Logic Detector

packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/core/GestureHandler.kt

@@ -31,13 +31,26 @@ open class GestureHandler {
   var tag = 0
   var view: View? = null
     private set
+
+  // Host detector view is a reference to a Native Detector designated to handle events from a
+  // Logic Detector to which the gesture is assigned.
+  var hostDetectorView: RNGestureHandlerDetectorView? = null
+
   val viewForEvents: RNGestureHandlerDetectorView
     get() {
-      assert(actionType == ACTION_TYPE_NATIVE_DETECTOR) {
+      assert(usesNativeOrLogicDetector(actionType)) {
         "[react-native-gesture-handler] `viewForEvents` can only be used with NativeDetector."
       }
 
-      val detector = if (this is NativeViewGestureHandler) this.view?.parent else view
+      val detector = if (actionType ==
+        ACTION_TYPE_LOGIC_DETECTOR
+      ) {
+        this.hostDetectorView
+      } else if (this is NativeViewGestureHandler) {
+        this.view?.parent
+      } else {
+        view
+      }
 
       if (detector !is RNGestureHandlerDetectorView) {
         throw Error(
@@ -1005,6 +1018,7 @@ open class GestureHandler {
     const val ACTION_TYPE_JS_FUNCTION_OLD_API = 3
     const val ACTION_TYPE_JS_FUNCTION_NEW_API = 4
     const val ACTION_TYPE_NATIVE_DETECTOR = 5
+    const val ACTION_TYPE_LOGIC_DETECTOR = 6
     const val POINTER_TYPE_TOUCH = 0
     const val POINTER_TYPE_STYLUS = 1
     const val POINTER_TYPE_MOUSE = 2
@@ -1039,6 +1053,9 @@ open class GestureHandler {
       }
       return null
     }
+
+    fun usesNativeOrLogicDetector(actionType: Int): Boolean =
+      actionType == ACTION_TYPE_NATIVE_DETECTOR || actionType == ACTION_TYPE_LOGIC_DETECTOR
   }
 
   private data class PointerData(

packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/react/RNGestureHandlerDetectorView.kt

@@ -15,8 +15,11 @@ class RNGestureHandlerDetectorView(context: Context) : ReactViewGroup(context) {
   private var handlersToAttach: List<Int>? = null
   private var nativeHandlers: MutableSet<Int> = mutableSetOf()
   private var attachedHandlers: MutableSet<Int> = mutableSetOf()
+  private var attachedLogicHandlers: MutableMap<Int, MutableSet<Int>> = mutableMapOf()
   private var moduleId: Int = -1
 
+  data class LogicChildren(val handlerTags: List<Int>, val viewTag: Int)
+
   fun setHandlerTags(handlerTags: ReadableArray?) {
     val newHandlers = handlerTags?.toArrayList()?.map { (it as Double).toInt() } ?: emptyList()
     if (moduleId == -1) {
@@ -37,6 +40,35 @@ class RNGestureHandlerDetectorView(context: Context) : ReactViewGroup(context) {
     handlersToAttach = null
   }
 
+  fun setLogicChildren(newLogicChildren: ReadableArray?) {
+    val logicChildrenToDetach = attachedLogicHandlers.keys.toMutableSet()
+
+    val mappedChildren = newLogicChildren?.mapLogicChildren().orEmpty()
+
+    for (child in mappedChildren) {
+      if (!attachedLogicHandlers.containsKey(child.viewTag)) {
+        attachedLogicHandlers[child.viewTag] = mutableSetOf()
+      }
+
+      logicChildrenToDetach.remove(child.viewTag)
+
+      attachHandlers(
+        child.handlerTags,
+        child.viewTag,
+        GestureHandler.ACTION_TYPE_LOGIC_DETECTOR,
+        attachedLogicHandlers[child.viewTag]!!,
+      )
+    }
+
+    val registry = RNGestureHandlerModule.registries[moduleId]
+      ?: throw Exception("Tried to access a non-existent registry")
+
+    for (tag in logicChildrenToDetach) {
+      registry.detachHandler(tag)
+      attachedLogicHandlers.remove(tag)
+    }
+  }
+
   private fun shouldAttachGestureToChildView(tag: Int): Boolean {
     val registry = RNGestureHandlerModule.registries[moduleId]
       ?: throw Exception("Tried to access a non-existent registry")
@@ -57,39 +89,40 @@ class RNGestureHandlerDetectorView(context: Context) : ReactViewGroup(context) {
     super.removeViewAt(index)
   }
 
