Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!cs.utexas.edu!sun-barr!newstop!sun!frisbee!jcb
From: jcb@frisbee.Sun.COM (Jim Becker)
Newsgroups: comp.windows.x
Subject: Re: Delayed screen snapshots
Keywords: X screen snapshot
Message-ID: <133176@sun.Eng.Sun.COM>
Date: 20 Mar 90 19:30:28 GMT
References: <312@gazette.bcm.tmc.edu>
Sender: news@sun.Eng.Sun.COM
Lines: 60

klong@wilkins.bcm.tmc.edu (Kevin Long) writes:

   I need something to take a snap shot of a region of my screen, but delay
   doing it for enough time for me to bring up a pop-up menu.

   Other ideas/suggestions?  I'll repost what I learn.

A bit over a year ago I needed to write a program that did this, and
took a different approach than others. This program I also posted to
the net, around Feb 89, and should still be around somewhere.

The need was to get bitmaps of main application windows and popups to
be integrated into the text/graphics help system that I developed.

The approach that I took was really simple, and just a few pages of
code. Here goes:

	1) create a master window that defines the outline that will
           be snapshot. the content of this is null, just the placement
	   and size is of interest.

	2) map the window, so the user can define the area of the
           snapshot via window manager resize and movement.
	
	3) run a loop that *polls* the keyboard a couple of times	
	   a second with XQueryKeymap().

	4) notice when certain non-typical keys are pressed. perform
	   actions associated with the keys. I had front, back and
	   snapshot bound to the physical keys.

	5) when the user hits the desired key, do a XGetWindowAttributes()
	   to synch the size and position of the master outline
	   window on the root window.

	6) save the area where the window is using the storage means
	   of interest. at the time I saved in pixwin formats. one
	   can also do an XGetImage() to get the bits. note that the
           master window should be backed before getting the image!
	   (the image is lifted from the RootWindow)

	7) have some scheme where the snapshots are numbered, and
	   allow the user to make lots of them.

I  whipped  up this program in a couple of hours. Not fancy but it got
the  job  done  for  our  tech  writers to generate hundreds of screen
snapshots to be integrated into the help text content.

The popups that I wrote also grabbed the server, so I added a variable
to the interface system that checked a global  variable  that  toggled
the server grab. (It was called `DONTGRABSERVER'!)

This code should be out there on the archive servers somewhere, called
snap.c.  It  isn't  fancy,  but it worked great. Something simple that
gets the job done. KISS?


-Jim Becker
--    
	 Jim Becker / jcb%frisbee@sun.com  / Sun Microsystems