Let's Make a Bar Chart

BasicBarChartDemo.kt

package kubed.demo

import javafx.application.Application
import javafx.geometry.Insets
import javafx.scene.Group
import javafx.scene.Scene
import javafx.scene.paint.Color
import javafx.stage.Stage
import kubed.scale.scaleLinear
import kubed.selection.selectAll
import kubed.shape.rect

class BasicBarChartDemo : Application() {
    override fun start(primaryStage: Stage?) {
        val data = listOf(4.0, 8.0, 15.0, 16.0, 23.0, 42.0)

        val margin = Insets(20.0, 10.0, 20.0, 10.0)

        val outerWidth = 420.0
        val outerHeight = 500.0
        val innerWidth = outerWidth - margin.left - margin.right

        val barHeight = 20.0

        val xScale = scaleLinear<Double> {
            domain(0.0, data.max()!!.toDouble())
            range(0.0, innerWidth)
        }

        val rect = rect<Double> {
            width { d, _ -> xScale(d)  }
            translateY { _, i -> (barHeight + 1) * i }

            height(barHeight)
            fill(Color.STEELBLUE)
        }

        val chart = Group()
        chart.prefWidth(outerWidth)
        chart.prefHeight(outerHeight)
        chart.translateX = margin.left
        chart.translateY = margin.top

        chart.selectAll<Double>()
             .data(data)
             .enter()
             .append { d, i, _ -> rect(d, i) }

        val scene = Scene(chart)
        primaryStage?.scene = scene
        primaryStage?.show()
    }

    companion object {
        @JvmStatic
        fun main(vararg args: String) {
            launch(BasicBarChartDemo::class.java, *args)
        }
    }
}