[GRASS-user] "Automatic" redraw of map display in 6.4 when underlying raster changes?

[Rainer M Krug]

On Fri, Oct 7, 2011 at 5:22 AM, Glynn Clements <glynn at gclements.plus.com>wrote:

>
> Rainer M Krug wrote:
>
> > > Monitoring the filesystem is likely to be unreliable, as there's no
> > > straightforward way to determine when files are in a consistent state.
> >
> > Thanks for pointing this out and saving me some work - otherwise I might
> > have chosen that path...
>
> Also, doing this at the library level would have similar issues,
> albeit less severe.
>
> E.g. when a module finishes writing the actual raster data (i.e.
> G_close_cell() or Rast_close()), often the next thing it does is to
> write metadata (categories, colour table, history). There is no
> specific "event" which signals that the output raster is "complete".
>
> Generating notifications on "close" operations would ensure that
> individual files are consistent, but that doesn't mean that the raster
> as a whole is consistent.
>
> This is something that has been discussed in the past, but without
> resolution. Improvements in this area are certainly desirable; e.g.
> reading a map in another mapset relies upon luck, as there is no
> mechanism to ensure that the owner of that mapset isn't modifying the
> map in question at the time. Unfortunately, the issues are complex,
> making it hard to decide what should be done, let alone doing it.
>

Thanks a lot for all your input - I think I will put in a mechanism in the
model (i.e. writing a file when a layer has been updated ) which I can react
on from an external viewer / application.

Cheers,

Rainer

>
> --
> Glynn Clements <glynn at gclements.plus.com>
>



-- 
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology,
UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

Tel :       +33 - (0)9 53 10 27 44
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email:      Rainer at krugs.de

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