Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ulowell!apollo!oj
From: oj@apollo.COM (Ellis Oliver Jones)
Newsgroups: comp.sys.apollo
Subject: Re: system calls and FORTRAN
Summary: more uses the vt100 emulator
Keywords: Aegis, system calls, more, FORTRAN, VT100, fonts
Message-ID: <432acc9f.d5b2@apollo.COM>
Date: 12 May 89 00:47:00 GMT
References: <621@imsl.UUCP>
Reply-To: oj@apollo.com (Ollie Jones)
Organization: Apollo Computer, Chelmsford, MA
Lines: 46

In article <621@imsl.UUCP> dy@imsl.UUCP (Demetrios Yannakopoulos) writes:
>		pad_$inq_windows(..., wind-struct, ...)
>    .....the returned height 
>    which is in number of lines, is not always accurate. It can be +/- one 
>    line off (apparently, it is rounded up/down to the nearest number of 
>    full lines). Hence, the next "more" screen can one line too much or one 
>    line less! 

By default, these quantities are relative to character sizes in
the current font.   You can cause them to be reported in pixels instead
by using
            pad_$set_scale ( stream_id, 1, 1, &status);

>    During the "more" utility the input pad disappears (!)

Indeed, the more(1) utility invokes the VT100 emulator.  The VT100 emulator
uses these fonts: /sys/dm/fonts/vt100l.dw     (double wide)
                  /sys/dm/fonts/vt100l.dhb    (double high, bottom)
                  /sys/dm/fonts/vt100l.dht    (double high, top)
                  /sys/dm/fonts/vt100l        (ordinary, default)
                  /sys/dm/fonts/vt100l.b      (bold)
(Under some circumstances it uses the vt100s series instead.  To find
out what fonts it's using at any given moment, do /com/las vt100_server .)

Possibly the reason for your problem is that these vt100 emulator fonts
are different from your dm default, and therefore the pad-height
computation is being done with wrong input data.

You could try doing a pad_$set_scale before your pad_$inq_windows,
and computing the rounding based on the VT100 font sizes rather than
the DM default font sizes. 

>    I have called the Apollo guys (...or should I say H-P ???)
Slack the rope, hangman!  :-)  We still have a few more days of being Apollo 
before the beginning of the H-P era!

>   ...I have been told that there are two: the top (big) one which is usually
>    read-only, and the bottom read-write one (usually one line plus 
>    "something" height).
Yes, that's so.  See the writeup on pad_$create for more info.

>    Why does the bottom pad disappear during the
>    "write"-ing of the text in the upper screen?
The VT100 emulator calls pad_$raw which hides the input pad.

/Ollie Jones (speaking for myself, not for Apollo or any other company.)