Cfrgtkky

In a desire to promote open access to research results, I would like to add a small open access logo in the list of bibliographic references I cite in my papers. This logo could be added automatically as soon as the pair "eprint + eprinttype" (for instance with arxiv) is used with biblatex. It could also be added manually for works that are openly accessible on publisher's websites (called gold access). Since I do not know where to start to achieve the above goal, I do not provide any MWE.

EDIT Based on the comments by moewe and gusbrs, I am providing an MWE (the url links were chosen randomly and the OA logo is provided for compilation purposes)

documentclass{article}

usepackage{graphicx}

usepackage{filecontents}

begin{filecontents*}{jobname.bib}

@article{bib:A,

    author={Authors},

    title={Title},

    journal={Journal name},

    year={2018},

}

@article{bib:B,

    author={Authors},

    title={Title},

    journal={Journal name},

    year={2018},

    eprinttype={oai},

    eprint={hal-01917888},

    keywords={OA}

}

@article{bib:C,

    author={Authors},

    title={Title},

    journal={Journal name},

    year={2018},

    eprinttype={arxiv},

    eprint={arXiv:1811.03094},

    keywords={OA}

}

end{filecontents*}



usepackage[backend=bibtex,style=numeric,eprint=true]{biblatex}

addbibresource{MWEOA.bib}



% new eprinttype

defoaitourl#1{http://hal.archives-ouvertes.fr/#1}

DeclareFieldFormat{eprint:oai}{%

    ifhyperref

        {href{oaitourl#1}{hal:~nolinkurl{#1}}}

        {hal:~nolinkurl{#1}}}



% OA logo in the margin  

newcommand{impmark}{strutvadjust{domark}}

newcommand{domark}{%

  vbox to 0pt{

    kern-3dpstrutbox %manual control of the logo top alignment

    struthfillrlap{kern1emincludegraphics[height=10pt]{OA}}

    vss

  }%

}

renewbibmacro*{begentry}{ifkeyword{OA}{impmark}{}}



usepackage[hidelinks]{hyperref}



begin{document}

nocite{*}

printbibliography

end{document}

which looks like

However, it would not be nice to add two features:

1. when the eprinttype (of the type arxiv or oai) field is not empty, the Open Access logo should be printed automatically (that is without using the keywords entry OA).


2. the logo should be clickable with the url address stemming from the information given in the eprinttype and eprint fields.

This is a partial answer, namely to the requirement of automatically placing the logo for arxiv and oai eprinttypes, without requiring adding the keyword manually in the bib file. But I've kept the possibility of manually adding the keyword, for any arbitrary entry.

Essentially, we can perform a test to check whether eprinttype is equal to arxiv or oai:

renewbibmacro*{begentry}{%

  iffieldequalstr{eprinttype}{arxiv}

  {impmark}

  {iffieldequalstr{eprinttype}{oai}

    {impmark}

    {ifkeyword{OA}{impmark}{}}}}

In full:

documentclass{article}

usepackage{graphicx}

usepackage{filecontents}

begin{filecontents*}{jobname.bib}

@article{bib:A,

    author={Authors},

    title={Title},

    journal={Journal name},

    year={2018},

}

@article{bib:B,

    author={Authors},

    title={Title},

    journal={Journal name},

    year={2018},

    eprinttype={oai},

    eprint={hal-01917888},

}

@article{bib:C,

    author={Authors},

    title={Title},

    journal={Journal name},

    year={2018},

    eprinttype={arxiv},

    eprint={arXiv:1811.03094},

}

end{filecontents*}



usepackage[backend=bibtex,style=numeric,eprint=true]{biblatex}

addbibresource{jobname.bib}



% new eprinttype

defoaitourl#1{http://hal.archives-ouvertes.fr/#1}

DeclareFieldFormat{eprint:oai}{%

    ifhyperref

        {href{oaitourl#1}{hal:~nolinkurl{#1}}}

        {hal:~nolinkurl{#1}}}



% OA logo in the margin

newcommand{impmark}{strutvadjust{domark}}

newcommand{domark}{%

  vbox to 0pt{

    kern-3dpstrutbox

    struthfillrlap{kern1emincludegraphics[height=10pt]{OA}}

    vss

  }%

}

renewbibmacro*{begentry}{%

  iffieldequalstr{eprinttype}{arxiv}

  {impmark}

  {iffieldequalstr{eprinttype}{oai}

    {impmark}

    {ifkeyword{OA}{impmark}{}}}}



usepackage[hidelinks]{hyperref}



begin{document}

nocite{*}

printbibliography

end{document}

As for the second requirement, the relevant information would be either in eprint or url or doi fields. In general, you would have to wrap the includegraphics inside domark in a href. But the first and third of these cases would have to be dealt with conditionals, and the links built with a "linkbase+field" somehow.

