Question

我在eclipse中做了一些搜索和一些试验和错误，但是当我使用Swing在Scala中编写GUI时，我对听众和反应的理解似乎存在差距。

每个侦听器是否都获得了一个反应块，或者我是否在所有可能生成事件的组件上注册了侦听器，并对带有case语句的大型反应块中的每个组件做出反应？

听众和反应块究竟属于哪里。

这是我的GUI代码的缩写版本：

import scala.swing._
import scala.swing.event.ButtonClicked
import scala.swing.event.KeyTyped
import scala.swing.event.KeyPressed

object HumanGUI extends SimpleGUIApplication {

 val basicPane = new java.awt.Dimension(800, 200)
 val botPane = new java.awt.Dimension(400, 200)
 val felt = new java.awt.Color(35, 125, 35)

 def top = new MainFrame {

    title = "Blackjack GUI"

    val ConnectionPanel = new BoxPanel(Orientation.Vertical) {
      background = felt
      preferredSize = new java.awt.Dimension(155, 90)
      minimumSize = preferredSize
      maximumSize = preferredSize

      val ipAddressLabel = new Label("House IP:")
      ipAddressLabel.foreground = java.awt.Color.WHITE
      ipAddressLabel.horizontalTextPosition = scala.swing.Alignment.Left

      val portLabel = new Label("House port:")
      portLabel.foreground = java.awt.Color.WHITE
      portLabel.horizontalTextPosition = scala.swing.Alignment.Left

      val ipAddressTextField = new TextField
      val portTextField = new TextField

      contents += ipAddressLabel
      contents += ipAddressTextField
      contents += portLabel
      contents += portTextField
    }

    val DetailPanel = new BoxPanel(Orientation.Vertical) {
      background = felt
      preferredSize = new java.awt.Dimension(100, 160)
      minimumSize = preferredSize
      maximumSize = preferredSize

      val nameLabel = new Label("Your name:")
      nameLabel.foreground = java.awt.Color.WHITE
      nameLabel.horizontalTextPosition = scala.swing.Alignment.Left

      val bankrollLabel = new Label("Bankroll:")
      bankrollLabel.foreground = java.awt.Color.WHITE
      bankrollLabel.horizontalTextPosition = scala.swing.Alignment.Left

      val betLabel = new Label("Bet:")
      betLabel.foreground = java.awt.Color.WHITE
      betLabel.horizontalTextPosition = scala.swing.Alignment.Left

      val nameTextField = new TextField
      val bankrollTextField = new TextField
      val betTextField = new TextField

      val goButton = new Button("Go!")

      contents += nameLabel
      contents += nameTextField
      contents += bankrollLabel
      contents += bankrollTextField
      contents += betLabel
      contents += betTextField
      contents += goButton
    }

    val PlayPanel = new BoxPanel(Orientation.Vertical) {
      background = felt
      val hitButton = new Button("Hit")
      val stayButton = new Button("Stay")
      val doubleButton = new Button("Double")
      val quitButton = new Button("Quit")

      contents += hitButton
      contents += stayButton
      contents += doubleButton
      contents += quitButton
    }

    val playerPanel = new BoxPanel(Orientation.Horizontal) {
      background = felt
      border = new javax.swing.border.LineBorder(java.awt.Color.WHITE)
      preferredSize = basicPane
      minimumSize = basicPane
      maximumSize = basicPane
      opaque = true

      contents += ConnectionPanel
      contents += DetailPanel
      contents += PlayPanel
    }

    contents = new BoxPanel(Orientation.Vertical) {
      contents += playerPanel
    }
  }
}

所以问题是我在哪里放置听众和反应块？我想对PlayPanel中的按钮以及ConnectionPanel和DetailPanel中的文本字段做出反应我是否尽可能地将听众和反应块放在我感兴趣的元素附近，或者在MainFrame部分的末尾放置一大块听众和反应？它甚至重要吗？

修改
我已经取得了重大进展，并且拥有了我需要的大部分工作，并且更好地理解了我以前没有得过的概念。

摘自Odersky的“Scala编程”对我的帮助最大。具体来说，这个页面的例子是：

http://www.artima.com/pins1ed/gui-programming.html

代码来自文本的第一版，所以我怀疑Scala 2.9中是否有更好的方法，但很清楚简洁并总结了我误解的内容。

从一个简单的华氏温度到摄氏温度转换的例子，我开始明白监听器和反应块属于MainFrame的内容块之后。

所以我最终得到了：

object HumanGUI extends SimpleSwingGUIApplication {
  def top = new MainFrame {
    title = "My Blackjack GUI"

