Looking for a Prawn-Like PDF Generation Library in Elixir

There (sadly) is no real equivalence to Prawn for Elixir.

There are 2 libraries, pdf and mudbrick. The first is more mature, uses GenServers to store the state of the pdf being build, where the second one is very new and still lacking a lot of features, but it uses a struct to store the state.
Mudbrick is easy to extend with your own features, where pdf is practically impossible to extend.
Mudbrick supports OpenType (otf) fonts, pdf, adobe type mananger (atm).

If you do not want to shell out to something like htmltopdf, these are currently the most feasible options.

The font-handling in pdf was recently rewritten, making it compile several times faster.

I have been using pdf for several years, tried mudbrick, I like it, but is not yet there.

If You really miss prawn, You can run it in Elixir with erlport…

We have had great success with https://wkhtmltopdf.org/

Within our phoenix application, a simple GenServer calls out to the wkhtmltopdf binary, passing along generated html and returning the resulting pdf file.

The html itself is generated from a bunch of $template.html.heex files and for each new PDF document type we simply add a new *.html.heex file.

We produce a lot of different types of pdf reports, and regularly add new ones so this approach (converting html → pdf) makes it easy to assign that task to anyone who can write html, and allows us to produce some very rich, and complex page / document designs.

Nothing can compare to the production experience of GitHub - bitcrowd/chromic_pdf: Convenient HTML to PDF/A rendering library for Elixir based on Chrome & Ghostscript · GitHub imo

I wanted to bring it up but assumed they were not okay with the Chromium dependence.

Here we are using GitHub - gutschilla/elixir-pdf-generator: Create PDFs with wkhtmltopdf or puppeteer/chromium from Elixir. · GitHub for simple PDF and it has been working fine for the last years

+1 for wkhtmltopdf

Nice. Didn’t know about mudbrick. A modern native Elixir PDF writer would be so cool for the ecosystem.

It depends what you’re looking for, but we use typst (https://typst.app/). We use it to generate high quality output for work instructions (images, pixel perfect layout, table of contents etc etc). Having used it for that, I’d also use it for things like database reports, invoice generation etc. It’s also deterministic - it doesn’t rely on browser engines etc to interpret CSS, so once you have placed elements on a page, they stay put.

There’s a command-line version that compiles to a single binary (it’s written in Rust, so easy enough to add to your docker builder image for most platforms [I think that’s the lingo - I’m no docker whiz]. Build time is a couple of minutes, but the guys at Alembic designed the docker build to minimise the likelihood that it needs to be recompiled for each deploy). We’re currently just calling it with System.cmd. The main downer is you have to assemble all the inputs (e.g. images, JSON data extracts) into the directory where the main .typ file is, so no referencing images on the web. There are Elixir bindings, but for our use-case isn’t wasn’t worth the extra dependency.

The output quality is awesome (it is designed as a Latex successor). Coding up the layout is very similar to composing views with Phoenix function components. Some of the syntax takes a bit of getting used to, but it’s still the least fighting I’ve been through to get nice quality output from a database to a PDF or printer, by a long way, in >30 years of doing this kind of stuff.

Edit: PS - tables allow fine control on layout, styling, row/col-spans etc.

Took a look at what I used last time around, and it was https://weasyprint.org, probably due to the nice templates out of the box.. you render the html, path to the css file, and call it using Rambo (you might need {:rambo, github: "/myobie/rambo", branch: "aarch64-apple"},)..

defmodule RamboPdf do
  def create_pdf(item) do
    css = Path.join([PDFfile.path(), "templates/invoice", "invoice.css"])

    # grab data, and EEx.eval_file with the template file
    html =
      PDF.gen_data(item)
      |> PDF.populate_html("templates/invoice", "invoice.html")

    output_file = Path.join([PDFfile.path(), "output", "#{item.room}.pdf"])
    # https://doc.courtbouillon.org/weasyprint/stable/api_reference.html#command-line-api

    task =
      Task.async(fn ->
        Rambo.run("weasyprint", ["--encoding", "utf8", "-q", "-s", css, "-", "-"],
          in: html,
          log: false,
          timeout: 20_000
        )

        # System.cmd("weasyprint", ["--encoding", "utf8", "-q", "-s", css, "-", "-", html])
      end)

    task_output = Task.await(task, :infinity)

    case task_output do
      {:ok, %Rambo{err: _err, out: output, status: 0}} ->
        File.write(output_file, output, [:binary])
        output

      error ->
        IO.inspect("error")
        IO.inspect(error)
    end
  end
end