\input{glyphtounicode} with \pdfgentounicode=1 creates unwanted hyperlinks from link-like text

Question

I often use \input{glyphtounicode} \pdfgentounicode=1 to generate PDF-files whose contents paste with the correct Unicode codepoints. However I noticed that as a side effect of these commands, some weblinks are created that I didn't explicit call for (using for example hyperref).

\documentclass{article}

% If at least one of the following two lines is omitted,
% the two text strings won't generate weblinks.
\input{glyphtounicode}
\pdfgentounicode=1


\begin{document}

www.google.com

http://www.google.com/

\end{document}

If either of the two relevant commands above is omitted, www.google.com and http://www.google.com/ will not appear as hyperlinks in the generated PDF-file. (I use Adobe Reader to view them.) Why? How can I prevent these text strings from producing hyperlinks?

Answer 1

Why are these links generated?

In this case, Adobe Reader is deducing that they are links. (Ulrike Fischer) But this is viewer-dependent: the TeXworks viewer doesn't produce automatic links, but Preview does (and even without glyphtounicode.tex's mechanics). (Joseph Wright)

How can I prevent these text strings from producing hyperlinks?

For Adobe Reader XI, one can enable or disable the following checkbox: Preferences → General → Basic Tools → Create links from URLs.

Why is link creation dependent on the two commands \input{glyphtounicode} and \pdfgentounicode=1?

The reader is using the names of the glyphs to decide whether a sequence of glyphs is a link. Usage of the glyph names depends on these two crucial lines. (adapted from Ulrike Fischer)

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The most important parts from glyphtounicode.tex seem to be the following lines:

\pdfglyphtounicode{a}{0061}
\pdfglyphtounicode{b}{0062}
...
\pdfglyphtounicode{z}{007A}

and

\pdfglyphtounicode{colon}{003A}
\pdfglyphtounicode{slash}{002F}
\pdfglyphtounicode{period}{002E}

Without colon or slash, the lower text will have only its second part appear as a link. Without period, only the lower text is linked, but it is linked in its entirety.

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The lower-case letters seem to have duplicates

\pdfglyphtounicode{Asmall}{0061}
\pdfglyphtounicode{Bsmall}{0062}
...
\pdfglyphtounicode{Zsmall}{007A}

that seem to not make a difference.

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As for the capital letters:

\pdfglyphtounicode{A}{0041}
\pdfglyphtounicode{B}{0042}
...
\pdfglyphtounicode{Z}{005A}

With

WWW.GOOGLE.COM

HTTP://WWW.GOOGLE.COM/

the lower but not the upper text will be linked. Without capital letters, www.GOOGLE.COM is still recognized. This indicates that the capital letters play a role, but there are some details to explore.

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Thanks to Ulrike Fischer for significant contributions to the solution. Herbert deserves credit for an idea and Joseph Wright and egreg for data points.