    //The fields I want to work with are instantiated as object
    object ipAddressTextField extends TextField { columns = 15 }
    object portNumberTextField extends TextField {columns = 5 }

    //other panels, objects, etc would go here
    val OtherPanel = new BoxPanel(Orientation.Horizontal) {
       label = "Other Panel"
    }

    //and here we have the contents += block for the mainframe, other panels, etc from 
    //above would be added to the main frame here
    contents = new BoxPanel(Orientation.Vertical) {
      contents += ipAddressTextField
      contents += portNumberTextField
    }

    //here's the listen to, listening on the object created above, and it's enclosed in 
    //in backticks, a good explanation of that is found in the link below
    listenTo(`ipAddressTextField`)
    reactions += {
      case EditDone('ipAddressTextField`) =>
        //do something!
    }
  }

Need clarification on Scala literal identifiers (backticks)

所以似乎我的问题的答案是listenTo和react块属于MainFrame块，但应该出现在它的内容+ = {// contents}块之后。

eclipse中的其他试验和错误表明，虽然这个解决方案适用于我，但显然还有更多我不理解的内容。例如，如果我试图在内部听取并对它们做出反应，我无法让KeyPress事件的监听器工作 val OtherPanel = new BoxPanel（Orientation.Horizontal）{}
上面代码的一部分，我能够得到一个注册按钮并按此工作：

val OtherPanel = new BoxPanel(Orientation.Horizontal) {
  val betLabel = new Label("Bet:")
  val betTextField = new TextField
  val goButton = new Button("Go!")

  listenTo(goButton)
  reactions += {
    case ButtonClicked(b) =>
      betTextField.text = "Go!"
  }

  contents += betLabel
  contents += betTextField
  contents += goButton
}

为什么这有效，但我尝试按照

的方式做一些事情

val OtherPanel = new BoxPanel(Orientation.Horizontal) {
  val betLabel = new Label("Bet:")
  val betTextField = new TextField
  val goButton = new Button("Go!")

listenTo(betTextField)
reactions += {
  case KeyTyped(betTextField, Enter, _, _) => {
    println("Caught enter")
  }

  contents += betLabel
  contents += betTextField
  contents += goButton
}

没有工作仍然令我困惑。我假设它应该工作，我只是做错了。也许用一个案例EditDone而不是一个案例KeyTyped（，，，）来融合这种方法会有效但我现在有点太过于无法跟进在那。

我还没有接受答案，因为我希望看到这个的人可以澄清我仍然不理解的观点。如果这种情况没有发生且问题仍未得到解决，我可能会接受@ som-snytt的回答，因为他的代码非常有用。

Answer 1

Swing很有教育意义，Scala-Swing很有教育意义。特别是如果课程是“摇摆历史：兴衰”。

我的第一个Scala程序也使用了Swing。我已经忘记了细节，但我会分享我在源头上看到的内容。

显然，我有一个名为LightBox的主UI组件处理一些UI事件，还有一个协调的中介组件LightBoxMediator。

有趣的部分是，使用蛋糕模式进行合成，并将业务逻辑（或游戏逻辑）交互转移到一个“适当”调整UI的组件中。 LightBox也发布了事件。

因此，您的问题的答案将是：利用发布者框架，但将UI事件与应用程序事件区分开来。（这个小游戏也有基于演员的控制器。）

也许这足以说明关注点的分离：

/**
 * Draws the House of Mirrors.
 * The LightBox is just a list of rays (line segments) and gates (various objects).
 * The UI emits requests to move and rotate gates.
 */
class LightBox extends Panel {

  this.peer.addComponentListener(
    new ComponentAdapter {
      override def componentResized(e: ComponentEvent) {
        if (e.getID == ComponentEvent.COMPONENT_RESIZED && e.getComponent == LightBox.this.peer) {
          calculateScale()
        }
      }
    }
  )

  listenTo(mouse.clicks, mouse.moves, mouse.wheel, keys)

  reactions += {
    case KeyPressed(_, Key.N, _, _) => highlightNextMoveableGate()
    case KeyPressed(_, Key.P, _, _) => highlightPreviousMoveableGate()
    case e: MousePressed => startDrag(e)
    case e: MouseDragged => doDrag(e)
    case e: MouseReleased => endDrag(e)
    case e: MouseWheelMoved => wheeling(e)
    case _ => null // println ("Unreacted event")
  }

