Scores Without Margins

% !TEX program = LuaLaTeX+se

% This document produces a pdf containing the score with no margin.
% It is based on this solution:
% http://tex.stackexchange.com/questions/291630/best-way-to-know-bottom-line-height-of-a-pdf/291664#291664
%
% It contains advanced commands quite difficult to understand, but should be straightforward
% to adapt to your needs.
%
\documentclass[11pt]{article}
\usepackage{gregoriotex}
\usepackage{libertine}
% Do not load geometry, fullpage, or any package changing width
% or margins.

\hoffset-1in
\voffset-1in
\newbox\scorebox

% using the "commentary" header of the gabc file
\gresetheadercapture{commentary}{grecommentary}{string}

\begin{document}

% here the final "9" of the commentary would be cut too sharp. The reason is that
% the italic "9" glyph in the libertine font is larger than its bounding box, the
% dimension of which that TeX is actually aware (which is normal for italic), so we
% have manually insert the italic correction (`\/`), the small kern which is normally
% used when switching from italics to upright fonts.
% In the libertine font, the “f” is also slightly taller than its bounding box, so we have
% to prevent it from getting cut off too.  Unfortunately, there isn’t a convenient
% measure of this built in, so we have to fudge this ourselves with a strut.  Adjust the
% 0.8em to your taste.
% We use an admittedly strange trick to fix these, redefining grecommentary.
\let\grevanillacommentary\grecommentary
\def\grecommentary#1{\grevanillacommentary{#1\/\rule{0pt}{0.8em}}}

\setbox\scorebox=\vbox{\hsize=10cm\relax % change the width of the score here
	\gregorioscore[a]{PopulusSion}
}
\pdfpagewidth\wd\scorebox
\pdfpageheight\dimexpr\ht\scorebox+\dp\scorebox\relax
\shipout\box\scorebox
\end{document}