[GRASS5] GRASS5.1: d.what.vect very slow over ssh connection

Glynn Clements glynn.clements at virgin.net
Wed Jun 4 04:20:30 EDT 2003

Radim Blazek wrote:

> > > I sometimes connect from home to my work computer via ssh and launch 5.1
> > > through this connection with X forwarding. Everything works quite well,
> > > except for d.what.vect which is extremely slow in starting up and in
> > > giving back the cross cursor after displaying information about an object.
> > >
> > > Any ideas why this would be ?
> > 
> > This is probably similar to the problem with d.what.sites, since the
> > 'flashing sites' feature was added. Glynn gave some reasons why it might
> > be very slow over a slow network connection here:
> > http://www.intevation.de/rt/webrt?serial_num=1759&display=History
> > 
> > I have also noticed from my extremely limited testing of 5.1 that
> > d.what.vect is very slow just on a slow computer even when working
> > directly at the console. Maybe the 'flashing' feature needs tidied up a
> > bit.
> I think, that this is caused by my hack for R_get_location_with_*(),
> which makes possible to quit this function from module.

No, that isn't the problem. Both d.what.vect and d.what.sites were
modified to "flash" the selected line/site. This works by saving the
screen contents with R_panel_save(), then repeatedly drawing the
"flash" then erasing it with R_panel_restore(). Each call to the
R_panel_* functions sends the entire screen contents over the X
connection (XGetImage(), XPutImage()), which is what makes it so slow.

Glynn Clements <glynn.clements at virgin.net>

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