和调解员

trait ViewComponents {
  this: ControllerComponents with ModelComponents =>

  val lightBoxMediator: LightBoxMediator
  val statusBarMediator: StatusBarMediator
  val statusIconMediator: StatusIconMediator
  val applicationMediator: ApplicationMediator

  /**
   * Handles update notifications from the application
   * and user input from the LightBox.
   */
  class LightBoxMediator(val ui: LightBox) extends Reactor with Observing {

    /** Attempt to track our selection across updates: the point is where the gate should end up. */
    private var selectionContinuity: (Option[Gate], Option[Point]) = (None, None)

    listenTo(ui, ui.keys, ui.mouse.clicks)

    reactions += {
      case KeyPressed(_, Key.Q, _, _) => sys.exit()
      case KeyPressed(_, Key.Space, _, _) => rotateSelectedGate()
      case KeyPressed(_, Key.Enter, _, _) => rotateOtherwiseSelectedGate()
      case KeyPressed(_, Key.Up, _, _) => moveUp()
      case KeyPressed(_, Key.Down, _, _) => moveDown()
      case KeyPressed(_, Key.Left, _, _) => moveLeft()
      case KeyPressed(_, Key.Right, _, _) => moveRight()
      case KeyPressed(_, Key.PageUp, _, _) => previousLevel()
      case KeyPressed(_, Key.PageDown, _, _) => nextLevel()
      case DragEvent(from, to) => handleDrag(from, to)
      case ClickEvent(where, button) => handleClick(where, button)
      //case x => println("Unreacted event " + x)
    }

    observe(controller.modelEvents) { e => e match {
        case LevelLoaded(v) => onLevelLoaded(v)
        case TraceResult(s) => onTrace(s)
        case unknown => println("Lightbox mediator ignored: "+ unknown)
      }
      true
    }

刚刚注意到其他问题。巧合的是，我正在清理旧代码，实际上是一个小应用程序从sfgate.com获取图像（当然，当他们更改网站时停止工作;但通常你可以右击 - 现在保存），我碰巧请注意以下关于重新订阅的评论。我依旧记得关于UIElement是一个懒惰的发布者的一点，因为我记得头脑一巴掌。但如果我没有写出微薄的评论，那么这些信息就会在古代历史中丢失。

我认为有人想要支持scala-swing并且可能会照顾头部。

package com.maqicode.sfg.jfc

import java.awt.Color
import java.awt.Color.{WHITE => White, RED => Red}
import java.net.{URI, URISyntaxException}
import javax.swing._

import swing.TextField
import swing.event.{EditDone, MouseEntered, ValueChanged}

import com.maqicode.sfg.BadGateURLException
import com.maqicode.sfg.GateUrlTranslator.translate

abstract class URIField extends TextField {

  reactions += {
    case e: EditDone => editDone(e)
    case other: ValueChanged => editing(other)
    case m: MouseEntered => onMouseEntered()
    case _ => null
  }
  // necessary to resubscribe this so that onFirstSubscribe registers ActionListener
  listenTo(this, mouse.moves)

  def onMouseEntered() {
    val t: Option[String] = ClipboardInput.contents
    if (t.isDefined && t.get != this.text) {
      this.text = t.get
      submitURL(t.get)
    }
  }

  def editing(e: ValueChanged) {
    clearError()
  }

  def editDone(e: EditDone) {
    submitURL(this.text)
  }

  def submitURL(s: String) {
    val u = s.trim
    if (!u.isEmpty)
      try {
        submitURI(translate(new URI(u)))
        clearError()
      } catch {
        case t: BadGateURLException => flagError()
        case t: URISyntaxException => flagError()
      }
  }

  def flagError() {
    colorCode(Red)
  }

  def clearError() {
    colorCode(White)
  }

  private def colorCode(c: Color) {
    if (this.background != c) this.background = c
  }

  def submitURI(uri: URI): Unit
}

Scala Swing中的听众和反应

1 个答案: