCodeEncoder::ECIEncodings> encodings;
     bool useAlignmentMarkers = true;
 
     bool detect(InputArray in, OutputArray points) const override;
@@ -978,6 +979,8 @@ public:
     String decodeCurved(InputArray in, InputArray points, OutputArray straight_qrcode);
 
     std::string detectAndDecodeCurved(InputArray in, OutputArray points, OutputArray straight_qrcode);
+
+    QRCodeEncoder::ECIEncodings getEncoding(size_t codeIdx);
 };
 
 QRCodeDetector::QRCodeDetector() {
@@ -994,6 +997,12 @@ QRCodeDetector& QRCodeDetector::setEpsY(double epsY) {
     return *this;
 }
 
+QRCodeEncoder::ECIEncodings QRCodeDetector::getEncoding(size_t codeIdx) {
+    auto& encodings = std::dynamic_pointer_cast<ImplContour>(p)->encodings;
+    CV_Assert(codeIdx < encodings.size());
+    return encodings[codeIdx];
+}
+
 bool ImplContour::detect(InputArray in, OutputArray points) const
 {
     Mat inarr;
@@ -1035,6 +1044,8 @@ public:
         uint8_t total_num = 1;
     } structure_info;
 
+    QRCodeEncoder::ECIEncodings eci;
+
 protected:
     double getNumModules();
     Mat getHomography() {
@@ -2802,7 +2813,6 @@ static std::string encodeUTF8_bytesarray(const uint8_t* str, const size_t size)
 
 bool QRDecode::decodingProcess()
 {
-    QRCodeEncoder::ECIEncodings eci;
     const uint8_t* payload;
     size_t payload_len;
 #ifdef HAVE_QUIRC
@@ -2966,6 +2976,7 @@ std::string ImplContour::decode(InputArray in, InputArray points, OutputArray st
         alignmentMarkers = {qrdec.alignment_coords};
         updateQrCorners = qrdec.getOriginalPoints();
     }
+    encodings.resize(1, qrdec.encoding);
     return ok ? decoded_info : std::string();
 }
 
@@ -2999,6 +3010,7 @@ String ImplContour::decodeCurved(InputArray in, InputArray points, OutputArray s
     {
         qrdec.getStraightBarcode().convertTo(straight_qrcode, CV_8UC1);
     }
+    encodings.resize(1, qrdec.encoding);
 
     return ok ? decoded_info : std::string();
 }

modules/python/src2/cv2_convert.cpp

@@ -739,14 +739,16 @@ bool pyopencv_to(PyObject* obj, String &value, const ArgInfo& info)
 template<>
 PyObject* pyopencv_from(const String& value)
 {
-    return PyString_FromString(value.empty() ? "" : value.c_str());
+    PyObject* ret = PyString_FromString(value.empty() ? "" : value.c_str());
+    return ret ? ret : Py_None;
 }
 
 #if CV_VERSION_MAJOR == 3
 template<>
 PyObject* pyopencv_from(const std::string& value)
 {
-    return PyString_FromString(value.empty() ? "" : value.c_str());
+    PyObject* ret = PyString_FromString(value.empty() ? "" : value.c_str());
+    return ret ? ret : Py_None;
 }
 #endif
 

modules/python/src2/gen2.py

@@ -133,6 +133,9 @@ static PyGetSetDef pyopencv_${name}_getseters[] =
 
 static PyMethodDef pyopencv_${name}_methods[] =
 {
+#ifdef PYOPENCV_EXTRA_METHODS_${name}
+    PYOPENCV_EXTRA_METHODS_${name}
+#endif
 ${methods_inits}
     {NULL,          NULL}
 };