Merge pull request #24426 from dkurt:qrcode_eci_encoding

Consider QRCode ECI encoding #24426

### Pull Request Readiness Checklist

related: https://github.com/opencv/opencv/pull/24350#pullrequestreview-1661658421

1. Add `getEncoding` method to obtain ECI number
2. Add `detectAndDecodeBytes`, `decodeBytes`, `decodeBytesMulti`, `detectAndDecodeBytesMulti` methods in Python (return `bytes`) and Java (return `byte[]`)
3. Allow Python bytes to std::string conversion in general and add `encode(byte[] encoded_info, Mat qrcode)` in Java


    Python example with Kanji encoding:
    ```python
    img = cv.imread("test.png")
    detect = cv.QRCodeDetector()
    data, points, straight_qrcode = detect.detectAndDecodeBytes(img)
    print(data)
    print(detect.getEncoding(), cv.QRCodeEncoder_ECI_SHIFT_JIS)
    print(data.decode("shift-jis"))
    ```
    ```
    b'\x82\xb1\x82\xf1\x82\xc9\x82\xbf\x82\xcd\x90\xa2\x8aE'
    20 20
    こんにちは世界
    ```

    source: https://github.com/opencv/opencv/blob/ba4d6c859d21536f84e0328c16f4cc3e96bf3065/modules/objdetect/test/test_qrcode_encode.cpp#L332

    ![test](https://github.com/opencv/opencv/assets/25801568/0b5eefa8-918a-4c42-9acb-830f23c0ea9f)


See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

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(int codeIdx);
 };
 
 QRCodeDetector::QRCodeDetector() {
@@ -994,6 +997,13 @@ QRCodeDetector& QRCodeDetector::setEpsY(double epsY) {
     return *this;
 }
 
+QRCodeEncoder::ECIEncodings QRCodeDetector::getEncoding(int codeIdx) {
+    auto& encodings = std::dynamic_pointer_cast<ImplContour>(p)->encodings;
+    CV_Assert(codeIdx >= 0);
+    CV_Assert(codeIdx < static_cast<int>(encodings.size()));
+    return encodings[codeIdx];
+}
+
 bool ImplContour::detect(InputArray in, OutputArray points) const
 {
     Mat inarr;
@@ -1035,6 +1045,8 @@ public:
         uint8_t total_num = 1;
     } structure_info;
 
+    QRCodeEncoder::ECIEncodings eci;
+
 protected:
     double getNumModules();
     Mat getHomography() {
@@ -2802,7 +2814,6 @@ 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
@@ -2895,7 +2906,7 @@ bool QRDecode::decodingProcess()
             return true;
         case QRCodeEncoder::EncodeMode::MODE_KANJI:
             // FIXIT BUG: we must return UTF-8 compatible string
-            CV_LOG_WARNING(NULL, "QR: Kanji is not supported properly");
+            eci = QRCodeEncoder::ECIEncodings::ECI_SHIFT_JIS;
             result_info.assign((const char*)payload, payload_len);
             return true;
         case QRCodeEncoder::EncodeMode::MODE_ECI:
@@ -2966,6 +2977,7 @@ std::string ImplContour::decode(InputArray in, InputArray points, OutputArray st
         alignmentMarkers = {qrdec.alignment_coords};
         updateQrCorners = qrdec.getOriginalPoints();
     }
+    encodings.resize(1, qrdec.eci);
     return ok ? decoded_info : std::string();
 }
 
@@ -2999,6 +3011,7 @@ String ImplContour::decodeCurved(InputArray in, InputArray points, OutputArray s
     {
         qrdec.getStraightBarcode().convertTo(straight_qrcode, CV_8UC1);
     }
+    encodings.resize(1, qrdec.eci);
 
     return ok ? decoded_info : std::string();
 }
@@ -4111,20 +4124,22 @@ bool ImplContour::decodeMulti(
         straight_qrcode.assign(tmp_straight_qrcodes);
     }
 
-    decoded_info.clear();
+    decoded_info.resize(info.size());
+    encodings.resize(info.size());
     for (size_t i = 0; i < info.size(); i++)
     {
         auto& decoder = qrdec[i];
+        encodings[i] = decoder.eci;
         if (!decoder.isStructured())
         {
-            decoded_info.push_back(info[i]);
+            decoded_info[i] = 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("");
+            decoded_info[i] = "";
             continue;
         }
 
@@ -4145,7 +4160,7 @@ bool ImplContour::decodeMulti(
                 break;
             }
         }
-        decoded_info.push_back(decoded);
+        decoded_info[i] = decoded;
     }
 
     alignmentMarkers.resize(src_points.size());