Re: [Groff] Pic: problem with "shaded"

[Ted Harding]

The reason is found. See below:

On 04-Oct-03 Ted Harding wrote:
> Many thanks to all who responded to my request below, regarding the
> strange behaviour of "shaded" which I observed. Universally, no-one
> else had any problem!
> 
>> There is a problem with "shaded" in pic (groff 1.18.1, Red Hat 9):
>> 
>> .PS
>> line from (0,0) to (0,2)
>> line from (0,0) to (2,0)
>> box width 1 height 1 with .sw at (1,1)
>> box shaded "green" width 1 height 1 with .sw at (1,1)
>> .PE
>> 
>> The green box is shifted up relative to where it should be (i.e.
>> the position of the outline box). I can't locate the problem here
>> ... any help?
> 
> Anyway, I've found out the following about it. It occurs when I run
> groff with my "personal" set of macros (tmac.ted) as well as the ms
> macros (which I use all the time). With tmac.ted as well as ms, I get
> the problem. With ms macros only, I do not get the problem.
> [snip]
> So I feel a bit stuck. Short of going through tmac.ted and elimiinating
> all conveivable candidates one by one until I pin it down, I don't see
> how to proceed from here.

Well I did that, and now know which macro is associated with the problem.
By default I define the "blank line macro" to have no effect, since I
often like to get clearer input layout by having blank lines. So, in my
"private macros", I define:

  .de no_blank_line_effect
  ..
  .blm no_blank_line_effect

With these lines in, I get the above problem. If I comment them out,
the problem disappears. Likewise if, with the above definitions active,
I do

  .blm

in the document. Again no problem.

Now I don't understand why this should happen. What has it got to do
with how "shade" works in pic, or with how the escape sequence "\M"
works in troff?

With thanks,
Ted.


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Date: 04-Oct-03                                       Time: 23:51:08
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