前言

此文為 C ++ 在 OpenCV 的寫上文字的用法

sample code

#include <opencv2/opencv.hpp>

// create 640*480 Mat
cv::Mat image = cv::Mat::zeros(cv::Size(640, 480), CV_8UC3);
// set to blue color
image.setTo(cv::Scalar(100, 0, 0));

// set string and variables
std::string text = "Hello World!";
int font_face = cv::FONT_HERSHEY_COMPLEX;
double font_scale = 2;
int thickness = 2;
int baseline;
// get text size
cv::Size text_size = cv::getTextSize(text, font_face, font_scale, thickness, &baseline);

// decide text position
cv::Point origin;
origin.x = image.cols / 2 - text_size.width / 2;
origin.y = image.rows / 2 + text_size.height / 2;
cv::putText(image, text, origin, font_face, font_scale, cv::Scalar(0, 255, 255), thickness, 8, 0);

// show result
cv::imshow("image", image);
cv::waitKey(0);
return 0;

C++ compile

g++ test.cpp -o test.out -std=c++11 `pkg-config --cflags --libs opencv` 
./test.out

• test.cpp：為要編譯的程式碼
• test.out：為編譯結果的 binary (執行也是用此執行檔執行)

執行結果

Reference

https://blog.csdn.net/guduruyu/article/details/68491211