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/plugins/litho/build.gradle

@@ -6,6 +6,7 @@
  */
 
 apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
 
 android {
     compileSdkVersion rootProject.compileSdkVersion

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

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and 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.flipper.plugins.uidebugger.litho
+
+import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
+import com.facebook.flipper.plugins.uidebugger.descriptors.Descriptor
+import com.facebook.litho.DebugComponent
+import com.facebook.litho.LithoView
+
+object LithoViewDescriptor : Descriptor<LithoView>() {
+  override fun getId(node: LithoView): String = System.identityHashCode(node).toString()
+
+  override fun getName(node: LithoView): String = "LithoView"
+
+  override fun getChildren(node: LithoView, children: MutableList<Any>) {
+    val debugComponent = DebugComponent.getRootInstance(node)
+    if (debugComponent != null) {
+      children.add(debugComponent)
+    }
+  }
+
+  override fun getActiveChild(node: LithoView): Any? = null
+
+  override fun getData(node: LithoView, builder: MutableMap<String, InspectableObject>) {}
+}
+
+object DebugComponentDescriptor : Descriptor<DebugComponent>() {
+  override fun getId(node: DebugComponent): String = System.identityHashCode(node).toString()
+
+  override fun getName(node: DebugComponent): String {
+    return node.component.simpleName
+  }
+
+  // TODO the mutable list thing doesnt make sense for non chained descriptors, should just return
+  override fun getChildren(node: DebugComponent, children: MutableList<Any>) {
+    val mountedView = node.mountedView
+    val mountedDrawable = node.mountedDrawable
+
+    if (mountedView != null) {
+      children.add(mountedView)
+    } else if (mountedDrawable != null) {
+      children.add(mountedDrawable)
+    } else {
+      for (child in node.childComponents) {
+        children.add(child)
+      }
+    }
+  }
+
+  override fun getActiveChild(node: DebugComponent): Any? = null
+
+  // todo same here
+  override fun getData(node: DebugComponent, builder: MutableMap<String, InspectableObject>) {}
+}

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

@@ -0,0 +1,53 @@
+package com.facebook.flipper.plugins.uidebugger.litho
+
+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
+import com.facebook.flipper.plugins.uidebugger.observers.TreeObserverBuilder
+import com.facebook.litho.LithoView
+
+class LithoViewTreeObserver(val context: Context) : TreeObserver<LithoView>() {
+
+  var nodeRef: LithoView? = null
+  override fun subscribe(node: Any) {
+    node as LithoView
+
+    nodeRef = node
+
+    val listener: (view: LithoView) -> Unit = {
+      val start = System.currentTimeMillis()
+
+      val (nodes, skipped) = context.layoutTraversal.traverse(it)
+
+      for (observerRoot in skipped) {
+        if (!children.containsKey(observerRoot.identityHashCode())) {
+          val observer = context.observerFactory.createObserver(observerRoot, context)!!
+          observer.subscribe(observerRoot)
+          children[observerRoot.identityHashCode()] = observer
+        }
+      }
+
+      context.treeObserverManager.emit(
+          SubtreeUpdate("Litho", nodes, start, System.currentTimeMillis()))
+    }
+    node.setOnDirtyMountListener(listener)
+
+    listener(node)
+  }
+
+  override fun unsubscribe() {
+    nodeRef?.setOnDirtyMountListener(null)
+    nodeRef = null
+  }
+}
+
+object LithoViewTreeObserverBuilder : TreeObserverBuilder<LithoView> {
+  override fun canBuildFor(node: Any): Boolean {
+    return node is LithoView
+  }
+
+  override fun build(context: Context): TreeObserver<LithoView> {
+    return LithoViewTreeObserver(context)
+  }
+}

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

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and 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.flipper.plugins.uidebugger.litho
+
+import com.facebook.flipper.plugins.uidebugger.descriptors.DescriptorRegister
+import com.facebook.flipper.plugins.uidebugger.observers.TreeObserverFactory
+import com.facebook.litho.DebugComponent
+import com.facebook.litho.LithoView
+
+object UIDebuggerLithoSupport {
+
+  fun addDescriptors(register: DescriptorRegister) {
+    register.register(LithoView::class.java, LithoViewDescriptor)
+    register.register(DebugComponent::class.java, DebugComponentDescriptor)
+  }
+
+  fun addObserver(observerFactory: TreeObserverFactory) {
+    observerFactory.register(LithoViewTreeObserverBuilder)
+  }
+}

android/sample/src/debug/java/com/facebook/flipper/sample/FlipperInitializer.java

@@ -22,6 +22,9 @@ import com.facebook.flipper.plugins.network.NetworkFlipperPlugin;
 import com.facebook.flipper.plugins.sharedpreferences.SharedPreferencesFlipperPlugin;
 import com.facebook.flipper.plugins.sharedpreferences.SharedPreferencesFlipperPlugin.SharedPreferencesDescriptor;
 import com.facebook.flipper.plugins.uidebugger.UIDebuggerFlipperPlugin;
+import com.facebook.flipper.plugins.uidebugger.descriptors.DescriptorRegister;
+import com.facebook.flipper.plugins.uidebugger.litho.UIDebuggerLithoSupport;
+import com.facebook.flipper.plugins.uidebugger.observers.TreeObserverFactory;
 import com.facebook.litho.config.ComponentsConfiguration;
 import com.facebook.litho.editor.flipper.LithoFlipperDescriptors;
 import java.util.Arrays;
@@ -56,7 +59,15 @@ public final class FlipperInitializer {
     client.addPlugin(CrashReporterPlugin.getInstance());
     client.addPlugin(new DatabasesFlipperPlugin(context));
     client.addPlugin(NavigationFlipperPlugin.getInstance());
-    client.addPlugin(new UIDebuggerFlipperPlugin((Application) context));
+
+    DescriptorRegister descriptorRegister = DescriptorRegister.Companion.withDefaults();
+    TreeObserverFactory treeObserverFactory = TreeObserverFactory.Companion.withDefaults();
+    UIDebuggerLithoSupport.INSTANCE.addDescriptors(descriptorRegister);
+    UIDebuggerLithoSupport.INSTANCE.addObserver(treeObserverFactory);
+
+    client.addPlugin(
+        new UIDebuggerFlipperPlugin(
+            (Application) context, descriptorRegister, treeObserverFactory));
     client.start();
 
     final OkHttpClient okHttpClient =

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(),
+          descriptorRegister = descriptorRegister ?: DescriptorRegister.withDefaults(),
-          TreeObserverFactory.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)
   }
 }