Re: [gphoto-devel] Libgphoto2 for embedded system

[vincent <vi...@gm...>]

Le mercredi 24 mars 2010 à 10:39 +0100, Marcus Meissner a écrit :
> On Tue, Mar 23, 2010 at 11:05:47PM +0100, vincent wrote:
> > Dear,
> > 
> > I am a team member which developing an embedded system. The system is
> > composed of an ARM type processor and varied peripheral, including a
> > Canon G10 numerical camera.
> > The main program should have to manage the camera and the others
> > peripheral in dispatching his workload in order to manage all his
> > peripheral at the same times.
> > The program should have to pictures shooting and to download it. I would
> > like, for this, to use the “libgphoto2” library managing the PTP
> > protocol.
> > 
> > After library testing, I have difficulties to manage the pictures
> > downloading. The “gp_camera_file_get” function return control the
> > program only at the end, so this downloading time is too much important
> > comparing at the others program tasks.
> > To have more time for the other tasks execution, I would like to cut the
> > downloading in several phases. I would like, download the pictures parts
> > in following the size that I have defined before.
> > 
> > The solution, I thought, is to develop a new function similar to
> > “gp_camera_file_get” for which I pass a parameter, a structure including
> > the downloading context :
> > 	- File identifier
> > 	- Packet size for download (int)
> > 	- Complete file size (int)
> > 	- Size of downloaded data (int)
> > 	- ...
> > >From the main program, I will be able to test if remaining data to be
> > downloaded, and call the function in indicating the size of data to
> > download.
> > 
> > - Have you a more simply solution to offer me ? 
> 
> Why are you not handling the cameras in threads? That way you have a master
> thread who just checks if the camera control thread is finished downloading?

I would not use thread in order to know the program actions every time.

> > - Do you think this solution is well and feasible ?
> 
> I am actually considering to add something like this, but more like:
> 
> 	sizeread = gp_camera_file_read (Camera*, folder, filename, type, targetbuffer, sizetoread);

Can you explain what is the parameter targetbuffer ?

> (and also gp_camera_file_seek similar to the unix seek).

I thought develop a function similar to gp_camera_file_seek.

> > - Do you think it would be interesting to integrate this functionality
> > in the library ?
> 
> I guess yes. Your solution could not be done perhaps with threading though ;)

I prefer using gp_camera_file_read, if this function is suitable for my
needs.

> Ciao, Marcus

Thanks
-- 
Vincent

Can you explain what is the parameter targetbuffer of function gp_camera_file_read ?

Thanks
-- 
Vincent