[Mono-list] P/Invoke question

[Jonathan Pryor]

On Thu, 2005-03-17 at 11:47 +0000, James Fitzsimons wrote:
> > For instance, you could declare the P/Invoke function
> > to take an array of CvPoint2D32f elements, then
> > construct this array in the code that calls this
> > function (the wrapper) with the appropriate size.
> > Perhaps, if you know CvPoint2D32f to be of type float,
> > you could even pass this array to the Marshal.Copy
> > function directly.
> 
> This was actually what I originally had in mind, however CvPoint2D32f
> is actually a struct that looks like this (from memory)
> struct CvPoint2D32f 
> {
>    float x;
>    float y;
> }
> 
> So I guess the question becomes how do I marshal an array of structs?
> Or, could I marshal it as an array of floats of size 2 * number of
> CvPoint2D32f's, and put it back into struct form once it has been
> returned from the C function?

Structures can be marshaled just like any other type.

	Struct CvPoint2D32f {
		public float x;
		public float y;
	}

	// ...
	[DllImport ("...")]
	public static extern void Foo (CvPoint2D32f[] points, int length);

 - Jon