Here is a non-fancytooltips solution that supports any driver, including xelatex, allowing you to use OpenType and TrueType fonts. It makes use of the macro
\tooltip[<link text colour>]{<link text>}[<tip box colour>]{<tip text>}
for generating draggable boxes in the PDF display of AdobeReader.
The macro for creating an inline citation pop-up is:
\citeTip{<bib key>}
Inside the macro, after inserting \cite{<bib key>}, a phantom "|" is passed as <link text> to the first \tooltip argument, and \fullcite{<bib key>} as <tip text> to the second \tooltip argument.
The example uses biblatex/biber. The workflow is latex->biber->latex, run on the base-name of the document source file.
Any flavour of latex can be used. Of course, the fontspec- related lines must be commented out for other drivers than xelatex or lualatex.
\documentclass[
a4paper,12pt,
% dvipdfmx %uncomment this for latex->dvipdfmx
]{article}
\usepackage[sorting=none]{biblatex}
%\usepackage{fontspec}
%\setmainfont{Times New Roman}
\usepackage[T1]{fontenc} %standard fonts
\usepackage{lmodern}
\usepackage{hyperref}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% usage: \citeTip{<bib key>}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\newcommand{\citeTip}[1]{%
\cite{#1}%
\makebox[0pt][l]{%
\tooltip*[black!0]{|}{\parbox[b]{\textwidth}{\fullcite{#1}}}%
}%
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% tooltips with LaTeX v. 2017/11/28
%
% \tooltip[*[*[*[*]]]][<link colour>]{<link text>}[<tip box colour>]{<tip text>}
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% \tooltip --> draggable tip, visible on mouse-over, hidden on mouse-out
%
% \tooltip* --> draggable tip, toggle visiblity on mouse-over
%
% \tooltip** --> NON-draggable tip, visible on mouse-over, hidden on mouse-out
%
% \tooltip*** --> NON-draggable tip, toggle visiblity on mouse-over
%
% \tooltip**** --> NON-draggable tip, toggle visiblity on mouse-click (Evince!)
%
% Default link colour can be set with
%
% \usepackage[linkcolor=<colour>]{hyperref}
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\usepackage{pdfbase}[2017/03/16]
\usepackage{xparse,ocgbase}
\usepackage{xcolor,calc}
\usepackage{tikzpagenodes}
\usetikzlibrary{calc}
\ExplSyntaxOn
\let\tpPdfLink\pbs_pdflink:nn
\let\tpPdfAnnot\pbs_pdfannot:nnnn\let\tpPdfLastAnn\pbs_pdflastann:
\let\tpAppendToFields\pbs_appendtofields:n
\def\tpPdfXform{\pbs_pdfxform:nnnnn{1}{1}{}{}}
\let\tpPdfLastXform\pbs_pdflastxform:
\ExplSyntaxOff
\makeatletter
\NewDocumentCommand{\tooltip}{%
ssssO{\ifdefined\@linkcolor\@linkcolor\else blue\fi}mO{yellow!20}m%
}{{%
\leavevmode%
\IfBooleanT{#2}{%
%for variants with two and more stars, put tip box on a PDF Layer (OCG)
\ocgbase@new@ocg{tipOCG.\thetcnt}{%
/Print<</PrintState/OFF>>/Export<</ExportState/OFF>>%
}{false}%
\xdef\tpTipOcg{\ocgbase@last@ocg}%
%prevent simultaneous visibility of multiple non-draggable tooltips
\ocgbase@add@ocg@to@radiobtn@grp{tool@tips}{\ocgbase@last@ocg}%
}%
\tpPdfLink{%
\IfBooleanTF{#4}{%
/Subtype/Link/Border[0 0 0]/A <</S/SetOCGState/State [/Toggle \tpTipOcg]>>
}{%
/Subtype/Screen%
/AA<<%
\IfBooleanTF{#3}{%
/E<</S/SetOCGState/State [/Toggle \tpTipOcg]>>%
}{%
\IfBooleanTF{#2}{%
/E<</S/SetOCGState/State [/ON \tpTipOcg]>>%
/X<</S/SetOCGState/State [/OFF \tpTipOcg]>>%
}{
\IfBooleanTF{#1}{%
/E<</S/JavaScript/JS(%
var fd=this.getField('tip.\thetcnt');%
if(typeof(click\thetcnt)=='undefined'){%
var click\thetcnt=false;%
var fdor\thetcnt=fd.rect;var dragging\thetcnt=false;%
