\documentclass{article}
\usepackage{scrtime}
\usepackage{hyperref}
\usepackage{url}
\usepackage{verbatim}
\usepackage{listings}
\lstset{language=R}
\usepackage{graphicx}
\DeclareGraphicsExtensions{.pdf}
\newcommand{\code}[1]{{\tt #1}}
\SweaveOpts{warning=FALSE,dev="png"}
\title{\code{knitr} $\to$ \LaTeX $\to$ HTML testing}
\date{\today @ \thistime}

\begin{document}

\maketitle

\section{introduction}

I have been trying to find an Sweave $\to$ \LaTeX\ $\to$ HTML
pathway that works via \code{knitr} \ldots

I think I can get it to work now, although it's not as pretty as I'd like. The bottom line is that to get this working you need to 
\begin{itemize}
\item include \verb+render_listings()+ in an R chunk near the top of your file (I prefer the default highlighting on aesthetic grounds, but this works better with existing \LaTeX-to-HTML tools)
\item add \verb+\usepackage{graphicx}+; \verb+\DeclareGraphicsExtension{.pdf}+;
  \verb+\usepackage{listings}+; \verb+\lstset{language=R}+ to the preamble of your document, and make sure that
  the \href{http://biostat.mc.vanderbilt.edu/wiki/pub/Main/SweaveTemplate/Sweavel.sty}{Sweavel.sty} file is available.
\item make sure you have \code{myhtml.cfg} file available (see the end of this document)
\item run \code{htlatex} as follows:
\begin{verbatim}
htlatex $*.tex myhtml "" "" "-interaction=nonstopmode"
\end{verbatim}
where (of course) \verb+$*+ is the basename of your document (this line is from a Makefile)
\end{itemize}

\section{example}

<<setup,cache=FALSE>>=
## normally also include=FALSE
render_listings()
@ 

(An equation)
\begin{equation}
a+b
\end{equation}

Some code:

<<>>=
## here's a comment ...
(x <- 5^2)
y <- 17
@ 

A figure:
<<>>=
set.seed(101)
plot(rnorm(10),rnorm(10))
@ 

Inline R expression: the value of $x$ is \Sexpr{x}.

Session info:
<<>>=
sessionInfo()
@ 

\section{issues}
\begin{itemize}
  \item The assignment arrow \verb+<-+ 
    inside the \code{Sinput} chunk
    confuses \code{htlatex} --- have to run \code{htlatex}
    with \code{interaction=nonstopmode} (see below) --- but 
    the final document seems to come out OK.  
    Is there a fix to \code{Sweavel.sty}, or something
    else, that will make it work?
  \item I don't have pretty syntax highlighting working for htlatex yet.
\end{itemize}

\section{references}
\begin{itemize}
\item From Yihui Xie, about using \verb+render_listings()+
  (and the fact that he prefers to start with a markdown document):
  \url{https://groups.google.com/forum/#!msg/knitr/Dv2JmcDcuBo/dYkp2rEuSlAJ}
\item{htlatex image processing: \url{http://tex.stackexchange.com/questions/46156/pdf-image-files-and-htlatex}}
\item{htlatex formatting (I don't have this working right yet): \url{http://tex.stackexchange.com/questions/7216/how-to-get-tex4ht-to-respect-listings-styling-better}}
\item{more on htlatex/listings formatting (haven't tried this yet):
    \url{http://tex.stackexchange.com/questions/64054/latex-to-html-preserving-code-coloring-from-listings}}
\end{itemize}

\section{latexml}

\code{latexml} is an alternative conversion program that I haven't managed to get working equally well \ldots

<<eval=FALSE>>=
system("latexml --dest='knitr_listings_test.xml' knitr_listings_test.tex")
system("latexmlpost --dest='knitr_listings_test.xhtml' knitr_listings_test.xml")
@ 

\section{\code{myhtml.cfg}}
  
\VerbatimInput[frame=single]{myhtml.cfg}

\end{document}