Re: [Chicken-users] how to create a cairo_matrix_t (defined by define-foreign-type) ?

[Markus Klotzbuecher]

Hi Christian,

On Fri, Jan 27, 2012 at 11:44:55AM +0100, Christian Kellermann wrote:
> Hi all fans of cairo bindings,
> 
> * Christian Kellermann <address@hidden> [120117 21:06]:
> > * Markus Klotzbuecher <address@hidden> [120115 18:02]:
> > > Is this branch available somewhere? I would prefer a correct but
> > > untested version to my wrong but coincidentally working one :-)
> > 
> > I am not sure yet what's best. What I am using now is this:
> > 
> > 
> > (define %fill-matrix
> >   (foreign-lambda* (c-pointer cairo_matrix_t)
> >                    ((f64vector v))
> >                    "cairo_matrix_t *m = malloc(sizeof(cairo_matrix_t));
> >                     int i=0;
> >                     m->xx = v[i++];
> >                     m->xy = v[i++];
> >                     m->yx = v[i++];
> >                     m->yx = v[i++];
> >                     m->x0 = v[i++];
> >                     m->y0 = v[i++];
> >                     C_return(m);"))
> > 
> > (define (cairo-transform/matrix ctx v)
> >   (when (not (= (vector-length v) 6))
> >     (error "Vector size mismatch should be 6, is " (vector-length v)))
> >   (let ((m (%fill-matrix v)))
> >     (cairo-transform ctx m)
> >     (free m)))
> > 
> > (define new-matrix
> >   (foreign-lambda* cairo_matrix_t ()
> >     "C_return(malloc(sizeof(cairo_matrix_t)));"))
> > 
> > There is still a freeing operation missing, I tend to use the
> > cairo-transform/matrix procedure most of the time though.
> > 
> > What do others think?
> 
> Markus did you have a chance to have a look at the code? I would
> love to release a new cairo version. If there are any missing
> features on your wishlist, please let me know!

The new-matrix works fine for me. (I only need to store the current
ctx, before I temporarily set it to the identity matrix for writing
something in device space).

I tried to test cairo-transform/matrix using csi too, but I get the
following error:

#;1> (use cairo)
; loading /usr/local/lib/chicken/6/cairo.import.so ...
; loading /usr/local/lib/chicken/6/srfi-1.import.so ...
; loading /usr/local/lib/chicken/6/srfi-4.import.so ...
; loading /usr/local/lib/chicken/6/srfi-13.import.so ...
; loading /usr/local/lib/chicken/6/lolevel.import.so ...
; loading /usr/local/lib/chicken/6/cairo.so ...
#;2> (define m (new-matrix))
#;3> (cairo-transform/matrix m (make-f64vector 6 1))

Error: (vector-length) bad argument type: #f64(1.0 1.0 1.0 1.0 1.0 1.0)

        Call history:

        <syntax>          (cairo-transform/matrix m (make-f64vector 6 1))
        <syntax>          (make-f64vector 6 1)
        <eval>              (cairo-transform/matrix m (make-f64vector 6 1))
        <eval>    (make-f64vector 6 1)  <--
#;3> 

Should the two "vector-length" be "f64vector-length" or am I missing
something?

Thanks!
Markus