feat: add cpp demo for wechatqrcode (#279)

* feat: add cpp demo for wechatqrcode

* refactor: change to class based

* fix: make cpp11 compatible

* fix: add opencv_contrib in readme

models/qrcode_wechatqrcode/CMakeLists.txt

@@ -0,0 +1,11 @@
+cmake_minimum_required(VERSION 3.24.0)
+project(opencv_zoo_qrcode_wechatqrcode)
+
+set(OPENCV_VERSION "4.10.0")
+set(OPENCV_INSTALLATION_PATH "" CACHE PATH "Where to look for OpenCV installation")
+
+# Find OpenCV
+find_package(OpenCV ${OPENCV_VERSION} REQUIRED HINTS ${OPENCV_INSTALLATION_PATH})
+
+add_executable(demo demo.cpp)
+target_link_libraries(demo ${OpenCV_LIBS})

models/qrcode_wechatqrcode/README.md

@@ -9,6 +9,8 @@ Notes:
 
 ## Demo
 
+### Python
+
 Run the following command to try the demo:
 
 ```shell
@@ -21,6 +23,23 @@ python demo.py --input /path/to/image -v
 python demo.py --help
 ```
 
+### C++
+
+Install latest OpenCV (with opencv_contrib) and CMake >= 3.24.0 to get started with:
+
+```shell
+# A typical and default installation path of OpenCV is /usr/local
+cmake -B build -D OPENCV_INSTALLATION_PATH=/path/to/opencv/installation .
+cmake --build build
+
+# detect on camera input
+./build/demo
+# detect on an image
+./build/demo -i=/path/to/image -v
+# get help messages
+./build/demo -h
+```
+
 ### Example outputs
 
 ![webcam demo](./example_outputs/wechat_qrcode_demo.gif)

