Add mechanism to enforce certain Views always being visible in the Vi…

…ew hierarchy

Summary:
See comments in ReactClippingProhibitedView for details and motivation behind this new feature.

You may have a View class inherit from the ReactClippingProhibitedView interface in order to enable this feature for instances of that View type.

This can be added to Views that should /never/ be clipped from the View hierarchy - namely, TTRC components or other telemetry components that always need to be rendered in order for some feature to function.

Changelog: [Added] Opt-in mechanism to allow native Android Views to be marked as "not clippable", soft exceptions will be logged if these Views are clipped from the View hierarchy

Reviewed By: sshic

Differential Revision: D29472439

fbshipit-source-id: b3be53df836b452aed5dc40514ff585ce0ad812b

ReactAndroid/src/main/java/com/facebook/react/ReactRootView.java

@@ -49,6 +49,7 @@
 import com.facebook.react.uimanager.IllegalViewOperationException;
 import com.facebook.react.uimanager.JSTouchDispatcher;
 import com.facebook.react.uimanager.PixelUtil;
+import com.facebook.react.uimanager.ReactClippingProhibitedView;
 import com.facebook.react.uimanager.ReactRoot;
 import com.facebook.react.uimanager.RootView;
 import com.facebook.react.uimanager.RootViewUtil;
@@ -329,9 +330,29 @@ private void removeOnGlobalLayoutListener() {
   }
 
   @Override
-  public void onViewAdded(View child) {
+  public void onViewAdded(final View child) {
     super.onViewAdded(child);
 
+    // See comments in {@code ReactRootViewProhibitedChildView} for why we want this mechanism.
+    if (child instanceof ReactClippingProhibitedView) {
+      UiThreadUtil.runOnUiThread(
+          new Runnable() {
+            @Override
+            public void run() {
+              if (!child.isShown()) {
+                ReactSoftException.logSoftException(
+                    TAG,
+                    new IllegalViewOperationException(
+                        "A view was illegally added as a child of a ReactRootView. "
+                            + "This View should not be a direct child of a ReactRootView, because it is not visible and will never be reachable. Child: "
+                            + child.getClass().getCanonicalName().toString()
+                            + " child ID: "
+                            + child.getId()));
+              }
+            }
+          });
+    }
+
     if (mShouldLogContentAppeared) {
       mShouldLogContentAppeared = false;
 

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

@@ -0,0 +1,26 @@
+/*
+ * 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.uimanager;
+
+/**
+ * Some Views may not function if added directly to a ViewGroup that clips them. For example, TTRC
+ * markers may rely on `onDraw` functionality to work properly, and will break if they're clipped
+ * out of the View hierarchy for any resaon.
+ *
+ * <p>This situation can occur more often in Fabric with View Flattening. We may prevent this sort
+ * of View Flattening from occurring in the future, but the connection is not entirely certain.
+ *
+ * <p>This can occur either because ReactViewGroup clips them out, using the ordinarary subview
+ * clipping feature. It is also possible if a View is added directly to a ReactRootView below the
+ * fold of the screen.
+ *
+ * <p>Generally the solution is to prevent View flattening in JS by adding `collapsable=false` to a
+ * parent component of the clipped view, and/or move the View higher up in the hierarchy so it is
+ * always rendered within the first page of the screen.
+ */
+public interface ReactClippingProhibitedView {}

ReactAndroid/src/main/java/com/facebook/react/views/view/ReactViewGroup.java

@@ -29,6 +29,7 @@
 import com.facebook.common.logging.FLog;
 import com.facebook.infer.annotation.Assertions;
 import com.facebook.react.bridge.ReactContext;
+import com.facebook.react.bridge.ReactSoftException;
 import com.facebook.react.bridge.UiThreadUtil;
 import com.facebook.react.common.annotations.VisibleForTesting;
 import com.facebook.react.modules.i18nmanager.I18nUtil;
@@ -38,6 +39,7 @@
 import com.facebook.react.uimanager.IllegalViewOperationException;
 import com.facebook.react.uimanager.MeasureSpecAssertions;
 import com.facebook.react.uimanager.PointerEvents;
+import com.facebook.react.uimanager.ReactClippingProhibitedView;
 import com.facebook.react.uimanager.ReactClippingViewGroup;
 import com.facebook.react.uimanager.ReactClippingViewGroupHelper;
 import com.facebook.react.uimanager.ReactPointerEventsView;
@@ -549,7 +551,7 @@ protected void dispatchSetPressed(boolean pressed) {
   }
 
   /*package*/ void addViewWithSubviewClippingEnabled(
-      View child, int index, ViewGroup.LayoutParams params) {
+      final View child, int index, ViewGroup.LayoutParams params) {
     Assertions.assertCondition(mRemoveClippedSubviews);
     Assertions.assertNotNull(mClippingRect);
     Assertions.assertNotNull(mAllChildren);
@@ -564,6 +566,29 @@ protected void dispatchSetPressed(boolean pressed) {
     }
     updateSubviewClipStatus(mClippingRect, index, clippedSoFar);
     child.addOnLayoutChangeListener(mChildrenLayoutChangeListener);
+
+    if (child instanceof ReactClippingProhibitedView) {
+      UiThreadUtil.runOnUiThread(
+          new Runnable() {
+            @Override
+            public void run() {
+              if (!child.isShown()) {
+                ReactSoftException.logSoftException(
+                    TAG,
+                    new IllegalViewOperationException(
+                        "Child view has been added to Parent view in which it is clipped and not visible."
+                            + " This is not legal for this particular child view. Child: ["
+                            + child.getId()
+                            + "] "
+                            + child.toString()
+                            + " Parent: ["
+                            + getId()
+                            + "] "
+                            + toString()));
+              }
+            }
+          });
+    }
   }
 
   /*package*/ void removeViewWithSubviewClippingEnabled(View view) {