W3CPointerEvents: emit click events based on pointerDown/pointerUp (#37541)

Summary:
Pull Request resolved: #37541

This diff makes changes to emit bubbling click events (i.e. [these](https://www.w3.org/TR/uievents/#click)) based on the existing pointer-down/pointer-up events. As per the [pointer events spec](https://www.w3.org/TR/pointerevents3/#the-click-auxclick-and-contextmenu-events), click events are still dispatched as PointerEvents (i.e. conform to the PointerEvent interface).

Changelog: [Internal] [Added] - W3CPointerEvents: emit click events based on pointerDown/pointerUp

Reviewed By: NickGerleman

Differential Revision: D45666344

fbshipit-source-id: 08829d3a24fef6851c1c3c29d4fa51b31ec68931

Author: Alex Danoff

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/BaseViewManager.java

@@ -700,6 +700,16 @@ public void setPointerMoveCapture(@NonNull T view, boolean value) {
     setPointerEventsFlag(view, PointerEventHelper.EVENT.MOVE_CAPTURE, value);
   }
 
+  @ReactProp(name = "onClick")
+  public void setClick(@NonNull T view, boolean value) {
+    setPointerEventsFlag(view, PointerEventHelper.EVENT.CLICK, value);
+  }
+
+  @ReactProp(name = "onClickCapture")
+  public void setClickCapture(@NonNull T view, boolean value) {
+    setPointerEventsFlag(view, PointerEventHelper.EVENT.CLICK_CAPTURE, value);
+  }
+
   /* Experimental W3C Pointer events end */
 
   @ReactProp(name = "onMoveShouldSetResponder")

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/JSPointerDispatcher.java

@@ -41,6 +41,7 @@ public class JSPointerDispatcher {
 
   private Map<Integer, List<ViewTarget>> mLastHitPathByPointerId;
   private Map<Integer, float[]> mLastEventCoordinatesByPointerId;
+  private Map<Integer, List<ViewTarget>> mCurrentlyDownPointerIdsToHitPath;
   private Set<Integer> mHoveringPointerIds = new HashSet<>();
 
   private int mChildHandlingNativeGesture = -1;
@@ -53,6 +54,7 @@ public class JSPointerDispatcher {
 
   public JSPointerDispatcher(ViewGroup viewGroup) {
     mRootViewGroup = viewGroup;
+    mCurrentlyDownPointerIdsToHitPath = new HashMap<>();
   }
 
   public void onChildStartedNativeGesture(
@@ -87,6 +89,30 @@ public void onChildEndedNativeGesture() {
     mChildHandlingNativeGesture = -1;
   }
 
+  // returns the section of the hit path shared by both lists, or an empty list if there's no such
+  // section
+  private static List<ViewTarget> findHitPathIntersection(
+      final List<ViewTarget> hitsA, final List<ViewTarget> hitsB) {
+    if (hitsA.isEmpty()) {
+      return new ArrayList<>();
+    }
+    if (hitsB.isEmpty()) {
+      return new ArrayList<>();
+    }
+
+    Set<ViewTarget> inA = new HashSet<>(hitsA);
+
+    List<ViewTarget> intersection = new ArrayList<>();
+
+    for (final ViewTarget vt : hitsB) {
+      if (inA.contains(vt)) {
+        intersection.add(vt);
+      }
+    }
+
+    return intersection;
+  }
+
   private void onUp(
       int activeTargetTag,
       PointerEventState eventState,
@@ -127,6 +153,18 @@ private void onUp(
           eventDispatcher);
     }
 
+    List<ViewTarget> hitPathDown = mCurrentlyDownPointerIdsToHitPath.remove(activePointerId);
+    if (hitPathDown != null
+        && isAnyoneListeningForBubblingEvent(activeHitPath, EVENT.CLICK, EVENT.CLICK_CAPTURE)) {
+      List<ViewTarget> hitPathForClick = findHitPathIntersection(hitPathDown, activeHitPath);
+      if (!hitPathForClick.isEmpty()) {
+        final ViewTarget clickTarget = hitPathForClick.get(0);
+        eventDispatcher.dispatchEvent(
+            PointerEvent.obtain(
+                PointerEventHelper.CLICK, clickTarget.getViewId(), eventState, motionEvent));
+      }
+    }
+
     if (motionEvent.getActionMasked() == MotionEvent.ACTION_UP) {
       mPrimaryPointerId = UNSET_POINTER_ID;
     }
@@ -175,6 +213,12 @@ private void onDown(
           eventDispatcher);
     }
 
