bugGNU roff - Bugs: bug #44530, [pic] some dotted/dashed lines...

 
 

bug #44530: [pic] some dotted/dashed lines come out solid

Submitter:  Scott Tracey <streez>
Submitted:  Fri 13 Mar 2015 01:19:04 AM UTC
   
 
Category:  Preprocessor pic Severity:  3 - Normal
Item Group:  Documentation Status:  Confirmed
Privacy:  Public Assigned to:  gbranden
Open/Closed:  Open Planned Release:  None
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Wed 11 Aug 2021 04:09:49 PM UTC, comment #2: 

Doug was good enough to respond to me via email since Savannah seems to have deployed a CAPTCHA against non-logged-in users that only machine intelligences can penetrate.


The complaint identifies an infelicitous feature, but technically not
a bug. The spacing of dots scales with other graphics. The spacing is
settable.

The particular example,

     line from 0 to 100 dotted

should give full coordinates for the points:

     line from 0,0 to 100,0 dotted

You can set the spacing between dots. This will place them 5 units apart:

      line from 0,0 to 100,0 dotted 5

The spacing of dashes can be set the same way.
The length of dashes is set by the dashwid variable.

I commend /usr/share/doc/groff/pic.ps as an eminently
readable reference, the presence of which is not widely
known.


With that clue in hand, I am able to reproduce the problem.  I think updating the documentation might be a sufficient remedy.

Thanks, Doug!

G. Branden Robinson <gbranden>
Group administrator
Wed 11 Aug 2021 01:15:23 PM UTC, comment #1: 

Hi Doug,

Here's a blast from the past.

original submission:

> It appears that the number of dots and dashes in an interrupted
> line is determined without regard to scaling. Thus
> .PS 1i
> line from 0 to 100 dotted
> .PE
> produces in grops a heavy solid line, the result of
> cramming hundreds of standard-size dots into an inch.
>
> http://lists.gnu.org/archive/html/bug-groff/2015-03/msg00000.html


I'm having a problem because apparently the syntax of your reproducer is defective in some way, and I don't understand the grammar of pic well enough to remedy it in a way that I am sure will reproduce the problem you're seeing.

Can you (or someone reading this with more skill than I in pic--few people have less) supply a reproducer?


$ groff -p -ms
.LP
.PS 1i
line from 0 to 100 dotted
.PE
pic:<standard input>:3: syntax error before 'to'
pic:<standard input>:3: giving up on this picture


If I bust it down to just 'line dotted', I get a dotted line that doesn't reproduce the problem; I assume the unitless numbers have something to do with the density problem, or did in groff 1.22.3, the current release when this bug was filed in 2015--but "git log src/preproc/pic/*.{h,cpp}" tells me there have been no changes to pic features since then.

G. Branden Robinson <gbranden>
Group administrator
Fri 13 Mar 2015 01:19:04 AM UTC, original submission:  

It appears that the number of dots and dashes in an interrupted
line is determined without regard to scaling. Thus
.PS 1i
line from 0 to 100 dotted
.PE
produces in grops a heavy solid line, the result of
cramming hundreds of standard-size dots into an inch.

http://lists.gnu.org/archive/html/bug-groff/2015-03/msg00000.html

Scott Tracey <streez>

 

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    Follow 8 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2021-08-11 gbranden Item GroupIncorrect behaviour Documentation
        StatusNeed Info Confirmed
        Assigned toNone gbranden
    2021-08-11 gbranden StatusNone Need Info
        SummarySome dotted/dashed pic lines come out solid [pic] some dotted/dashed lines come out solid
    2021-08-11 gbranden Carbon-Copy- Added douglas mcilroy <douglas.mcilroy@dartmouth.edu>
    2021-03-01 gbranden CategoryNone Preprocessor pic
    2015-03-13 streez Carbon-Copy- Added streez

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