round robin image rotation what is the best way to do in opencv

Question

I want to do a round robin image rotation as shown below.

The x vertical line

Answer 1

Mat outImg(inputImg.size(),inputImg.type());
inputImg(Rect(0, 0, shiftX, height)).copyTo(outImg(Rect(width-shiftX, 0, shiftX, height)));
inputImg(Rect(shiftX, 0, width-shiftX, height)).copyTo(outImg(Rect(0, 0, width-shiftX, height)));