From 560652cfe86d50243d145f860b0b5dcc4a64bf58 Mon Sep 17 00:00:00 2001
From: Valentin Shergin <shergin@fb.com>
Date: Fri, 16 Nov 2018 18:18:57 -0800
Subject: [PATCH] Fabric: Proper implementation `-[RCTSurfaceTouchHandler
 reset]`

Summary:
Apparently, if a gesture recognizer got 'reset', OS does not call `touchesCancelled:` method, so we have to do it manually.
To implement this we have to split `_dispatchTouches:eventType:` into two methods: the first converts Objective-C touches to C++ touches, the second consumes that. We have to do this because during reset we don't have a collection of UIKit touches.

Reviewed By: mdvacca

Differential Revision: D13072807

fbshipit-source-id: 677e2febf9f96dcdfaadfadf5b9ab3893f93e796
---
 React/Fabric/RCTSurfaceTouchHandler.mm | 51 ++++++++++++++++++++------
 1 file changed, 39 insertions(+), 12 deletions(-)

diff --git a/React/Fabric/RCTSurfaceTouchHandler.mm b/React/Fabric/RCTSurfaceTouchHandler.mm
index d25653a74..14d1a807f 100644
--- a/React/Fabric/RCTSurfaceTouchHandler.mm
+++ b/React/Fabric/RCTSurfaceTouchHandler.mm
@@ -209,16 +209,26 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithTarget:(id)target action:(SEL)action
   }
 }
 
-- (void)_dispatchTouches:(NSSet<UITouch *> *)touches eventType:(RCTTouchEventType)eventType
+- (std::vector<ActiveTouch>)_activeTouchesFromTouches:(NSSet<UITouch *> *)touches
+{
+  std::vector<ActiveTouch> activeTouches;
+  activeTouches.reserve(touches.count);
+
+  for (UITouch *touch in touches) {
+    activeTouches.push_back(_activeTouches.at(touch));
+  }
+
+  return activeTouches;
+}
+
+- (void)_dispatchActiveTouches:(std::vector<ActiveTouch>)activeTouches eventType:(RCTTouchEventType)eventType
 {
   TouchEvent event = {};
   std::unordered_set<ActiveTouch, ActiveTouch::Hasher, ActiveTouch::Comparator> changedActiveTouches = {};
   std::unordered_set<SharedTouchEventEmitter> uniqueEventEmitter = {};
   BOOL isEndishEventType = eventType == RCTTouchEventTypeTouchEnd || eventType == RCTTouchEventTypeTouchCancel;
 
-  for (UITouch *touch in touches) {
-    const auto &activeTouch = _activeTouches[touch];
-
+  for (const auto &activeTouch : activeTouches) {
     if (!activeTouch.eventEmitter) {
       continue;
     }
@@ -276,7 +286,8 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithTarget:(id)target action:(SEL)action
   [super touchesBegan:touches withEvent:event];
 
   [self _registerTouches:touches];
-  [self _dispatchTouches:touches eventType:RCTTouchEventTypeTouchStart];
+  [self _dispatchActiveTouches:[self _activeTouchesFromTouches:touches]
+                     eventType:RCTTouchEventTypeTouchStart];
 
   if (self.state == UIGestureRecognizerStatePossible) {
     self.state = UIGestureRecognizerStateBegan;
@@ -290,7 +301,8 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithTarget:(id)target action:(SEL)action
   [super touchesMoved:touches withEvent:event];
 
   [self _updateTouches:touches];
-  [self _dispatchTouches:touches eventType:RCTTouchEventTypeTouchMove];
+  [self _dispatchActiveTouches:[self _activeTouchesFromTouches:touches]
+                     eventType:RCTTouchEventTypeTouchMove];
 
   self.state = UIGestureRecognizerStateChanged;
 }
@@ -300,7 +312,8 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithTarget:(id)target action:(SEL)action
   [super touchesEnded:touches withEvent:event];
 
   [self _updateTouches:touches];
-  [self _dispatchTouches:touches eventType:RCTTouchEventTypeTouchEnd];
+  [self _dispatchActiveTouches:[self _activeTouchesFromTouches:touches]
+                     eventType:RCTTouchEventTypeTouchEnd];
   [self _unregisterTouches:touches];
 
   if (AllTouchesAreCancelledOrEnded(event.allTouches)) {
@@ -315,7 +328,8 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithTarget:(id)target action:(SEL)action
   [super touchesCancelled:touches withEvent:event];
 
   [self _updateTouches:touches];
-  [self _dispatchTouches:touches eventType:RCTTouchEventTypeTouchCancel];
+  [self _dispatchActiveTouches:[self _activeTouchesFromTouches:touches]
+                     eventType:RCTTouchEventTypeTouchCancel];
   [self _unregisterTouches:touches];
 
   if (AllTouchesAreCancelledOrEnded(event.allTouches)) {
@@ -327,10 +341,23 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithTarget:(id)target action:(SEL)action
 
 - (void)reset
 {
-  // Technically, `_activeTouches` must be already empty at this point,
-  // but just to be sure, we clear it explicitly.
-  _activeTouches.clear();
-  _identifierPool.reset();
+  [super reset];
+
+  if (_activeTouches.size() != 0) {
+    std::vector<ActiveTouch> activeTouches;
+    activeTouches.reserve(_activeTouches.size());
+
+    for (auto const &pair : _activeTouches) {
+      activeTouches.push_back(pair.second);
+    }
+
+    [self _dispatchActiveTouches:activeTouches
+                       eventType:RCTTouchEventTypeTouchCancel];
+
+    // Force-unregistering all the touches.
+    _activeTouches.clear();
+    _identifierPool.reset();
+  }
 }
 
 - (BOOL)canPreventGestureRecognizer:(__unused UIGestureRecognizer *)preventedGestureRecognizer