How a custom control is advised it gains or looses focus?

Question

Hey, at least I have a question to ask, instead of answering them... :-)
Actually, I already asked it in another thread, in one of my answers: [onMouseClicked Event Is Failing To Fire|http://forums.sun.com/thread.jspa?threadID=5391008] but I fear it is lost in a rather lengthly message, so I ask it in its own thread, because I was to bring the attention of knowledgeable people (hello Sun people! :-D).
The question is simple: In a custom control in JavaFX 1.2, with skin and behavior, how a control is advised when it gains or looses focus?
The purpose is to let the skin to change the look of the component upon these events, like it is done for standard controls (eg. putting a border around the focused control).
If the control is clicked, you know (unless it is disabled) that it will have the focus. But I see no way to see the lost of focus, nor when we gain (or loose) it with Tab/Shift+Tab (if it has focusTraversable to true).
I looked for onFocus() and onBlur() events (or similar), but found nothing. No mixin, nothing related in javafx.scene.input.TextInput and friends, etc.
I explored the Web but since 1.2 is still new, I found not much information. Only a fragment of source code in [Re: Further location optimizations|http://markmail.org/message/gsevtlkeq45rrdun] where I see scene.getFocusOwner() but this one isn't easily usable because it is package protected (and it is not an event, anyway).
A possible solution would be to have a timer to inspect the state focused of the nodes, but it is so kludgy I didn't even tried to implement it!
I hope I just missed the information... If there is no easy/official/working way in 1.2, I hope this will be corrected for next version!

Answer 1

That's a very good remark, handling of focus highlight shouldn't be done at control (model)'s level. I hesitated to put it in behavior, but it feels more natural in the skin, so I did as you suggested.
you'll need an interface, and JavaFX does not do thatYou have mixins. But I didn't used them here.
focused variable never is set to trueHave you included the
public override var focusTraversable = true;
line?
To support multiple skins, my control becomes:
public class StyledControl extends Control
  // Data related to the control (the model)
  public var count: Integer;
  public override var focusTraversable = true;
  init
    if (skin == null)  // Not defined in instance
      // Define a default styler
      skin = ControlStyler {}
  package function Incr(): Void
    if (count < 9)
      count++;
}quite bare bones (I intendedly keep the model simple).
Note I still define a default skin in case user doesn't provide it: they shouldn't care about this detail unless they want to change it.
I defined an abstract default skin, implementing most variables (particularly the public ones that can be styled) and the focus change:
public abstract class DefaultControlStyler extends Skin
  //-- Skinable properties
  public var size: Number = 20;
  public var fill: Color = Color.GRAY;
  public var textFill: Color = Color.BLACK;
  public var focusFill: Color = Color.BLUE;
  package var mainPart: Node; // Decorations (id, focus) are kept out of layout
  package var focusHighlight: Node;
  package var idDisplay: Text;
  package var valueDisplay: Text;
  init
    behavior = ControlBehavior { info: bind control.id }
    node = Group
      //-- Behavior: call controller for actions
      onMouseReleased: function (evt: MouseEvent): Void
        (behavior as ControlBehavior).HandleClick(evt);
  postinit
    // Once defined by the sub-class, insert into the node
    insert [ mainPart, idDisplay, valueDisplay ] into (node as Group).content;
  public abstract function ShowIncrement(): Void;
  var hasFocus = bind control.focused on replace
    if (hasFocus)
      ShowFocus();
    else
      HideFocus();
  // Default handling of  focus display, can be overriden if needed
  public function ShowFocus(): Void
    insert focusHighlight into (node as Group).content;
  public function HideFocus(): Void
    delete focusHighlight from (node as Group).content;
  public override function contains(localX: Number, localY: Number): Boolean
    return mainPart.contains(localX, localY);
  public override function intersects(localX: Number, localY: Number,
      localWidth: Number, localHeight: Number): Boolean
    return mainPart.intersects(localX, localY, localWidth, localHeight);
}and the concrete skins implement the mainPart, idDisplay, valueDisplay, focusHighlight nodes, override ShowIncrement with an animation, override getPrefWidth and getPrefHeight to set to mainPart size and might override ShowFocus or HideFocus (if we want it behind mainPart for example).
The behavior is:
public class ControlBehavior extends Behavior
  public var info: String; // Only for debug information...
  // Convenience vars, to avoid casting each time
  var control = bind skin.control as StyledControl;
  var csSkin = bind skin as DefaultControlStyler;
  public override function callActionForEvent(evt: KeyEvent)
    println("{info}{control.count}: KeyEvent: {evt}");
    if (evt.char == '+')
      Incr();
  package function HandleClick(evt: MouseEvent): Void
    control.requestFocus();
    Incr();
  function Incr(): Void
    control.Incr();
    println("{info}: Ouch! -> {control.count}");
    csSkin.ShowIncrement();
}and knows only the abstract default skin (to apply feedback of user input to skin).
I use it as follow:
Stage
  title: "Test Styling Controls"
  scene: Scene
    width:  500
    height: 500
    content:
      HBox
        translateX: 50
        translateY: 100
        spacing: 50
        content:
          StyledControl { id: "Bar" },
          StyledControl { /* No id */ layoutInfo: LayoutInfo { vpos: VPos.BOTTOM } },
          StyledControl { id: "Foo" },
          StyledControl { id: "Gah" },
          StyledControl { id: "Bu", skin: AltCtrlStyler {} },
    stylesheets: "{__DIR__}../controlStyle.css"
}BTW, I tried layoutY: 50 in place of the layoutInfo definition, but the control remained at default place. Am I reading incorrectly the ref. or is this a bug?