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dan@upvote.au ⁨3⁩ ⁨days⁩ ago

Strangely, this kinda makes sense. PDF is based on PostScript, which is the file type that gets sent to printers. It’s just skipping the final “send to printer” part and sends it to a file instead.

A fascinating thing (in a scary way) is that PostScript is technically a Turing-complete programming language. When a document is printed using PostScript, your computer generates a script that the printer runs in order to produce the document.

PDF is essentially “the safe parts” of PostScript, with all the dynamic parts removed. PDFs are statically laid out when they’re created, rather than having to run arbitrary code to lay them out like PostScript does.

For printing, PCL has somewhat taken over, and it’s less scary (it just has preset commands rather than allowing arbitrary code in a full programming language with loops, functions, logic, etc), but PostScript is still used today for higher-end printers and print jobs.

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MonkderVierte@lemmy.zip ⁨3⁩ ⁨days⁩ ago

A fascinating thing (in a scary way) is that PostScript is technically a full programming language with loops, functions, logic, and a built-in font rendering and 2D graphics engine.

It also had a extension to create NextStep UI with it.

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- cruseo@piefed.world ⁨3⁩ ⁨days⁩ ago
  This is how the nextstep UI was so smooth and sharp and so well built for design, especially output to print. And how that translated to macOS (although the graphics display subsystem and macOS is based on PDF, not postscript). It’s also part of the entire print sub systems, and how it was always so easy to create a PDF in the manner the OP suggests. That functionality was really only added to other operating systems later with plugins.
  
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cenotaph@piefed.zip ⁨3⁩ ⁨days⁩ ago
You can run doom on a pdf

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- Evil_Shrubbery@thelemmy.club ⁨3⁩ ⁨days⁩ ago
  Ok but that’s a really low bar, you could just list on what Doom can’t run :).
  
  Also if you print doom.pdf, does the printer run it like this
  Image
  or like this
  Image
  ?
  
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  - edgemaster72@lemmy.world ⁨3⁩ ⁨days⁩ ago
    A Bringus reference? On my Lemmy?
    
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    Evil_Shrubbery@thelemmy.club ⁨2⁩ ⁨days⁩ ago
    Oh, til.
    I see some cool nerd shit tho, nice.
    
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thinkingofyouihaveananxietydisorder@quokk.au ⁨3⁩ ⁨days⁩ ago
it is at least theoretically possible to boot from a PDF.

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beanson@lemmy.ml ⁨3⁩ ⁨days⁩ ago
I’ve seen some pretty feature rich PDFs - before WebGIS got really good, people would often disseminate digital maps and geographic reports via GeospatialPDF which is an extension for PDF. You can do all kinds of stuff in there related to measuring distances, coordinate transformations and zoom/pan around the maps. Some of these files would end up being >500MB. Probably still used quite a lot field work I imagine.

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KittyCat@lemmy.world ⁨3⁩ ⁨days⁩ ago
Not just 2d, I’ve received some unholy pdfs with fully imbedded 3d models.

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- dan@upvote.au ⁨3⁩ ⁨days⁩ ago
  I forgot to mention that PDF added new features on top of PostScript, including 3D models.
  
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