models/qrcode_wechatqrcode/demo.cpp

@@ -0,0 +1,192 @@
+#include <iostream>
+#include <opencv2/opencv.hpp>
+#include <opencv2/wechat_qrcode.hpp>
+#include <string>
+#include <vector>
+
+class WeChatQRCode {
+   public:
+    WeChatQRCode(const std::string& detect_prototxt,
+                 const std::string& detect_model,
+                 const std::string& sr_prototxt, const std::string& sr_model,
+                 int backend_target_index)
+        : backend_target_index_(backend_target_index) {
+        
+        const std::vector<std::pair<int, int>> backend_target_pairs = {
+            {cv::dnn::DNN_BACKEND_OPENCV, cv::dnn::DNN_TARGET_CPU},
+            {cv::dnn::DNN_BACKEND_CUDA, cv::dnn::DNN_TARGET_CUDA},
+            {cv::dnn::DNN_BACKEND_CUDA, cv::dnn::DNN_TARGET_CUDA_FP16},
+            {cv::dnn::DNN_BACKEND_TIMVX, cv::dnn::DNN_TARGET_NPU},
+            {cv::dnn::DNN_BACKEND_CANN, cv::dnn::DNN_TARGET_NPU}};
+
+        if (backend_target_index_ < 0 ||
+            backend_target_index_ >= backend_target_pairs.size()) {
+            throw std::invalid_argument("Invalid backend-target index");
+        }
+
+        // initialize detector
+        detector_ = cv::makePtr<cv::wechat_qrcode::WeChatQRCode>(
+            detect_prototxt, detect_model, sr_prototxt, sr_model);
+    }
+
+    std::pair<std::vector<std::string>, std::vector<cv::Mat>> detect(
+        const cv::Mat& image) {
+        std::vector<std::string> results;
+        std::vector<cv::Mat> points;
+        results = detector_->detectAndDecode(image, points);
+        return {results, points};
+    }
+
+    cv::Mat visualize(const cv::Mat& image,
+                      const std::vector<std::string>& results,
+                      const std::vector<cv::Mat>& points,
+                      cv::Scalar points_color = cv::Scalar(0, 255, 0),
+                      cv::Scalar text_color = cv::Scalar(0, 255, 0),
+                      double fps = -1) const {
+        cv::Mat output = image.clone();
+
+        if (fps >= 0) {
+            cv::putText(output, "FPS: " + std::to_string(fps), cv::Point(0, 15),
+                        cv::FONT_HERSHEY_SIMPLEX, 0.5, text_color);
+        }
+
+        double fontScale = 0.5;
+        int fontSize = 1;
+
+        for (size_t i = 0; i < results.size(); ++i) {
+            const auto& p = points[i];
+
+            for (int r = 0; r < p.rows; ++r) {
+                cv::Point point(p.at<float>(r, 0), p.at<float>(r, 1));
+                cv::circle(output, point, 10, points_color, -1);
+            }
+
+            int qrcode_center_x = (p.at<float>(0, 0) + p.at<float>(2, 0)) / 2;
+            int qrcode_center_y = (p.at<float>(0, 1) + p.at<float>(2, 1)) / 2;
+
+            int baseline = 0;
+            cv::Size text_size =
+                cv::getTextSize(results[i], cv::FONT_HERSHEY_DUPLEX, fontScale,
+                                fontSize, &baseline);
+
+            cv::Point text_pos(qrcode_center_x - text_size.width / 2,
+                               qrcode_center_y + text_size.height / 2);
+
+            cv::putText(output, results[i], text_pos, cv::FONT_HERSHEY_DUPLEX,
+                        fontScale, text_color, fontSize);
+        }
+
+        return output;
+    }
+
+   private:
+    int backend_target_index_;
+    cv::Ptr<cv::wechat_qrcode::WeChatQRCode> detector_;
+};
+
+int main(int argc, char** argv) {
+    
+    cv::CommandLineParser parser(
+        argc, argv,
+        "{help h                |                             | Show this help message.}"
+        "{input i               |                             | Set path to the input image. Omit for using default camera.}"
+        "{detect_prototxt_path  | detect_2021nov.prototxt     | Set path to detect.prototxt.}"
+        "{detect_model_path     | detect_2021nov.caffemodel   | Set path to detect.caffemodel.}"
+        "{sr_prototxt_path      | sr_2021nov.prototxt         | Set path to sr.prototxt.}"
+        "{sr_model_path         | sr_2021nov.caffemodel       | Set path to sr.caffemodel.}"
+        "{backend_target bt     | 0                           | Choose one of the backend-target pairs to run this demo.}"
+        "{save s                | false                       | Specify to save file with results.}"
+        "{vis v                 | false                       | Specify to open a new window to show results.}");
+
+    if (parser.has("help")) {
+        parser.printMessage();
+        return 0;
+    }
+
+    // get paths
+    std::string detect_prototxt = parser.get<std::string>("detect_prototxt_path");
+    std::string detect_model = parser.get<std::string>("detect_model_path");
+    std::string sr_prototxt = parser.get<std::string>("sr_prototxt_path");
+    std::string sr_model = parser.get<std::string>("sr_model_path");
+    int backend_target_index = parser.get<int>("backend_target");
+
+    // input check
+    std::string input_path = parser.get<std::string>("input");
+    bool save_result = parser.get<bool>("save");
+    bool visualize_result = parser.get<bool>("vis");
+
+    try {
+        WeChatQRCode qrDetector(detect_prototxt, detect_model, sr_prototxt,
+                                sr_model, backend_target_index);
+
+        if (!input_path.empty()) {
+            // process image
+            cv::Mat image = cv::imread(input_path);
+            if (image.empty()) {
+                std::cerr << "Could not read the image" << std::endl;
+                return -1;
+            }
+
+            std::pair<std::vector<std::string>, std::vector<cv::Mat>> detectionResult = qrDetector.detect(image);
+            auto& results = detectionResult.first;
+            auto& points = detectionResult.second;
+
+            for (const auto& result : results) {
+                std::cout << result << std::endl;
+            }
+
+            cv::Mat result_image = qrDetector.visualize(image, results, points);
+
+            if (save_result) {
+                cv::imwrite("result.jpg", result_image);
+                std::cout << "Results saved to result.jpg" << std::endl;
+            }
+
+            if (visualize_result) {
+                cv::imshow(input_path, result_image);
+                cv::waitKey(0);
+            }
+        } else {
+            // process camera
+            cv::VideoCapture cap(0);
+            if (!cap.isOpened()) {
+                std::cerr << "Error opening camera" << std::endl;
+                return -1;
+            }
+
+            cv::Mat frame;
+            cv::TickMeter tm;
+
+            while (true) {
+                cap >> frame;
+                if (frame.empty()) {
+                    std::cout << "No frames grabbed" << std::endl;
+                    break;
+                }
+
+                std::pair<std::vector<std::string>, std::vector<cv::Mat>> detectionResult = qrDetector.detect(frame);
+                auto& results = detectionResult.first;
+                auto& points = detectionResult.second;
+
+                tm.start();
+                double fps = tm.getFPS();
+                tm.stop();
+
+                cv::Mat result_frame = qrDetector.visualize(
+                    frame, results, points, cv::Scalar(0, 255, 0),
+                    cv::Scalar(0, 255, 0), fps);
+                cv::imshow("WeChatQRCode Demo", result_frame);
+
+                tm.reset();
+
+                if (cv::waitKey(1) >= 0) break;
+            }
+        }
+
+    } catch (const std::exception& ex) {
+        std::cerr << "Error: " << ex.what() << std::endl;
+        return -1;
+    }
+
+    return 0;
+}