Convert Markdown-ish to PDF with Groff MOM

Convert Markdown-ish to PDF with Groff MOM
================-=========================

Last edited: $Date: 2021/02/16 20:20:41 $

There are many ways one can generate a PDF file from
a Markdown file. One example is to use Pandoc to
generate LaTeX and use pdflatex to generate a PDF.

Groff can be a lot faster and require a lot less
resources. TeX Live packages can be quite large and
if you don't need a lot of features this can be
overkill.

[Mom Macros for GNU
Troff](https://www.schaffter.ca/mom/mom-01.html) is
a nice toolbox to create beautiful documents.

I use this to convert small Markdown-ish meeting
notes into a PDF document.

We all appreciate the plain text format, but for
some people in our organisation this is not the
case.

A small awk script can do wonders.

Example document
----------------

This is a small example of the format I use for
meeting notes.

# Notes of the meeting with a special name
- Date: 16 februari 2021
- Time: 14:00 - 15:00
## A nice header
Some information and some sentences. A lot more text. You can
never have enough text.
## Another nice header
Here we have another paragraph filled with very interesting
text.

This is another paragraph.

## Bullets are nice
- There can never be too much bullets.
- Some more are nice to look at
- Always have at least three bullets

### A lower header
This paragraph is right between a third level headers, because
we want a lot of headers.

#### Sublists
This is a small test of sublists. Remember that bullets are great.
- This is a bullet on the first level.
- This too is a bullet on the first level.
- This is a bullet on the second level.
- This too is a bullet on the second level.
- This is the third bullet on the second level.
- This again is a bullet on the first level.
- This too is a bullet on the first level.

Small awk script
----------------

This is the awk script that I use to convert the
Markdown-ish file to the Groff mom format.

BEGIN {
inlisting = 0;
inlisting2 = 0;
inlisting3 = 0;
inparagraph = 0;
print ".PAPER A4"
print ".TITLE_STYLE COLOR YELLOW"
print ".TITLE \"The Screaming Butterflies\" \"Flower Power Workgroup\""
print ".PDF_TITLE \"\\*[$TITLE]"
print ".\\\" Formatting style, margins"
print ".PRINTSTYLE TYPESET"
print ".L_MARGIN 2.5c"
print ".R_MARGIN 2.5c"
print ".B_MARGIN 2.5c"
print ".NEWCOLOR YELLOW #e36c0a"
print ".HEADING_STYLE 1 COLOR YELLOW"
print ".HEADING_STYLE 2 COLOR YELLOW"
print ".\\\" General defaults"
print ".FAMILY P"
print ".FT R"
print ".PT_SIZE 11"
print ".AUTOLEAD 3 3"
print ".PARA_INDENT 0 \\\" No indent because we're spacing paragraphs."
print ".HYPHENATION 0 \\\" No hypenantion of words at end of line."
print ".START"
}
{
if ( $0 ~ /^# / ) { reset_list(); printf ".HEADING 1 \"%s\"\n", substr($0, 3); }
else if ( $0 ~ /^## / ) { reset_list(); printf ".HEADING 2 \"%s\"\n", substr($0, 4); }
else if ( $0 ~ /^### / ) { printf ".HEADING 3 \"%s\"\n", substr($0, 5); }
else if ( $0 ~ /^#### / ) { printf ".HEADING 4 \"%s\"\n", substr($0, 6); }
else if ( $0 ~ /^- / ) {
if ( inlisting2 == 1 ) {
inlisting2 = 0;
print ".LIST OFF"
}
if ( inlisting == 0 ) {
inlisting = 1;
print ".SP .25v"
print ".LIST"
}
print ".ITEM"; print substr($0, 3)
}
else if ( $0 ~ /^\t- / ) {
if ( inlisting == 0 ) {
inlisting = 1;
print ".SP .25v"
print ".LIST"
}
if ( inlisting2 == 0 ) {
inlisting2 = 1;
print ".LIST"
}
print ".ITEM"; print substr($0, 4)
}
else if ( $0 ~ /^\t\t- / ) {
if ( inlisting == 0 ) {
inlisting = 1;
print ".SP .25v"
print ".LIST"
}
if ( inlisting2 == 0 ) {
inlisting2 = 1;
print ".LIST"
}
if ( inlisting3 == 0 ) {
inlisting3 = 1;
print ".LIST"
}
print ".ITEM"; print substr($0, 5)
}
else if ( $0 ~ /^ / ) {
if ( inlisting == 1 || inlisting2 == 1 || inlisting3 == 1) {
gsub("^ *", "", $0)
}
}
else {
if ( inlisting3 == 1 ) {
inlisting3 = 0;
print ".LIST OFF"
}
if ( inlisting2 == 1 ) {
inlisting2 = 0;
print ".LIST OFF"
}
if ( inlisting == 1 ) {
inlisting = 0;
print ".LIST OFF"
print ".SP .25v"
}
if ( inparagraph == 0 ) {
inparagraph = 1;
print ".PP"
}
print $0
}
}
function reset_list()
{
if ( inlisting3 == 1 ) {
inlisting3 = 0;
print ".LIST OFF"
}
if ( inlisting2 == 1 ) {
inlisting2 = 0;
print ".LIST OFF"
}
if ( inlisting == 1 ) {
inlisting = 0;
print ".LIST OFF"
print ".SP .25v"
}
}

This script creates headers with a color and allows
for three levels of lists.

I have just hacked it together in short time and
stopped when it worked, so there is probably a lot
of room for improvement.

Run the awk script and pdfmom
-----------------------------

To use the script, this is the worfklow:

awk -f name-of-the-awk-script > tempfile.mom
pdfmom tempfile.mom > final.pdf

See also
--------

Some very informative resources are:

- Documentation of the Groff mom macros set:
https://tools.ietf.org/doc/groff/html/mom/toc.html
- Comprihensive pages Mom Macros for GNU Troff at
schaffter.ca:
https://www.schaffter.ca/mom/mom-01.html