Hello!
I've been playing around with displaying images in the Emacs SLIME REPL
from MIT/GNU Scheme, works very nicely so far. Now I've tried to get a
halfway decent binding for cairo (http://cairographics.org) working, but
run into a problem:
There is a function
cairo_status_t [an int]
cairo_surface_write_to_png_stream(
cairo_surface_t *surface, [the graphical data, just an alien]
cairo_write_func_t write_func, [the actual callback function]
void *closure); [some arbitrary data that is passed to the
callback]
cairo_write_func_t is defined as follows:
cairo_status_t (*cairo_write_func_t) (void *closure,
const unsigned char *data,
unsigned int length);
[see http://cairographics.org/manual/cairo-PNG-Support.html]
I'd like to make this accessible from Scheme, preferably by just calling
it in C, and returning all the data it writes as a vector8 (so a
string).
I've not been successful in declaring the callback, and if I just return
a char* from a wrapper function, it will be truncated at the first
#\nul.
How can I either implement the callback, so that I get at the data and
length in a Scheme function, or so that I can read all the incoming data
in C, and then pass it all back to Scheme correctly?
Thanks for any help, greetings!
Peter
_______________________________________________
MIT-Scheme-devel mailing list
MIT-Scheme-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/mit-scheme-devel
