Android - Fabric - dispatch events to other react component on the scene

[zabojad]

Hi there !

I've been trying to update several third party libraries so that they support both old and new architecture.

I'm struggling on this one: ibitcy/react-native-hole-view#22

The legacy code of this lib draws a "hole" in the component UI and re-dispatches all touch events to the components behind it.

The related code to that in the lib is:

// ...
class RNHoleView(context: Context) : ReactViewGroup(context) {
// ...
    private val mEventDispatcher: EventDispatcher

    init {
        // ...
        val uiManager = (context as ReactContext).getNativeModule(UIManagerModule::class.java)
        mEventDispatcher = uiManager!!.eventDispatcher
    }
// ...
    override fun dispatchTouchEvent(ev: MotionEvent): Boolean {
        val inside = isTouchInsideHole(ev.x.toInt(), ev.y.toInt())
        if (inside) {
            passTouchEventToViewAndChildren(getRoot(), ev)
        }
        return !inside
    }

    private fun passTouchEventToViewAndChildren(v: ViewGroup, ev: MotionEvent) {
        val childrenCount = v.childCount
        for (i in 0 until childrenCount) {
            val child = v.getChildAt(i)
            if (child.id > 0 && isViewInsideTouch(ev, child) && child.visibility == View.VISIBLE) {
                try {
                    mEventDispatcher.dispatchEvent(
                            TouchEvent.obtain(
                                    child.id,
                                    TouchEventType.START,
                                    ev,
                                    ev.eventTime,
                                    ev.x,
                                    ev.y,
                                    TouchEventCoalescingKeyHelper()
                            )
                    )
                } catch (e: Exception) {
                }
                if (child is ViewGroup && child.childCount > 0) {
                    passTouchEventToViewAndChildren(child, ev)
                }
            }
        }
    }
// ...

At runtime, when touching the component's "hole", I'm getting errors like those below in logcat:

Unhandled SoftException
com.facebook.react.bridge.ReactNoCrashSoftException: Cannot find EventEmitter for receivedTouches: ReactTag[10] UIManagerType[2] EventName[topTouchStart]
	at com.facebook.react.uimanager.events.ReactEventEmitter.receiveTouches(ReactEventEmitter.java:103)
	at com.facebook.react.uimanager.events.TouchEvent.dispatchModern(TouchEvent.java:192)
	at com.facebook.react.uimanager.events.EventDispatcherImpl$DispatchEventsRunnable.run(EventDispatcherImpl.java:370)
	at android.os.Handler.handleCallback(Handler.java:938)
	at android.os.Handler.dispatchMessage(Handler.java:99)
	at com.facebook.react.bridge.queue.MessageQueueThreadHandler.dispatchMessage(MessageQueueThreadHandler.java:27)
	at android.os.Looper.loopOnce(Looper.java:226)
	at android.os.Looper.loop(Looper.java:313)
	at com.facebook.react.bridge.queue.MessageQueueThreadImpl$4.run(MessageQueueThreadImpl.java:228)
	at java.lang.Thread.run(Thread.java:1012)

Now, I understand that the UIManager should probably not be used with the new architecture but how can I dispatch events to the other components ?

Thanks in advance for any help on this...

[zabojad]

I've tried passing a surface id to TouchEvent.obtain() but I'm still getting the same error.

Also, I always get the value 1 as surface id, not sure if that is normal...

println("debug 1 "+UIManagerHelper.getSurfaceId(v))
println("debug 2 "+UIManagerHelper.getSurfaceId(getRoot()))
println("debug 3 "+UIManagerHelper.getSurfaceId(this as ViewGroup))

[zabojad]

OK, I've fixed my problem by changing the way I get the event dispatcher I use.

I now do this:

    private fun passTouchEventToViewAndChildren(v: ViewGroup, ev: MotionEvent) {
        val childrenCount = v.childCount
        for (i in 0 until childrenCount) {
            val child = v.getChildAt(i)
            if (child.id > 0 && isViewInsideTouch(ev, child) && child.visibility == View.VISIBLE) {
                try {
                    val mmEventDispatcher = UIManagerHelper.getEventDispatcherForReactTag((context as ReactContext), child.id) ;
                    mmEventDispatcher!!.dispatchEvent(
                            TouchEvent.obtain(
                                    UIManagerHelper.getSurfaceId(child),
                                    child.id,
                                    TouchEventType.START,
                                    ev,
                                    ev.eventTime,
                                    ev.x,
                                    ev.y,
                                    TouchEventCoalescingKeyHelper()
                            )
                    )
                } catch (e: Exception) {
                }
                if (child is ViewGroup && child.childCount > 0) {
                    passTouchEventToViewAndChildren(child, ev)
                }
            }
        }
    }

It works on both old and new arch.