HAL: camera

[Sean Middleditch]

On Wed, 2004-01-14 at 13:27, Kevin Krammer wrote:
> On Wednesday 14 January 2004 16:01, Sean Middleditch wrote:

> > Hmm, those too should perhaps be different capabilities, or sub
> > capabilities?  The interfaces used for scanners are different than those
> > used for digital cameras, so again apps need to be able to
> > differentiate.
> 
> The interface might be different depending on what you want to do.
> I think I read on the SANE site that it can handle (assuming a proper backend) 
> any raster image source, e.g. scanners, cameras, framegrabbers, etc.
> 
> A scanning framework might want to look for all raster images sources and not 
> care if it is a camera.

The capabilities system is great for this (assuming we have defined a
good set of capabilities), because you could list the device as having
both 'still image' capibility and 'camera' ability.  I would still,
honestly, rather have an app dedicated to cameras to reading images from
them (especially since cameras often do things a scanner doesn't, such
as letting you delete the image, put images back onto it and other
things a well designed scanner app probably wouldn't waste UI for, even
if the SANE backend allows), but if a scanner app wanted a list of all
connected devices it can read images from, HAL would make that easy.

> 
> I have to admit that I have not the slightest idea about your capabilities 
> system (just reading the mails sporadically) but maybe still image source 
> should be a top level capability.

or perhaps make a 'multimedia' category: multimedia.image,
multimedia.video, multimedia.audio, etc.  cameras could then have
capabilities to represent things like camera.image, camera.movie,
camera.control, camera.storage, or other things a camera application
might need to know, and scanner category likewise could know about
specialized scanner capabilities (I have little experience with these,
so I'm not fit to comment on those).

is it considered 'bad form' to have multiple capabilities (in different
namespaces/categories) for the same thing?  hierarchy kinda sucks when
its overly rigid as it can't express things as they really are, but it
does avoid a lot of clutter and guesswork.  ("ok, which of the 10 image
capabilities should I put for this device?")

> 
> Cheers,
> Kevin
-- 
Sean Middleditch <elanthis at awesomeplay.com>
AwesomePlay Productions, Inc.