[sane-devel] More front end developer Q's

Henning Meier-Geinitz henning at meier-geinitz.de
Mon Sep 22 10:24:41 BST 2003


On Mon, Sep 22, 2003 at 11:09:54AM +0200, Guy Brooker wrote:
> 1. How can I determine the native resolution in X and Y of the current
> scanner ?

You can't. And you usually don't need to.

> For my EPSON GT-7000, the epson backend returns resolutions up to 2400, and
> a default of 50. However EPSONs docs say the native resolution of the
> scanner is 600 dpi.

Well, it's up to the backend author to decide if the backend does
interpolation. I don't recommend doing that. There is one exception:
scanners that can do e.g. 600x1200 dpi. In this case, interpolating
600 dpi to 1200 dpi is ok in my mind.

> 2. What calls should an application make to determine if a scanner is
> actually online and ready ? sane_start() followed by sane_cancel() ?

If the backend shows the scanner in its device list, it should be
online at that point of time (sane_get_devices).

Why do you want to test it again later? If you do a real scan 2
seconds after the test someone could have turned off the scanner in
the meanwhile.


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