Replace root view resolver with curtains (facebook#5572)

Summary:

Curtains allows a common entrypoint into accessing the root views, this means multiple tools can access it without clobbering each others observable array list

it also means we can get rid of some nasty reflection code that we don't maintain as well as curtains

Differential Revision: D56015851

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

@@ -20,7 +20,6 @@ class ApplicationRef(val application: Application) {
   // the root view resolver will at least find the decor view, this is the case for various
   // kinds of custom overlays
   // 2. Dialog fragments
-  val rootsResolver: RootViewResolver = RootViewResolver()
   val windowManagerUtility = WindowManagerUtility()
   val activitiesStack: List<Activity>
     get() {

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

@@ -17,6 +17,8 @@ import com.facebook.flipper.plugins.uidebugger.descriptors.ViewDescriptor
 import com.facebook.flipper.plugins.uidebugger.util.StopWatch
 import com.facebook.flipper.plugins.uidebugger.util.Throttler
 import com.facebook.flipper.plugins.uidebugger.util.objectIdentity
+import curtains.Curtains
+import curtains.OnRootViewsChangedListener
 
 /**
  * The UIDebugger does 3 things:
@@ -44,61 +46,66 @@ class DecorViewTracker(private val context: UIDContext, private val snapshotter:
 
   fun start() {
 
-    val applicationRef = context.applicationRef
-
-    val rootViewListener =
-        object : RootViewResolver.Listener {
-          override fun onRootViewAdded(rootView: View) {}
-
-          override fun onRootViewRemoved(rootView: View) {}
-
-          override fun onRootViewsChanged(rootViews: List<View>) {
-            // remove predraw listen from current view as its going away or will be covered
-            Log.i(LogTag, "Removing pre draw listener from ${currentDecorView?.objectIdentity()}")
-            currentDecorView?.viewTreeObserver?.removeOnPreDrawListener(preDrawListener)
+    val rootViewChangedListener = OnRootViewsChangedListener { view, added ->
+      if (currentDecorView != null) {
+        // remove predraw listen from current view as its going away or will be covered
+        Log.d(LogTag, "Removing pre draw listener from ${currentDecorView?.objectIdentity()}")
+        currentDecorView?.viewTreeObserver?.removeOnPreDrawListener(preDrawListener)
+      }
+
+      val decorViewToActivity: Map<View, Activity> = ActivityTracker.decorViewToActivityMap
+
+      // at the time of this callback curtains.rootViews is not updated yet, so we need to use the
+      // 'view' and 'added' params to the callback to see any new root views
+      val topView =
+          if (added && ApplicationRefDescriptor.isUsefulRoot(decorViewToActivity[view] ?: view)) {
+            view
+          } else {
+            // this is technically the preview set of root view but this is the branch where the new
+            // root view is not 'useful' or we are popping a view off the stack so the old roots are
+            // fine here
+            Curtains.rootViews.lastOrNull {
+              ApplicationRefDescriptor.isUsefulRoot(decorViewToActivity[it] ?: it)
+            }
+          }
 
-            // setup new listener on top most view, that will be the active child in traversal
+      if (topView != null) {
+        val throttler = Throttler(500) { currentDecorView?.let { traverseSnapshotAndSend(it) } }
 
-            val decorViewToActivity: Map<View, Activity> = ActivityTracker.decorViewToActivityMap
+        preDrawListener =
+            ViewTreeObserver.OnPreDrawListener {
+              throttler.trigger()
+              true
+            }
 
-            val topView =
-                rootViews.lastOrNull { view ->
-                  val activityOrView = decorViewToActivity[view] ?: view
-                  ApplicationRefDescriptor.isUsefulRoot(activityOrView)
-                }
+        topView.viewTreeObserver.addOnPreDrawListener(preDrawListener)
+        currentDecorView = topView
 
-            if (topView != null) {
-              val throttler =
-                  Throttler(500) { currentDecorView?.let { traverseSnapshotAndSend(it) } }
+        Log.i(LogTag, "Added pre draw listener to ${topView.objectIdentity()}")
 
-              preDrawListener =
-                  ViewTreeObserver.OnPreDrawListener {
-                    throttler.trigger()
-                    true
-                  }
+        // schedule traversal immediately when we detect a new decor view
+        throttler.trigger()
+      }
+    }
 
-              topView.viewTreeObserver.addOnPreDrawListener(preDrawListener)
-              currentDecorView = topView
+    Curtains.onRootViewsChangedListeners.add(rootViewChangedListener)
 
-              Log.i(LogTag, "Added pre draw listener to ${topView.objectIdentity()}")
+    // On subscribe, trigger a traversal on whatever roots we have
+    val decorViewToActivity: Map<View, Activity> = ActivityTracker.decorViewToActivityMap
 
-              // schedule traversal immediately when we detect a new decor view
-              throttler.trigger()
-            }
-          }
+    val topView =
+        Curtains.rootViews.lastOrNull {
+          ApplicationRefDescriptor.isUsefulRoot(decorViewToActivity[it] ?: it)
         }
+    if (topView != null) {
+      rootViewChangedListener.onRootViewsChanged(topView, true)
+    }
 
-    context.applicationRef.rootsResolver.attachListener(rootViewListener)
-    // On subscribe, trigger a traversal on whatever roots we have
-    rootViewListener.onRootViewsChanged(applicationRef.rootsResolver.rootViews())
-
-    Log.i(
-        LogTag,
-        "Starting tracking root views, currently ${context.applicationRef.rootsResolver.rootViews().size} root views")
+    Log.i(LogTag, "Starting tracking root views, currently ${Curtains.rootViews.size} root views")
   }
 
   fun stop() {
-    context.applicationRef.rootsResolver.attachListener(null)
+    Curtains.onRootViewsChangedListeners.clear()
     currentDecorView?.viewTreeObserver?.removeOnPreDrawListener(preDrawListener)
     currentDecorView = null
     preDrawListener = null

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

@@ -162,7 +162,7 @@ internal object SnapshotCommon {
     }
 
     // something went wrong, use fallback, make sure to give bitmap back to pool first
-    Log.i(LogTag, "Using fallback snapshot method")
+    Log.d(LogTag, "Using fallback snapshot method")
     reusableBitmap?.readyForReuse()
     return fallback?.takeSnapshot(view)
   }

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

@@ -14,6 +14,7 @@ import com.facebook.flipper.plugins.uidebugger.core.ActivityTracker
 import com.facebook.flipper.plugins.uidebugger.core.ApplicationRef
 import com.facebook.flipper.plugins.uidebugger.model.Bounds
 import com.facebook.flipper.plugins.uidebugger.util.DisplayMetrics
+import curtains.Curtains
 
 object ApplicationRefDescriptor : ChainedDescriptor<ApplicationRef>() {
 
@@ -34,7 +35,7 @@ object ApplicationRefDescriptor : ChainedDescriptor<ApplicationRef>() {
   override fun onGetChildren(node: ApplicationRef): List<Any> {
     val children = mutableListOf<Any>()
 
-    val rootViews = node.rootsResolver.rootViews()
+    val rootViews = Curtains.rootViews
 
     val decorViewToActivity: Map<View, Activity> = ActivityTracker.decorViewToActivityMap