Properly capture chapter name

Question

I have a code that looks like the following:

\documentclass{scrbook}
\usepackage[automark]{scrpage2}
\usepackage{lipsum}


\let\oldchapter\chapter
\newcommand\temphead{}
\newcommand\chaphead{}
\renewcommand\chapter[2][\temphead]{%
    \renewcommand\temphead{#2}%
    \renewcommand\chaphead{#2}%                     
    \oldchapter[#1]{#2}}

\title{My title}

\makeatletter             
\let\titlehead\@title         
\makeatother

\cfoot[\rule{6mm}{0.8pt}\\\pagemark]{\rule{6mm}{0.8pt}\\\pagemark}
\ofoot[]{}
\lehead[]{}
\cehead[]{\titlehead}    
\cohead[]{\chaphead}                                          
\ohead[]{}

\renewcommand*{\chapterpagestyle}{scrplain}


\begin{document}
\pagestyle{scrheadings}

\chapter{My first chapter}

\lipsum
\lipsum


\chapter{My second chapter}

\end{document}

The goal is to display the chapter name on right pages, and the title of the book of left pages.

Now when the page preceding a new chapter is a right page, the chapter displayed is the one of the following chapter. My sample code shows it, as the last page of the first chapter says "My second chapter".

How can I fix this?

Answer 1

You can add \clearpage or (\cleardoublepage if needed) right before \chapter{My second chapter}.

Answer 2

The normal \chapter contains a \cleardoublepage (which acts like \clearpage in one-sided documents). You need to add a \cleardoublepage before changing the header to flush out the last page of the previous chapter. The second \cleardoublepage in the \oldchapter will no cause any empty pages.

\renewcommand\chapter[2][\temphead]{%
    \cleardoublepage
    \renewcommand\temphead{#2}%
    \renewcommand\chaphead{#2}%
    \oldchapter[#1]{#2}}

This makes your new \chapter work with \input and \include or in the main file.

Answer 3

The issue was that I used \input instead of \include to include chapter files. This caused the \chaphead macro to contain the wrong value. Any explanation as to why this would happen is welcome.