Re: [Groff] Suggestion for images in groff/gpic, current state

[Egil Kvaleberg]

On Tue, 2002-12-03 at 09:35, Werner LEMBERG wrote:

> Can someone please post the results of the following:
> 
>   M
>   .tm .w == \n[.w]
>   i
>   .tm .w == \n[.w]
>   \w'a'
>   .tm .w == \n[.w]
>   \w'aa'
>   .tm .w == \n[.w]
> 
> With `troff -Tps' I get
> 
>   .w == 8890
>   .w == 2780
>   .w == 5000
>   .w == 5000

Unix V7 on a PDP-11 gives:

$ cat test
M
.tm .w = \n(.w
i
.tm .w = \n(.w
\w'a'
.tm .w = \n(.w
\w'aa'
.tm .w = \n(.w
$ troff test
.w = 20
.w = 20
.w = 20
.w = 20
$

Apperantly, this does not work. .w is probably not really valid beyond
the current input line, and is probably set to the width of a space
(ending the lines with \c did no difference, btw).

To test this, I did:

$ cat test2
\kaM\kb\h'\n(.wu'\kc
.tm a = \na
.tm b = \nb
.tm c = \nc
$ troff test2
a = 0
b = 58
c = 116
$

Which means .w does the expected thing in this case. To test the
connection between \w and .w, I did:

$ cat test3
\kaM\h'\w!MMMM!u'\kb\h'\n(.wu'\kc
.tm a = \na
.tm b = \nb
.tm c = \nc
$ troff test3
a = 0
b = 290
c = 522
$

Appearantly, .w in this case takes on the value of the horizontal
movement. But is it due to \w or \h? Lets try:

$ cat test4
\kaM\h'1i'\kb\h'\n(.wu'\kc
.tm a = \na
.tm b = \nb
.tm c = \nc
$ troff test4
a = 0
b = 490
c = 922
$

Appearantly, the term "last character printed" also includes \h''.
Trying \v'', it turns out that this is also included, the width
obviously always being 0:

$ cat test5
\kaM\v'1i'\kb\h'\n(.wu'\kc
.tm a = \na
.tm b = \nb
.tm c = \nc
$ troff test5
a = 0
b = 58
c = 58
$

I did in fact not come up with any method of actually testing if \w
influences .w per se, since I found no way of invoking \w without
influencing .w by other means. So it all becomes a very academic
exercise. I would believe \w does not touch .w.

I'm quite hard pressed to believe that anyone has ever relied on the
above behaviour, so I suggest leaving groff exactly as it is. I can
always ask around, though.

Egil
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