React events: fix press end event dispatching (#15500)

This patch fixes an issue related to determining whether the end event occurs
within the responder region. Previously we only checked if the event target was
within the responder region for moves, otherwise we checked if the target was
within the event component. Since the dimensions of the child element can
change after activation, we need to recalculate the responder region before
deactivation as well if the target is not within the event component.

Author: necolas

packages/react-events/src/Press.js

@@ -52,10 +52,16 @@ type PressState = {
   isPressWithinResponderRegion: boolean,
   longPressTimeout: null | Symbol,
   pointerType: PointerType,
-  pressTarget: null | Element | Document,
+  pressTarget: null | Element,
   pressEndTimeout: null | Symbol,
   pressStartTimeout: null | Symbol,
-  responderRegion: null | $ReadOnly<{|
+  responderRegionOnActivation: null | $ReadOnly<{|
+    bottom: number,
+    left: number,
+    right: number,
+    top: number,
+  |}>,
+  responderRegionOnDeactivation: null | $ReadOnly<{|
     bottom: number,
     left: number,
     right: number,
@@ -312,7 +318,7 @@ function calculateDelayMS(delay: ?number, min = 0, fallback = 0) {
 }
 
 // TODO: account for touch hit slop
-function calculateResponderRegion(target, props) {
+function calculateResponderRegion(target: Element, props: PressProps) {
   const pressRetentionOffset = {
     ...DEFAULT_PRESS_RETENTION_OFFSET,
     ...props.pressRetentionOffset,
@@ -352,15 +358,33 @@ function isPressWithinResponderRegion(
   nativeEvent: $PropertyType<ReactResponderEvent, 'nativeEvent'>,
   state: PressState,
 ): boolean {
-  const {responderRegion} = state;
+  const {responderRegionOnActivation, responderRegionOnDeactivation} = state;
   const event = (nativeEvent: any);
+  let left, top, right, bottom;
+
+  if (responderRegionOnActivation != null) {
+    left = responderRegionOnActivation.left;
+    top = responderRegionOnActivation.top;
+    right = responderRegionOnActivation.right;
+    bottom = responderRegionOnActivation.bottom;
+
+    if (responderRegionOnDeactivation != null) {
+      left = Math.min(left, responderRegionOnDeactivation.left);
+      top = Math.min(top, responderRegionOnDeactivation.top);
+      right = Math.max(right, responderRegionOnDeactivation.right);
+      bottom = Math.max(bottom, responderRegionOnDeactivation.bottom);
+    }
+  }
 
   return (
-    responderRegion != null &&
-    (event.pageX >= responderRegion.left &&
-      event.pageX <= responderRegion.right &&
-      event.pageY >= responderRegion.top &&
-      event.pageY <= responderRegion.bottom)
+    left != null &&
+    right != null &&
+    top != null &&
+    bottom != null &&
+    (event.pageX >= left &&
+      event.pageX <= right &&
+      event.pageY >= top &&
+      event.pageY <= bottom)
   );
 }
 
@@ -408,7 +432,8 @@ const PressResponder = {
       pressEndTimeout: null,
       pressStartTimeout: null,
       pressTarget: null,
-      responderRegion: null,
+      responderRegionOnActivation: null,
+      responderRegionOnDeactivation: null,
       ignoreEmulatedMouseEvents: false,
     };
   },
@@ -469,7 +494,11 @@ const PressResponder = {
           }
 
           state.pointerType = pointerType;
-          state.pressTarget = target;
+          state.pressTarget = getEventCurrentTarget(event, context);
+          state.responderRegionOnActivation = calculateResponderRegion(
+            state.pressTarget,
+            props,
+          );
           state.isPressWithinResponderRegion = true;
           dispatchPressStartEvents(context, props, state);
           context.addRootEventTypes(rootEventTypes);
@@ -519,26 +548,34 @@ const PressResponder = {
       case 'touchmove': {
         if (state.isPressed) {
           // Ignore emulated events (pointermove will dispatch touch and mouse events)
-          // Ignore pointermove events during a keyboard press
+          // Ignore pointermove events during a keyboard press.
           if (state.pointerType !== pointerType) {
             return;
           }
 
-          if (state.responderRegion == null) {
-            state.responderRegion = calculateResponderRegion(
-              getEventCurrentTarget(event, context),
+          // Calculate the responder region we use for deactivation, as the
+          // element dimensions may have changed since activation.
+          if (
+            state.pressTarget !== null &&
+            state.responderRegionOnDeactivation == null
+          ) {
+            state.responderRegionOnDeactivation = calculateResponderRegion(
+              state.pressTarget,
               props,
             );
           }
-          if (isPressWithinResponderRegion(nativeEvent, state)) {
-            state.isPressWithinResponderRegion = true;
+          state.isPressWithinResponderRegion = isPressWithinResponderRegion(
+            nativeEvent,
+            state,
+          );
+
+          if (state.isPressWithinResponderRegion) {
             if (props.onPressMove) {
               dispatchEvent(context, state, 'pressmove', props.onPressMove, {
                 discrete: false,
               });
             }
           } else {
-            state.isPressWithinResponderRegion = false;
             dispatchPressEndEvents(context, props, state);
           }
         }
@@ -551,18 +588,38 @@ const PressResponder = {
       case 'mouseup':
       case 'touchend': {
         if (state.isPressed) {
-          // Ignore unrelated keyboard events
+          // Ignore unrelated keyboard events and verify press is within
+          // responder region for non-keyboard events.
           if (pointerType === 'keyboard') {
             if (!isValidKeyPress(nativeEvent.key)) {
               return;
             }
+            // If the event target isn't within the press target, check if we're still
+            // within the responder region. The region may have changed if the
+            // element's layout was modified after activation.
+          } else if (
+            state.pressTarget != null &&
+            !context.isTargetWithinElement(target, state.pressTarget)
+          ) {
+            // Calculate the responder region we use for deactivation if not
+            // already done during move event.
+            if (state.responderRegionOnDeactivation == null) {
+              state.responderRegionOnDeactivation = calculateResponderRegion(
+                state.pressTarget,
+                props,
+              );
+            }
+            state.isPressWithinResponderRegion = isPressWithinResponderRegion(
+              nativeEvent,
+              state,
+            );
           }
 
           const wasLongPressed = state.isLongPressed;
           dispatchPressEndEvents(context, props, state);
 
           if (state.pressTarget !== null && props.onPress) {
-            if (context.isTargetWithinElement(target, state.pressTarget)) {
+            if (state.isPressWithinResponderRegion) {
               if (
                 !(
                   wasLongPressed &&