Find some way to reduce the file size

[foosel]

Problem

The files its creates are hugh! A 2.4Mb file comes out as 23.2Mb...Maybe a files compression thing, and also not very high on the list given the size of todays harddrives, but nonetheless...

• Source

Solution

Apparently that's a known and so far unsolved issue with pdf-lib, see for example Hopding/pdf-lib#1338.

A first test on the command line with

ghostscript -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 \
    -dPDFSETTINGS=/printer -dNOPAUSE -dQUIET -dBATCH \
    -sOutputFile=output.pdf input.pdf

showed very promising results however, reducing a generated PDF from 55MB to 5.7MB.

It might be possible to get ghostscript to work via wasm and use that to optimize the PDF, as demonstrated by laurentmmeyer/ghostscript-pdf-compress.wasm. The downside of that is having to download the ghostscript wasm build, which is around 18MB. But compression could be made optional with a checkbox and things only loaded if necessary.

[foosel]

It turns out that just switching the card images from PNG to JPG already sufficed.

I actually also got Ghostscript to work in WebAssembly, but that turned out to be unusably slow with larger PDFs, so this approach was abandoned (and frankly, also a bit overengineered and backwards).