Here is one attempt that should address both requirements.

Instead of a OA keyword I went with an option openaccess, since I felt that an option would be more natural here. But it is straightforward to change the code to work with a keyowrd. (You only need to replace iftoggle{bbxpluton:openaccess} with ifkeyword{OA}).

The non-trivial bit was to obtain the URL to which the open access symbol should be linked. For certain eprint types the actual URL to link is only put together when the field is processed for printing, the full URL is never 'known' to biblatex. This was solved by defining the macro pluton@getoaurl. The macro needs a branch for each eprinttype you intend to use.

documentclass{article}

usepackage[utf8]{inputenc}

usepackage[T1]{fontenc}

usepackage{lmodern}

usepackage{tikz}

usepackage[backend=biber, style=numeric]{biblatex}

usepackage[hidelinks]{hyperref}



usepackage{kantlipsum}



makeatletter

newtoggle{bbxpluton:openaccess}

DeclareEntryOption[boolean]{openaccess}[true]{%

  settoggle{bbxpluton:openaccess}{#1}}





newcommand*{pluton@getoaurl}{%

  undefbbx@pluton@oaurl

  iftoggle{bbxpluton:openaccess}

    {% URL and DOI are only open access if indicated

     iffieldundef{url}

       {}

       {defbbx@pluton@oaurl{thefield{url}}}%

     iffieldundef{doi}

       {}

       {defbbx@pluton@oaurl{%

          https://doi.org/thefield{doi}}}%

     % the eprinttypes listed here are open access only if indicated

     iffieldundef{eprint}

       {}

       {ifboolexpr{   test {iffieldequalstr{eprinttype}{jstor}}

                    or test {iffieldequalstr{eprinttype}{JSTOR}}}

          {}

          {defbbx@pluton@oaurl{%

             http://www.jstor.org/stable/thefield{eprint}}}%

        ifboolexpr{   test {iffieldequalstr{eprinttype}{hdl}}

                    or test {iffieldequalstr{eprinttype}{HDL}}}

          {}

          {defbbx@pluton@oaurl{%

             http://hdl.handle.net/thefield{eprint}}}%

        ifboolexpr{   test {iffieldequalstr{eprinttype}{pubmed}}

                    or test {iffieldequalstr{eprinttype}{PubMed}}}

          {}

          {defbbx@pluton@oaurl{%

             http://www.ncbi.nlm.nih.gov/pubmed/thefield{eprint}}}%

       }%

    }

    {}%

  % eprinttype listed here are always open access

  iffieldundef{eprint}

    {}

    {ifboolexpr{   test {iffieldequalstr{eprinttype}{arxiv}}

                 or test {iffieldequalstr{eprinttype}{arXiv}}}

       {defbbx@pluton@oaurl{%

          https://arxiv.org/abx@arxivpath/thefield{eprint}}}

       {}%

     iffieldequalstr{eprinttype}{hal}

       {defbbx@pluton@oaurl{%

          http://hal.archives-ouvertes.fr/thefield{eprint}}}

       {}%

    }%

}



AtEveryBibitem{pluton@getoaurl}



renewbibmacro*{begentry}{%

  ifundefbbx@pluton@oaurl

    {}

    {oamark@link}}



% based on egreg's answer to https://tex.stackexchange.com/a/123451/35864

% originally CC BY-SA 3.0, but dual-licensed under LPPL

% see https://tex.meta.stackexchange.com/a/3333/35864

newcommand{oamark@link}{strutvadjust{dooamark@link}}

newcommand{dooamark@link}{%

  vbox to 0pt{

    kern-3dpstrutbox

    struthfillrlap{kern1em

      ifhyperref

        {href{bbx@pluton@oaurl}{oasymbol}}

        {oasymbol}}

    vss

  }%

}





% PLoS Open Access symbol based on

% https://commons.wikimedia.org/wiki/File:Open_Access_logo_PLoS_white.svg

% public domain/CC0 by PLoS & Wikipedia users Nina, Beao and JakobVoss

definecolor{oaploscol}{HTML}{f68212}

newcommand*{oaplossymbol}{%

  begin{tikzpicture}[x=.1pt,y=.1pt]

    fill[oaploscol] (06,73)   arc (180:0:26);

    fill[white]     (17,72.9) arc (180:-45:15);

    fill[oaploscol] (47,32) rectangle ++ (11,41.1);

    fill[oaploscol] (32,32) circle[radius=32];

    fill[white]     (32,32) circle[radius=21];

    fill[oaploscol] (32,32) circle[radius= 9];

  end{tikzpicture}

}



% Open-Acess.net Open Acess symbol

% redrawn with TikZ from

% http://open-access.net/fileadmin/logos/oa.svg

% public domain according to

% https://commons.wikimedia.org/wiki/File:Open_access.svg

% might be covered by open-access.net's overall CC-BY 4.0

% https://creativecommons.org/licenses/by/4.0/

% https://open-access.net/impressum/

% the site states no specific conditions for use of the logo

% other than

%   "Das Logo der Informationsplattform darf nachgenutzt werden,

%    gerne mit einem Link zu open-access.net"

