A general way to make Lined Background independent to papersize/orientation

Question

I have the following setup which generate lined-paper background in a4paper (modified from texblog and answer from this site)

I would like to make this code more papersize independent.

The value "28" on for-loop works for this papersize (A4), but for other papersize or orientation (Landscape/Potrait), it need to be adjusted.

I'm guessing I can put \paperheight somewhere in the for-loop, but I don't know how to convert that value (which is in inch or cm) into (coordinate-unit) after \draw.

Or maybe doing arithmetic with page.north west and page.south west, if that even possible.

Yes I know, I could just modified them manually (changing value 28 to 38 in for-loop when working in a3paper), but I'm interested on more automatic solution.

In short: I have those many \usepackage{geometry} commented in code, and would want to make a single \mygraphpaper definition that works on them all.

Layout document that I want to achieve: No left/right margin, the same x margin from top and bottom

\documentclass{article} 
\usepackage{tikz}
%\usepackage[landscape,a3paper]{geometry}
\usepackage[a4paper]{geometry}
%\usepackage[landscape,a5paper]{geometry}
%\usepackage[a5paper]{geometry}
%\usepackage[landscape,paperheight=8.17in,paperwidth=6.32in,top=1in,bottom=1in,right=1in,left=1in]{geometry}
\usetikzlibrary{calc}
\def\mygraphpaper{%
  \begin{tikzpicture}
  \foreach \i in {4,5,...,28}{
  \draw[gray] ($(current page.north west)+(0,-\i)$) -- ($(current page.north east)+(0,-\i)$);}
  \end{tikzpicture}%
}
\usepackage{background}
\backgroundsetup{
  angle=0,
  contents=\mygraphpaper,
  color=black,
  scale=1,
}

\begin{document}
\pagenumbering{gobble}
$\,$
\end{document}

Answer 1

For two parameters where #1 stands for the distance between the first horizontal line to the top of the page and #2 for the minimum distance to the bottom you can use define \mygraphpaper as such

\newcommand*\mygraphpaper[2]{%
  \begin{tikzpicture}[remember picture,overlay]
  \foreach[parse=true] \i in {0,...,(\paperheight-(#1)-(#2))/1cm}{
  \draw[gray] ([yshift={-\i cm-(#1)}]current page.north west) -- ++(right:\paperwidth);}
  \end{tikzpicture}%
}

Note that I've used rememer picture and overlay so that the special current page node gets recognized correctly and we don't have to deal with whereever background decides to place this content.

Note however, that the everypage package that is used by everypage is deprecated.

---

With a LaTeX version of the past two years, you can (should) use the shipout/background hook which acts as a picture that has its origin at the top left corner of the page. Since you're only drawing horizontal lines, you can just draw it that way without having to use PGF/TikZ

The same math as before gets us the needed number of iterations for \multiput.

Code (TikZ + background/everypage)

\documentclass{article} 
\usepackage{tikz}
%\usepackage[landscape,a3paper]{geometry}
\usepackage[a4paper]{geometry}
%\usepackage[landscape,a5paper]{geometry}
%\usepackage[a5paper]{geometry}
%\usepackage[landscape,paperheight=8.17in,paperwidth=6.32in,top=1in,bottom=1in,right=1in,left=1in]{geometry}
\usetikzlibrary{calc}
\newcommand*\mygraphpaper[2]{%
  \begin{tikzpicture}[remember picture,overlay]
  \foreach[parse=true] \i in {0,...,(\paperheight-(#1)-(#2))/1cm}{
  \draw[gray] ([yshift={-\i cm-(#1)}]current page.north west) -- ++(right:\paperwidth);}
  \end{tikzpicture}%
}
\usepackage{background}
\backgroundsetup{
  angle=0,
  contents=\mygraphpaper{3.5cm}{5cm},
  color=black,
  scale=1,
}

\begin{document}
\pagenumbering{gobble}
$\,$
\end{document}

Code (shipout/background + picture)

\documentclass{article}
%\usepackage[landscape,a3paper]{geometry}
\usepackage[a4paper]{geometry}
%\usepackage[landscape,a5paper]{geometry}
%\usepackage[a5paper]{geometry}
%\usepackage[landscape,paperheight=8.17in,paperwidth=6.32in,top=1in,bottom=1in,right=1in,left=1in]{geometry}
\usepackage{xcolor}
\newcommand*\mygraphpaper[2]{%
  \color{gray}
  \setlength\unitlength{1cm}
  \linethickness{.4pt}
  \multiput(0,-#1)(0,-1){\fpeval{1+trunc((\paperheight-#1cm-#2cm)/1cm,0)}}{%
    \line(1,0){\paperwidth}
  }
}
\AddToHook{shipout/background}{\mygraphpaper{3.5}{5}}
\begin{document}
\pagenumbering{gobble}
$\,$
\end{document}

Answer 2

You could use the grid operation from TikZ (the negative (or zero) value for xstep will remove the vertical lines, so you just get your horizontal rules):

\documentclass{article} 
\usepackage{tikz}
%\usepackage[landscape,a3paper]{geometry}
\usepackage[a4paper]{geometry}
%\usepackage[landscape,a5paper]{geometry}
%\usepackage[a5paper]{geometry}
%\usepackage[landscape,paperheight=8.17in,paperwidth=6.32in,top=1in,bottom=1in,right=1in,left=1in]{geometry}
\usetikzlibrary{calc}

\def\mygraphpaper{%
  \begin{tikzpicture}[remember picture]
    \draw[ystep=1cm, xstep=-1cm, gray] ([yshift=-2cm]current page.north west) grid ([yshift=2cm]current page.south east);
  \end{tikzpicture}%
}
\usepackage{background}
\backgroundsetup{
  angle=0,
  contents=\mygraphpaper,
  color=black,
  scale=1,
}

\begin{document}
\pagenumbering{gobble}
$\,$
\end{document}