kotlinlang #tornadofx

@ValV Working on an individual screen is nice in Scene Builder, but you hit a wall because an app is made up of multiple screens. Also, screens start to get unwieldy and need to be broken up into sub-screens. I've been working with Scene Builder last week and this week and the code is very fragmented.

carlw

09/25/2018, 8:52 PM

i think WYSIWYG is great for XCode because they're enforcing a particular navigation pattern which is simple because it's for iOS. I haven't used anything like that for a MacOS app.

carlw

09/25/2018, 8:54 PM

I did some ASP.NET coding recently that tied HTML to a C# backing class. That was ok, but the webapp followed a strict MVC architecture.

carlw

09/25/2018, 8:57 PM

this rant is coming from a screenful of fx:include

ValV

09/25/2018, 9:08 PM

@carlw, agree, but for beginning, for those who are not quite familiar with GUI components, such builders can save some time. BTW, how to understand MVC architecture?

arxenix

09/25/2018, 9:08 PM

I seem to be having issues with TornadoFX's event bus, maybe im just using it incorrectly? In the

init{}

block of my main view, I have this:

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runAsync {
            filters = tracker.fetchFilters()
            println("done fetching filters! ${filters.size}")
            fire(SearchFiltersEvent(filters))

            sort = tracker.fetchSorts()
            println("done fetching sort!")

            fire(RequestItemsEvent)
        }

SearchFiltersEvent is marked as RunOn.ApplicationThread, and RequestItemsEvent is marked as RunOn.BackgroundThread For some reason, the subscriber for SearchFiltersEvent gets the event, but the subscriber for RequestItemsEvent doesn't.

arxenix

09/25/2018, 9:09 PM

any ideas why?

ValV

09/25/2018, 9:14 PM

@arxenix, have you created it as

object RequestItemsEvent : FXEvent(BackgroundThread)

arxenix

09/25/2018, 9:16 PM

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class SearchFiltersEvent(val searchFilters: List<SearchFilter>): FXEvent()
object RequestItemsEvent: FXEvent(EventBus.RunOn.BackgroundThread)

arxenix

09/25/2018, 9:16 PM

yes

arxenix

09/25/2018, 9:17 PM

Interestingly, if I wrap

fire(RequestItemsEvent)

with a delay, it works properly

arxenix

09/25/2018, 9:17 PM

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Timer().schedule( timerTask {
                fire(RequestItemsEvent)
            }, 2000L)

ValV

09/25/2018, 9:19 PM

Perhaps, message is fired before subscriber is ready

ValV

09/25/2018, 9:19 PM

Since it's launched in a separate thread

arxenix

09/25/2018, 9:21 PM

arxenix

09/25/2018, 9:21 PM

how should I make sure that it is ready?

ValV

09/25/2018, 9:22 PM

I don't know to implement a mutex in TFX, but I think, it could solve the problem

arxenix

09/25/2018, 9:22 PM

shouldn't the event bus put my message into a queue or something, and send it to the subscriber when it is ready?

ValV

09/25/2018, 9:27 PM

I dunno, it seems that it is not. I'm new to TFX, I may not know everything, but it's an interesting question

edvin

09/25/2018, 9:41 PM

The EventBus does not queue anything, so only listeners subscribed at the time the event is fired will receive them. The EventBus is kept as simple as possible, so if you need persistence for your messages you might want to use a more complete message passing framework with TornadoFX. Most probably you can modify your application slightly to overcome this issue. Could you post a minimal sample app perhaps?

edvin

09/25/2018, 9:45 PM

@arxenix Since you're starting a background thread in the

init

block of your main view, there is a distinct possibility that your event will fire before the rest of your UI is set up. You could probably just wrap the emission in a

runLater

- this will cause it to be queued on the UI thread, but you wouldn't have a guarantee in this case either. I'd move that code to a controller, but also initialize it from

onDock

since other UI elements are supposed to get notified of the event.

arxenix

09/25/2018, 10:33 PM

Minimal sample:

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object ComputeRequest: FXEvent(EventBus.RunOn.BackgroundThread)
fun heavyComputation() {
    println("not really")
}
class MainView : View("Hello TornadoFX") {
    init {
        subscribe<ComputeRequest> {
            heavyComputation()
        }
        fire(ComputeRequest)
    }
    override val root = hbox {
        label("Hello World")
    }
}

arxenix

09/25/2018, 10:33 PM

heavyComputation()

never gets called

arxenix

09/25/2018, 10:35 PM

@edvin do you know whats going on in this sample?

arxenix

09/25/2018, 10:37 PM

If I move the

subscribe

and

fire

to an onDock() instead of init block, it works perfectly, but I don't really get why

ValV

09/25/2018, 10:44 PM

@arxenix,

fire(...)

inside just

init { ... }

will not reach the target. You should do

init { runLater { fire(...) } }

. 'Cause

runLater

will be executed after View is built up and ready

ValV

09/25/2018, 10:47 PM

AFAIK

onDock()

is executed after a View is ready

arxenix

09/25/2018, 10:56 PM

thanks, I think I get it now 🙂

arxenix

09/25/2018, 11:01 PM

I'm having 1 more issue in my project. any idea why these gridPane constraints dont seem to get applied?

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val card = find<ResultCardFragment>(mapOf(ResultCardFragment::item to item))
                    this@gridpane += card.apply {
                        gridpaneConstraints {
                            columnRowIndex(idx % 5, idx / 5)
                            columnSpan = 1
                            rowSpan = 1
                        }
                    }

Something simple like this works as expected:

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this@gridpane += text(item.title) {
                        gridpaneConstraints {
                            columnRowIndex(idx % 5, idx / 5)
                            columnSpan = 1
                            rowSpan = 1
                        }
                    }

arxenix

09/25/2018, 11:03 PM

nvm, figured it out 🙂 changed to

card.root.apply