% on https://open-access.net/ueber-uns/

% see also https://open-access.net/community/materialien/

% logo by

% Medien + Design

% Center for Digital Systems

% Competence Center for E-Learning and Multimedia

% Freie Universität Berlin

definecolor{oanetgreen}{HTML}{356031}

definecolor{oanetyellow}{HTML}{f9c63a}

definecolor{oanetintersect}{HTML}{89923a}



newcommand*{oanetsymbol}{%

  begin{tikzpicture}[x=1.1pt,y=1.1pt]

    fill[oanetgreen] (4,4) circle[radius=4.3];

    fill[oanetyellow] (11,4) ++ (0:4.3) arc (0:300:4.3)

      -- (11,4) ++ (300:4.3) -- cycle;

    begin{scope}

      clip (4,4) circle[radius=4.3];

      fill[oanetintersect] (11,4) circle[radius=4.3];

    end{scope}

    fill[white] (4,4) circle[radius=2.7];

    fill[white] (11,4) circle[radius=2.7];

    fill[oanetyellow] (11,4) ++ (2.7,.1) rectangle ++(1.6,-4.1);

  end{tikzpicture}

}



% reusable box for the symbol, so the image is not

% processed on every use

newsavebox{oasymbolbox}

% choose oaplossymbol or oanetsymbol here

sbox{oasymbolbox}{oaplossymbol}

newcommand*{oasymbol}{usebox{oasymbolbox}}



newcommand*{halurl}[1]{http://hal.archives-ouvertes.fr/#1}

DeclareFieldFormat{eprint:hal}{%

  ifhyperref

    {href{halurl{#1}}{hal:~nolinkurl{#1}}}

    {hal:~nolinkurl{#1}}}

makeatother





usepackage{filecontents}

begin{filecontents*}{jobname.bib}

@article{bib:A,

  author  = {Anne Uthor},

  title   = {Generic Title},

  journal = {Journal},

  year    = {2018},

}

@article{bib:B,

  author     = {Anne Uthor},

  title      = {Open Access Title (HAL)},

  journal    = {Open Journal},

  year       = {2018},

  eprinttype = {hal},

  eprint     = {hal-01917888},

}

@article{bib:C,

  author     = {Anne Uthor},

  title      = {Open Access Title (arXiv)},

  journal    = {Closed Journal},

  year       = {2018},

  eprinttype = {arxiv},

  eprint     = {1811.03094},

}

@article{bib:D,

  author     = {Anne Uthor},

  title      = {Open Access Title (DOI)},

  journal    = {Open Journal},

  year       = {2018},

  doi        = {12345/67898.0},

  options    = {openaccess},

}

@article{bib:E,

  author     = {Anne Uthor},

  title      = {Open Access (URL)},

  journal    = {Open Journal},

  year       = {2018},

  url        = {https://example.com/~author/my_paper.pdf#page20},

  options    = {openaccess},

}

@article{bib:F,

  author     = {Anne Uthor},

  title      = {emph{Not} Open Access (DOI)},

  journal    = {Closed Journal},

  year       = {2018},

  doi        = {12345/67898.0},

}

end{filecontents*}



addbibresource{jobname.bib}

begin{document}

kant[1]

nocite{*}

printbibliography

end{document}

edit: Extended and simplified the open access URL detection (hyperref can accept the URLs in a macro even with different levels of expansion). Place the TikZ-drawn logos in a reusable box to improve performance.

Articles with a DOI can be open access too, and unpaywall.org has an API that can tell us whether a DOI is known to have an open access version. Just for fun, here's a version that does just that, using oldschool bibtex and modern luatex.

In your .bst file, add the function

FUNCTION {openaccess.check}

{

  doi empty$

    'skip$

    { "MyMaybeOpenAccess{" doi * "}" * write$ }

  if$

}

and call it in the code that handles an article (just after output.bibitem for example.

In your document preamble, define a macro

newcommand{MyMaybeOpenAccess}[1]{%

  directlua{

  local http = require('socket.http')

  local url = 'https://api.unpaywall.org/v2/' .. luastring{#1} .. '?email=your@email'

  body, code, headers, status = http.request(url)

  if code == 200 and body then

     local found = string.match(body, '"is_oa": ([a-z]+)')

     if found == "true" then

        tex.print("noexpand\marginpar{noexpand\includegraphics[width=0.3cm]{open-access-logo}}")

     end

  end

}}

(For serious use, would also need to handle isbn and eprint fields, cache accesses to the API, include the OA URL under the logo, and so on.)