Glimmer DSL for JFX 0.0.1
JRuby JavaFX Desktop Development GUI Library

Glimmer DSL for JFX enables building desktop applications with JavaFX via JRuby.
JavaFX has been Java's next generation technology for a while for desktop application GUI development. Unfortunately, when it divorced itself from its JavaFX Script roots, it became no better than Java Swing in syntax.
Furthermore, the whole stage and scene production metaphor made everything more complicated to get into it for software engineers who encountered it for the first time. After all, desktop developers simply think of windows, not stages or scenes. The metaphor unfortunately pushes software engineers into thinking of low-level details (e.g. nodes) that are not important in developing business desktop applications.
FXML attempted to rectify the situation by making JavaFX more declarative than its Swing-like Java syntax. Unfortunately, XML, like its cousin HTML, brings all the same problems web developers face in day-to-day in suffering through multi-language dissonance to desktop software engineering. That defeats the whole point about desktop software engineering being a lot more productive than web development for simple local apps. FXML was really just a step back into the wrong direction.
Glimmer DSL for JFX aims to overcome the hurdles of JavaFX by providing a declarative hierarchical alternative to FXML in pure Ruby as one language (not multi-language mixing dissonance), which supercharges productivity and maintainability in developing JavaFX applications similarly to Glimmer DSL for SWT through:
- Declarative DSL syntax that visually maps to the GUI control hierarchy while still allowing View logic in the same language
- Convention over configuration via smart defaults and automation of low-level details
- Requiring the least amount of syntax possible to build GUI
- Custom Keyword support
- Bidirectional Data-Binding without the complexity of static typing to declaratively wire and automatically synchronize GUI with Business Models
- Scaffolding for new custom components, apps, and gems
- Native-Executable packaging on Mac, Windows, and Linux.
Hello, World!

window {
title 'Hello, World!'
label('Hello, World!')
}
NOTE: Glimmer DSL for JFX is currently in early alpha mode (incomplete proof-of-concept). Please help make better by contributing, adopting for small or low risk projects, and providing feedback. It is still an early alpha, so the more feedback and issues you report the better.
Other Glimmer DSL gems you might be interested in:
Prerequisites
Note: On the Mac, if you have Glimmer DSL for SWT installed, and it added export JRUBY_OPTS="$JRUBY_OPTS -J-XstartOnFirstThread"
to your .zprofile
, .zshrc
, .bash_profile
, or .bashrc
, make sure to disable it before using Glimmer DSL for JFX. Unfortunately, it is not compatible with it and will hang its apps until disabled.
Setup
Make sure to download the right JavaFX SDK for your platform and CPU architecture from https://gluonhq.com/products/javafx/ and then set the PATH_TO_FX environment variable to the location of the lib directory in the extracted SDK directory.
Option 1: Install
Run this command to install directly:
gem install glimmer-dsl-jfx -v0.0.1
Option 2: Bundler
Add the following to Gemfile
:
gem 'glimmer-dsl-jfx', '0.0.1'
And, then run:
bundle
Usage
Require the library and mixin the Glimmer
module to utilize the Glimmer GUI DSL for JFX:
require 'glimmer-dsl-jfx'
include Glimmer
window {
title 'Hello, World!'
label('Hello, World!')
}
For actual application development outside of simple demos, mixin the Glimmer
module into a custom application class instead:
require 'glimmer-dsl-jfx'
class SomeApplication
include Glimmer
def launch
window {
title 'Hello, World!'
label('Hello, World!')
}
end
end
SomeApplication.new.launch
Glimmer GUI DSL
The Glimmer GUI DSL enables development of desktop graphical user interfaces in a manner similar to HTML, but in one language, Ruby, thus avoiding the multi-language separation dissonance encountered on the web, especially given that Ruby looping/conditional constructs do not need scriptlets to be added around View code. This makes desktop development extremely productive.
1 - Keywords
Always start with window
, which simplifies/replaces both the Stage
and Scene
concepts, having both their properties. Additionally, window
removes the need to extend Application
as it does so automatically internally.
Inside window
, you may declare any JavaFX control with its keyword, which is the underscored version of the class name. For example, label
is the keyword for javafx.scene.control.Label
Examples:
v_box
label
button
2 - Arguments
You may pass any arguments that a JavaFX control constructor accepts to its Glimmer keyword.
Example (Label
and Button
have a constructor signature that accepts a string representing the text property):
label('Full Name')
button('Submit Form')
The recommended style is to always wrap arguments with parentheses for control keywords.
3 - Content Block
You may pass a content block to any JavaFX control keyword, which contains properties and/or nested controls.
Example:
window {
title 'Hello, Window!'
width 320
height 240
v_box {
label('Hello, Label!')
button('Hello, Button!')
}
}
The recommended style for the content block is always curly braces {}
to denote as View nesting code different from looping/conditional logic, which utilizes do;end
instead.
Property arguments never have parentheses.
4 - Listeners
You may declare listeners with their on_
-prefixed event method name as found in the JavaFX Javadoc. For example: on_action
, on_key_pressed
, on_key_released
, on_key_typed
, on_mouse_clicked
, and on_mouse_moved
.
For example, Button
has an onAction
method. In Glimmer, you simply underscore that:
window {
title 'Hello, Button!'
button('Click') { |b|
on_action do
b.text = 'Clicked'
end
}
}
The recommended style for listeners is always a do; end
block.
5 - Component Proxy & Methods
When utilizing the Glimmer GUI DSL, you get back proxy objects that wrap JavaFX Javadoc controls. To access the original control wrapped by the proxy object, you may call the #jfx
method.
Furthermore, you may invoke any method available on the control indirectly on the proxy object, like the #text
method on label
.
label1 = label('Full Name')
label1.text
6 - Observe Model Attributes
In Smalltalk-MVC (Model View Controller Architectural Pattern), the View is an active View that observes the Model for changes and updates itself.

