edevis's profile - activity

We are encountering SEH exceptions when calling cvGetSize for a CvMat. Here is small example:

using System;
using System.Runtime.InteropServices;

namespace ConsoleApplication1
{
    internal struct _CvMat
    {
        public int type;
        public int step;
        public IntPtr refcount;
        public int hdr_refcount;
        public IntPtr data;
        public int rows;
        public int cols;
    }

    public struct Size
    {
        public int Width;
        public int Height;
    }

    unsafe class Program
    {
        [DllImport("opencv_world300", CallingConvention = CallingConvention.Cdecl)]
        internal static extern Size cvGetSize(_CvMat* arr);

        [DllImport("opencv_world300", CallingConvention = CallingConvention.Cdecl)]
        internal static extern _CvMat* cvCreateMat(int rows, int cols, int type);

        [DllImport("opencv_world300", CallingConvention = CallingConvention.Cdecl)]
        internal static extern void cvReleaseMat(ref _CvMat* mat);

        static void Main(string[] args)
        {
            var ptr = cvCreateMat(30, 30, 0);
            Size size = cvGetSize(ptr); // Causes SEH exception
            cvReleaseMat(ref ptr);
        }
    }
}

This problem seems to be existing in 2.4.x as well, as Emgu.CV (popular C# Wrapper) is not using a cvGetSize, instead directly using the CvMat rows and cols members with a comment that the call is not working.

When doing the same in pure C the function calls are working as expected. In C# only this specific function is causing a problem.

The calling convention is correct, the types seem to be correctly defined. When looking at the members of the CvMat when calling cvGetSize, type and step are set to 0 before the error occurs.

Can anyone reproduce this? Anybody knows where this comes from?