FilePro Must Haves...

[Bob Rasmussen]

On Thu, 19 Jan 2006, Bill Campbell wrote:

> The default display for most xterms is 25x80, and my guess would be that
> Windows programs like Anzio, putty, and teraterm default to 24x80 or 25x80
> as well.
> ...

Let me describe an actual capability now in place, to demonstrate what is
possible.

A user runs xterm or Anzio, over a telnet or SSH connection. TERM is vt220
or similar. Screen size is 80x24.

User runs 'vi' and brings up a file. Note that vi uses terminfo for its
terminal information. Then user tells client to change window size to
90x36. Vi reacts by adjusting the screen display, so 90x36 characters are
visible and placed properly.

How can this work, you might ask.

The daemons (sshd, telnetd) have protocols by which the client can tell
the daemon what the window size (rows and columns) is at startup, and
whenever it changes. When the user changes the client's window size, the
following happens:

1. Client notifies daemon of new window size.

2. Daemon sends a signal (SIGWNCH) to associated processes.

3. Vi gets signal, for which it has a handler routine specified.

4. Vi makes a call to Unix to get current window size.

5. Vi reallocates its screen buffer and repaints the screen.

So don't tell me that we're restricted by the terminfo/termcap, etc. It is
very easy to program, and standards exist.

Likewise there are standards (mostly as defined by xterm) for sending
mouse actions (such as clicks) to the program running on the server,
giving the coordinates in row and column. A program on the server that
deals with special key handling (recognizing arrow keys, function keys,
etc.) can  also look for the sequences generated by mouse actions. This
can cause actions in the application program - I'll leave the details to
others.

Acucobol implemented mouse action support in their character-based
environment about 10 years ago.

Technically, this stuff is all easy, and the problems have been addressed
before by others. So is this an issue of "we don't know how to do this",
or is it "we don't want to devote the development resources to this"?

Regards,
....Bob Rasmussen,   President,   Rasmussen Software, Inc.

personal e-mail: ras at anzio.com
 company e-mail: rsi at anzio.com
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