OpenCvSharp.CPlusPlus.Cv2.DrawMatches throws exception.

[rblenis]

I think OpenCvSharp.CPlusPlus.Cv2.DrawMatches suffers the garbage collection problem seen previously in many OpenCvSharp.Cv methods, requiring the GC.KeepAlive fix. There are probably many other methods in the OpenCvSharpCPlusPlus.Cv2 dll that need this fix as well.

version: OpenCvSharp 2.4.10-20170306

Environment

Windows 10, and Ubuntu 17.04 (mono). Application running in release mode (hasn't happened in debug mode yet)

What did you do when you faced the problem?

cried. jk.

Example code:

...
var view = new OpenCvSharp.CPlusPlus.Mat();
var bmp = OpenCvSharp.Extensions.BitmapConverter.ToMat(plp.bmp);
OpenCvSharp.CPlusPlus.Cv2.DrawMatches( bmp,
AlgData.KeyPoints, mpatchImg, keypts, matches, view);

        var file = Path.Combine(AppDataFolder, "view.png");
        view.SaveImage(file);
    }

Output:

Unhandled Exception: System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
at OpenCvSharp.CPlusPlus.NativeMethods.features2d_drawMatches1(IntPtr img1, KeyPoint[] keypoints1, Int32 keypoints1Length, IntPtr img2, KeyPoint[] keypoints2, Int32 keypoints2Length, DMatch[] matches1to2, Int32 matches1to2Length, IntPtr outImg, CvScalar matchColor, CvScalar singlePointColor, Byte[] matchesMask, Int32 matchesMaskLength, Int32 flags)
at OpenCvSharp.CPlusPlus.Cv2.DrawMatches(Mat img1, IEnumerable1 keypoints1, Mat img2, IEnumerable1 keypoints2, IEnumerable1 matches1To2, Mat outImg, Nullable1 matchColor, Nullable1 singlePointColor, IEnumerable1 matchesMask, DrawMatchesFlags flags)

What did you intend to be?

not an exception