Incompatibility between memoir settrimmedsize and PDF-X?

Question

I'm trying to generate a pdf-x with pdfxpackage.

If I compile the following mwe with LuaLaTeX or XeLaTeX

\documentclass{memoir}
\usepackage{lipsum}

\setstocksize{29.7cm}{21cm}
\settrimmedsize{21cm}{13cm}{*}
\settypeblocksize{*}{9.1cm}{1.618}
\setlrmargins{1.5cm}{*}{*}
\setulmargins{2.12cm}{*}{2}
\checkandfixthelayout

\usepackage[x-1a]{pdfx}

\begin{document}

\lipsum

\end{document}

the layout gets messed up. It seems that the problem is between pdfx and memoir's \settrimmedsize: if I set the trimmed size identical with the stock size, the problem disappears.

As a matter of fact, the problem disappears also when I generate pdf type a-1b (with \usepackage[a-1b]{pdfx}).

Does anyone have an idea where the issue come from, and how to fix it?

Answer 1

pdfx doesn't take memoir's dimensions into account and uses \paperwidth instead of \stockwidth for the mediabox. You can reset this like this (with lualatex and pdflatex, xelatex needs different code), but you probably will have to adapt the values of the other boxes too--I simply copied the values currently used by pdfx.

\documentclass{memoir}

\usepackage{lipsum}

\setstocksize{29.7cm}{21cm}
\settrimmedsize{21cm}{13cm}{*}
\settypeblocksize{*}{9.1cm}{1.618}
\setlrmargins{1.5cm}{*}{*}
\setulmargins{2.12cm}{*}{2}
\checkandfixthelayout

\usepackage[x-1a]{pdfx}

\ExplSyntaxOn
\exp_args:Nx
\pdfpagesattr
  {
    /MediaBox[0~0~\dim_to_decimal:n{0.996264009963\stockwidth}~\dim_to_decimal:n{0.996264009963\stockheight}]
    /BleedBox[0~0~\dim_to_decimal:n{0.996264009963\stockwidth}~\dim_to_decimal:n{0.996264009963\stockheight}]
    /CropBox[0~0~\dim_to_decimal:n{0.996264009963\stockwidth}~\dim_to_decimal:n{0.996264009963\stockheight}]
    /TrimBox[25~20~\dim_to_decimal:n{0.996264009963\stockwidth-25pt}~\dim_to_decimal:n{0.996264009963\stockheight-20pt}]
  }
\ExplSyntaxOff   
   
\begin{document}

\lipsum

\end{document}