Refactor findTargetPathAndCoordinatesForTouch to improve perf of event delivery

Summary:
Refactor of TouchTargetHelper.findTargetPathAndCoordinatesForTouch to avoid unnecessary lookup of views during the dispatching of Hover Events

changelog: [internal] internal

Reviewed By: lunaleaps, mdvacca

Differential Revision: D32296003

fbshipit-source-id: 93834c37331ad5d75645a5665a1c8c3d965765fb

ReactAndroid/src/main/java/com/facebook/react/uimanager/JSPointerDispatcher.java

@@ -13,6 +13,7 @@ import android.view.ViewGroup;
 import com.facebook.common.logging.FLog;
 import com.facebook.infer.annotation.Assertions;
 import com.facebook.react.common.ReactConstants;
+import com.facebook.react.uimanager.TouchTargetHelper.ViewTarget;
 import com.facebook.react.uimanager.events.EventDispatcher;
 import com.facebook.react.uimanager.events.PointerEvent;
 import com.facebook.react.uimanager.events.PointerEventHelper;
@@ -40,7 +41,7 @@ public class JSPointerDispatcher {
 
   // Set globally for hover interactions, referenced for coalescing hover events
   private long mHoverInteractionKey = TouchEvent.UNSET;
-  private List<Integer> mLastHitPath = Collections.emptyList();
+  private List<ViewTarget> mLastHitPath = Collections.emptyList();
   private final float[] mLastEventCoordinates = new float[2];
 
   public JSPointerDispatcher(ViewGroup viewGroup) {
@@ -56,7 +57,7 @@ public class JSPointerDispatcher {
       return;
     }
 
-    List<Integer> hitPath =
+    List<ViewTarget> hitPath =
         TouchTargetHelper.findTargetPathAndCoordinatesForTouch(
             motionEvent.getX(), motionEvent.getY(), mRootViewGroup, mTargetCoordinates);
     dispatchCancelEvent(hitPath, motionEvent, eventDispatcher);
@@ -74,11 +75,14 @@ public class JSPointerDispatcher {
 
     int surfaceId = UIManagerHelper.getSurfaceId(mRootViewGroup);
     int action = motionEvent.getActionMasked();
-    List<Integer> hitPath =
+    List<ViewTarget> hitPath =
         TouchTargetHelper.findTargetPathAndCoordinatesForTouch(
             motionEvent.getX(), motionEvent.getY(), mRootViewGroup, mTargetCoordinates);
 
-    int targetTag = hitPath.get(0);
+    if (hitPath.isEmpty()) {
+      return;
+    }
+    int targetTag = hitPath.get(0).getViewId();
 
     if (supportsHover) {
       if (action == MotionEvent.ACTION_HOVER_MOVE) {
@@ -105,7 +109,7 @@ public class JSPointerDispatcher {
       if (!supportsHover) {
         // Enter root -> child
         for (int i = hitPath.size(); i-- > 0; ) {
-          int tag = hitPath.get(i);
+          int tag = hitPath.get(i).getViewId();
           eventDispatcher.dispatchEvent(
               PointerEvent.obtain(PointerEventHelper.POINTER_ENTER, surfaceId, tag, motionEvent));
         }
@@ -161,7 +165,7 @@ public class JSPointerDispatcher {
       if (!supportsHover) {
         // Leave child -> root
         for (int i = 0; i < hitPath.size(); i++) {
-          int tag = hitPath.get(i);
+          int tag = hitPath.get(i).getViewId();
           eventDispatcher.dispatchEvent(
               PointerEvent.obtain(PointerEventHelper.POINTER_LEAVE, surfaceId, tag, motionEvent));
         }
@@ -195,7 +199,7 @@ public class JSPointerDispatcher {
       MotionEvent motionEvent,
       EventDispatcher eventDispatcher,
       int surfaceId,
-      List<Integer> hitPath) {
+      List<ViewTarget> hitPath) {
 
     int action = motionEvent.getActionMasked();
     if (action != MotionEvent.ACTION_HOVER_MOVE) {
@@ -222,13 +226,17 @@ public class JSPointerDispatcher {
 
     // If child is handling, eliminate target tags under handling child
     if (mChildHandlingNativeGesture > 0) {
-      int index = hitPath.indexOf(mChildHandlingNativeGesture);
-      if (index > 0) {
-        hitPath.subList(0, index).clear();
+      int index = 0;
+      for (ViewTarget viewTarget : hitPath) {
+        if (viewTarget.getViewId() == mChildHandlingNativeGesture) {
+          hitPath.subList(0, index).clear();
+          break;
+        }
+        index++;
       }
     }
 
-    int targetTag = hitPath.size() > 0 ? hitPath.get(0) : -1;
+    int targetTag = hitPath.isEmpty() ? -1 : hitPath.get(0).getViewId();
     // If targetTag is empty, we should bail?
     if (targetTag == -1) {
       return;
@@ -252,26 +260,31 @@ public class JSPointerDispatcher {
       // If something has changed in either enter/exit, let's start a new coalescing key
       mTouchEventCoalescingKeyHelper.incrementCoalescingKey(mHoverInteractionKey);
 
