Re: [Gnumed-devel] packaging help needed - TWAIN, XSANE, SANE

[Karsten Hilbert]

On Sun, Aug 30, 2009 at 05:57:44PM -0700, Jim Busser wrote:

> >TWAIN is a strange beast: It is a low
> >level API to a high level user interface. The vendor TWAIN
> >drivers have gotten very sophisticated including a GUI to
> >control scanning etc.
> >
> >>What does a user experience when on Windows twainmodule was loaded?
> >
> >A vendor-specific GUI opens which ranges from crap to
> >deluxe.
> 
> So... if (via Windows twainmodule) it is a vendor-specific GUI that
> opens, how is that different than just using the vendor's front-end
> GUI independently?

a) we'd have to *know* how to call said vendor-specific GUI

b) there must actually be a *way* to call said
   vendor-specific GUI as if it were an application

c) said vendor-specific GUI would have to provide a way to
provide GNUmed with a list of files it saved scans in upon
completion - apart from the already established way via the
TWAIN API

> ... does the vendor GUI still write the file (even if only
> temporarily into some \temp directory) to disk?

That's up to the whims of said GUI which is exactly why the
TWAIN API exists.

> ... whether or not an image file is written to disk, does
> twainmodule have access to either the object in memory and/or the
> name and location of any file(s) that were saved, permitting GNUmed
> to automagically list the part(s) in the "Attach documents" plugin's
> "Parts" display area?

That is precisely what it does. Exactly the same as with
XSane or sane.

> >>Does this result in the opening-up of a standard WIndows default
> >>client
> 
> Half of me *was* remembering that when I opened JPGs or TIFFs on an
> unaltered Windows box, some kind of generic image browser opened
> (although I did not watch closely, and I suppose it could have been
> an Adobe plugin).

> I did imagine that in the same way as Apple provides "Image Capture"
> that Windows might ship with something that could access a TWAIN
> scanner despite that the scanner vendor could still supply software
> that would overwrite a Windows preference and/or the scanner's
> driver might preferentially call.

There does indeed exist something called "Windows Imaging"
which did have a frontend for scanning. Newer versions of
Windows may also come with builtin scanner access -- which
will amount to, say, explorer accessing the TWAIN drivers --
just as GNUmed does. That solution hasn't gotten much
traction, though, because most vendor-side
GUI-behind-the-TWAIN-driver is better than that.

Karsten
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