Draw rectangle in OpenCV
c++, opencv
Solution
The `cv::rectangle` function that accepts two `cv::Point`'s takes both the top left and the bottom right corner of a rectangle (pt1 and pt2 respectively in the documentation). If that rectangle is used with the `cv::rectangle` function that accepts a `cv::Rect`, then you will get the same result.
// just some valid rectangle arguments
int x = 0;
int y = 0;
int width = 10;
int height = 20;
// our rectangle...
cv::Rect rect(x, y, width, height);
// and its top left corner...
cv::Point pt1(x, y);
// and its bottom right corner.
cv::Point pt2(x + width, y + height);
// These two calls...
cv::rectangle(img, pt1, pt2, cv::Scalar(0, 255, 0));
// essentially do the same thing
cv::rectangle(img, rect, cv::Scalar(0, 255, 0))
Problem
I want to draw a rectangle in OpenCV by using this function: ``` rectangle(Mat& img, Rect rec, const Scalar& color, int thickness=1, int lineType=8, int shift=0 ) ``` But when I use it I am facing some errors. My question is: can anyone explain the function with an example? I found some examples but with another function: ``` rectangle(Mat& img, Point pt1, Point pt2, const Scalar& color, int thickness=1, int lineType=8, int shift=0) ``` This example on the second function: ``` rectangle(image, pt2, pt1, Scalar(0, 255, 0), 2, 8, 0); ``` This function I understand, but with the first function I'm facing a problem in parameter `Rect`. I don't know how I can deadlier it?