kotlinとJavaFXでバウンスボックスとカウンター表示をするサンプル01

kotlin_javafx_sample_01_bouncing_box_and_counter.kt

// http://krr.blog.shinobi.jp/javafx/javafx%203d%20%E5%BA%A7%E6%A8%99%E5%A4%89%E6%8F%9B%EF%BC%88%E5%B9%B3%E8%A1%8C%E7%A7%BB%E5%8B%95%E3%83%BB%E5%9B%9E%E8%BB%A2%E3%83%BB%E6%8B%A1%E7%B8%AE%EF%BC%89
// https://gamedevelopment.tutsplus.com/ja/tutorials/introduction-to-javafx-for-game-development--cms-23835
import javafx.animation.AnimationTimer
import javafx.application.Application
import javafx.geometry.Point2D
import javafx.scene.Group
import javafx.scene.Scene
import javafx.scene.canvas.Canvas
import javafx.scene.canvas.GraphicsContext
import javafx.scene.paint.Color
import javafx.scene.text.Font
import javafx.stage.Stage

fun random(min: Double = 0.0, max: Double = 1.1) = (Math.random() * (max - min + 1)) + min

fun random(min: Int = 0, max: Int = 1) = ((Math.random() * (max - min + 1)) + min).toInt()

fun randomASCII(upper: Boolean = true) = (if (upper) random(65, 90) else random(97, 122)).toChar()

fun randomString(n: Int = 5) = (1..n).map { randomASCII() }.joinToString(separator = "")

const val answer = "CAT"


var x = 0.0
var vx = 5.0
var y = 0.0
var vy = 4.0
var count = 0
var foundFlag = false
var degrees = 0.0
fun draw(ctx:GraphicsContext) {
    ctx.fill = Color(1.0, 1.0, 1.0, 0.9)
    //ctx.clearRect(0.0,0.0, ctx.canvas.width, ctx.canvas.height)
    ctx.fillRect(0.0,0.0, ctx.canvas.width, ctx.canvas.height)

    ctx.font = Font("Meiryo", 30.0)
    ctx.fill = Color.BLACK
    ctx.fillText("こんにちは二重世界!!${count++}", 60.0, 60.0)

    x += vx
    vx *= (if (0 <= x && x <= ctx.canvas.width-50.0) 1 else -1)

    y += vy
    vy *= (if (0 <= y && y <= ctx.canvas.height-50.0) 1 else -1)

    ctx.fill = Color.BLUE
    ctx.fillRect(x, y, 50.0, 50.0)


    if (foundFlag) {
        ctx.fill = Color.BLACK
        ctx.fillText("FOUND    : $answer", 60.0, 90.0)
    } else {
        val s = randomString(3)
        val msg = if (s == answer) "FOUND    : $s" else "NOT FOUND: $s"
        ctx.fill = Color.BLACK
        ctx.fillText("$msg", 60.0, 90.0)
        if (s == answer) {
            foundFlag = true
        }
    }
    ctx.save()
    //ctx.translate(ctx.canvas.width/2, ctx.canvas.height/2) // move to origin.
    ctx.translate(0.0, 0.0) // 原点(origin)を移動。
    ctx.scale(1.0,1.0)
    ctx.rotate(degrees)
    ctx.translate(-50.0, -50.0) // 高さと幅の半分を戻す。
    degrees++;
    //ctx.translate(-100.0, -50.0)
    ctx.fill = Color.RED
    ctx.fillRect(0.0, 0.0, 100.0, 100.0)
    ctx.restore()

    val kr = KRect(ctx.canvas.width/2, ctx.canvas.height/2, 100.0, 100.0)
    kr.scale = Point2D(2.0, 2.0)
    kr.degrees = degrees
    kr.display(ctx)
}

class KRect(var x: Double = 0.0, var y: Double = 0.0, var w: Double = 0.0, var h: Double = 0.0) {
    var degrees: Double = 0.0
    var scale: Point2D = Point2D(1.0, 1.0)
    var color: Color = Color.BLACK
    fun display(ctx: GraphicsContext): KRect {
        ctx.save()
        //ctx.translate(ctx.canvas.width/2, ctx.canvas.height/2) // move to origin.
        ctx.translate(x, y) // 原点(origin)を移動。
        ctx.scale(scale.x, scale.y)
        ctx.rotate(degrees)
        ctx.translate(-w/2, -h/2) // 高さと幅の半分を戻す。
        //ctx.translate(-100.0, -50.0)
        ctx.fill = color
        ctx.fillRect(0.0, 0.0, w, h)
        ctx.restore()
        return this
    }
}


class App1 : Application() {
    lateinit var canvas: Canvas
    lateinit var ctx: GraphicsContext

    override fun start(primaryStage: Stage) {
        canvas = Canvas(640.0, 480.0)
        ctx = canvas.graphicsContext2D
        val root = Group()
        root.children.add(canvas)

        // 無名クラスは、Kotlinではオブジェクト式を使う
        object : AnimationTimer() {
            override fun handle(now: Long) {
                draw(ctx)
            }
        }.start()

        primaryStage.title = "KotlinでJavaFX"
        primaryStage.scene = Scene(root, canvas.width, canvas.height)
        primaryStage.show()
    }

    // コンパニオンオブジェクトと@JvmStaticで、staticメソッドを作成
    companion object {
        @JvmStatic
        fun main(args: Array<String>) {
            Application.launch(App1::class.java, *args) // *で可変長配列に変換
        }
    }
}