+    // store some information if we might need to emit a click later on
+    if (isAnyoneListeningForBubblingEvent(activeHitPath, EVENT.CLICK, EVENT.CLICK_CAPTURE)) {
+      mCurrentlyDownPointerIdsToHitPath.put(
+          eventState.getActivePointerId(), new ArrayList<>(activeHitPath));
+    }
+
     boolean listeningForDown =
         isAnyoneListeningForBubblingEvent(activeHitPath, EVENT.DOWN, EVENT.DOWN_CAPTURE);
     if (listeningForDown) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/events/PointerEvent.java

@@ -91,6 +91,10 @@ public String getEventName() {
     return mEventName;
   }
 
+  private boolean isClickEvent() {
+    return mEventName.equals(PointerEventHelper.CLICK);
+  }
+
   @Override
   public void dispatch(RCTEventEmitter rctEventEmitter) {
     if (mMotionEvent == null) {
@@ -190,7 +194,8 @@ private WritableMap createW3CPointerEvent(int index) {
     pointerEvent.putString("pointerType", pointerType);
 
     boolean isPrimary =
-        mEventState.supportsHover(pointerId) || pointerId == mEventState.mPrimaryPointerId;
+        !isClickEvent() // compatibility click events should not be considered primary
+            && (mEventState.supportsHover(pointerId) || pointerId == mEventState.mPrimaryPointerId);
     pointerEvent.putBoolean("isPrimary", isPrimary);
 
     // https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent
@@ -223,8 +228,8 @@ private WritableMap createW3CPointerEvent(int index) {
     pointerEvent.putDouble("tiltY", 0);
 
     pointerEvent.putInt("twist", 0);
-
-    if (pointerType.equals(PointerEventHelper.POINTER_TYPE_MOUSE)) {
+    // note: click events should have width = height = 1
+    if (pointerType.equals(PointerEventHelper.POINTER_TYPE_MOUSE) || isClickEvent()) {
       pointerEvent.putDouble("width", 1);
       pointerEvent.putDouble("height", 1);
     } else {
@@ -241,8 +246,12 @@ private WritableMap createW3CPointerEvent(int index) {
     pointerEvent.putInt(
         "buttons", PointerEventHelper.getButtons(mEventName, pointerType, buttonState));
 
-    pointerEvent.putDouble(
-        "pressure", PointerEventHelper.getPressure(pointerEvent.getInt("buttons"), mEventName));
+    final double pressure =
+        isClickEvent() // click events need pressure=0
+            ? 0
+            : PointerEventHelper.getPressure(pointerEvent.getInt("buttons"), mEventName);
+
+    pointerEvent.putDouble("pressure", pressure);
     pointerEvent.putDouble("tangentialPressure", 0.0);
 
     return pointerEvent;
@@ -264,6 +273,7 @@ private List<WritableMap> createPointersEventData() {
       case PointerEventHelper.POINTER_LEAVE:
       case PointerEventHelper.POINTER_OUT:
       case PointerEventHelper.POINTER_OVER:
+      case PointerEventHelper.CLICK:
         pointersEventData = Arrays.asList(createW3CPointerEvent(activePointerIndex));
         break;
     }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/events/PointerEventHelper.java

@@ -25,6 +25,8 @@ public class PointerEventHelper {
   public static enum EVENT {
     CANCEL,
     CANCEL_CAPTURE,
+    CLICK,
+    CLICK_CAPTURE,
     DOWN,
     DOWN_CAPTURE,
     ENTER,
@@ -49,6 +51,7 @@ public static enum EVENT {
   public static final String POINTER_UP = "topPointerUp";
   public static final String POINTER_OVER = "topPointerOver";
   public static final String POINTER_OUT = "topPointerOut";
+  public static final String CLICK = "topClick";
 
   // https://w3c.github.io/pointerevents/#the-buttons-property
   public static int getButtons(String eventName, String pointerType, int buttonState) {
@@ -117,6 +120,8 @@ public static boolean isListening(@Nullable View view, EVENT event) {
       case UP_CAPTURE:
       case CANCEL:
       case CANCEL_CAPTURE:
+      case CLICK:
+      case CLICK_CAPTURE:
         return true;
     }