[GRASS5] PNG driver problem

David Piasecki piasecda at nv.doe.gov
Wed Aug 25 16:26:55 EDT 2004

Oh, I see now. It's not a separate command. It's simply an environment 
variable. Sounds like it's being written every time you perform an 
operation like d.rast. Isn't that a little slow? In some cases, I can 
see it as beneficial. Now you can load layers and watch them appear one 
at a time. However, now you have the overhead of writing out a PNG file 
with every operation. Do you know if there will be a future command for 
writing the PNG file so we can call it when we please?

As a temporary work around, what do you think of a GRASS script which 
executes a sequence of commands before exiting? Would the PNG driver 
consider that as a single operation and write once, or will it write 
everything automatically?


On Aug 25, 2004, at 1:12 PM, Glynn Clements wrote:

> David Piasecki wrote:
>> I looked around last night and couldn't seem to find the version of 
>> the
>> PNG driver you mentioned. I downloaded the latest 5.3 CVS snapshot, 
>> and
>> the documentation for the PNG driver did not mention any option for
>> writing to a file other than calling d.mon stop=PNG. Is the
>> documentation incorrect, or am I looking in the wrong place? Should I
>> be looking for the latest CVS snapshot of 5.7? I tried, but I wasn't
>> able to find it, though I'm still somewhat new to CVS. It often feels
>> like a guessing game when trying to figure out what's available.
> The change was made within the last week (2004/08/19 21:04:08 for the
> 5.3 source code; the manual page and 5.7 were updated on the 20th). If
> you obtained the code directly from CVS, it should be present. If you
> downloaded a CVS snapshot tar file, it may or may not be present,
> depending upon the date of the snapshot; the 2004_08_21 snapshots
> (both 5.3 and 5.7) should include it.
> The file "pngdriver" manual page (generated from the file
> html/html/pngdriver.html) should say:
>    Environment variables
>        Several environment variables effect the operation of  the
>        PNG driver.
> [snip]
>                      GRASS_PNG_AUTO_WRITE=[TRUE|FALSE]
>                      if set to "TRUE", the  image  file  will  be
>                      written  after each operation (i.e. whenever
>                      a  client  disconnects),  rather  than  only
>                      being  written  out  when  the driver termi­
>                      nates.
> -- 
> Glynn Clements <glynn.clements at virgin.net>

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