Re: [PATCH zbar 1/1] Add simple dbus IPC API to zbarcam.

[Mauro Carvalho Chehab <mchehab+samsung@kernel.org>]

Em Wed, 16 Jan 2019 13:37:58 -0700
James Hilliard <james.hilliard1@gmail.com> escreveu:

> On Wed, Jan 16, 2019 at 7:37 AM Mauro Carvalho Chehab
> <mchehab+samsung@kernel.org> wrote:
> >
> > Hi James,
> >
> > Em Wed, 16 Jan 2019 16:54:55 +0800
> > james.hilliard1@gmail.com escreveu:
> >  
> > > From: James Hilliard <james.hilliard1@gmail.com>
> > >
> > > This is useful for running zbarcam as a systemd service so that other
> > > applications can receive scan messages through dbus.  
> >
> > Nice approach!
> >
> > Yet, I would try to write it on a different way, making sure that it
> > could also be using by zbarimg.
> >
> > I mean, if you add the dbus bindings inside the zbar core, it
> > shouldn't matter if the source image comes via a webcam or via a
> > scanned image. Both will be able to send the scancodes via dbus.  
> Which function should I call send_dbus() from in that case?

Good question.

Tests required, but I suspect that you could add it at processor.c,
inside _zbar_process_image().

I suspect that, if you do something like:

	if(nsyms) {
            /* FIXME only call after filtering */
            _zbar_mutex_lock(&proc->mutex);
            _zbar_processor_notify(proc, EVENT_OUTPUT);
            _zbar_mutex_unlock(&proc->mutex);
            if(proc->handler)
                proc->handler(img, proc->userdata);
+	    if(proc->is_dbus_enabled)
+		zbar_send_code_via_dbus(proc->userdata);
        }

should work.

You could easily check if this is working by calling:

	$ ./zbarimg/zbarimg ./examples/barcode.png
	EAN-13:9876543210128
	scanned 1 barcode symbols from 1 images in 0.2 seconds


(I would add a flag to allow enabling/disabling it by applications).


> >
> > As a future approach, we may even think on making the interface
> > duplex in the future, e. g. allowing any camera application to
> > send an image via dbus and let zbar to decode it and return
> > the decoded bar codes.  
> That could be useful, probably too difficult for me to implement
> myself though(I don't write a lot of c usually).

As I said, this is just an idea for a future possible development.

Not sure how this would actually work, as dbus may not be the best
interface for passing images.


Thanks,
Mauro