This can be achieved with the Glimmer GUI DSL using the observe
keyword, which takes a model (any object, including self
) and attribute Symbol or String expression (e.g. :count
or 'address.street'
).
The model is automatically enhanced as an Glimmer::DataBinding::ObservableModel
/ Glimmer::DataBinding::ObservableHash
/ Glimmer::DataBinding::ObservableArray
depending on its type to support notifying observers of attribute changes (when performed using the attribute writer, which automatically calls added method notify_observers(attribute)
)
Note that it is usually recommended to observe external model objects (not self
), but self
is OK in very simple cases or presentation-related attributes only.
Example:
require 'glimmer-dsl-jfx'
class Counter
attr_accessor :count
def initialize
self.count = 0
end
end
class HelloButton
include Glimmer
def initialize
@counter = Counter.new
observe(@counter, :count) do |new_count|
@button.text = "Click To Increment: #{new_count}"
end
end
def launch
window {
title 'Hello, Button!'
@button = button('Click To Increment: 0') {
on_action do
@counter.count += 1
end
}
}
end
end
HelloButton.new.launch

Smart Defaults and Conventions
window
automatically builds an Application
object, sets Stage
properties and sets a Scene
in primary stage.
Girb (Glimmer IRB)
You can run the girb
command (bin/girb
if you cloned the project locally):
girb
This gives you irb
with the glimmer-dsl-jfx
gem loaded and the Glimmer
module mixed into the main object for easy experimentation with GUI.
Samples
Hello Samples
Hello, World!
Run with gem installed:
jruby -r glimmer-dsl-jfx -e "require 'samples/hello/hello_world'"
Or run from locally cloned project directory:
jruby -r ./lib/glimmer-dsl-jfx samples/hello/hello_world.rb

samples/hello/hello_world.rb:
require 'glimmer-dsl-jfx'
include Glimmer
window {
title 'Hello, World!'
label('Hello, World!')
}
Hello, Button!
Run with gem installed:
jruby -r glimmer-dsl-jfx -e "require 'samples/hello/hello_button'"
Or run from locally cloned project directory:
jruby -r ./lib/glimmer-dsl-jfx samples/hello/hello_button.rb

Version 1 (without model) - samples/hello/hello_button.rb:
require 'glimmer-dsl-jfx'
include Glimmer
window {
title 'Hello, Button!'
@button = button('Click To Increment: 0') {
on_action do
button_text_match = @button.text.match(/([^0-9]+)(\d+)$/)
count = button_text_match[2].to_i + 1
@button.text = "#{button_text_match[1]}#{count}"
end
}
}
Version 2 (with model) - samples/hello/hello_button2.rb:
require 'glimmer-dsl-jfx'
class Counter
attr_accessor :count
def initialize
self.count = 0
end
end
class HelloButton
include Glimmer
def initialize
@counter = Counter.new
end
def launch
window {
title 'Hello, Button!'
@button = button('Click To Increment: 0') {
on_action do
@counter.count += 1
@button.text = "Click To Increment: #{new_count}"
end
}
}
end
end
HelloButton.new.launch
Resources
Process
Glimmer Process
Help
Issues
If you encounter issues that are not reported, discover missing features that are not mentioned in TODO.md, or think up better ways to use JavaFX than what is possible with Glimmer DSL for JFX, you may submit an issue or pull request on GitHub. In the meantime while waiting for a fix, you may try older gem versions of Glimmer DSL for JFX in case you find one that does not have the issue and actually works.
Chat
If you need live help, try to 
Planned Features and Feature Suggestions
These features have been planned or suggested. You might see them in a future version of Glimmer DSL for JFX. You are welcome to contribute more feature suggestions.
TODO.md
Change Log
CHANGELOG.md
Contributing
- Check out the latest master to make sure the feature hasn't been
implemented or the bug hasn't been fixed yet.
- Check out the issue tracker to make sure someone already hasn't
requested it and/or contributed it.
- Fork the project.
- Start a feature/bugfix branch.
- Commit and push until you are happy with your contribution.
- Make sure to add tests for it. This is important so I don't break it
in a future version unintentionally.
- Please try not to mess with the Rakefile, version, or history. If
you want to have your own version, or is otherwise necessary, that
is fine, but please isolate to its own commit so I can cherry-pick
around it.
Contributors
Click here to view contributor commits.
Copyright
MIT
Copyright (c) 2021 Andy Maleh.
--
Built for Glimmer (DSL Framework).