TornadoFX – JavaFX Framework for Kotlin

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Here you can get Kotlin tutorials on Android but due to mass request about Kotlin library for desktop application. So today i am going to tell you about TornadoFX which is a JavaFX Framework for Kotlin.

JavaFX is a software platform for creating and delivering desktop applications, as well as rich internet applications (RIAs) that can run across a wide variety of devices. JavaFX is intended to replace Swing as the standard GUI library for Java SE, but both will be included for the foreseeable future.

Now let’s focus on JavaFX Framework for Kotlin:

TornadoFX - JavaFX Framework for Kotlin
TornadoFX – JavaFX Framework for Kotlin

Features

  • Supports both MVC, MVP and their derivatives
  • Dependency injection
  • Type safe GUI builders
  • Type safe CSS builders
  • First class FXML support
  • Async task execution
  • EventBus with thread targeting
  • Hot reload of Views and Stylesheets
  • OSGi support
  • REST client with automatic JSON conversion
  • Zero config, no XML, no annotations

 

Important version note

TornadoFX requires Kotlin 1.1.2 and jvmTarget 1.8. Make sure you update your IDE plugins (Kotlin + TornadoFX).

After updating IntelliJ IDEA, make sure your Kotlin target version is 1.1 (Project Settings -> Modules -> Kotlin -> Language Version / API Version)

Remember to update your build system to configure the jvmTarget as well.

For Maven, you add the following configuration block to kotlin-maven-plugin:

<configuration>
    <jvmTarget>1.8</jvmTarget>
</configuration>

For Gradle, it means configuring the kotlinOptions of the Kotlin compilation task:

compileKotlin {
    kotlinOptions.jvmTarget= "1.8"
}

Failing to do so will yield errors about the compiler not being able to inline certain calls.

You also need a full rebuild of your code after a version upgrade. If you run into trouble, try to clean caches and restart IDEA (File -> Invalidate caches / Restart).

1Generate a quickstart application with Maven

mvn archetype:generate -DarchetypeGroupId=no.tornado \
  -DarchetypeArtifactId=tornadofx-quickstart-archetype \
  -DarchetypeVersion=1.7.14

2Add TornadoFX to your project

Maven

<dependency>
    <groupId>no.tornado</groupId>
    <artifactId>tornadofx</artifactId>
    <version>1.7.14</version>
</dependency>

3Gradle

compile 'no.tornado:tornadofx:1.7.14'

5Snapshots are published to Sonatype

Configure your build environment to use snapshots if you want to try out the latest features:

<repositories>
   <repository>
     <id>snapshots-repo</id>
     <url>https://oss.sonatype.org/content/repositories/snapshots</url>
     <releases><enabled>false</enabled></releases>
     <snapshots><enabled>true</enabled></snapshots>
   </repository>
 </repositories>

Snapshots are published every day at GMT 16:00 if there has been any changes.

6What does it look like? (Code snippets)

Create a View

class HelloWorld : View() {
    override val root = hbox {
        label("Hello world")
    }
}

Load the root node from HelloWorld.fxml and inject controls by fx:id

import javafx.scene.control.Label
import javafx.scene.layout.HBox
import tornadofx.*

class HelloWorld : View() {
    override val root: HBox by fxml()
    val myLabel: Label by fxid()
    
    init {
        myLabel.text = "Hello world"
    }
}

 

Start your application and show the primary View and add a type safe stylesheet

import javafx.scene.text.FontWeight
import tornadofx.*

class HelloWorldApp : App(HelloWorld::class, Styles::class)

class Styles : Stylesheet() {
    init {
        label {
            fontSize = 20.px
            fontWeight = FontWeight.BOLD
            backgroundColor += c("#cecece")
        }    
    }    
}

Start app and load a type safe stylesheet

Use Type Safe Builders to quickly create complex user interfaces

class MyView : View() {
    private val persons = FXCollections.observableArrayList(
            Person(1, "Samantha Stuart", LocalDate.of(1981,12,4)),
            Person(2, "Tom Marks", LocalDate.of(2001,1,23)),
            Person(3, "Stuart Gills", LocalDate.of(1989,5,23)),
            Person(3, "Nicole Williams", LocalDate.of(1998,8,11))
    )

    override val root = tableview(persons) {
        column("ID", Person::id)
        column("Name", Person::name)
        column("Birthday", Person::birthday)
        column("Age", Person::age)
        columnResizePolicy = SmartResize.POLICY
    }
}

RENDERED UI

Create a Customer model object that can be converted to and from JSON and exposes both a JavaFX Property and getter/setter pairs:

import tornadofx.getValue
import tornadofx.setValue

class Customer : JsonModel {
    val idProperty = SimpleIntegerProperty()
    var id by idProperty

    val nameProperty = SimpleStringProperty()
    var name by nameProperty

    override fun updateModel(json: JsonObject) {
        with(json) {
            id = int("id") ?: 0
            name = string("name")
        }
    }

    override fun toJSON(json: JsonBuilder) {
        with(json) {
            add("id", id)
            add("name", name)
        }
    }
}

Create a controller which downloads a JSON list of customers with the REST api:

class HelloWorldController : Controller() {
    val api : Rest by inject()
    
    fun loadCustomers(): ObservableList<Customer> = 
        api.get("customers").list().toModel() 
}

Configure the REST API with a base URI and Basic Authentication:

with (api) {
    baseURI = "http://contoso.com/api"
    setBasicAuth("user", "secret")
}

Load customers in the background and update a TableView on the UI thread:

runAsync {
    controller.loadCustomers()
} ui {
    customerTable.items = it
}

Load customers and apply to table declaratively:

customerTable.asyncItems { controller.loadCustomers() }

Define a type safe CSS stylesheet:

class Styles : Stylesheet() {
    companion object {
        // Define css classes
        val heading by cssclass()
        
        // Define colors
        val mainColor = c("#bdbd22")
    }

    init {
        heading {
            textFill = mainColor
            fontSize = 20.px
            fontWeight = BOLD
        }
        
        button {
            padding = box(10.px, 20.px)
            fontWeight = BOLD
        }

        val flat = mixin {
            backgroundInsets += box(0.px)
            borderColor += box(Color.DARKGRAY)
        }

        s(button, textInput) {
            +flat
        }
    }
}

 

 

Create an HBox with a Label and a TextField with type safe builders:

hbox {
    label("Hello world") {
        addClass(heading)
    }
    
    textfield {
        promptText = "Enter your name"
    }
}

Get and set per component configuration settings:

// set prefWidth from setting or default to 200.0
node.prefWidth(config.double("width", 200.0))

// set username and age, then save
with (config) {
    set("username", "john")
    set("age", 30)
    save()
}

Create a Fragment instead of a View. A Fragment is not a Singleton like View is, so you will create a new instance and you can reuse the Fragment in multiple ui locations simultaneously.

class MyFragment : Fragment() {
    override val root = hbox {
    }
}

Open it in a Modal Window:

find(MyFragment::class).openModal()

Lookup and embed a View inside another Pane in one go

add(MyFragment::class)

Inject a View and embed inside another Pane

val myView: MyView by inject()
 
init {
    root.add(myFragment)
}

Swap a View for another (change Scene root or embedded View)

button("Go to next page") {
    action {
        replaceWith(PageTwo::class, ViewTransition.Slide(0.3.seconds, Direction.LEFT)
    }
}

Open a View in an internal window over the current scene graph

button("Open") {
    action {
        openInternalWindow(MyOtherView::class)
    }
}

That’s it !! Hope you enjoy this article and share with your friends.

 

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