- Fix mounting of views when a re-order happen caused by changes in viewflattening

Summary:
This diff fixes a bug that is reproducible when a view is reordered in a different level of hierarchy in the react tree.
Even if this is not supported by react, this can still happen because of viewFlattening.

Reviewed By: shergin

Differential Revision: D14817452

fbshipit-source-id: 13425b0e6a280affe681e80b4a6daa17ee56251a

ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java

@@ -39,6 +39,7 @@ import com.facebook.react.fabric.jsi.EventBeatManager;
 import com.facebook.react.fabric.jsi.EventEmitterWrapper;
 import com.facebook.react.fabric.jsi.FabricSoLoader;
 import com.facebook.react.fabric.jsi.StateWrapperImpl;
+import com.facebook.react.fabric.mounting.mountitems.CreateMountItem;
 import com.facebook.react.fabric.mounting.MountingManager;
 import com.facebook.react.fabric.mounting.mountitems.BatchMountItem;
 import com.facebook.react.fabric.mounting.mountitems.DeleteMountItem;
@@ -73,7 +74,6 @@ public class FabricUIManager implements UIManager, LifecycleEventListener {
   public static final String TAG = FabricUIManager.class.getSimpleName();
   public static final boolean DEBUG =
       PrinterHolder.getPrinter().shouldDisplayLogMessage(ReactDebugOverlayTags.FABRIC_UI_MANAGER);
-
   private static final Map<String, String> sComponentNames = new HashMap<>();
   private static final int FRAME_TIME_MS = 16;
   private static final int MAX_TIME_IN_FRAME_FOR_NON_BATCHED_OPERATIONS_MS = 8;
@@ -203,6 +203,21 @@ public class FabricUIManager implements UIManager, LifecycleEventListener {
     }
   }
 
+  @DoNotStrip
+  @SuppressWarnings("unused")
+  private MountItem createMountItem(
+    String componentName, int reactRootTag, int reactTag, boolean isLayoutable) {
+    String component = sComponentNames.get(componentName);
+    if (component == null) {
+      throw new IllegalArgumentException("Unable to find component with name " + componentName);
+    }
+    ThemedReactContext reactContext = mReactContextForRootTag.get(reactRootTag);
+    if (reactContext == null) {
+      throw new IllegalArgumentException("Unable to find ReactContext for root: " + reactRootTag);
+    }
+    return new CreateMountItem(reactContext, reactRootTag, reactTag, component, isLayoutable);
+  }
+
   @DoNotStrip
   @SuppressWarnings("unused")
   private MountItem removeMountItem(int reactTag, int parentReactTag, int index) {

ReactAndroid/src/main/java/com/facebook/react/fabric/jsi/jni/Binding.cpp

@@ -328,12 +328,37 @@ local_ref<JMountItem::javaobject> createDeleteMountItem(
   return deleteInstruction(javaUIManager, mutation.oldChildShadowView.tag);
 }
 
+local_ref<JMountItem::javaobject> createCreateMountItem(
+    const jni::global_ref<jobject>& javaUIManager,
+    const ShadowViewMutation& mutation,
+    const Tag rootTag) {
+  static auto createJavaInstruction =
+      jni::findClassStatic(UIManagerJavaDescriptor)
+          ->getMethod<alias_ref<JMountItem>(jstring, jint, jint, jboolean)>(
+              "createMountItem");
+
+  auto newChildShadowView = mutation.newChildShadowView;
+
+  local_ref<JString> componentName =
+      getPlatformComponentName(newChildShadowView);
+
+  jboolean isLayoutable = newChildShadowView.layoutMetrics != EmptyLayoutMetrics;
+
+  return createJavaInstruction(
+      javaUIManager,
+      componentName.get(),
+      rootTag,
+      newChildShadowView.tag,
+      isLayoutable);
+}
+
 void Binding::schedulerDidFinishTransaction(
     MountingTransaction &&mountingTransaction) {
   SystraceSection s("FabricUIManager::schedulerDidFinishTransaction");
 
   auto telemetry = mountingTransaction.getTelemetry();
   auto mutations = mountingTransaction.getMutations();
+  auto surfaceId = mountingTransaction.getSurfaceId();
 
   std::vector<local_ref<jobject>> queue;
   // Upper bound estimation of mount items to be delivered to Java side.
@@ -345,6 +370,7 @@ void Binding::schedulerDidFinishTransaction(
       JArrayClass<JMountItem::javaobject>::newArray(size);
 
   auto mountItems = *(mountItemsArray);
+  std::unordered_set<Tag> deletedViews;
 
   int position = 0;
   for (const auto& mutation : mutations) {
@@ -355,6 +381,14 @@ void Binding::schedulerDidFinishTransaction(
         oldChildShadowView.layoutMetrics == EmptyLayoutMetrics;
 
     switch (mutation.type) {
+      case ShadowViewMutation::Create: {
+        if (mutation.newChildShadowView.props->revision > 1
+            || deletedViews.find(mutation.newChildShadowView.tag) != deletedViews.end()) {
+          mountItems[position++] =
+              createCreateMountItem(javaUIManager_, mutation, surfaceId);
+        }
+      break;
+      }
       case ShadowViewMutation::Remove: {
         if (!isVirtual) {
           mountItems[position++] =
@@ -365,6 +399,8 @@ void Binding::schedulerDidFinishTransaction(
       case ShadowViewMutation::Delete: {
         mountItems[position++] =
             createDeleteMountItem(javaUIManager_, mutation);
+
+        deletedViews.insert(mutation.oldChildShadowView.tag);
         break;
       }
       case ShadowViewMutation::Update: {
@@ -407,8 +443,8 @@ void Binding::schedulerDidFinishTransaction(
           // Insert item
           mountItems[position++] = createInsertMountItem(javaUIManager_, mutation);
 
-          // Props
-          if (mutation.newChildShadowView.props->revision > 1) {
+          if (mutation.newChildShadowView.props->revision > 1 ||
+              deletedViews.find(mutation.newChildShadowView.tag) != deletedViews.end()) {
             mountItems[position++] =
                 createUpdatePropsMountItem(javaUIManager_, mutation);
           }

ReactAndroid/src/main/java/com/facebook/react/fabric/mounting/mountitems/CreateMountItem.java

@@ -0,0 +1,43 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+package com.facebook.react.fabric.mounting.mountitems;
+
+import com.facebook.react.fabric.mounting.MountingManager;
+import com.facebook.react.uimanager.ThemedReactContext;
+
+public class CreateMountItem implements MountItem {
+
+  private final String mComponent;
+  private final int mRootTag;
+  private final int mReactTag;
+  private final ThemedReactContext mContext;
+  private final boolean mIsLayoutable;
+
+  public CreateMountItem(
+    ThemedReactContext context,
+    int rootTag,
+    int reactTag,
+    String component,
+    boolean isLayoutable) {
+    mContext = context;
+    mComponent = component;
+    mRootTag = rootTag;
+    mReactTag = reactTag;
+    mIsLayoutable = isLayoutable;
+  }
+
+  @Override
+  public void execute(MountingManager mountingManager) {
+    mountingManager.createViewWithProps(mContext, mComponent, mReactTag, null, mIsLayoutable);
+  }
+
+  @Override
+  public String toString() {
+    return "CreateMountItem [" + mReactTag + "]";
+  }
+}
+