来点学术的，求PI值动画

import javafx.animation.KeyFrame
import javafx.animation.Timeline
import javafx.event.ActionEvent
import javafx.event.EventHandler
import javafx.geometry.Pos
import javafx.scene.paint.Color
import javafx.scene.shape.Circle
import tornadofx.*

class MyApp : App(蒙特卡洛算法求Pi::class)
class 蒙特卡洛算法求Pi : View("learn 蒙特卡洛算法") {
    //    动画计时器
    val result = stringProperty()
    val numPoint = intProperty()
    val Msg = stringProperty()
    val numPointInCircle = intProperty()
    var pause = true
    lateinit var circle0: Circle
    override val root = borderpane {
        val eventHandler = EventHandler<ActionEvent> {
            val p = point((0..600).random().toDouble(), (0..600).random().toDouble())
            val c = Circle(p.x, p.y, 1.0)
            //  判断圆circle0是否包含点p，方法2
            if (circle0.contains(p)) {
                c.fill = Color.RED
                numPointInCircle.value++
            }
            center.add(c)
            numPoint.value++
            val piEstimate = 4.0 * numPointInCircle.value / numPoint.value
            Msg.value = "总点数：${numPoint.value} -- 圆内点数：${numPointInCircle.value} -- Pi估计值:  ${piEstimate} "
        }
        //动画
        val animation = Timeline(KeyFrame(1.millis, eventHandler)) //速度
        animation.cycleCount = 300000  //次数
//        animation.play()
        top = vbox(5) {
            label(result) {
                isWrapText = true
            }
            label(Msg)
            hbox(5) {
                alignment = Pos.CENTER
                button("run"){
                    setPrefSize(200.0,50.0)
                    action {
                        if (!pause) {
                            animation.pause()
                            text = "run"
                            pause = true
                        } else {
                            text = "pause"
                            animation.play()
                            pause = false
                        }
                    }
                }
            }
        }
        center = group {
            rectangle(0, 0, 600, 600) {
                fill = Color.YELLOW
            }
            circle0 = circle(300, 300, 300) {
                fill = Color.AZURE
            }
            prefHeight = 800.0
            prefWidth = 800.0
        }
    }
}