-  private fun attachHandlers(newHandlers: List<Int>) {
+  private fun attachHandlers(
+    newHandlers: List<Int>,
+    viewTag: Int = this.id,
+    actionType: Int = GestureHandler.ACTION_TYPE_NATIVE_DETECTOR,
+    attachedHandlers: MutableSet<Int> = this.attachedHandlers,
+  ) {
     val registry = RNGestureHandlerModule.registries[moduleId]
       ?: throw Exception("Tried to access a non-existent registry")
 
-    val changes = mutableMapOf<Int, GestureHandlerMutation>()
-
-    for (tag in attachedHandlers) {
-      changes[tag] = GestureHandlerMutation.Detach
-    }
+    val handlersToDetach = attachedHandlers.toMutableSet()
 
     for (tag in newHandlers) {
-      changes[tag] = if (changes.containsKey(tag)) GestureHandlerMutation.Keep else GestureHandlerMutation.Attach
-    }
-
-    for (entry in changes) {
-      val tag = entry.key
-
-      if (entry.value == GestureHandlerMutation.Attach) {
+      handlersToDetach.remove(tag)
+      if (!attachedHandlers.contains(tag)) {
         if (shouldAttachGestureToChildView(tag)) {
           // It might happen that `attachHandlers` will be called before children are added into view hierarchy. In that case we cannot
           // attach `NativeViewGestureHandlers` here and we have to do it in `addView` method.
           nativeHandlers.add(tag)
         } else {
-          registry.attachHandlerToView(tag, this.id, GestureHandler.ACTION_TYPE_NATIVE_DETECTOR)
+          registry.attachHandlerToView(tag, viewTag, actionType)
+          if (actionType == GestureHandler.ACTION_TYPE_LOGIC_DETECTOR) {
+            registry.getHandler(tag)?.hostDetectorView = this
+          }
           attachedHandlers.add(tag)
         }
-      } else if (entry.value == GestureHandlerMutation.Detach) {
-        registry.detachHandler(tag)
-        nativeHandlers.remove(tag)
-        attachedHandlers.remove(tag)
       }
     }
 
+    for (tag in handlersToDetach) {
+      registry.detachHandler(tag)
+      nativeHandlers.remove(tag)
+      attachedHandlers.remove(tag)
+    }
+
     val child = getChildAt(0)
 
     // This covers the case where `NativeViewGestureHandlers` are attached after child views were created.
@@ -132,13 +165,22 @@ class RNGestureHandlerDetectorView(context: Context) : ReactViewGroup(context) {
       registry.detachHandler(tag)
       attachedHandlers.remove(tag)
     }
-  }
 
-  companion object {
-    private enum class GestureHandlerMutation {
-      Attach,
-      Detach,
-      Keep,
+    for (child in attachedLogicHandlers) {
+      for (tag in child.value) {
+        registry.detachHandler(tag)
+      }
+      child.value.clear()
     }
   }
+
+  private fun ReadableArray.mapLogicChildren(): List<LogicChildren> = List(size()) { i ->
+    val child = getMap(i) ?: return@List null
+    val handlerTags = child.getArray("handlerTags")?.toIntList().orEmpty()
+    val viewTag = child.getInt("viewTag")
+
+    LogicChildren(handlerTags, viewTag)
+  }.filterNotNull()
+
+  private fun ReadableArray.toIntList(): List<Int> = List(size()) { getInt(it) }
 }

packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/react/RNGestureHandlerDetectorViewManager.kt

@@ -37,6 +37,10 @@ class RNGestureHandlerDetectorViewManager :
     view.setModuleId(value)
   }
 
+  override fun setLogicChildren(view: RNGestureHandlerDetectorView, value: ReadableArray?) {
+    view.setLogicChildren(value)
+  }
+
   override fun onDropViewInstance(view: RNGestureHandlerDetectorView) {
     view.onViewDrop()
     super.onDropViewInstance(view)

packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/react/events/RNGestureHandlerEvent.kt

