TWAIN Default Source

  • Thread starter Thread starter robinsoh
  • Start date Start date
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robinsoh

Hello,
Is it possible to set a source as the new default source in TWAIN
without using the TWAIN select scanner user interface via the
MSG_USERSELECT call. I have been unable to find such a call documented
in the TWAIN specification, which seems a bit odd.

- Harry
 
Hello,
Is it possible to set a source as the new default source in TWAIN
without using the TWAIN select scanner user interface via the
MSG_USER call. I have been unable to find such a call documented
in the TWAIN specification, which seems a bit odd.

- Harry
Click to expand...
I would think not.

Every program that I have seen does a Select TWAIN source before acquiring.
However as an example, Irfanview will remember the selection until you
select another source.
 
There is no reason to display the TWAIN interface before each acquire.
Upon application startup I simply query the source manager for the
default source and display its name conviently in a status bar on my
main window. If a user does not wish to use this source, he/she can
simply select one from a scanner menu populated with a list of scanners
available. Popping up the annoying TWAIN interface upon each acquire or
when they want to explicitly select a new source before scanning is
time consuming and annoying to power users, however, it seems this is
common place among TWAIN enabled applications. Furthermore trying a
user interface element, whose only job is to display a selectable list
of sources, into the only means of setting a default source is poor API
construction. Sorry for the rant :-)

This can be resolved by making the application remember the last source
selected and upon subsequent application startups, simply iterate
through the list of aviable sources until you watch the one saved by
the application. This isn't exactly the solution I was looking for, but
it works
 
It takes less than 5 seconds to choose the scanner if the interface requires
that.
What do people like you do when you are stuck in traffic on a freeway?
 
Birdman,
Imagine if you where using Internet Explorer or Firefox and where
presented with a popup model dialog box each time you wished to
navigate to a bookmarked site, rather then being able to access them
via the failure bookmarks menu item. This isn't necessarily about
patience, I for one am a very patient person, it's about proper
interface design, accessibility to key application features and the
negative impact of coupleing the selection of the TWAIN default source
and the user select interface.

If you look at the SANE project
(http://www.sane-project.org/intro.html), they state as a motivating
force behind the project, "Simply put, TWAIN does not separate the
user-interface from the driver of a device". While this exactly a
device driver / user-interface issue, TWAIN is still combining
interface-elements with core API functionality, which makes life
difficult.
 
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