From a08b1b656630c561327920b6034647aef370f6bc Mon Sep 17 00:00:00 2001
From: Adrian Kretz <me@akretz.com>
Date: Mon, 21 Apr 2025 16:40:33 +0200
Subject: [PATCH] Merge pull request #27244 from akretz:fix_issue_27183

Fix QR code encoder with autoversion #27244

The autodetected version is not honored in the `QRCodeEncoderImpl::encode*` methods. This fixes #27183

### Pull Request Readiness Checklist

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.
- [ ] The feature is well documented and sample code can be built with the project CMake
---
 modules/objdetect/src/qrcode_encoder.cpp      |  2 ++
 modules/objdetect/test/test_qrcode_encode.cpp | 35 +++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/modules/objdetect/src/qrcode_encoder.cpp b/modules/objdetect/src/qrcode_encoder.cpp
index d1c05d2525..14b51c254d 100644
--- a/modules/objdetect/src/qrcode_encoder.cpp
+++ b/modules/objdetect/src/qrcode_encoder.cpp
@@ -397,7 +397,9 @@ void QRCodeEncoderImpl::generateQR(const std::string &input)
         original = Mat(Size(version_size, version_size), CV_8UC1, Scalar(255));
         masked_data = original.clone();
         Mat qrcode = masked_data.clone();
+        std::swap(version_level, tmp_version_level);
         generatingProcess(input_info, qrcode);
+        std::swap(version_level, tmp_version_level);
         final_qrcodes.push_back(qrcode);
     }
 }
diff --git a/modules/objdetect/test/test_qrcode_encode.cpp b/modules/objdetect/test/test_qrcode_encode.cpp
index 87142e4690..f6cf1c069f 100644
--- a/modules/objdetect/test/test_qrcode_encode.cpp
+++ b/modules/objdetect/test/test_qrcode_encode.cpp
@@ -590,4 +590,39 @@ INSTANTIATE_TEST_CASE_P(/**/, Objdetect_QRCode_decoding, testing::ValuesIn(std::
     {"err_correct_2L.png", "Version 2 QR Code Test Image"},
 }));
 
+TEST(Objdetect_QRCode_Encode_Decode_Long_Text, regression_issue27183)
+{
+    const int len = 135;
+    Ptr<QRCodeEncoder> encoder = QRCodeEncoder::create();
+
+    std::string input;
+    input.resize(len);
+    cv::randu(Mat(1, len, CV_8U, &input[0]), 'a', 'z' + 1);
+    Mat qrcode;
+    encoder->encode(input, qrcode);
+
+    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);
+
+    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 j = 0; j < corners.size(); j++)
+    {
+        corners[j].x = corners[j].x * width_ratio;
+        corners[j].y = corners[j].y * height_ratio;
+    }
+
+    QRCodeDetector detector;
+    cv::String decoded_msg;
+    Mat straight_barcode;
+    EXPECT_NO_THROW(decoded_msg = detector.decode(resized_src, corners, straight_barcode));
+    ASSERT_FALSE(straight_barcode.empty());
+    EXPECT_EQ(input, decoded_msg);
+}
+
 }} // namespace