Defining a command for changing the line width or the right and left margins?

Question

I am trying define a multi-parameter command which would break up the text to be only 34 characters per line or I suppose another way to look at it would be to have a left margin of 2.7in (1in more than my default) and a right margin of 2.4in (1.3in more than my default).

Essentially what I want are 34 characters (in a mono-spaced font) per line via a command, is this possible?

This is the command that I have so far, which is non-functional, but it's the only thing I can think would work:

\newcommand{\di}[1]{\setlength{\textwidth}{34em}#1}

Here's a MWE

\documentclass[12pt]{letter}
\usepackage{fontspec}
\setmainfont{Courier New}
\setmonofont{Courier New}
\usepackage[width=8.50in, height=11.00in, left=1.70in, right=1.3in, top=0.50in, bottom=1.00in]{geometry}
\newcommand{\di}[1]{\setlength{\textwidth}{34em}#1}   

\begin{document}
Some regular text here...

\di{I want this text to only be 34 characters long}

\end{document}

Do you really want to change the page margins mid document? I think a minipage or parbox placed at an appropriate place can do what you want. — Johannes_B, Oct 21 '14 at 06:05
@Johannes_B Well, I will be needing hundreds of these things mixed into differently formatted text, so I would like to simply be able to define a short command, if possible. — Manofzelego, Oct 21 '14 at 06:09
Define a command that uses a minipage, or rather an eenvironment. — Johannes_B, Oct 21 '14 at 06:13
Something like \newcommand{\di}[1]{\parbox[t]{34ex}{#1}}. Adjust 34ex` appropriately. — , Oct 21 '14 at 06:19
Just noticed you are using letter, do you rely on letter? There is none in your example. — Johannes_B, Oct 21 '14 at 06:21
@Johannes_B Not at all, that should be probably be anything but letter. — Manofzelego, Oct 21 '14 at 06:25
Is the text in the box going to be breakable over multiple pages? — Johannes_B, Oct 21 '14 at 06:25
@HarishKumar That seems to work, but oddly enough I can't use any em values. — Manofzelego, Oct 21 '14 at 06:26
@Johannes_B No, it never will be breaking over to multiple pages in my case. — Manofzelego, Oct 21 '14 at 06:28
@HarishKumar Do you know if it is possible to stop the text from justifying when using \newcommand{\di}[1]{\parbox[t]{34ex}{#1}}? — Manofzelego, Oct 21 '14 at 07:06
Use \raggedright: \newcommand{\di}[1]{\parbox[t]{34ex}{\raggedright #1}} — , Oct 21 '14 at 07:09

score 2 · Answer 1 · edited Apr 13 '17 at 12:34

The changepage package provides this function. The simplest way is to use the adjustwidth environment. You have to specify an amount by which to increase the size of the margins, which you can calculate based on the textwidth, your default margins, and the desired textwidth of the new narrow block.

One problem is defining that narrower textwidth based on characters: as you can see in the test section of the example below, 34 em is actually wider than your default textwidth. 34 ex is too narrow. So in the example I used \settowidth and just typed thirty-four characters. A non-hard-coded solution would be better.

A second problem is that most of the typewriter fonts do not allow justification (see What to do with both "underfull \hbox" and "overfull \hbox" in the same line?). With a narrow text block, many lines spill over the edge. This is not a problem with a proportional font, which I used for one of the images below (by commenting out the second line of code).

\documentclass[12pt,letterpaper]{article}
\renewcommand*\familydefault{\ttdefault}
\newlength{\Lmargin}
\newlength{\Rmargin}
\newlength{\NarrowBlock}
\newlength{\NarrowMargin}
\setlength{\Lmargin}{1.7in}
\setlength{\Rmargin}{1.3in}
\settowidth{\NarrowBlock}{123456789012345678901234567890123}
\usepackage[left=\Lmargin, right=\Rmargin, top=0.5in, bottom=1in]{geometry}
\setlength{\NarrowMargin}{\textwidth}
\addtolength{\NarrowMargin}{-\NarrowBlock}
\addtolength{\NarrowMargin}{-0.5\NarrowMargin}

\newlength{\Test}
\usepackage{lipsum}
\usepackage[strict]{changepage}

\begin{document}

\section{Lengths}

Textwidth: \the\textwidth; Lmargin: \the\Lmargin; Rmargin: \the\Rmargin

NarrowBlock: \the\NarrowBlock; NarrowMargin \the\NarrowMargin

Test at 34em \setlength{\Test}{34em} \the\Test;
Test at 34ex \setlength{\Test}{34ex} \the\Test

\section{Trial}

\lipsum[1]

\begin{adjustwidth}{\NarrowMargin}{\NarrowMargin}
1234567890123456789012345678901234

\lipsum[2]
\end{adjustwidth}

\lipsum[3]
\end{document}

rmdefault ttdefault

(FYI - I used a LaTeX default font command so these could be tested on any engine.)

In your first example, you can add \usepackage{microtype} to get a better result... — Paul Gaborit, Oct 24 '14 at 05:56

Defining a command for changing the line width or the right and left margins?

1 Answers1