OpenCV Draw rectangle from center x,y

Question

I want to draw a rectangle using only a point to the center. So pretty much a rectangle around my center point. What is the easiest way of doing this?Thanks.

Solution

Considering that center=(x,y), then:

cv::rectangle( image, 
               cvPoint(x-w/2,y-h/2),
               cvPoint(x+w/2,y+h/2),
               CV_RGB(r,g,b), 1, 8
             );

CvRect stores the top-left point as reference. So:

CvRect myrect=cvRect(x-w/2,y-h/2,w,h);

Comments

[Carpetfizz]

Why y+h/2/2 on the 3rd line?

[LovaBill]

maybe a typo? dont really remember. try it and fix it! :)

[Carpetfizz]

Fixed! Bottom point should be center + height / 2 not center + height / 4