The problems

Changes in jdk9 have affected the ability to call inherited protected methods with jruby. For regular java classes, there is an expectation that inheriting java classes can call a protected method of the parent. But at the moment headius (lead jruby developer) is reluctant to create a jruby fix as this would probably expose other methods that would not normally available. The most serious problem is that we face is that we use a protected method run_sketch to initiate sketches in JRubyArt and propane, but there is also an issue with the control_panel library, where we call the protected method fireStateChanged on our Slider class, that inherits from swing JSlider.

Other changes affect the ability to use proprietary code, currently this most affects FX2D and FX3D sketches, but may also affect hacks on MacOS, these things might be fixed by processing developers but not until September 2018 at the earliest.

Fixing run_sketch

A bit radical but it works we create a public runPropane() method for PApplet that mirrors runSketch(), except that it is publicly accessible.


tar xzvf processing-0264-3.3.7.tar.gz

See github project processing-core for the modification to PApplet and polyglot maven build. All that is the required is to modify propane app.rb to call runPropane instead of run_sketch. However not 100% sure fix preserves processing MacOS hacks, we do however take the opportunity to use our own icons.

Fixing control_panel

We can avoid calling the fireStateChanged if we initialize the slider values directly in the sketch. This is less neat but workable, first we create a method.

module ControlPanel
  def self.app_value(name, val)"@#{name}", val)

so we can call it initially as well as in our change_listener

add_change_listener do
  update_label(label, name, value)
  ControlPanel.app_value(name, value) if proc
val = initial.nil? ? (range.first + range.last) * 50 : initial * 100
ControlPanel.app_value(name, val)

previously it was sufficient to fireStateChanged and let the change_listener initialize the sketch values. If the val is new that fires state changed for us, otherwise label only shows after slider is moved.