# Re: TWAIN not so broken after all?

Jon Harju (jonh@jflinc.com)
Sun, 21 Mar 1999 20:09:21 -0600

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At 01:05 AM 3/21/99 +0000, you wrote:
>In browsing through some of the TWAIN 1.6 documentation on the web, I noticed
>that there is a "ShowUI" feature which may optionally be supported by a
>TWAIN Source (ugly Windows scanner program to you or me). If supported, this
>feature allows a TWAIN application program to turn off the Windows UI and
>directly manipulate most/all of the TWAIN Source features.
>
>It seems to me that IF a significant number of consumer scanners out there
>do have this feature enabled then one could potentially develop a Win32
>SANE backend which simply turned off the ugly TWAIN Source UI and provided
>as many features as it advertises (which may unfortunately not be all the
>features of the scanner) to the SANE system.
>
>The advantage to the end-user is that they get network transparent access
>to the scanner, and no longer need use the ugly TWAIN UI.
>
>Can anyone with TWAIN know-how (I know there are one or two people on this
>list who have some) comment on the availability of ShowUI in consumer land?

I think I might be able to help you with that question...

You are right about the availability of this feature, and you could
technically write a sane backend that would transparently handle it. The
ShowUI feature is available on most of the scanners (the exceptions are
most hand scanners and others that have little or no option for
programmatic control between the PC and the scanner).

I think the real problem is finding enough TWAIN Drivers that promote the
Scanner Capabilities properly. These are the key to programmatic control
with TWAIN, and without them ShowUI is useless. You will find that many
consumer level scanner Data Sources are poorly implemented since their
primary marketing focus is "does it work with Photoshop?", a product that
does not take advantage of any programmatic control.

However, if you go up on the scale and start getting into the production
level scanners, you will find that they have very robust implementations.
Most apps using them are custom and suppress the GUI.

As to the technical implementation of a SANE backend, well there are a few
things that tie it to Windows, like the event handling is entirely through
the Windows Message pump... no command line operation possible.

I can see the advantage to network-ability, but really... wouldn't it just
be better to try and bring SANE to Windows? The real effort, not matter
what would be trying to get the Windows Application developers to buy into
SANE, the drivers are already available with source so there is limited
benifit to wrapping TWAIN with SANE.

Regards,
Jon Harju

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