}%
if(fd.display==display.hidden){%
fd.delay=true;fd.display=display.visible;fd.delay=false;%
}else{%
if(!click\thetcnt&&!dragging\thetcnt){fd.display=display.hidden;}%
if(!dragging\thetcnt){click\thetcnt=false;}%
}%
this.dirty=false;%
)>>%
}{%
/E<</S/JavaScript/JS(%
var fd=this.getField('tip.\thetcnt');%
if(typeof(click\thetcnt)=='undefined'){%
var click\thetcnt=false;%
var fdor\thetcnt=fd.rect;var dragging\thetcnt=false;%
}%
if(fd.display==display.hidden){%
fd.delay=true;fd.display=display.visible;fd.delay=false;%
}%
this.dirty=false;%
)>>%
/X<</S/JavaScript/JS(%
if(!click\thetcnt&&!dragging\thetcnt){fd.display=display.hidden;}%
if(!dragging\thetcnt){click\thetcnt=false;}%
this.dirty=false;%
)>>%
}%
/U<</S/JavaScript/JS(click\thetcnt=true;this.dirty=false;)>>%
/PC<</S/JavaScript/JS (%
var fd=this.getField('tip.\thetcnt');%
try{fd.rect=fdor\thetcnt;}catch(e){}%
fd.display=display.hidden;this.dirty=false;%
)>>%
/PO<</S/JavaScript/JS(this.dirty=false;)>>%
}%
}%
>>%
}%
}{{\color{#5}#6}}%
\sbox\tiptext{%
\IfBooleanT{#2}{%
\ocgbase@oc@bdc{\tpTipOcg}\ocgbase@open@stack@push{\tpTipOcg}}%
\fcolorbox{black}{#7}{#8}%
\IfBooleanT{#2}{\ocgbase@oc@emc\ocgbase@open@stack@pop\tpNull}%
}%
\edef\twd{\the\wd\tiptext}%
\edef\tht{\the\ht\tiptext}%
\edef\tdp{\the\dp\tiptext}%
\measureremainder{\whatsleft}\tipshift=0pt%
\ifdim\whatsleft<\twd\setlength\tipshift{\whatsleft-\twd}\fi%
\IfBooleanF{#2}{\tpPdfXform{\tiptext}}%
\raisebox{\heightof{#6}+\tdp}[0pt][0pt]{\makebox[0pt][l]{\hspace{\tipshift}%
\IfBooleanTF{#2}{\usebox{\tiptext}}{%
\tpPdfAnnot{\twd}{\tht}{\tdp}{%
/Subtype/Widget/FT/Btn/T (tip.\thetcnt)%
/AP<</N \tpPdfLastXform>>%
/MK<</TP 1/I \tpPdfLastXform/IF<</S/A/FB true/A [0.0 0.0]>>>>%
/Ff 65536/F 3%
/AA <<%
/U <<%
/S/JavaScript/JS(%
var fd=event.target;%
var mX=this.mouseX;var mY=this.mouseY;%
var drag=function(){%
var nX=this.mouseX;var nY=this.mouseY;%
var dX=nX-mX;var dY=nY-mY;%
var fdr=fd.rect;%
fdr[0]+=dX;fdr[1]+=dY;fdr[2]+=dX;fdr[3]+=dY;%
fd.rect=fdr;mX=nX;mY=nY;%
};%
if(!dragging\thetcnt){%
dragging\thetcnt=true;Int=app.setInterval("drag()",1);%
}%
else{app.clearInterval(Int);dragging\thetcnt=false;}%
this.dirty=false;%
)%
>>%
>>%
}%
\tpAppendToFields{\tpPdfLastAnn}%
}%
}}%
\stepcounter{tcnt}%
}}
\makeatother
\newsavebox\tiptext\newcounter{tcnt}
\newlength{\whatsleft}\newlength{\tipshift}
\newcommand{\measureremainder}[1]{%
\begin{tikzpicture}[overlay,remember picture]
\path let \p0 = (0,0), \p1 = (current page.east) in
[/utils/exec={\pgfmathsetlength#1{\x1-\x0}\global#1=#1}];
\end{tikzpicture}%
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{filecontents*}{my.bib}
@article{einstein05,
author={Albert Einstein},
title="Zur Elektrodynamik bewegter K{\"o}rper",
journal={Annalen der Physik und Chemie},
volume={17},
year={1905},
pages={891--921}
}
@article{einstein15,
author={Albert Einstein},
title="Die Grundlage der allgemeinen Relativit{\"a}tstheorie",
journal={Annalen der Physik},
volume={354},
year={1916},
pages={769--822}
}
\end{filecontents*}
\addbibresource{my.bib}
\begin{document}
The principles of the Special Relativity Theory were first published in
1905\citeTip{einstein05}. Einstein coined the term `Special Relativity
Theory' while working on the General Relativity Theory, published in
1916\citeTip{einstein15}.
\printbibliography
\end{document}
my $pdflatex="pdflatex";intomy $pdflatex="lualatex";in the Perl script.perl ~/path/fancy-preview filename --pdflatex="/path/lualatex"