Get two short subtitles out of a too long title

Question

Is there a way to get n shorter strings out of a long one in Latex? Let's say I have something like \title{A very long title} and I want it to be broken into two pieces such that I can later use colorbox{red}{A very} and \color{blue}{long title}. The break point should be calculated through a distance provided by the user.

Answer 1

I don't think you need anything special for the \chapter command:

\chapter[The real long title]
  {\textcolor{red}{The real}\\
   \textcolor{green}{long title}}

is all you need. You can abstract it with new commands:

\documentclass{book}
\usepackage{xcolor}
\usepackage{xparse}
\newcommand{\firstchapline}[1]{\textcolor{red}{#1}}
\newcommand{\secondchapline}[1]{\textcolor{green}{#1}}

\makeatletter
\NewDocumentCommand{\coloredchapter}{som}
 {\IfBooleanTF{#1}
   {\chapter*{#3}}
   {\IfNoValueTF{#2}
     {\make@coloredchapter{#3}}
     {\chapter[#2]{#3}}%
   }%
 }
 \newcommand{\make@coloredchapter}[1]{%
   \begingroup
   \let\firstchapline\@firstofone
   \let\secondchapline\@firstofone
   \let\\\space
   \protected@edef\x{\endgroup\noexpand\chapter[#1]}%
   \x{#1}}
\makeatletter

\begin{document}
\frontmatter
\tableofcontents
\mainmatter
\coloredchapter{\firstchapline{A really}\\\secondchapline{long title}}
\coloredchapter[Short title]{\firstchapline{A really}\\\secondchapline{long title}}
\coloredchapter*{\firstchapline{A really}\\\secondchapline{long title}}
\end{document}