/// <summary>
        /// Initialize instance with .NET string <see cref="s"/>
        /// </summary>
        /// <param name="s">.NET string to wrap into a UTF8 sequence of unmanaged bytes.</param>
        public Utf8String(string s)
        {
            Contract.Requires(s != null, "s is not null");

            // This code is not optimized. One could actually read the string and copy the content
            // directly in _handle without hitting any allocation. This would require us to include
            // the logic of converting .NET strings into UTF8 ourselves, something we do not want
            // to do for the time being. For now we only avoid the allocation of an extra byte array
            // for small strings (see the implementation of GetUtf8Bytes).
            int nb;

            byte[] bytes = GetUtf8Bytes(s, out nb);
            IntPtr lPtr  = SDL.SDL_malloc((IntPtr)(nb + 1));

            if (lPtr == IntPtr.Zero)
            {
                throw new OutOfMemoryException("Cannot Allocate Utf8String");
            }
            else
            {
                Marshal.Copy(bytes, 0, lPtr, nb);
                ((byte *)lPtr)[nb] = 0;
            }
            _count    = nb;
            _capacity = nb + 1;
            _handle   = lPtr;

            Contract.Ensures((_handle != IntPtr.Zero), "handle set");
            Contract.Ensures((_capacity >= s.Length + 1), "capacity_greater_than_input");
            Contract.Ensures(ReferenceEquals(s, String()) || (String().Equals(s)), "string_set");
        }
        public IntPtr MarshalManagedToNative(object ManagedObj)
        {
            if (ManagedObj == null)
            {
                return(IntPtr.Zero);
            }
            var str = ManagedObj as string;

            if (str == null)
            {
                throw new ArgumentException("ManagedObj must be a string.", "ManagedObj");
            }
            var bytes = Encoding.UTF8.GetBytes(str);
            var mem   = SDL.SDL_malloc((IntPtr)bytes.Length + 1);

            Marshal.Copy(bytes, 0, mem, bytes.Length);
            ((byte *)mem)[bytes.Length] = 0;
            return(mem);
        }