Changing the hyperref target for back references in biblatex bibliography

Question

In my bibliography style, I have added a trigger to change the biblatex bibliography back reference mechanism to refer to the paragraph numbers in the margins ("runners") instead of pages.

\def\blx@addbackref@i#1{%
  \ifbacktracker
    \blx@leavevmode
    \if@filesw
      \protected@write\@mainaux{}{\string\abx@aux@backref
        {\the\c@instcount}{#1}{\the\c@refsection}%
        {\ifbool{bbx:runner}%
          {\therunner}%
          {\thepage}}%
      {\noexpand\the\c@page}}%
    \fi
  \fi%
 }

\therunner is added to a paragraph by using the macro from the jurabook class

\newcommand*{\rn}[2][]{%
  \if@dorunners%
    \stepcounter{runner}%
    #2\marginpar%
      [\hfill{\small\sffamily\therunner}\hspace*{\jb@runnersspace@length}]%
      {\hspace*{\jb@runnersspace@length}{\small\sffamily\therunner}\hfill}%
    \protected@edef\@currentlabel{\therunner}%
   \else%
    #2
  \fi% do NOT delete the percentage sign
  \ifthenelse{\equal{#1}{\@empty}}%
    {}% nix
    %else
    {\label{#1}}%
}

Since the runner mechanism is the only feature from the jurabook class I needed, I have copied that macro into my preamble rather than using the entire class.

If I now set the biblatex option runner to true, thus switching bbx:runner to true, the back reference numbers shown in the bibliography show the paragraph numbers shown in the document margins rather than the page numbers for each cited entry.

However, if I click the number, the link takes me to the page corresponding to the number rather than the paragraph corresponding to the number. This means that I have an entry that is cited in paragraph number 10 on page 6, the number shown in the bibliography will be 10. Clicking that number, however, takes me to page number 10.

Does anyone know how I need to adjust the back referencing mechanism to make the paragraph the hyperref target of the numbers shown in the biblatex bibliography?

Answer 1

A whole lot goes on under the hood to collect and set the list of page numbers in back references. One easy way out of your problem is to make the page hyperlinks set by the pageref bibliography macro point to runners via \hypertarget.

The document below illustrates this approach. I've closely followed the code you provided, but you might prefer other ways to set paragraph numbers. \hypertarget links to the baseline of its second argument, which is too low for runners. I've adapted the solution in this post to raise the link.

\documentclass[twoside]{report}
\usepackage[T1]{fontenc}
\usepackage[ngerman]{babel}
\usepackage{csquotes}
\usepackage[backref]{biblatex}
\usepackage[colorlinks]{hyperref}
\usepackage{lipsum}

\newtoggle{bbx:runner}
\toggletrue{bbx:runner}

\iftoggle{bbx:runner}
  {\DefineBibliographyStrings{german}{%
     backrefpage = {siehe Rn\adddot},
     backrefpages = {siehe Rn\adddot}}}
  {}

\newcounter{runner}
\renewcommand{\therunner}{%
  \iftoggle{bbx:runner}{\arabic{runner}}{\thepage}}

\newlength{\runnersep}
\setlength{\runnersep}{0.5em}

\makeatletter

\patchcmd{\blx@addbackref@i}{\thepage}{\therunner}{}{}
\patchcmd{\blx@addbackref@i}{\c@page}{\c@runner}{}{}

\newcommand{\backreftarget}[1]{%
  \Hy@raisedlink{\hypertarget{page.#1}{}}\small#1}

\newcommand*{\rn}[2][]{%
  \iftoggle{bbx:runner}
    {\stepcounter{runner}#2%
     \marginpar%
       [\hfill{\backreftarget{\therunner}}\hspace*{\runnersep}]%
       {\hspace*{\runnersep}{\backreftarget{\therunner}}\hfill}}
    {\setcounter{runner}{\value{page}}#2}%
  \protected@edef\@currentlabel{\therunner}%
  \ifblank{#1}{}{\phantomsection\label{#1}}}

\makeatother

\newcommand*{\rnref}[1]{%
  \iftoggle{bbx:runner}{Rn.~\ref{#1}}{S.~\ref{#1}}}

\addbibresource{biblatex-examples.bib}

\begin{document}
\rn{Filler} text \parencite{ctan,markey}. \lipsum[1] \vfill
\rn{Filler} text \parencite{companion}. See \rnref{run}. \lipsum[2]
\chapter{Titel}
\rn{Filler} text \parencite{companion,markey}. \lipsum[3]
\chapter{Titel}
\rn[run]{Filler} text \parencite{companion,markey}. \lipsum[4]
\printbibliography
\end{document}

Here's the bibliography from the resulting document.

Commenting out \toggletrue{bbx:runner} back-references page numbers.

Answer 2

I wanted to add a small detail to Audrey's solution. It bugged me that after I implemented the code, I would get warnings from hyperref like

destination with the same identifier (name{page.19}) has been already used

I figured they were due to the fact that a destination by the same name is already set by the page numbering mechanism. So I changed

\newcommand{\backreftarget}[1]{%
  \Hy@raisedlink{\hypertarget{page.#1}{}}\small#1}

to

\newcommand{\backreftarget}[1]{%
  {\Hy@raisedlink{\hypertarget{runner.#1}{}}}\small#1}

and added another \iftoggle{bbx:runner} test to change every instance of \hyperlink{page. to \hyperlink{runner. in the pageref format, pageref:comp and pageref:dump bibliography macros defined in biblatex.def. These edits can easily be made using egreg's extension of etoolbox patch commands.

\makeatletter

\def\act@on@bibmacro#1#2{%
  \expandafter#1\csname abx@macro@\detokenize{#2}\endcsname}
\def\patchbibmacro{\act@on@bibmacro\patchcmd}

\def\act@on@listformat#1#2{%
  \expandafter#1\csname abx@lfd@*@\detokenize{#2}\endcsname}
\def\patchlistformat{\act@on@listformat\patchcmd}

\iftoggle{bbx:runner}
  {\patchlistformat{pageref}{page.}{runner.}{}{}%
   \patchbibmacro{pageref:comp}{page.}{runner.}{}{}%
   \patchbibmacro{pageref:comp}{page.}{runner.}{}{}%
   \blx@tempcnta\z@%
   \loop\ifnum\blx@tempcnta<10
     \patchbibmacro{pageref:dump}{page.}{runner.}{}{}%
     \advance\blx@tempcnta\@ne
   \repeat}
  {}

\makeatother