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Yu Shen
Yu Shen

Reputation: 2910

Scala/Swing: listenTo to just created button in the scope of BoxPanel does not work?

I'm building an application with variable number and configuration of buttons, and the application needs to listen the button clicked event, and process them.

Due to the requirements of variable number of buttons, and configurations, I feel that I must call listenTo for the just dynamically created button, in the BoxPanel scope. But I found that the buttons' event would not be received.

However, if I remember a created button, and call listenTo outside of the scope of BoxPanel, then its event would be received.

I'm wondering what's the matter why listenTo not working in the scope of BoxPanel? I didn't see any compiler error for such usage anyway.

Below is my sample code:

import scala.swing._
import scala.swing.event._

object TouchSelectUI extends SimpleSwingApplication {
  val touchMap = Vector(
    Vector("a", "b", "c"),
    Vector("d", "e", "g")
    // more may be defined in the future
  )
  val keyDemension = new Dimension(40, 25)
  def top = new MainFrame {
    title = "Touch Select Experiment"
    val input = new TextArea {
      columns = 80
      text = ""
    }
    var aButtonRemebered = new Button()
    contents = new FlowPanel {
      require(touchMap.size > 0, {println("The touch key definition is empty!")})
      for (c <- 0 until touchMap(0).size) {
    contents += new BoxPanel(Orientation.Vertical) {
      for (r <- 0 until touchMap.size) {
        val key = new Button {
        text = touchMap(r)(c)
          }
        contents += key
        aButtonRemebered = key
        listenTo(key) // listenTo here does not work.
      }
    }
      }
    contents += input 
    }

    //listenTo(aButtonRemebered) // Here listTo would work to deliver the event to the following reaction!
    reactions += {
      case ButtonClicked(b) => {
    println(s"Button clicked!")
    val c = b.text
    input.text = input.text + c
      }
    }
  }
}

Thanks a lot for your help!

Yu

Upvotes: 0

Views: 684

Answers (1)

EECOLOR
EECOLOR

Reputation: 11244

Is this what you mean?

object TouchSelectUI extends SimpleSwingApplication {

  //..

  def top = new MainFrame {

    val main = this

    //..

    contents = new FlowPanel {
      //..
      for (c <- 0 until touchMap(0).size) {
        contents += new BoxPanel(Orientation.Vertical) {
          for (r <- 0 until touchMap.size) {
            val key = new Button
            //..
            main listenTo key
          }
        }
      }
    }
  }
}

Edit

Luigi Plinge has a good suggestion, instead of this:

  def top = new MainFrame {

    val main = this

You could also do this:

  def top = new MainFrame { main =>

And he also provided the following links:

Upvotes: 1

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