[Bug]: Replace pngquant with something not requiring Rust

[barracuda156]

What were you trying to do?

The whole project is pure Python, but one dependency, pngquant, pulls in Rust. This is undesirable, since Rust is a huge thing to build and is not supported on a number of platforms. There are alternatives for processing png files, can something else be used instead of pngquant?

Where are you installing/running from?

source build

OCRmyPDF version

No response

What operating system are you working on?

macOS

Operating system details and version

No response

Simple sanity checks

• Operating system is currently supported by its vendor (not end of life)
• Python version is compatible with OCRmyPDF
• This issue is not about a specific input file

Relevant log output

No response

[jbarlow83]

pngquant is optional, not required, so if it poses difficulty it can be omitted.

On macOS, the recommended installation procedure is to use Homebrew, which should give you pre-compiled binaries of pngquant and everything else, on supported releases. (If Apple can't afford to support EOL macOS, I can't either.)

One could also write a plugin to replace pngquant with some other PNG utility if desired.

[barracuda156]

@jbarlow83 Thank you for responding. I use MacPorts, but I have opened an issue there, so hopefully pngquant is moved to a variant (in order for it not be a hard dependency).