@@ -26,8 +26,8 @@ class RNGestureHandlerEvent private constructor() : Event<RNGestureHandlerEvent>
     dataBuilder: GestureHandlerEventDataBuilder<T>,
     eventHandlerType: EventHandlerType,
   ) {
-    val view = if (handler.actionType == GestureHandler.ACTION_TYPE_NATIVE_DETECTOR) {
-      handler.viewForEvents!!
+    val view = if (GestureHandler.usesNativeOrLogicDetector(handler.actionType)) {
+      handler.viewForEvents
     } else {
       handler.view!!
     }
@@ -45,7 +45,7 @@ class RNGestureHandlerEvent private constructor() : Event<RNGestureHandlerEvent>
     EVENTS_POOL.release(this)
   }
 
-  override fun getEventName() = if (actionType == GestureHandler.ACTION_TYPE_NATIVE_DETECTOR) {
+  override fun getEventName() = if (GestureHandler.usesNativeOrLogicDetector(actionType)) {
     if (eventHandlerType == EventHandlerType.ForAnimated) {
       NATIVE_DETECTOR_ANIMATED_EVENT_NAME
     } else if (eventHandlerType == EventHandlerType.ForReanimated) {
@@ -64,7 +64,7 @@ class RNGestureHandlerEvent private constructor() : Event<RNGestureHandlerEvent>
 
   override fun getCoalescingKey() = coalescingKey
 
-  override fun getEventData(): WritableMap = if (actionType == GestureHandler.ACTION_TYPE_NATIVE_DETECTOR) {
+  override fun getEventData(): WritableMap = if (GestureHandler.usesNativeOrLogicDetector(actionType)) {
     createNativeEventData(dataBuilder!!)
   } else {
     createEventData(dataBuilder!!)

packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/react/events/RNGestureHandlerEventDispatcher.kt

@@ -71,7 +71,7 @@ class RNGestureHandlerEventDispatcher(private val reactApplicationContext: React
           RNGestureHandlerEvent.createEventData(handlerFactory.createEventBuilder(handler))
         sendEventForDeviceEvent(RNGestureHandlerEvent.EVENT_NAME, data)
       }
-      GestureHandler.ACTION_TYPE_NATIVE_DETECTOR -> {
+      GestureHandler.ACTION_TYPE_NATIVE_DETECTOR, GestureHandler.ACTION_TYPE_LOGIC_DETECTOR -> {
         val eventHandlerType = if (handler.dispatchesAnimatedEvents) {
           EventHandlerType.ForAnimated
         } else if (handler.dispatchesReanimatedEvents) {
@@ -87,7 +87,7 @@ class RNGestureHandlerEventDispatcher(private val reactApplicationContext: React
           eventHandlerType,
         )
 
-        handler.viewForEvents!!.dispatchEvent(event)
+        handler.viewForEvents.dispatchEvent(event)
       }
     }
   }
@@ -136,7 +136,7 @@ class RNGestureHandlerEventDispatcher(private val reactApplicationContext: React
         sendEventForDeviceEvent(RNGestureHandlerStateChangeEvent.EVENT_NAME, data)
       }
 
-      GestureHandler.ACTION_TYPE_NATIVE_DETECTOR -> {
+      GestureHandler.ACTION_TYPE_NATIVE_DETECTOR, GestureHandler.ACTION_TYPE_LOGIC_DETECTOR -> {
         val eventHandlerType = if (handler.dispatchesReanimatedEvents) {
           EventHandlerType.ForReanimated
         } else {
@@ -152,7 +152,7 @@ class RNGestureHandlerEventDispatcher(private val reactApplicationContext: React
           eventHandlerType,
         )
 
-        handler.viewForEvents!!.dispatchEvent(event)
+        handler.viewForEvents.dispatchEvent(event)
       }
     }
   }
@@ -188,15 +188,15 @@ class RNGestureHandlerEventDispatcher(private val reactApplicationContext: React
         val data = RNGestureHandlerTouchEvent.createEventData(handler)
         sendEventForDeviceEvent(RNGestureHandlerEvent.EVENT_NAME, data)
       }
-      GestureHandler.ACTION_TYPE_NATIVE_DETECTOR -> {
+      GestureHandler.ACTION_TYPE_NATIVE_DETECTOR, GestureHandler.ACTION_TYPE_LOGIC_DETECTOR -> {
         val eventHandlerType = if (handler.dispatchesReanimatedEvents) {
           EventHandlerType.ForReanimated
         } else {
           EventHandlerType.ForJS
         }
         val event = RNGestureHandlerTouchEvent.obtain(handler, handler.actionType, eventHandlerType)
 
