[Gtk-sharp-list] binding another libraries

Jonathan Pryor jonpryor@vt.edu
Wed, 08 Sep 2004 19:39:47 -0400

Strictly speaking, mono-list would be more appropriate for this
question, but I'll answer it anyway.

On Mon, 2004-09-06 at 05:27, juanjo molinero wrote:

> struct EpegImage{
>    struct JpegImage image;
>    int w;
>    int h;
> }

At a minimum, you need to know the size of a JpegImage.  This is
unavoidable, but you can get it from your C compiler using a short

	printf ("sizeof(JpegImage)=%i\n", sizeof(struct JpegImage));

Once you have the structure size, you just need to tell the runtime
marshaller how large the nested structure is:

	[StructLayout(LayoutKind.Sequential, Size=SIZE_FROM_ABOVE)]
	struct JpegImage {}

	struct EpegImage {
		JpegImage ignored;
		public int w;
		public int h;

However, this is non-portable (between 32-bit and 64-bit platforms) if
JpegImage contains pointers (or something else that varies with the
platform, such as intptr_t).  As such, it would be preferable to use the
actual declaration of JpegImage, if at all possible, so that you don't
need a managed wrapper library for each target platform.

 - Jon