Bridging the gap between scalafx and FXML with generated proxies
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vigoo Merge pull request #29 from TobsCore/master
Removes debugging statement
Latest commit fdfca99 Sep 17, 2017


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The scalafx library is a great UI DSL that wraps JavaFX classes and provides a nice syntax to work with them from Scala.

This library bridges FXML and scalafx by automatically building proxy classes, enabling a more clear controller syntax.


The main branch contains the initial implementation of the compile time proxy generator, which uses macro annotations. This requires the addition of the macro paradise compiler plugin, but has no runtime dependencies. It depends on ScalaFX 8 and JavaFX 8.

The SFX-2 branch is the compile time proxy generator for ScalaFX 2.2 using JavaFX 2.

On the dynamic branch there is the first version of the proxy generator which executes runtime. This has a disadvantage of having scala-compiler.jar as a dependency, but has no special compile-time dependencies.

The latest published version is 0.4. To use it in SBT add:

addCompilerPlugin("org.scalamacros" % "paradise" % "2.1.0" cross CrossVersion.full)

libraryDependencies += "org.scalafx" %% "scalafxml-core-sfx8" % "0.4"


The controller's, referenced from the FXML's through the fx:controller attribute, can be implemented as simple Scala classes, getting all the bound controls though the constructor:

import scalafx.scene.control.TextField
import scalafx.scene.control.Button
import scalafx.scene.control.ListView
import scalafx.event.ActionEvent
import scalafxml.core.macros.sfxml

class TestController(input: TextField,
                     create: Button,
                     recentInputs: ListView[String],
                     dep: AnAdditionalDependency) {

	// event handlers are simple public methods:
	def onCreate(event: ActionEvent) {
		// ...

Accessing the controller

As the controller class is replaced in compile time by a generated one, we cannot directly use it to call the controller of our views. Instead we have to define a public interface for them and then use it as the type given for the getController method of FXMLLoader.

The example below shows this:

trait UnitConverterInterface {
  def setInitialValue(value: Double)

class UnitConverterPresenter(// ... 
  extends UnitConverterInterface {
  // ...

// Instead of FXMLView, we create a new ScalaFXML loader
val loader = new FXMLLoader(
  // ...

val root = loader.getRoot[jfxs.Parent]

val controller = loader.getController[UnitConverterInterface]

stage = new JFXApp.PrimaryStage() {
  title = "Unit converter"
  scene = new Scene(root)

Nested controllers

Nested controllers can be used in a similar way as described above, by defining a public interface for them first, using this interface as the type of the injected value in the parent controller, but explicitly marking the original controller class with a @nested annotation.

The following example demonstrates this:

trait NestedControllerInterface {
  def doSomething(): Unit

class NestedController(label: Label) extends NestedControllerInterface {

  println(s"Nested controller initialized with label: $label")

  override def doSomething(): Unit = {
    label.text = "Nested controller called!"
    println("Nested controller called")

class WindowController(nested: VBox,
                       @nested[NestedController] nestedController: NestedControllerInterface) {


Third party control libraries

scalafxml recognizes factory JavaFX and ScalaFX controls, and assumes everything else to be an external non-UI dependency to be get from a dependency provider. When using third party control libraries, there are two possibilities:

  • Listing the third party control package in the @sfxml annotation
  • Using the @FXML annotation for these controls

The following example shows how to do this with JFoenix using the first method:

class TestController(input: JFXTextField,
                     create: JFXButton)

or with the second approach:

class TestController(@FXML input: JFXTextField,
                     @FXML create: JFXButton)

Dependency injection

Beside the JavaFX controls, additional dependencies can be injected to the controller as well. This injection process is extensible.


It is also possible to simply give the dependencies by their type or by their name:

object SimpleDemo extends JFXApp {

  stage = new JFXApp.PrimaryStage() {
    title = "Test window"
    scene = new Scene(
		    new DependenciesByType(Map(
		      typeOf[AnAdditionalDependency] -> new AnAdditionalDependency("dependency by type"))))



The following example uses SubCut for injecting the additional dependency:

object SubCutDemo extends JFXApp {

  implicit val bindingModule = newBindingModule(module => {
    import module._

    bind [AnAdditionalDependency] toSingle(new AnAdditionalDependency("subcut dependency"))

  stage = new JFXApp.PrimaryStage() {
    title = "Test window"
    scene = new Scene(
			new SubCutDependencyResolver()))


The following example demonstrates how to use MacWire to inject additional dependencies:

object MacWireDemo extends JFXApp {

  class Module {
    def testDependency = TestDependency("MacWire dependency")

  lazy val wired: Wired = wiredInModule(new Module)

  stage = new JFXApp.PrimaryStage() {
    title = "Hello world"
    scene = new Scene(
      new MacWireDependencyResolver(wired)))


The same example with Guice:

object GuiceDemo extends JFXApp {

  val module = new AbstractModule {
    def configure() {
      bind(classOf[TestDependency]).toInstance(new TestDependency("guice dependency"))
  implicit val injector = Guice.createInjector(module)

  stage = new JFXApp.PrimaryStage() {
    title = "Hello world"
    scene = new Scene(
      new GuiceDependencyResolver()))


  • sbt 0.13 is required