fix(Android): missing transition events with formSheet presentation

android/src/main/java/com/swmansion/rnscreens/ScreenStackFragment.kt

@@ -45,8 +45,9 @@ import com.swmansion.rnscreens.bottomsheet.useSingleDetent
 import com.swmansion.rnscreens.bottomsheet.useThreeDetents
 import com.swmansion.rnscreens.bottomsheet.useTwoDetents
 import com.swmansion.rnscreens.bottomsheet.usesFormSheetPresentation
+import com.swmansion.rnscreens.events.ScreenAnimationDelegate
 import com.swmansion.rnscreens.events.ScreenDismissedEvent
-import com.swmansion.rnscreens.events.ScreenEventDelegate
+import com.swmansion.rnscreens.events.ScreenEventEmitter
 import com.swmansion.rnscreens.ext.recycle
 import com.swmansion.rnscreens.transition.ExternalBoundaryValuesEvaluator
 import com.swmansion.rnscreens.utils.DeviceUtils
@@ -366,7 +367,14 @@ class ScreenStackFragment :
                 }
             animatorSet.play(alphaAnimator).with(slideAnimator)
         }
-        animatorSet.addListener(ScreenEventDelegate(this))
+        animatorSet.addListener(
+            ScreenAnimationDelegate(
+                this,
+                ScreenEventEmitter(this.screen),
+                if (enter) ScreenAnimationDelegate.AnimationType.ENTER
+                else ScreenAnimationDelegate.AnimationType.EXIT
+            )
+        )
         return animatorSet
     }
 

android/src/main/java/com/swmansion/rnscreens/events/ScreenAnimationDelegate.kt

@@ -0,0 +1,88 @@
+package com.swmansion.rnscreens.events
+
+import android.animation.Animator
+import android.util.Log
+import com.swmansion.rnscreens.ScreenStackFragmentWrapper
+
+// The goal is to make this universal delegate for handling animation progress related logic.
+// At this moment this class works only with form sheet presentation.
+class ScreenAnimationDelegate(
+    private val wrapper: ScreenStackFragmentWrapper,
+    private val eventEmitter: ScreenEventEmitter?,
+    private val animationType: AnimationType,
+) : Animator.AnimatorListener {
+    enum class AnimationType {
+        ENTER,
+        EXIT
+    }
+
+    private var currentState: LifecycleState = LifecycleState.INITIALIZED
+
+    private fun progressState() {
+        currentState =
+            when (currentState) {
+                LifecycleState.INITIALIZED -> LifecycleState.START_DISPATCHED
+                LifecycleState.START_DISPATCHED -> LifecycleState.END_DISPATCHED
+                LifecycleState.END_DISPATCHED -> LifecycleState.END_DISPATCHED
+            }
+    }
+
+    override fun onAnimationStart(animation: Animator) {
+        if (currentState === LifecycleState.INITIALIZED) {
+            progressState()
+
+            // These callbacks do not work as expected from this call site, TODO: investigate it.
+            // To fix it quickly we emit required events manually
+//            wrapper.onViewAnimationStart()
+
+            when (animationType) {
+                AnimationType.ENTER -> eventEmitter?.dispatchOnWillAppear()
+                AnimationType.EXIT -> eventEmitter?.dispatchOnWillDisappear()
+            }
+
+            val isExitAnimation = animationType === AnimationType.EXIT
+            eventEmitter?.dispatchTransitionProgress(
+                0.0f,
+                isExitAnimation,
+                isExitAnimation,
+            )
+        }
+    }
+
+    override fun onAnimationEnd(animation: Animator) {
+        if (currentState === LifecycleState.START_DISPATCHED) {
+            progressState()
+            animation.removeListener(this)
+
+//            wrapper.onViewAnimationEnd()
+
+            when (animationType) {
+                AnimationType.ENTER -> eventEmitter?.dispatchOnAppear()
+                AnimationType.EXIT -> eventEmitter?.dispatchOnDisappear()
+            }
+
+            val isExitAnimation = animationType === AnimationType.EXIT
+            eventEmitter?.dispatchTransitionProgress(
+                1.0f,
+                isExitAnimation,
+                isExitAnimation,
+            )
+
+            wrapper.screen.endRemovalTransition()
+        }
+    }
+
+    override fun onAnimationCancel(animation: Animator) = Unit
+
+    override fun onAnimationRepeat(animation: Animator) = Unit
+
+    private enum class LifecycleState {
+        INITIALIZED,
+        START_DISPATCHED,
+        END_DISPATCHED,
+    }
+
+    companion object {
+        const val TAG = "ScreenEventDelegate"
+    }
+}

android/src/main/java/com/swmansion/rnscreens/events/ScreenEventEmitter.kt

@@ -0,0 +1,36 @@
+package com.swmansion.rnscreens.events
+
+import com.facebook.react.uimanager.UIManagerHelper
+import com.swmansion.rnscreens.Screen
+import com.swmansion.rnscreens.ScreenFragment
+
+// TODO: Consider taking weak ref here or accepting screen as argument in every method
+// to avoid reference cycle.
+class ScreenEventEmitter(val screen: Screen) {
+    val reactEventDispatcher
+        get() = screen.reactEventDispatcher
+
+    val reactSurfaceId
+        get() = UIManagerHelper.getSurfaceId(screen)
+
+    fun dispatchOnWillAppear() =
+        reactEventDispatcher?.dispatchEvent(ScreenWillAppearEvent(reactSurfaceId, screen.id))
+
+    fun dispatchOnAppear() =
+        reactEventDispatcher?.dispatchEvent(ScreenAppearEvent(reactSurfaceId, screen.id))
+
+    fun dispatchOnWillDisappear() =
+        reactEventDispatcher?.dispatchEvent(ScreenWillDisappearEvent(reactSurfaceId, screen.id))
+
+    fun dispatchOnDisappear() =
+        reactEventDispatcher?.dispatchEvent(ScreenDisappearEvent(reactSurfaceId, screen.id))
+
+    fun dispatchOnDismissed() =
+        reactEventDispatcher?.dispatchEvent(ScreenDismissedEvent(reactSurfaceId, screen.id))
+
+    fun dispatchTransitionProgress(progress: Float, isExitAnimation: Boolean, isGoingForward: Boolean) {
+        val sanitizedProgress = progress.coerceIn(0.0f, 1.0f)
+        val coalescingKey = ScreenFragment.getCoalescingKey(sanitizedProgress)
+        reactEventDispatcher?.dispatchEvent(ScreenTransitionProgressEvent(reactSurfaceId, screen.id, sanitizedProgress, isExitAnimation, isGoingForward, coalescingKey))
+    }
+}