Inject JankStats with Hilt

app/src/main/java/com/google/samples/apps/nowinandroid/MainActivity.kt

@@ -17,32 +17,25 @@
 package com.google.samples.apps.nowinandroid
 
 import android.os.Bundle
-import android.util.Log
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.compose.material3.windowsizeclass.ExperimentalMaterial3WindowSizeClassApi
 import androidx.compose.material3.windowsizeclass.calculateWindowSizeClass
-import androidx.compose.runtime.remember
 import androidx.core.view.WindowCompat
 import androidx.metrics.performance.JankStats
-import androidx.metrics.performance.PerformanceMetricsState
 import com.google.samples.apps.nowinandroid.ui.NiaApp
 import dagger.hilt.android.AndroidEntryPoint
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.asExecutor
+import javax.inject.Inject
 
 @OptIn(ExperimentalMaterial3WindowSizeClassApi::class)
 @AndroidEntryPoint
 class MainActivity : ComponentActivity() {
 
-    private lateinit var jankStats: JankStats
+    @Inject
+    lateinit var lazyStats: dagger.Lazy<JankStats>
 
-    private val jankFrameListener = JankStats.OnFrameListener { frameData ->
-        // Make sure to only log janky frames.
-        if (frameData.isJank) {
-            Log.v("NiA Jank", frameData.toString())
-        }
-    }
+    @Inject
+    lateinit var jankFrameListener: JankStats.OnFrameListener
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -54,21 +47,19 @@ class MainActivity : ComponentActivity() {
         setContent {
             NiaApp(calculateWindowSizeClass(this))
         }
-
-        jankStats = JankStats.createAndTrack(
-            window,
-            Dispatchers.Default.asExecutor(),
-            jankFrameListener
-        )
     }
 
     override fun onResume() {
         super.onResume()
-        jankStats.isTrackingEnabled = true
+        isTrackingEnabled(true)
     }
 
     override fun onPause() {
         super.onPause()
-        jankStats.isTrackingEnabled = false
+        isTrackingEnabled(false)
+    }
+
+    private fun isTrackingEnabled(enabled: Boolean) {
+        lazyStats.get().isTrackingEnabled = enabled
     }
 }

app/src/main/java/com/google/samples/apps/nowinandroid/di/JankStatsModule.kt

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.di
+
+import android.app.Activity
+import android.util.Log
+import android.view.Window
+import androidx.metrics.performance.JankStats
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.android.components.ActivityComponent
+import java.util.concurrent.Executor
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.asExecutor
+
+@Module
+@InstallIn(ActivityComponent::class)
+object JankStatsModule {
+    @Provides
+    fun providesOnFrameListener(): JankStats.OnFrameListener {
+        return JankStats.OnFrameListener { frameData ->
+            // Make sure to only log janky frames.
+            if (frameData.isJank) {
+                // We're currently logging this but would better report it to a backend.
+                Log.v("NiA Jank", frameData.toString())
+            }
+        }
+    }
+
+    @Provides
+    fun providesWindow(activity: Activity): Window {
+        return activity.window
+    }
+
+    @Provides
+    fun providesDefaultExecutor(): Executor {
+        return Dispatchers.Default.asExecutor()
+    }
+
+    @Provides
+    fun providesJankStats(
+        window: Window,
+        executor: Executor,
+        frameListener: JankStats.OnFrameListener
+    ): JankStats {
+        return JankStats.createAndTrack(window, executor, frameListener)
+    }
+}

app/src/main/java/com/google/samples/apps/nowinandroid/ui/NiaApp.kt

@@ -69,7 +69,7 @@ fun NiaApp(windowSizeClass: WindowSizeClass) {
         val metricsStateHolder = PerformanceMetricsState.getForHierarchy(LocalView.current)
         val navController = rememberNavController()
         navController.addOnDestinationChangedListener { _, destination, _ ->
-            metricsStateHolder.state?.addState("Navigation", "Jank at ${destination.route}")
+            metricsStateHolder.state?.addState("Navigation", "${destination.route}")
         }
         val niaTopLevelNavigation = remember(navController) {
             NiaTopLevelNavigation(navController)