[sane-devel] [janitorial] New backend: escl

[Till Kamppeter]

On 15/12/2019 10:38, Till Kamppeter wrote:
> On 15/12/2019 05:10, Olaf Meeuwissen wrote:
>> Hi list,
>>
>> I thought you might like to know that I've merged the escl backend
>> yesterday.  This backend was written by Touboul Nathane and Thierry
>> Huchard at Ordissimo.  It is licensed under the terms of the GPL,
>> either version 3 or, at your option, any later version.
>>
>> The backend should support many of the large range of devices that
>> support Apple's AirPrint protocol.  For a long list of potentially
>> supported devices see
>>
>>    https://support.apple.com/en-us/HT201311
>>
>> The backend's description file does not list any specific devices yet
>> but the merge request listed a few devices that are known to work for
>> some definition of work ;-)
>>
>> Please note that the escl backend only supports these devices over a
>> network connection, not via USB or similar connections.
>>
>> The backend currently only supports image data transfer in JPEG format
>> but Thierry indicated he wanted to add support for PNG and PDF as well.
>>
>> For the gory details see merge request 242.
>>
>>    https://gitlab.com/sane-project/backends/merge_requests/242
>>
>> On a related note, there is another merge request for a canon_lide70
>> backend.  I'll be getting to that shortly, relatively speaking :-)
>>
>> Hope this helps,
> 
> I have the HP DeskJet 2540 MF device here. Its DNS-SD record is:
> 
> ----------
> Found service 'Deskjet 2540 series [E7DDC7]' of type '_uscan._tcp' in domain 
> 'local' on 3.1.
> Service data for service 'Deskjet 2540 series [E7DDC7]' of type '_uscan._tcp' in 
> domain 'local' on 3.0:
>      Host HP5CB901E7DDC7.local (192.168.223.1), port 8080, TXT data: 
> ['duplex=F', 'is=platen', 'cs=binary,color,grayscale', 'rs=/eSCL', 
> 'representation=', 'UUID=1c852a4d-b800-1f08-abcd-5cb901e7ddc7', 'note=', 
> 'adminurl=http://HP5CB901E7DDC7.local.', 'ty=HP Deskjet 2540 series', 
> 'pdl=application/octet-stream,application/pdf,image/jpeg', 'vers=2.0', 'txtvers=1']
> ----------
> 
> Seems that it also supports eSCL, with JPEG and PDF as output format.
> 
>     Till

Seeing that my HP does eSCL, I have investigated the source code of HPLIP, the 
free software HP printer/MF device driver suite, and it seems to also support 
eSCL for scanning, containing the source file

scan/sane/escl.c
scan/sane/escl.h

This could perhaps contain missing pieces for your eSCL backend, like PDF (or 
any uncompressed raster) output, USB support, ...

In the list of supported models

data/models/models.dat

on all with "scan-type=9" sSCL is used by HPLIP (see also io/hpmud/hpmud.h), but 
there are more models, like ny DeskJet 2540 which supports eSCL according to its 
DNS-SD record.

    Till

    Till