-      List<Integer> enterTargetTags = hitPath.subList(0, hitPath.size() - firstDivergentIndex);
-      if (enterTargetTags.size() > 0) {
+      List<ViewTarget> enterViewTargets = hitPath.subList(0, hitPath.size() - firstDivergentIndex);
+      if (enterViewTargets.size() > 0) {
         // root -> child
-        for (int i = enterTargetTags.size(); i-- > 0; ) {
-          int enterTargetTag = enterTargetTags.get(i);
+        for (int i = enterViewTargets.size(); i-- > 0; ) {
           eventDispatcher.dispatchEvent(
               PointerEvent.obtain(
-                  PointerEventHelper.POINTER_ENTER, surfaceId, enterTargetTag, motionEvent));
+                  PointerEventHelper.POINTER_ENTER,
+                  surfaceId,
+                  enterViewTargets.get(i).getViewId(),
+                  motionEvent));
         }
       }
 
       // Fire all relevant exit events
-      List<Integer> exitTargetTags =
+      List<ViewTarget> exitViewTargets =
           mLastHitPath.subList(0, mLastHitPath.size() - firstDivergentIndex);
-      if (exitTargetTags.size() > 0) {
+      if (exitViewTargets.size() > 0) {
         // child -> root
-        for (Integer exitTargetTag : exitTargetTags) {
+        for (ViewTarget exitViewTarget : exitViewTargets) {
           eventDispatcher.dispatchEvent(
               PointerEvent.obtain(
-                  PointerEventHelper.POINTER_LEAVE, surfaceId, exitTargetTag, motionEvent));
+                  PointerEventHelper.POINTER_LEAVE,
+                  surfaceId,
+                  exitViewTarget.getViewId(),
+                  motionEvent));
         }
       }
     }
@@ -287,7 +300,7 @@ public class JSPointerDispatcher {
   }
 
   private void dispatchCancelEvent(
-      List<Integer> hitPath, MotionEvent motionEvent, EventDispatcher eventDispatcher) {
+      List<ViewTarget> hitPath, MotionEvent motionEvent, EventDispatcher eventDispatcher) {
     // This means the gesture has already ended, via some other CANCEL or UP event. This is not
     // expected to happen very often as it would mean some child View has decided to intercept the
     // touch stream and start a native gesture only upon receiving the UP/CANCEL event.
@@ -297,16 +310,19 @@ public class JSPointerDispatcher {
         "Expected to not have already sent a cancel for this gesture");
     int surfaceId = UIManagerHelper.getSurfaceId(mRootViewGroup);
 
-    int targetTag = hitPath.get(0);
-    // Question: Does cancel fire on all in hit path?
-    Assertions.assertNotNull(eventDispatcher)
-        .dispatchEvent(
-            PointerEvent.obtain(
-                PointerEventHelper.POINTER_CANCEL, surfaceId, targetTag, motionEvent));
+    if (!hitPath.isEmpty()) {
+      int targetTag = hitPath.get(0).getViewId();
+      // Question: Does cancel fire on all in hit path?
+      Assertions.assertNotNull(eventDispatcher)
+          .dispatchEvent(
+              PointerEvent.obtain(
+                  PointerEventHelper.POINTER_CANCEL, surfaceId, targetTag, motionEvent));
 
-    for (int tag : hitPath) {
-      eventDispatcher.dispatchEvent(
-          PointerEvent.obtain(PointerEventHelper.POINTER_LEAVE, surfaceId, tag, motionEvent));
+      for (ViewTarget viewTarget : hitPath) {
+        eventDispatcher.dispatchEvent(
+            PointerEvent.obtain(
+                PointerEventHelper.POINTER_LEAVE, surfaceId, viewTarget.getViewId(), motionEvent));
+      }
     }
 
     mTouchEventCoalescingKeyHelper.removeCoalescingKey(mDownStartTime);

ReactAndroid/src/main/java/com/facebook/react/uimanager/TouchTargetHelper.java

@@ -25,6 +25,7 @@ import com.facebook.react.uimanager.common.ViewUtil;
 import java.util.ArrayList;
 import java.util.EnumSet;
 import java.util.List;
+import java.util.Objects;
 
 /**
  * Class responsible for identifying which react view should handle a given {@link MotionEvent}. It
@@ -109,11 +110,12 @@ public class TouchTargetHelper {
    * @param eventY the Y screen coordinate of the touch location
    * @param viewGroup the container view to traverse
    * @param viewCoords an out parameter that will return the X,Y value in the target view
-   * @return If a target was found, returns a path through the view tree of all react tags that are
-   *     a container for the touch target, ordered from target to root (last element)
+   * @return If a target was found, returns a {@link Lis<ViewTarget>} containing the path through
+   *     the view tree of all react tags and views that are a container for the touch target,
+   *     ordered from target to root (last element)
    */
   @SuppressLint("ResourceType")
-  public static List<Integer> findTargetPathAndCoordinatesForTouch(
+  public static List<ViewTarget> findTargetPathAndCoordinatesForTouch(
       float eventX, float eventY, ViewGroup viewGroup, float[] viewCoords) {
     UiThreadUtil.assertOnUiThread();
 
