From:	MERC::"uunet!CRVAX.SRI.COM!RELAY-INFO-VAX" 12-JUL-1992 08:04:21.96
To:	gdcarson@icaen.uiowa.edu, info-vax@sri.com
CC:	
Subj:	Re: X Windows - Needs pipe or socket or somthing

Reply-To: mahan@tgv.com


In article <1992Jul10.210100.18737@news.uiowa.edu> you write:
#
#Hello All;
#	Here's the situation, I have an X windows display program, that shows
#images generated in a fortran image processing program.  I can display the
#normal end process results, but would also like to display the intermediate
#results.  The fortran program generates points as it does a search through the
#image, these points then become the new image array points.  The trouble is
#that I have thus far only figured out how to send an entire image array to the
#X windows program.  I would like to be able to send the new data to the display
#program point by point and have it redraw accordingly.  The data is initially
#passed to the display program as an integer array, and the fortran program does
#its thing on that array.  Meaning that it changes the data points in the array
#as it does its processing.
#	The system we are on is a fast VMS box.  Is there any way to cause the
#X windows program to accecpt the new points from the fortran program if I start
#the X program as a spawned process from the fortran program?  Or does any one
#have any other suggestions?  Please respond in mail, and I can post a summary
#if there seems to be any interest in this area.
#	Thanks for advance for all your help.
#

Here is my suggestion.

Establish a communications link between the Fortran program and the X Display
program via Mailboxes.   The method to use in the X program depends on wheter
you are writing using Xt routines or Xlib routines.  If the program uses
Xt... then post an asynchronous read on the Mailbox using an EFN for 
notification.  Then use XtAddInput() to have the toolkit watch the EFN and
call the routine you specify when there is input to read.

If on the other hand you are using Xlib (no Xt calls at all) used the follow-
ing:  Post an asynchronous read on the Mailbox using AST's.  When the AST is
fired, have it set a global flag indicating that input has been recieved.
In you event loop, check the global flag as often as you like.

This should allow you to feed your display program one point at a time.

--
Patrick L. Mahan

--- TGV Window Washer ------------------------------- Mahan@TGV.COM ---------

Waking a person unnecessarily should not be considered  - Lazarus Long
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