Bug#883182: libsane-hpaio: SCL scan resolutions list too restrictive
Thank you for your detailed report, Geoff.
On Thu 30 Nov 2017 at 11:44:27 +0000, Geoff Clare wrote:
> Package: libsane-hpaio
> Version: 3.14.6-1+deb8u1
> Severity: normal
>
> Dear Maintainer,
>
> Somewhere between 3.10 and 3.14 the supported resolutions for SCL
> scanners changed from a range to a list. This manifests in xsane
> as a change from a text box where you can enter any resolution
> you want to a drop-down list of resolutions to choose from.
3.10 takes us before wheezy; I am not prepared to test beyond jessie,
which gives a list of resolutions for one of my HP devices:
brian@desktop:~$ scanimage -A -d hpaio:/net/envy_4500_series?ip=192.168.7.235 | grep resolution
--resolution 75|100|200|300|600|1200|2400dpi [75]
Sets the resolution of the scanned image.
> To me this change is an unacceptable loss of functionality.
> (I'll explain why at the end).
Your point is taken.
> I found that I could reinstate the old functionality by commenting out
> one line in the SetResolutionListSCL() function in scan/sane/scl-pml.c:
>
> hpaio->option[OPTION_SCAN_RESOLUTION].constraint_type = SANE_CONSTRAINT_WORD_LIST;
My knowledge of how libsane-hpaio's and libhpmud0's code drives a
scanner is non-existent, so I am not in a position to comment on
this.
> Please consider making one of the following changes:
>
> 1. Comment out that line (or make an equivalent change). This is the
> simplest option, but I suppose is unlikely to be accepted upstream and
> so would need to be maintained indefinitely as a debian patch.
>
> 2. Provide a configuration option (in /etc/hp/hplip.conf?) so that it is
> possible to choose between a resolution range and a list.
>
> 3. Provide a configuration option to override the default list of
> supported resolutions, which is hard-coded in SetResolutionListSCL().
>
> 4. Change the list of supported resolutions in SetResolutionListSCL() so
> that it has a few new ones in between the existing ones. E.g. instead of:
>
> ... 300, 600, 1200, 2400, ...
>
> it has:
>
> ... 300, 400, 500, 600, 700, 800, 900, 1000, 1200, 1400, 1600, 1800,
> 2000, 2400, ...
>
> These options are in decreasing order of preference for me, but your
> preference may differ (as may upstream's).
>
> As to why the new SCL resolution list is an unacceptable loss of
> functionality for me, it's because I like to scan 6x4 photos at 800 dpi.
> I could achieve the same result by scanning at 1200 and then scaling the
> photo afterwards, but this is not an acceptable solution because my
> scanner behaves completely differently at 1200 dpi. Instead of scanning
> quite quickly in one continuous motion like it does at 800, at 1200 it
> scans extremely slowly with many back-and-forth motions that drive me
> nuts.
>
> I'm sure there must be many other Debian users with HP SCL scanners who
> would prefer that the list of resolutions was not so restrictive.
It is doubtful whether the Printing Team would carry and maintain
patches of this nature. About the best I can suggest is to contact
upstream at
https://bugs.launchpad.net/hplip ,
make them aware of #883182 and first ascertain why the change has
come about. Posting the link here would help. An informative and
positive reponse from upstream would go a long way to determining
the direction the status of this report takes,
Regards,
Brian.
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