Add iOS implementation of the button property of the PointerEvent object

Summary:
Changelog: [iOS][Internal] - Add iOS implementation of the button property of the PointerEvent object

This implements the `button` property on the PointerEvent object by storing the button which caused the down event in the `ActiveTouch` and reporting that button through `pointerdown` and `pointerup` events and -1 on all others. This diff also includes a small fix to the `pressure` property which was introduced due to `button` being correctly implemented.

Reviewed By: yungsters

Differential Revision: D38632543

fbshipit-source-id: 9dbbb23a9251f2e661faf37fdf206b9f0b26bc5f

React/Fabric/RCTSurfaceTouchHandler.mm

@@ -94,6 +94,11 @@ struct ActiveTouch {
    */
   bool isPrimary;
 
+  /*
+   * The button number that was pressed (if applicable) when the event was fired.
+   */
+  int button;
+
   /*
    * A component view on which the touch was begun.
    */
@@ -168,6 +173,16 @@ static int ButtonMaskToButtons(UIEventButtonMask buttonMask)
   return 0;
 }
 
+static int ButtonMaskToButton(UIEventButtonMask buttonMask)
+{
+  if (@available(iOS 13.4, *)) {
+    if ((buttonMask & UIEventButtonMaskSecondary) > 0) {
+      return 2;
+    }
+  }
+  return 0;
+}
+
 static void UpdateActiveTouchWithUITouch(
     ActiveTouch &activeTouch,
     UITouch *uiTouch,
@@ -291,12 +306,20 @@ static PointerEvent CreatePointerEventFromActiveTouch(ActiveTouch activeTouch, R
 
   PointerEvent event = {};
   event.pointerId = touch.identifier;
-  event.pressure = touch.force;
   event.pointerType = PointerTypeCStringFromUITouchType(activeTouch.touchType);
   event.clientPoint = touch.pagePoint;
   event.screenPoint = touch.screenPoint;
   event.offsetPoint = touch.offsetPoint;
 
+  event.pressure = touch.force;
+  if (@available(iOS 13.4, *)) {
+    if (activeTouch.touchType == UITouchTypeIndirectPointer) {
+      // pointer events with a mouse button pressed should report a pressure of 0.5
+      // when the touch is down and 0.0 when it is lifted regardless of how it is reported by the OS
+      event.pressure = eventType != RCTTouchEventTypeTouchEnd ? 0.5 : 0.0;
+    }
+  }
+
   CGFloat pointerSize = activeTouch.majorRadius * 2.0;
   if (@available(iOS 13.4, *)) {
     if (activeTouch.touchType == UITouchTypeIndirectPointer) {
@@ -313,6 +336,11 @@ static PointerEvent CreatePointerEventFromActiveTouch(ActiveTouch activeTouch, R
 
   event.detail = 0;
 
+  event.button = -1;
+  if (eventType == RCTTouchEventTypeTouchStart || eventType == RCTTouchEventTypeTouchEnd) {
+    event.button = activeTouch.button;
+  }
+
   event.buttons = ButtonMaskToButtons(activeTouch.buttonMask);
   UpdatePointerEventModifierFlags(event, activeTouch.modifierFlags);
 
@@ -351,11 +379,13 @@ static PointerEvent CreatePointerEventFromIncompleteHoverData(
   event.tiltX = 0;
   event.tiltY = 0;
   event.detail = 0;
+  event.button = -1;
   event.buttons = 0;
   UpdatePointerEventModifierFlags(event, modifierFlags);
   event.tangentialPressure = 0.0;
   event.twist = 0;
   event.isPrimary = true;
+
   return event;
 }
 
@@ -511,13 +541,18 @@ RCT_NOT_IMPLEMENTED(-(instancetype)initWithTarget : (id)target action : (SEL)act
           }
           break;
       }
+
+      activeTouch.button = ButtonMaskToButton(event.buttonMask);
     } else {
       activeTouch.touch.identifier = _identifierPool.dequeue();
       if (_primaryTouchPointerId == -1) {
         _primaryTouchPointerId = activeTouch.touch.identifier;
         activeTouch.isPrimary = true;
       }
+
+      activeTouch.button = 0;
     }
+
     _activeTouches.emplace(touch, activeTouch);
   }
 }

ReactCommon/react/renderer/components/view/PointerEvent.cpp

@@ -40,6 +40,7 @@ std::vector<DebugStringConvertibleObject> getDebugProps(
       {"altKey", getDebugDescription(pointerEvent.altKey, options)},
       {"metaKey", getDebugDescription(pointerEvent.metaKey, options)},
       {"isPrimary", getDebugDescription(pointerEvent.isPrimary, options)},
+      {"button", getDebugDescription(pointerEvent.button, options)},
   };
 }
 

ReactCommon/react/renderer/components/view/PointerEvent.h

@@ -105,6 +105,11 @@ struct PointerEvent {
    * type.
    */
   bool isPrimary;
+  /*
+   * The button number that was pressed (if applicable) when the pointer event
+   * was fired.
+   */
+  int button;
 };
 
 #if RN_DEBUG_STRING_CONVERTIBLE

ReactCommon/react/renderer/components/view/TouchEventEmitter.cpp

@@ -92,6 +92,7 @@ static jsi::Value pointerEventPayload(
   object.setProperty(runtime, "altKey", event.altKey);
   object.setProperty(runtime, "metaKey", event.metaKey);
   object.setProperty(runtime, "isPrimary", event.isPrimary);
+  object.setProperty(runtime, "button", event.button);
   return object;
 }