以下是将给定的Python代码转换为C++函数的示例：

#include <opencv2/opencv.hpp>
#include <vector>

cv::Mat fillHole(const cv::Mat& srcBw) {
    cv::Mat temp = srcBw.clone();
    // Floodfill from point (0, 0)
    cv::floodFill(temp, cv::Point(0, 0), cv::Scalar(255));
    // Invert floodfilled image
    temp = ~temp;
    cv::imshow("temp", temp);

    // Invert floodfilled image
    cv::Mat out = srcBw | temp;

    return out;
}

std::vector<cv::Rect> getRoi(const cv::Mat& im_out, const cv::Mat& img) {
    std::vector<cv::Rect> roi_list;
    
    cv::Mat labels, stats, centroids;
    int num_labels = cv::connectedComponentsWithStats(im_out, labels, stats, centroids);
    
    for (int t = 1; t < num_labels; ++t) {
        int x = stats.at<int>(t, cv::CC_STAT_LEFT);
        int y = stats.at<int>(t, cv::CC_STAT_TOP);
        int w = stats.at<int>(t, cv::CC_STAT_WIDTH);
        int h = stats.at<int>(t, cv::CC_STAT_HEIGHT);
        int area = stats.at<int>(t, cv::CC_STAT_AREA);

        if (area < 500)
            continue;

        float cx = centroids.at<double>(t, 0);
        float cy = centroids.at<double>(t, 1);

        // 标出中心位置
        circle(img, cv:Point(static_cast<int>(cx), static_cast<int>(cy)), 2, CV_RGB(0, 255, 0), 2);
        // 画出外接矩形
        rectangle(img, cv::Point(x, y), cv::Point(x + w, y + h), CV_RGB(0, 255, 0), 2);
        // 保存roi的坐标和长宽
        roi_list.push_back(cv::Rect(x, y, w, h));
    }

    return roi_list;
}

cv::Mat colorImgShow(const cv::Mat& im_out, int num_labels, const cv::Mat& labels) {
    std::vector<cv::Vec3b> colors(num_labels);
    
    for (int i = 0; i < num_labels; ++i) {
        colors[i] = cv::Vec3b(rand() % 256, rand() % 256, rand() % 256);
    }
    
    colors[0] = cv::Vec3b(0, 0, 0);

    cv::Mat image(im_out.size(), CV_8UC3);
    
    for (int row = 0; row < im_out.rows; ++row) {
        for (int col = 0; col < im_out.cols; ++col) {
            int label = labels.at<int>(row, col);
            image.at<cv::Vec3b>(row, col) = colors[label];
        }
    }

    return image;
}

void saveRoi(const cv::Mat& src,const std::vector<cv::Rect>& roi_list) {
    for (size_t i = 0; i < roi_list.size(); ++i) {
        const cv::Rect& rect = roi_list[i];
        cv::Mat roi = src(rect);
        
        std:string filename = "money_roi/roi_" + std::to_string(i) + ".jpg";
        
        cv::imwrite(filename, roi);
        std::cout << "No." << std::setfill('0') << std::setw(2) << i << " Finished!" << std::endl;
    }
}

void processMoneyImage(const std::string& filename) {
    // Load image
    cv::Mat img = cv::imread(filename);
    
    // Preprocessing
    cv::Mat im_in;
    cvtColor(img, im_in, CV_BGR2GRAY);
    cv::threshold(im_in, im_in, 0, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);

    // Invert the foreground and background
    im_in = ~im_in;

    // Call fillHole function
    cv::Mat im_out = fillHole(im_in);

    // Get ROIs using connected components analysis
    std::vector<cv::Rect> roi_list = getRoi(im_out, img);

    // Visualize connected components
    cv:Mat color_image = colorImgShow(im_out, roi_list.size(), labels);

   // Save ROIs
   saveRoi(img, roi_list);

   // Display images.
   cv:imshow("Thresholded Image", im_in);
   cv:imshow("Colorful Image", color_image);
   cv:imshow("Foreground", img);
   
   // Write output images to files if needed
   
   ...
   
   cv:waitKey(0);
}

int main() {
    std:string filename = "money.png";
  
	  processMoneyImage(filename);

	  return 0;
}

请注意，上述代码可能需要根据您的项目设置进行进一步调整和优化。还需要包含必要的OpenCV库头文件，并确保在编译时链接相应的OpenCV库。


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