[sane-devel] Best way to stop scanimage?

[Jeff Sadowski]

I also run scanimage under script otherwise I don't get the continuous
output.

On Sat, Sep 30, 2017 at 6:09 PM, Jeff Sadowski <jeff.sadowski at gmail.com>
wrote:

> Thank you for the input.
>
> I'm redoing phpsane. I'll look at the others but I came up with a method
> that seems to work a little better then I have seen so far. Like I
> mentioned I'm using proc_open in a process that I put in the background and
> to allow me to watch the image as it is being pulled. I am pulling the
> selection interface I saw on phpsane. I talked to the developer of phpsane
> and he suggested I rebuild it. I can successfully pull scanner specific
> options and create a custom option list for them. I'll add the option to
> stop and try it out. But I will caution other users on that. I will cache
> options and scanner returns to speed things up.
>
> I was even successful at allowing an array input in html :-)
>
> On Sat, Sep 30, 2017 at 3:16 PM, Jeff <jffry at posteo.net> wrote:
>
>> On 29/09/17 15:52, Jeff Sadowski wrote:
>> > I am developing a php interface I'm calling it php saneng I have it on
>> > bitbucket for now and using proc_open. I will send the signal via
>>
>> You are not the first. Have you looked at
>> https://sourceforge.net/projects/phpsane/ or
>> https://github.com/anomen-s/php-sane or https://github.com/sbs20/scanserv
>> ?
>>
>> I should probably point a few things before you continue down the dark
>> path of making a wrapper around scanimage.
>>
>> When I started writing gscan2pdf back in 2006, it was exactly that, a
>> Gtk2 wrapper around scanimage, written in Perl.
>>
>> It seemed like a good idea to wrap scanimage at the time, but it quickly
>> became clear that the problem is that you have no way of handling option
>> reloads. You can make it work for one scanner easily enough, but in a
>> general sense, it is impossible.
>>
>> You are completely at the whim of the backend if an option, e.g. source
>> or depth, option force a reload. And they do, which changes unexpected
>> things. For instance some scanners support one page size (i.e. scan
>> size) for flatbed, and another for ADF.
>>
>> You can work around this by calling scanimage [extra options] --help
>> every time the user changes an option, but this will be slow. You can
>> make it quicker by caching the options, but this is error-prone.
>>
>> You will find that because of this, the order in which the options are
>> set is vitally important. i.e. for the above example, you have to set
>> the source option before the geometry options, as the range of geometry
>> options is changed by source. And confusingly, some backends have
>> different names for the same options.
>>
>> In the end, I wrote Perl bindings for the SANE API. This solved all of
>> the above problems, as you then get reload callbacks:
>>
>> http://search.cpan.org/~ratcliffe/Image-Sane-0.14/
>>
>> However, it is non-trivial. Here is a tutorial on writing PHP extensions
>> in C:
>>
>> http://web.archive.org/web/20110222035803/http://devzone.zen
>> d.com/article/1021
>>
>> Good luck.
>>
>> Regards
>>
>> Jeff
>>
>>
>> --
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>
>
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