Apply pointer entering/leaving tracking to touch-initiated pointer events

Summary:
Changelog: [iOS][Internal] - Apply pointer entering/leaving tracking to touch-initiated pointer events

This diff takes the refactoring done in the previous diff in this stack and applies it to the pointer events which are converted from discrete touch events. In addition this adds a check when an ActiveTouch is created to see if the pointer in question was hovering before the touch started or not, which is stored and leveraged once the touch is lifted to determine if we should treat the pointer as leaving the screen entirely or not.

Reviewed By: lunaleaps

Differential Revision: D38762330

fbshipit-source-id: 08452783e01bf5944c57b94a292805b2d69d4384

Author: vincentriemer

React/Fabric/RCTSurfaceTouchHandler.mm

@@ -101,6 +101,12 @@ typedef NS_ENUM(NSInteger, RCTTouchEventType) {
    */
   int button;
 
+  /*
+   * Informs the event system that when the touch is released it should be treated as the
+   * pointer leaving the screen entirely.
+   */
+  bool shouldLeaveWhenReleased;
+
   /*
    * A component view on which the touch was begun.
    */
@@ -550,10 +556,16 @@ - (void)_registerTouches:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
         _primaryTouchPointerId = activeTouch.touch.identifier;
         activeTouch.isPrimary = true;
       }
-
       activeTouch.button = 0;
     }
 
+    // If the pointer has not been marked as hovering over views before the touch started, we register
+    // that the activeTouch should not maintain its hovered state once the pointer has been lifted.
+    auto currentlyHoveredViews = [_currentlyHoveredViewsPerPointer objectForKey:@(activeTouch.touch.identifier)];
+    if (currentlyHoveredViews == nil || [currentlyHoveredViews count] == 0) {
+      activeTouch.shouldLeaveWhenReleased = YES;
+    }
+
     _activeTouches.emplace(touch, activeTouch);
   }
 }
@@ -639,20 +651,39 @@ - (void)_dispatchActiveTouches:(std::vector<ActiveTouch>)activeTouches eventType
     // emit w3c pointer events
     if (RCTGetDispatchW3CPointerEvents()) {
       PointerEvent pointerEvent = CreatePointerEventFromActiveTouch(activeTouch, eventType);
-      switch (eventType) {
-        case RCTTouchEventTypeTouchStart:
-          activeTouch.eventEmitter->onPointerDown(pointerEvent);
-          break;
-        case RCTTouchEventTypeTouchMove:
-          activeTouch.eventEmitter->onPointerMove(pointerEvent);
-          break;
-        case RCTTouchEventTypeTouchEnd:
-          activeTouch.eventEmitter->onPointerUp(pointerEvent);
-          break;
-        case RCTTouchEventTypeTouchCancel:
-          activeTouch.eventEmitter->onPointerCancel(pointerEvent);
-          break;
+
+      UIView *targetView = nil;
+      bool shouldLeave = (eventType == RCTTouchEventTypeTouchEnd && activeTouch.shouldLeaveWhenReleased) ||
+          eventType == RCTTouchEventTypeTouchCancel;
+      if (!shouldLeave) {
+        CGPoint clientLocation = CGPointMake(pointerEvent.clientPoint.x, pointerEvent.clientPoint.y);
+        targetView = FindClosestFabricManagedTouchableView([_rootComponentView hitTest:clientLocation withEvent:nil]);
       }
+
+      PointerHandler handler = ^(NSOrderedSet<RCTReactTaggedView *> *eventPathViews) {
+        switch (eventType) {
+          case RCTTouchEventTypeTouchStart:
+            activeTouch.eventEmitter->onPointerDown(pointerEvent);
+            break;
+          case RCTTouchEventTypeTouchMove: {
+            bool hasMoveEventListeners =
+                IsAnyViewInPathListeningToEvent(eventPathViews, ViewEvents::Offset::PointerMove) ||
+                IsAnyViewInPathListeningToEvent(eventPathViews, ViewEvents::Offset::PointerMoveCapture);
+            if (hasMoveEventListeners) {
+              activeTouch.eventEmitter->onPointerMove(pointerEvent);
+            }
+            break;
+          }
+          case RCTTouchEventTypeTouchEnd:
+            activeTouch.eventEmitter->onPointerUp(pointerEvent);
+            break;
+          case RCTTouchEventTypeTouchCancel:
+            activeTouch.eventEmitter->onPointerCancel(pointerEvent);
+            break;
+        }
+      };
+
+      [self handleIncomingPointerEvent:pointerEvent onView:targetView withHandler:handler];
     }
   }