Convert FpsDebugFrameCallback/AnimationsDebugModule to Kotlin (facebo…

…ok#44475)

Summary:
Pull Request resolved: facebook#44475

# Changelog:
[Internal] -

As the title says, this is preparing to complete the conversion of the whole corresponding module to Kotlin.

Reviewed By: christophpurrer

Differential Revision: D57095896

fbshipit-source-id: 87fe08aec974f5f1327189d0e74c3782c4391e85

packages/react-native/ReactAndroid/api/ReactAndroid.api

@@ -3193,33 +3193,34 @@ public final class com/facebook/react/modules/debug/DevSettingsModule : com/face
 	public fun toggleElementInspector ()V
 }
 
-public class com/facebook/react/modules/debug/FpsDebugFrameCallback : android/view/Choreographer$FrameCallback {
+public final class com/facebook/react/modules/debug/FpsDebugFrameCallback : android/view/Choreographer$FrameCallback {
 	public fun <init> (Lcom/facebook/react/bridge/ReactContext;)V
 	public fun doFrame (J)V
-	public fun get4PlusFrameStutters ()I
-	public fun getExpectedNumFrames ()I
-	public fun getFPS ()D
-	public fun getFpsInfo (J)Lcom/facebook/react/modules/debug/FpsDebugFrameCallback$FpsInfo;
-	public fun getJSFPS ()D
-	public fun getNumFrames ()I
-	public fun getNumJSFrames ()I
-	public fun getTotalTimeMS ()I
-	public fun reset ()V
-	public fun start ()V
-	public fun start (D)V
-	public fun startAndRecordFpsAtEachFrame ()V
-	public fun stop ()V
+	public final fun get4PlusFrameStutters ()I
+	public final fun getExpectedNumFrames ()I
+	public final fun getFps ()D
+	public final fun getFpsInfo (J)Lcom/facebook/react/modules/debug/FpsDebugFrameCallback$FpsInfo;
+	public final fun getJsFPS ()D
+	public final fun getNumFrames ()I
+	public final fun getNumJSFrames ()I
+	public final fun getTotalTimeMS ()I
+	public final fun reset ()V
+	public final fun start ()V
+	public final fun start (D)V
+	public static synthetic fun start$default (Lcom/facebook/react/modules/debug/FpsDebugFrameCallback;DILjava/lang/Object;)V
+	public final fun startAndRecordFpsAtEachFrame ()V
+	public final fun stop ()V
 }
 
-public class com/facebook/react/modules/debug/FpsDebugFrameCallback$FpsInfo {
-	public final field fps D
-	public final field jsFps D
-	public final field total4PlusFrameStutters I
-	public final field totalExpectedFrames I
-	public final field totalFrames I
-	public final field totalJsFrames I
-	public final field totalTimeMs I
+public final class com/facebook/react/modules/debug/FpsDebugFrameCallback$FpsInfo {
 	public fun <init> (IIIIDDI)V
+	public final fun getFps ()D
+	public final fun getJsFps ()D
+	public final fun getTotal4PlusFrameStutters ()I
+	public final fun getTotalExpectedFrames ()I
+	public final fun getTotalFrames ()I
+	public final fun getTotalJsFrames ()I
+	public final fun getTotalTimeMs ()I
 }
 
 public class com/facebook/react/modules/debug/SourceCodeModule : com/facebook/fbreact/specs/NativeSourceCodeSpec {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/devsupport/FpsView.kt

@@ -0,0 +1,101 @@
+/*
+ * 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.react.devsupport
+
+import android.view.View
+import android.widget.FrameLayout
+import android.widget.TextView
+import com.facebook.common.logging.FLog
+import com.facebook.react.R
+import com.facebook.react.bridge.ReactContext
+import com.facebook.react.common.ReactConstants
+import com.facebook.react.modules.debug.FpsDebugFrameCallback
+import java.util.Locale
+
+/**
+ * View that automatically monitors and displays the current app frame rate. Also logs the current
+ * FPS to logcat while active.
+ *
+ * NB: Requires API 16 for use of FpsDebugFrameCallback.
+ */
+internal class FpsView(reactContext: ReactContext?) : FrameLayout(reactContext!!) {
+  private val textView: TextView
+  private val frameCallback: FpsDebugFrameCallback
+  private val fpsMonitorRunnable: FPSMonitorRunnable
+
+  init {
+    inflate(reactContext, R.layout.fps_view, this)
+    textView = findViewById<View>(R.id.fps_text) as TextView
+    frameCallback = FpsDebugFrameCallback(reactContext!!)
+    fpsMonitorRunnable = FPSMonitorRunnable()
+    setCurrentFPS(0.0, 0.0, 0, 0)
+  }
+
+  override fun onAttachedToWindow() {
+    super.onAttachedToWindow()
+    frameCallback.reset()
+    frameCallback.start()
+    fpsMonitorRunnable.start()
+  }
+
+  override fun onDetachedFromWindow() {
+    super.onDetachedFromWindow()
+    frameCallback.stop()
+    fpsMonitorRunnable.stop()
+  }
+
+  private fun setCurrentFPS(
+      currentFPS: Double,
+      currentJSFPS: Double,
+      droppedUIFrames: Int,
+      total4PlusFrameStutters: Int
+  ) {
+    val fpsString =
+        String.format(
+            Locale.US,
+            "UI: %.1f fps\n%d dropped so far\n%d stutters (4+) so far\nJS: %.1f fps",
+            currentFPS,
+            droppedUIFrames,
+            total4PlusFrameStutters,
+            currentJSFPS)
+    textView.text = fpsString
+    FLog.d(ReactConstants.TAG, fpsString)
+  }
+
+  /** Timer that runs every UPDATE_INTERVAL_MS ms and updates the currently displayed FPS. */
+  private inner class FPSMonitorRunnable : Runnable {
+    private var shouldStop = false
+    private var totalFramesDropped = 0
+    private var total4PlusFrameStutters = 0
+
+    override fun run() {
+      if (shouldStop) {
+        return
+      }
+      totalFramesDropped += frameCallback.expectedNumFrames - frameCallback.numFrames
+      total4PlusFrameStutters += frameCallback.get4PlusFrameStutters()
+      setCurrentFPS(
+          frameCallback.fps, frameCallback.jsFPS, totalFramesDropped, total4PlusFrameStutters)
+      frameCallback.reset()
+      postDelayed(this, UPDATE_INTERVAL_MS.toLong())
+    }
+
+    fun start() {
+      shouldStop = false
+      post(this)
+    }
+
+    fun stop() {
+      shouldStop = true
+    }
+  }
+
+  companion object {
+    private const val UPDATE_INTERVAL_MS = 500
+  }
+}