Binding a view to a changing controller property - kotlin

Question

I'm working in Kotlin with the TornadoFX library. Imagine you have a toolbar which shows the tool that are useful for the current view you have. So we have a MainController which has a subController property which is the controller of some view next to the tool bar. So if our subController changes, the view should update. Also, if any property (e.g. selectedTool, tools) of the subController changes, the toolbar should update accordingly. Momentarily, the toolbar is not updated.
class ToolBar : View("Tool bar") {
private val controller: MainController by inject()
override val root = vbox {
tilepane {
for (tool in controller.subController.tools) {
button(tool.name, group).action {
controller.subController.changeTool(tool) // changes selected tool
}
}
}
this += controller.subController.selectedTool.options
}
}
Extra info: subController.tools is an ArrayList and subController.selectedTool is a Tool.
Now my question is, what's the recommended way to do this in TornadoFX?

Answer 1

You have several options. A Parent supports a function called bindChildren which accepts an observable list of items and a function to turn each of these items into a Node. You can use this to create your buttons in the toolbar:
tilepane {
bindChildren(controller.subController.tools) { tool ->
Button(tool.name) ...
}
}
You can also do this manually if you need more control:
tilepane {
controller.subController.tools.onChange {
children.clear()
// create new buttons here, like in your example
}
}
However, instead of injecting controller to access subController to get to the tools, you should have a ToolsModel which is injected into the current scope. The tools model could have a list of tools and the selected tools and can be injected into all views and controllers which needs it. You say that selectedTool is a Tool, but you're not showing what a Tool is, but judging from your code it looks like Tool.options is a Node subclass (?).
You can add/remove the tool.options element using the same technique, or even wrap it in a stackpane or other layoutcontainer to be able to identify the tool to remove (or simply remove all children of the stackpane) on change using the same technique.