[GRASSLIST:2702] Re: Grass 5.7 smart display

[Glynn Clements]

francesco.pirotti wrote:

> The problem:  
> showing on the monitor 156 maps takes a long time, even if you have a low 
> resolution and your region is covers only one of the maps. 
> 
> The solution?
> I am tweaking the tcl d.m scripts to make a "smart" display function which 
> will basically check the region that one is viewing, and only draws the maps 
> which are viewable from such region, thus avoiding extra drawing.  Plus I 
> would like the function to change the region resolution automatically to have 
> a region around 1000pixels x 1200pixels everytime.
> 
> Has anybody felt a need for such a thing?  Is there already some command for 
> this?  Is it just foolishness?

An alternative approach would be for d.rast to check whether the map
intersects the current region. If it doesn't, and the overlay (-o)
switch is used, then it can skip the drawing part (it still needs to
update the cell/cell_list/list pads, though).

That approach would be more generally useful than something which is
built into d.m. OTOH, it might still be too slow for 156 maps
(particularly on Cygwin, where simply spawning a program 156 times
would probably be too slow, even if the program itself did absolutely
nothing).

-- 
Glynn Clements <glynn.clements at virgin.net>