[GRASS5] XDRIVER and redraw - suggestion

[Markus Neteler]

Hi Glynn,

On Wed, Jan 30, 2002 at 05:31:26PM +0000, Glynn Clements wrote:
> 
> Markus Neteler wrote:
> 
> > while on the one hand the redraw function of XDRIVER is nice,
> > it can become rather annoying with large maps (say, 500MB-1GB
> > remote sensing data).
> > 
> > What about following suggestion: the XDRIVER reads the environmental
> > variable
> > XDRIVER_MAX_NREDRAW
> > which defines the maximal number of maps kept in the monitor
> > list. If not defined, no limitation, if defined, the user
> > can specify the maximum numbers of maps to be redrawn. Inthis
> > case the XDRIVER forgets about the older drawn maps.
> > 
> > It would be nice to have this optional variable.
> 
> Note that XDRIVER doesn't know anything about "maps"; it just has a
> list of commands which it runs whenever the monitor is resized. 
> Determining which commands constitute a "map" and which don't isn't
> straightforward; "d.rast" isn't the only command which draws maps.

yes, agreed.
 
> Ultimately the XDRIVER resize kludge is just a quick workaround to
> compensate for the absence of an interactive UI. Realistically, the
> monitors should just be dumb graphic "devices"; state management
> belongs elsewhere (the fact that, currently, there isn't a suitable
> "elsewhere" doesn't doesn't change that).

also agreed.
 
> If the command list is getting too long, use "d.erase".

Mhh, that's not unknown to me - but still inconvenient to be
the only way to solve the problem. The proposed variable would
change nothing for the standard behaviour of the monitor but
allows in (our?) particular case to improve the situation unless
a new, great system is written.

Probably you can think again about the idea? :-)

Thanks,

 Markus