Re: [PLUG] Screenshot of GDM?

[Bill Jonas <bill@billjonas.com>]

On Thu, Nov 07, 2002 at 10:20:28PM -0500, W. Chris Shank wrote:
> Anyone know how I can take a screenshot of the GDM graphical greeter 
> (aka: login screen)?

xwd(1)

I just noticed from playing around with it that you may need to actually
switch to the X display in question in order to have a usable picture.
I'm not sure if this is true in the general case or if it's just true
for my particular video card/X server combination or because I have DRI
enabled or what.  In any case, the following command worked for me:

$ sleep 2; xwd -display :0.0 -out dump.xwd -root

(Note that the "sleep 2" only gave me barely enough time to switch to
the X display so that I wouldn't get a garbled image.)

In any case, xwd(1)'s output isn't a very common graphics format:

$ file dump.xwd 
dump.xwd: XWD X-Windows Dump image data, "xwdump", 1280x1024x16

But display(1) and convert(1) ("apt-get install imagemagick" or
http://www.imagemagick.org/ or your favorite provider of RPMs) grok it
just fine.

$ display dump.xwd
$ convert dump.xwd dump.png
$ ls -lh dump.*
-rw-r--r--    1 bj       bj            34k Nov  8 09:23 dump.png
-rw-r--r--    1 bj       bj           2.5M Nov  8 09:22 dump.xwd

A former boss of mine, working with systems used in a kiosk application,
used xwd(1) to good effect for monitoring the X display.

Note that import(1), also from the ImageMagick package, will also do
what you want.  The difference is that you can specify any graphics
format as the output (it determines which format you want from the
output filename's extension), and the command-line format is slightly
different.  Also note that you may have the same garbling issue with
import(1) if you had it with xwd(1).  (Note that I didn't have the
problem when the display was active and I ssh'd in from another host.)

$ sleep 2; import -display :0.0 -window root import.png
$ display import.png 
$ ls -lh import.png
-rw-r--r--    1 bj       bj           122k Nov  8 09:36 import.png
$ file import.png dump.*
import.png: PNG image data, 1280 x 1024, 16-bit/color RGB, non-interlaced
dump.png:   PNG image data, 1280 x 1024, 8-bit colormap, non-interlaced
dump.xwd:   XWD X-Windows Dump image data, "xwdump", 1280x1024x16

Also note: If you don't have or don't want to install ImageMagick, the
Gimp handles XWD-format graphics files just fine.

HTH.

-- 
Bill Jonas    *    bill@billjonas.com    *    http://www.billjonas.com/
"They that can give up  essential  liberty to obtain a little temporary
safety deserve neither liberty nor safety."        -- Benjamin Franklin

Attachment: pgpFaW8Jzc6cg.pgp
Description: PGP signature