Take the events back from framework

Author: Kaushik Iska

shell/platform/android/io/flutter/embedding/android/MotionEventTracker.java

@@ -26,30 +26,12 @@ public static MotionEventId createUnique() {
       return MotionEventId.from(ID_COUNTER.incrementAndGet());
     }
 
-    public boolean equals(Object object) {
-      if (this == object) return true;
-      if (object == null || getClass() != object.getClass()) return false;
-      if (!super.equals(object)) return false;
-
-      MotionEventId that = (MotionEventId) object;
-
-      if (id != that.id) return false;
-
-      return true;
-    }
-
-    public int hashCode() {
-      int result = super.hashCode();
-      result = 31 * result + (int) (id ^ (id >>> 32));
-      return result;
-    }
-
     public long getId() {
       return id;
     }
   }
 
-  private final Map<MotionEventId, MotionEvent> eventById;
+  private final Map<Long, MotionEvent> eventById;
   private static MotionEventTracker INSTANCE;
 
   public static MotionEventTracker getInstance() {
@@ -66,7 +48,7 @@ private MotionEventTracker() {
   /** Tracks the event and returns a unique MotionEventId identifying the event. */
   public MotionEventId track(MotionEvent event) {
     MotionEventId eventId = MotionEventId.createUnique();
-    eventById.put(eventId, event);
+    eventById.put(eventId.id, event);
     return eventId;
   }
 
@@ -78,6 +60,6 @@ public MotionEventId track(MotionEvent event) {
   @Nullable
   public MotionEvent pop(MotionEventId eventId) {
     // TODO(kaushikiska) do the actual timestamp based book-keeping.
-    return eventById.remove(eventId);
+    return eventById.remove(eventId.id);
   }
 }

shell/platform/android/io/flutter/embedding/engine/systemchannels/PlatformViewsChannel.java

@@ -166,7 +166,8 @@ private void touch(@NonNull MethodCall call, @NonNull MethodChannel.Result resul
                   (int) args.get(11),
                   (int) args.get(12),
                   (int) args.get(13),
-                  (int) args.get(14));
+                  (int) args.get(14),
+                  ((Number) args.get(15)).longValue());
 
           try {
             handler.onTouch(touch);
@@ -380,6 +381,8 @@ public static class PlatformViewTouch {
     public final int source;
     /** TODO(mattcarroll): javadoc */
     public final int flags;
+    /** TODO(iskakaushik): javadoc */
+    public final long motionEventId;
 
     PlatformViewTouch(
         int viewId,
@@ -396,7 +399,8 @@ public static class PlatformViewTouch {
         int deviceId,
         int edgeFlags,
         int source,
-        int flags) {
+        int flags,
+        long motionEventId) {
       this.viewId = viewId;
       this.downTime = downTime;
       this.eventTime = eventTime;
@@ -412,6 +416,7 @@ public static class PlatformViewTouch {
       this.edgeFlags = edgeFlags;
       this.source = source;
       this.flags = flags;
+      this.motionEventId = motionEventId;
     }
   }
 }

shell/platform/android/io/flutter/plugin/platform/PlatformViewsController.java

@@ -21,6 +21,7 @@
 import androidx.annotation.VisibleForTesting;
 import io.flutter.embedding.android.FlutterImageView;
 import io.flutter.embedding.android.FlutterView;
+import io.flutter.embedding.android.MotionEventTracker;
 import io.flutter.embedding.engine.FlutterOverlaySurface;
 import io.flutter.embedding.engine.dart.DartExecutor;
 import io.flutter.embedding.engine.mutatorsstack.*;
@@ -93,6 +94,9 @@ public class PlatformViewsController implements PlatformViewsAccessibilityDelega
   // Platform view IDs that were displayed since the start of the current frame.
   private HashSet<Integer> currentFrameUsedPlatformViewIds;
 
+  // Used to acquire the original motion events using the motionEventIds.
+  private final MotionEventTracker motionEventTracker;
+
   private final PlatformViewsChannel.PlatformViewsHandler channelHandler =
       new PlatformViewsChannel.PlatformViewsHandler() {
 
@@ -301,8 +305,16 @@ private void ensureValidAndroidVersion(int minSdkVersion) {
         }
       };
 
-  private static MotionEvent toMotionEvent(
-      float density, PlatformViewsChannel.PlatformViewTouch touch) {
+  private MotionEvent toMotionEvent(float density, PlatformViewsChannel.PlatformViewTouch touch) {
+    MotionEventTracker.MotionEventId motionEventId =
+        MotionEventTracker.MotionEventId.from(touch.motionEventId);
+    MotionEvent trackedEvent = motionEventTracker.pop(motionEventId);
+    if (trackedEvent != null) {
+      return trackedEvent;
+    }
+
+    // TODO (kaushikiska) : warn that we are potentially using an untracked
+    // event in the platform views.
     PointerProperties[] pointerProperties =
         parsePointerPropertiesList(touch.rawPointerPropertiesList)
             .toArray(new PointerProperties[touch.pointerCount]);
@@ -339,6 +351,8 @@ public PlatformViewsController() {
     platformViewRequests = new SparseArray<>();
     platformViews = new SparseArray<>();
     mutatorViews = new SparseArray<>();
+
+    motionEventTracker = MotionEventTracker.getInstance();
   }
 
   /**