如何发送消息给演员阿卡

Question

I'm beginner in Scala and akka, and I want to send message to MessageSender actor if the keybutton was pressed, I draw a field and 2 objects, but when I run a program and then press up arrow, message in actor is not printing

//Boot
import akka.actor.{ActorSystem, Props}
import scalafx.Includes._
import scalafx.application
import scalafx.application.JFXApp
import scalafx.scene.Scene
import scalafx.scene.canvas.{Canvas, GraphicsContext}
import scalafx.scene.input.{KeyCode, KeyEvent}

object Boot extends JFXApp {



  val system = ActorSystem("MYsystem")
  val messageSender = system.actorOf(Props[MessageSender],"MessageSender")
  val wiDth = 500
  val heiDth = 500
  stage = new application.JFXApp.PrimaryStage {
    title = "Tanks"
    scene = new Scene(wiDth,heiDth) {
        val canvas = new Canvas(wiDth,heiDth)
        var g = canvas.graphicsContext2D
        val tank = new Objects(g)
        val thisTank = tank.drawTank(0,0)
        val thisBullet = tank.drawBullet(60,20)
        canvas.onKeyPressed = (e: KeyEvent) => {
            e.code match {
              case KeyCode.Up => messageSender ! MessageSender.Up

            }}
     content=canvas

    }
    }
  }

Message sender

object MessageSender {

  case object Left
  case object Right
  case object Up
  case object Down
  case object StartGame
  case object MakeShoot

}

class MessageSender extends Actor with ActorLogging{
import  MessageSender._
  override def receive: Receive = {
    case Up => println("sent up")



  }

}

Answer 1

I think this is an issue with your canvas not getting events. If you move the onKeyPressed handler to the Scene level it will work.

This is because you are missing the following:

canvas.setFocusTraversable(true)

here is a quick example I created:

class MsgActor extends Actor {
  def receive: Receive = {
    case keyCode: KeyCode =>
      println("incoming...\t" + keyCode.getName)
  }
}

object Boot extends JFXApp {

  implicit val system = ActorSystem("javafx")
  val msgActor = system.actorOf(Props(new MsgActor()))

  val canvas = new Canvas(500, 500)
  val gc = canvas.graphicsContext2D
  canvas.translateX = 0
  canvas.translateY = 0

  canvas.onKeyPressed = (e: KeyEvent) => e.getCode match {
    case code => msgActor ! code
  }

  // this is needed!
  canvas.setFocusTraversable(true)

  new application.JFXApp.PrimaryStage {
    title.value = "Tanks"
    width = 500
    height = 500
    scene = new Scene {
      fill = Color.AliceBlue
      content = canvas
    }
  }
}