Comment by shadowgovt

Comment by shadowgovt 2 days ago

PDF is a famously (and hilariously) wild document format because it satisfied the need of being able to recreate a work piece faithfully using thousands of kinds of outputs, some of which didn't even exist when the document was created, to ideally arbitrary pixel resolution (see https://www.youtube.com/watch?v=qbCniw-BcW0 for a delightful and informative talk including this topic).

As a result, in one of the modes of PDF you can save the entire font file for every font used by the PDF into the PDF itself, just in case it's not present on the recipient's machine. Costly? Sure! But what else are you going to do if your document uses a super-special font for displaying mathematical symbols or sanskrit or the glyphs of a language understood by fifty people on the planet and Unicode isn't widely adopted yet, having been invented just two years before PDF?

So in this case, the author grabbed a copy of a PDF version of the ad (because those ads are still available online), cracked open the document itself, and found the glyphs for the letters are sourced from a version of the font that was intentionally created to steal someone else's font work because the whole font file is in the document.

Suppafly 2 days ago

>Sure! But what else are you going to do if your document uses a super-special font for displaying mathematical symbols or sanskrit or the glyphs of a language understood by fifty people on the planet and Unicode isn't widely adopted yet, having been invented just two years before PDF?

Assuming it's for print/display and not future editing, I imagine you could convert the font strokes to vectors or similar.

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Macha a day ago

In fact many PDFs still do convert the text to shapes rather than use the font. It does cause problems when you need to copy text out though

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shadowgovt a day ago

You could. But in a thousand page document, that's a lot of memory used up to record a vector for every letter 'c'. So of course you do two layers: record modifiers and transforms on a canonical 'c', and then keep a canonical 'c' somewhere with all the other letters.
... But you already have that data structure: it's the font file itself.
(Possibly worth noting here also is that historically, Adobe owned both the PDF format and the file format for most popular fonts. So they were heavily incentivized to just reuse code they already owned here instead of reinventing a wheel).

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- Suppafly 20 hours ago
  
  > that's a lot of memory used up to record a vector for every letter 'c'.
  only if you do things in the dumbest way possible.
  
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