[Question] Struct width function in his fields

[Romakita]

Hello guys,

To begin, thanks for your awesome library :D.

I works libphoto2 integration inside nodejs module, and one the function used by libphoto2 require a complex structure like that:

 typedef struct _CameraFileHandler {
   // int (*size) (uint64_t *size); /* only for read? */
   int (*read) ( unsigned char *data, uint64_t *len);
   // int (*write) ( unsigned char *data, uint64_t *len);
} CameraFileHandler;

I tried to define a StructType like that:

const {refType} = require("ref");
const RefCB = refType("void");
const ffi = require("ffi-napi");

const StructCameraFileHandler = StructType({
  read: RefCB
});

const driver = ffi.Library("libgphoto2", {
   gp_file_new_from_handler: ["int", [refType(StructCameraFileHandler)]],
});

const file = new StructCameraFileHandler();
file.read = ffi.Callback("int", [StructPriv, types.CString, "int"], (data, length) => {
   console.log(data, length);
});

driver.gp_file_new_from_handler(file.ref());

But, my callback is never called. I'm not sure if the structure is correctly configured with ffi and ref-struct.
Do you have any idea ?

Thanks in advance ;)
See you,
Romain