@@ -121,7 +123,7 @@ public class TouchTargetHelper {
     viewCoords[0] = eventX;
     viewCoords[1] = eventY;
 
-    List<Integer> pathAccumulator = new ArrayList<>();
+    List<ViewTarget> pathAccumulator = new ArrayList<>();
     View targetView = findTouchTargetViewWithPointerEvents(viewCoords, viewGroup, pathAccumulator);
 
     if (targetView != null) {
@@ -140,7 +142,7 @@ public class TouchTargetHelper {
 
       int targetTag = getTouchTargetForView(reactTargetView, eventX, eventY);
       if (targetTag != reactTargetView.getId()) {
-        pathAccumulator.add(0, targetTag);
+        pathAccumulator.add(0, new ViewTarget(targetTag, (View) null));
       }
     }
 
@@ -178,7 +180,7 @@ public class TouchTargetHelper {
       float[] eventCoords,
       View view,
       EnumSet<TouchTargetReturnType> allowReturnTouchTargetTypes,
-      List<Integer> pathAccumulator) {
+      List<ViewTarget> pathAccumulator) {
     // We prefer returning a child, so we check for a child that can handle the touch first
     if (allowReturnTouchTargetTypes.contains(TouchTargetReturnType.CHILD)
         && view instanceof ViewGroup) {
@@ -303,7 +305,7 @@ public class TouchTargetHelper {
    * its descendants are the touch target.
    */
   private static @Nullable View findTouchTargetViewWithPointerEvents(
-      float eventCoords[], View view, @Nullable List<Integer> pathAccumulator) {
+      float eventCoords[], View view, @Nullable List<ViewTarget> pathAccumulator) {
     PointerEvents pointerEvents =
         view instanceof ReactPointerEventsView
             ? ((ReactPointerEventsView) view).getPointerEvents()
@@ -330,7 +332,7 @@ public class TouchTargetHelper {
           findTouchTargetView(
               eventCoords, view, EnumSet.of(TouchTargetReturnType.SELF), pathAccumulator);
       if (targetView != null && pathAccumulator != null) {
-        pathAccumulator.add(view.getId());
+        pathAccumulator.add(new ViewTarget(view.getId(), view));
       }
       return targetView;
 
@@ -341,7 +343,7 @@ public class TouchTargetHelper {
               eventCoords, view, EnumSet.of(TouchTargetReturnType.CHILD), pathAccumulator);
       if (targetView != null) {
         if (pathAccumulator != null) {
-          pathAccumulator.add(view.getId());
+          pathAccumulator.add(new ViewTarget(view.getId(), view));
         }
         return targetView;
       }
@@ -358,7 +360,7 @@ public class TouchTargetHelper {
         // make sure we exclude the View itself because of the PointerEvents.BOX_NONE
         if (reactTag != view.getId()) {
           if (pathAccumulator != null) {
-            pathAccumulator.add(view.getId());
+            pathAccumulator.add(new ViewTarget(view.getId(), view));
           }
           return view;
         }
@@ -372,7 +374,7 @@ public class TouchTargetHelper {
           && isTouchPointInView(eventCoords[0], eventCoords[1], view)
           && ((ReactCompoundViewGroup) view).interceptsTouchEvent(eventCoords[0], eventCoords[1])) {
         if (pathAccumulator != null) {
-          pathAccumulator.add(view.getId());
+          pathAccumulator.add(new ViewTarget(view.getId(), view));
         }
         return view;
       }
@@ -384,7 +386,7 @@ public class TouchTargetHelper {
               EnumSet.of(TouchTargetReturnType.SELF, TouchTargetReturnType.CHILD),
               pathAccumulator);
       if (result != null && pathAccumulator != null) {
-        pathAccumulator.add(view.getId());
+        pathAccumulator.add(new ViewTarget(view.getId(), view));
       }
       return result;
 
@@ -402,4 +404,47 @@ public class TouchTargetHelper {
     }
     return targetView.getId();
   }
+
+  public static class ViewTarget {
+    private final int mViewId;
+    private final @Nullable View mView;
+
+    private ViewTarget(int viewId, @Nullable View view) {
+      mViewId = viewId;
+      mView = view;
+    }
+
+    public int getViewId() {
+      return mViewId;
+    }
+
+    @Nullable
+    public View getView() {
+      return mView;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      // If the object is compared with itself then return true
+      if (o == this) {
+        return true;
+      }
+
+      // Check if o is an instance of ViewTarget. Note that "null instanceof ViewTarget" also
+      // returns false.
+      if (!(o instanceof ViewTarget)) {
+        return false;
+      }
+
+      ViewTarget other = (ViewTarget) o;
+      // We only need to compare view id, as we assume the same view id will always map to the same
+      // view. TargetView is not mutable so this should be safe.
+      return other.getViewId() == mViewId;
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hashCode(mViewId);
+    }
+  }
 }