aruco::CharucoBoard::draw() crashes with specific image size

System information (version)

OpenCV => 3.2.0-dev
Operating System / Platform => Linux Ubuntu 16.04 - 64 bit
Compiler => GCC 5.4.0

Detailed description

When calling cv::aruco::CharucoBoard::draw() using specific board and image sizes, code crashes with OpenCV Error: Assertion failed (!fixedSize() || ((Mat*)obj)->size.operator()() == Size(_cols, _rows)) in create. Specifically, I've been able to reproduce the problem when creating a 7x5 board and then drawing it at size 1600x1200 pixels.

Steps to reproduce

#include <opencv2/opencv.hpp>
#include <opencv2/aruco.hpp>
#include <opencv2/aruco/charuco.hpp>
int main(int argc, char **argv)
{
  int squares_x = 7,
      squares_y = 5;

  int bwidth = 1600,
      bheight = 1200;

  cv::Ptr<cv::aruco::Dictionary> dict = cv::aruco::getPredefinedDictionary(cv::aruco::DICT_4X4_50);
  cv::Ptr<cv::aruco::CharucoBoard> board = cv::aruco::CharucoBoard::create(squares_x, squares_y, 1.0, 0.75, dict);
  cv::Size sz(bwidth, bheight);
  cv::Mat mat;
  board->draw(sz, mat, 0, 1);
  cv::imshow("test", mat);
  cv::waitKey(-1);
  return 0;
}

This code triggers the bug. Changing the size of the board to, e.g. 9x7, or changing the size of the image to, eg. 1600x1201, does not trigger the bug.

Possible fix

I've managed to trace the bug to cv::aruco::_drawPlanarBoardImpl() at line 1683 (https://github.com/opencv/opencv_contrib/blob/master/modules/aruco/src/aruco.cpp#L1683):

if((outCorners[0].y == outCorners[1].y) && (outCorners[1].x == outCorners[2].x)) {
            // marker is aligned to image axes
            marker.copyTo(out(Rect(outCorners[0], dst_sz)));
            continue;
}

When using the parameters above, dst_sz == Size(172, 171) whereas marker.size() == Size(172,172), which causes the crash. I managed to fix it simply by adding the condition that marker.size() == dst_sz. It seems to work correctly, but I'm not expert enough on the matter to know whether it's the right fix.

opencv / opencv_contrib