using putText() diagonally? Using OpenCV

Question

Is it possible using the putText() method to draw text on a picture diagonally?

If not, beside using addWeighted() to blend two pictures together (where one of them

Answer 1

Have a look at this example using the idea of my comment:

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/opencv.hpp>
#include <iostream>

using namespace std;
using namespace cv;

/**
 * Rotate an image (source: http://opencv-code.com/quick-tips/how-to-rotate-image-in-opencv/)
 */
void rotate(cv::Mat& src, double angle, cv::Mat& dst)
{
    int len = std::max(src.cols, src.rows);
    cv::Point2f pt(len/2., len/2.);
    cv::Mat r = cv::getRotationMatrix2D(pt, angle, 1.0);

    cv::warpAffine(src, dst, r, cv::Size(len, len));
}


int main() {

    Mat img = imread("lenna.png", CV_LOAD_IMAGE_COLOR);

    // Create and rotate the text
    Mat textImg = Mat::zeros(img.rows, img.cols, img.type());
    putText(textImg, "stackoverflow", Point(0, img.cols/2), FONT_HERSHEY_SIMPLEX, 2.0,Scalar(20,20,20),2);
    rotate(textImg, -45, textImg);

    // Sum the images (add the text to the original img)
    img= img+textImg;

    namedWindow("WaterMark", CV_WINDOW_AUTOSIZE);
    imshow("WaterMark", img);

    waitKey(0);
    return 0;
}

Result: