% The UCW Macro Collection: Destinations and links
% Written by Martin Mares <mj@ucw.cz> in 2018 and placed into public domain
% -------------------------------------------------------------------------

\ucwdefmodule{link}

% Should clickable links be produced?
\newif\ifclickable
\clickabletrue

% Common style of all clickable links
\pdflinkmargin=1pt
\def\commonlinkargs{height \the\dimexpr\ht\strutbox-0.5pt\relax depth \the\dimexpr\dp\strutbox-0.5pt\relax attr {/C [0 0 0.5] /Border [0 0 2]}}

% Define a PDF destination for the current position at the page
\def\destpos#1{\ifclickable\pdfdest name {#1} xyz\relax\fi}

% Define a PDF destination for the current page
\def\destpage#1{\ifclickable\pdfdest name {#1} fit\relax\fi}

% Typeset a clickable link to the given destination
% \link{dest}{text}
\def\link#1#2{%
	\ifclickable
		\pdfstartlink\commonlinkargs goto name {#1}\relax
		#2%
		\pdfendlink\relax
	\else
		#2%
	\fi
}

% Typeset a clickable link to the given page number
% (This does not use named destinations. We use it in tables of contents and indices,
% where absolute page numbers are known from other sources.)
% \linkpage{page}{text}
\def\linkpage#1#2{\ifclickable\pdfstartlink\commonlinkargs goto page #1 {/Fit}\relax #2\pdfendlink\else #2\fi}

% Typeset a clickable URL
% Currently, all weird characters must be properly escaped.
\def\url#1{%
	\leavevmode
	\ifclickable
		\pdfstartlink\commonlinkargs user {/Subtype/Link /A << /Type/Action /S/URI /URI(#1) >>}\relax
	\fi
	\xurl #1^^X%
	\ifclickable
		\pdfendlink\relax
	\fi
}
\def\xurl#1:#2#3^^X{{\I #1:#2\ifx#2/\kern-0.1em\fi#3}}