-        handler.viewForEvents!!.dispatchEvent(event)
+        handler.viewForEvents.dispatchEvent(event)
       }
     }
   }

packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/react/events/RNGestureHandlerStateChangeEvent.kt

@@ -29,8 +29,8 @@ class RNGestureHandlerStateChangeEvent private constructor() : Event<RNGestureHa
     dataBuilder: GestureHandlerEventDataBuilder<T>,
     eventHandlerType: EventHandlerType,
   ) {
-    val view = if (handler.actionType == GestureHandler.ACTION_TYPE_NATIVE_DETECTOR) {
-      handler.viewForEvents!!
+    val view = if (GestureHandler.usesNativeOrLogicDetector(handler.actionType)) {
+      handler.viewForEvents
     } else {
       handler.view!!
     }
@@ -51,7 +51,7 @@ class RNGestureHandlerStateChangeEvent private constructor() : Event<RNGestureHa
     EVENTS_POOL.release(this)
   }
 
-  override fun getEventName() = if (actionType == GestureHandler.ACTION_TYPE_NATIVE_DETECTOR) {
+  override fun getEventName() = if (GestureHandler.usesNativeOrLogicDetector(actionType)) {
     if (eventHandlerType == EventHandlerType.ForReanimated) REANIMATED_EVENT_NAME else EVENT_NAME
   } else {
     EVENT_NAME
@@ -63,7 +63,7 @@ class RNGestureHandlerStateChangeEvent private constructor() : Event<RNGestureHa
   // TODO: coalescing
   override fun getCoalescingKey(): Short = 0
 
-  override fun getEventData(): WritableMap = if (actionType == GestureHandler.ACTION_TYPE_NATIVE_DETECTOR) {
+  override fun getEventData(): WritableMap = if (GestureHandler.usesNativeOrLogicDetector(actionType)) {
     createNativeEventData(dataBuilder!!, newState, oldState)
   } else {
     createEventData(dataBuilder!!, newState, oldState)

packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/react/events/RNGestureHandlerTouchEvent.kt

@@ -14,8 +14,8 @@ class RNGestureHandlerTouchEvent private constructor() : Event<RNGestureHandlerT
   private lateinit var eventHandlerType: EventHandlerType
 
   private fun <T : GestureHandler> init(handler: T, actionType: Int, eventHandlerType: EventHandlerType) {
-    val view = if (handler.actionType == GestureHandler.ACTION_TYPE_NATIVE_DETECTOR) {
-      handler.viewForEvents!!
+    val view = if (GestureHandler.usesNativeOrLogicDetector(handler.actionType)) {
+      handler.viewForEvents
     } else {
       handler.view!!
     }
@@ -33,7 +33,7 @@ class RNGestureHandlerTouchEvent private constructor() : Event<RNGestureHandlerT
     EVENTS_POOL.release(this)
   }
 
-  override fun getEventName() = if (actionType == GestureHandler.ACTION_TYPE_NATIVE_DETECTOR) {
+  override fun getEventName() = if (GestureHandler.usesNativeOrLogicDetector(actionType)) {
     if (eventHandlerType == EventHandlerType.ForReanimated) REANIMATED_EVENT_NAME else NATIVE_EVENT_NAME
   } else {
     EVENT_NAME

packages/react-native-gesture-handler/apple/RNGestureHandler.h

@@ -81,6 +81,7 @@
 @property (nonatomic) BOOL manualActivation;
 @property (nonatomic) BOOL dispatchesAnimatedEvents;
 @property (nonatomic) BOOL dispatchesReanimatedEvents;
+@property (nonatomic, nonnull, assign) NSNumber *hostDetectorTag;
 
 - (BOOL)isViewParagraphComponent:(nullable RNGHUIView *)view;
 - (nonnull RNGHUIView *)chooseViewForInteraction:(nonnull UIGestureRecognizer *)recognizer;

packages/react-native-gesture-handler/apple/RNGestureHandlerActionType.h

@@ -8,4 +8,5 @@ typedef NS_ENUM(NSInteger, RNGestureHandlerActionType) {
   RNGestureHandlerActionTypeJSFunctionNewAPI, // JS function or Animated.event with useNativeDriver: false using new
                                               // RNGH API
   RNGestureHandlerActionTypeNativeDetector,
+  RNGestureHandlerActionTypeLogicDetector,
 };