Basic Litho support

Summary: Added an initial litho Tree observer and descriptors, its quiet naive and will be improved in a future diff

Reviewed By: lblasa

Differential Revision: D39466931

fbshipit-source-id: 66a462882af2e585b9719ee2f61595449f99c5e5

android/src/main/java/com/facebook/flipper/plugins/uidebugger/UIDebuggerFlipperPlugin.kt

@@ -21,14 +21,18 @@ import kotlinx.serialization.json.Json
 
 const val LogTag = "FlipperUIDebugger"
 
-class UIDebuggerFlipperPlugin(val application: Application) : FlipperPlugin {
+class UIDebuggerFlipperPlugin(
+    val application: Application,
+    descriptorRegister: DescriptorRegister?,
+    observerFactory: TreeObserverFactory?
+) : FlipperPlugin {
 
   private val context: Context =
       Context(
           ApplicationRef(application),
           ConnectionRef(null),
-          DescriptorRegister.withDefaults(),
-          TreeObserverFactory.withDefaults())
+          descriptorRegister = descriptorRegister ?: DescriptorRegister.withDefaults(),
+          observerFactory = observerFactory ?: TreeObserverFactory.withDefaults())
 
   private val nativeScanScheduler = Scheduler(NativeScanScheduler(context))
 

android/src/main/java/com/facebook/flipper/plugins/uidebugger/observers/DecorViewTreeObserver.kt

@@ -14,6 +14,7 @@ import com.facebook.flipper.plugins.uidebugger.LogTag
 import com.facebook.flipper.plugins.uidebugger.SubtreeUpdate
 import com.facebook.flipper.plugins.uidebugger.TreeObserver
 import com.facebook.flipper.plugins.uidebugger.core.Context
+import com.facebook.flipper.plugins.uidebugger.identityHashCode
 
 typealias DecorView = View
 
@@ -40,6 +41,16 @@ class DecorViewObserver(val context: Context) : TreeObserver<DecorView>() {
             val start = System.currentTimeMillis()
             if (start - lastSend > throttleTimeMs) {
               val (nodes, skipped) = context.layoutTraversal.traverse(node)
+
+              for (observerRoot in skipped) {
+
+                if (!children.containsKey(observerRoot.identityHashCode())) {
+                  val observer = context.observerFactory.createObserver(observerRoot, context)!!
+                  observer.subscribe(observerRoot)
+                  children[observerRoot.identityHashCode()] = observer
+                }
+              }
+
               val traversalComplete = System.currentTimeMillis()
               context.treeObserverManager.emit(
                   SubtreeUpdate("DecorView", nodes, start, traversalComplete))

android/src/test/java/com/facebook/flipper/plugins/uidebugger/UIDebuggerFlipperPluginTest.kt

@@ -8,6 +8,8 @@
 package com.facebook.flipper.plugins.uidebugger
 
 import com.facebook.flipper.plugins.uidebugger.core.ApplicationRef
+import com.facebook.flipper.plugins.uidebugger.descriptors.DescriptorRegister
+import com.facebook.flipper.plugins.uidebugger.observers.TreeObserverFactory
 import org.junit.Assert
 import org.junit.Before
 import org.junit.Test
@@ -30,7 +32,11 @@ class UIDebuggerFlipperPluginTest {
   @Throws(Exception::class)
   @Test
   fun emptyTest() {
-    var plugin = UIDebuggerFlipperPlugin(app)
+    var plugin =
+        UIDebuggerFlipperPlugin(
+            app,
+            DescriptorRegister.Companion.withDefaults(),
+            TreeObserverFactory.Companion.withDefaults())
     Assert.assertNotNull(plugin)
   }
 }