KVision

Object oriented Web UI framework for Kotlin/JS.

KVision allows you to build user interface of modern web applications with the Kotlin language. It's designed to be object oriented in the "most classical" sense - it gives you a hierarchy of many different components, which are used to build application UI.

Unlike most of the popular web UI frameworks (AngularJS, React, Vue.js and others), KVision is not declarative - it is not designed to mix HTML code (or pseudo code) with a typical programming language like JavaScript. In KVision everything is just written in Kotlin, and your code can be reused not by creating any templates, but by using well known OOP design patterns - composition and inheritance.

This design is quite similar to many non-web UI programming libraries including Swing (Java), QT (C++) and WinForms (C#).

KVision is a new project in a development phase. Please create an issue for any bugs or feature requests.

Features

100% type safe and fully compiled dev environment.
Type safe DSL builders.
Based on Bootstrap styles, typography and components.
Utilizes Snabbdom fast virtual DOM implementation.
Integrates with libraries and components from Font awesome, Bootstrap Select (with AJAX extension), Awesome Bootstrap Checkbox, Trix editor, Bootstrap Datetime picker, Bootstrap touchspin, Bootstrap File Input, Handlebars and Navigo.
Includes sophisticated layout containers, including CSS flexbox, CSS grid and Bootstrap responsive 12 columns grid.
Includes convenient forms implementation, with support for many different input components and easy to use validation.
Data binding support for observable data model.
Easy to use Drag & Drop support.
Ready to explore KVision examples are available, built with Gradle and supporting Webpack's Hot Module Replacement (HMR) and Kotlin JavaScript DCE (dead code elimination).
Karma testing framework support.
IDE support (IntelliJ IDEA Community Edition).

Getting started

Development

Download KVision examples from GitHub:

git clone https://github.com/rjaros/kvision-examples.git

Enter one of the examples directory:

cd kvision-examples/showcase                        (on Linux)
cd kvision-examples\showcase                        (on Windows)

Run Gradle incremental build with:

./gradlew -t run                                    (on Linux)
gradlew.bat -t run                                  (on Windows)

Open http://localhost:8088/ in your browser.
Play with the code and see your changes immediately in the browser.

Production

To build complete application optimized for production run:

    ./gradlew -Pprod=true distZip                       (on Linux)
    gradlew.bat -Pprod=true distZip                     (on Windows)

Application package will be saved as build/distributions/showcase.zip.

Usage samples

Hello world

    val root = Root("root")
    val label = Label("Hello world!")
    root.add(label)

Basic components interactions

Simple, explicit way

    val root = Root("root")
    val panel = HPanel(spacing = 20, alignItems = FlexAlignItems.CENTER)
    val label = Label("Not yet clicked.")
    panel.add(label)
    var count = 0
    val button = Button("Click me")
    button.onClick {
        count++
        label.content = "You clicked the button $count times."
    }
    panel.add(button)
    root.add(panel)

Using Kotlin language features

    Root("root").add(
        HPanel(spacing = 20, alignItems = FlexAlignItems.CENTER).apply {
            val label = Label("Not yet clicked.").also { add(it) }
            var count = 0
            add(Button("Click me").onClick {
                label.content = "You clicked the button ${++count} times."
            })
        }
    )

Using type safe DSL builders

    Root("root") {
        hPanel(spacing = 20, alignItems = FlexAlignItems.CENTER) {
            val label = label("Not yet clicked.")
            var count = 0
            button("Click me") {
                onClick {
                    label.content = "You clicked the button ${++count} times."
                }
            }
        }
    }

Tab panel with JavaScript routing

    val firstPanel = Tag(TAG.DIV, "First")
    val secondPanel = Tag(TAG.DIV, "Second")
    val thirdPanel = Tag(TAG.DIV, "Third")

    Root("root").add(TabPanel().apply {
        addTab("First", firstPanel, route = "/first")
        addTab("Second", secondPanel, route = "/second")
        addTab("Third", thirdPanel, route = "/third")
    })

Type safe forms

    data class Model(val username: String?, val password: String?)

    Root("root").add(FormPanel {
        Model(it.string("username"), it.string("password"))
    }.apply {
        add(Model::username, Text(label = "Username"), required = true)
        add(Model::password, Password(label = "Password"), required = true)
        add(Button("OK").onClick {
            val data: Data = this@apply.getData()
            println("Username: ${data.username}")
            println("Password: ${data.password}")
        })
    })

Data binding with observable data model

    class Data(text: String) : BaseDataComponent() {
        var text: String by obs(text)
    }
    val model = observableListOf(
        Data("One"),
        Data("Two"),
        Data("Three")
    )
    Root("root").add(DataContainer(model, { index ->
        Label(model[index].text)
    }, child = HPanel(spacing = 10, wrap = FlexWrap.WRAP)))

    launch { // Kotlin coroutines
        while (true) {
            delay(1000)
            model.reverse()
        }
    }

API documentation

Full API documentation is available at https://rjaros.github.io/kvision/api/.