[texhax] LuaLaTeX: increase font expansion in narrow columns

[Arno Trautmann]

Hi all,

I just read an article an a seemingly Word-typeset document with very 
narrow columns when a picture was inserted between the columns. I don't 
have to tell how ugly the result was …

However, I got the idea that one could increase the quality of such 
documents by increasing the amount of font expansion for very narrow 
columns while keeping it at a lower amount for the rest of the document.
Consider the following document:

\documentclass[english,twocolumn]{scrartcl}
\usepackage{babel,blindtext}
\usepackage{microtype}
\usepackage{wrapfig}
\microtypesetup{stretch=50}
\begin{document}
\blindtext
\begin{wrapfigure}{i}{4.5cm}
\fbox{figure}
\end{wrapfigure}
\blindtext
\end{document}

Without the increased stretch, the word “This” will go to the next line.

Now, two problems arise:
• The amount of stretching cannot be changed in-document with the normal 
user interface of the microtype package.
• I want to do this automatically – I was thinking of using the 
pre_linebreak_filter for this in LuaLaTeX – but can I access the 
linewidth of the to-be-typeset line?

So – any comments on this? (Please postpone stylistic comments if this 
is a good thing to do – first I want to try before judging if it looks 
ugly ;) )

cheers
Arno