If Manjaro does not come with a pre-installed java, then the first step is to install a jdk the distro version (jdk16) should work.

sudo pacman -S jre-openjdk # current distro version jdk17

You can also use pacman to install jruby

sudo pacman -S jruby # current version jruby-9.3.0.0

It is probably a good idea to create a local gem store (rather needing to use sudo to install gems)

sudo pacman -S vim # all you need if your happy with vim

Vim is not installed by default

sudo pacman -S geany # if you prefer a GUI

Geany is not installed by default

mkdir -p ~/.gem/ruby/2.6.0 # current MRI version supported by jruby

Now set your GEM_HOME, GEM_PATH and amend your PATH as follows:-

echo "export GEM_HOME=\"\${HOME}/.gem/ruby/${MRI_RUBY}\"" >> ~/.bashrc
echo "export GEM_PATH=\"\${HOME}/.gem/ruby/${MRI_RUBY}\"" >> ~/.bashrc
echo "export PATH=\"\${PATH}:\${GEM_PATH}/bin\"" >> ~/.bashrc
source ~/.bashrc # to update environment without re-logging in

Now should be ready to install picrate and other gems. But speed up install time you should set --no-document option in ~/.gemrc

touch ~/.gemrc
echo "gem: --no-document" > ~/.gemrc

To install latest picrate and its dependencies:-

jgem install picrate

Geany is a good editor/ide for PiCrate on the RaspberryPI (install via pacman), but some may prefer vim. For geany you should edit/preferences/Terminal to Execute programs in the VTE.

For a first install:-

picrate --install # no args, install samples and geany config
# or
picrate -i Samples # to omit geany config

This installs example sketches in ~/projects/examples and ties them into a geany project examples.geany. It should also be possible to run sketches from the geany ide. The geany config creates picrate.rb template sketch so you can create a new sketch with template.

To create a template sketch from the command line:-

picrate -c my_sketch 600 400

creates file my_sketch.rb

#!/usr/bin/env jruby
# frozen_string_literal: false
require 'picrate'

class MySketch < Processing::App
  def settings
    size 200, 200
  end

  def setup
    sketch_title 'My Sketch'
  end

  def draw

  end
end
MySketch.new

Edit in vim (at command line) or geany (gui), you may need to install vim

vim my_sketch.rb
:!jruby % # from vim runs the sketch

To run sketches from command line:-

jruby --dev my_sketch.rb

Or even chmod +x my_sketch.rb to make an executable script.

See editors geany, for how to run sketches from a gui.

JWishy Sketch Running on RaspberryPI

jwishy_buster