Address review comments

* Introduce gradle plugin for firebase perf
* Create TrackScrollJank composable to mask tracking code

app/build.gradle.kts

@@ -24,7 +24,7 @@ plugins {
  id("jacoco")
  id("dagger.hilt.android.plugin")
  id("nowinandroid.spotless")
- id("com.google.firebase.firebase-perf") version "1.4.1"
+ id("nowinandroid.firebase-perf")
 }
 
 android {

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

@@ -31,12 +31,12 @@ import javax.inject.Inject
 @AndroidEntryPoint
 class MainActivity : ComponentActivity() {
 
+ /**
+ * Lazily inject [JankStats], which is used to track jank throughout the app.
+ */
  @Inject
  lateinit var lazyStats: dagger.Lazy<JankStats>
 
- @Inject
- lateinit var jankFrameListener: JankStats.OnFrameListener
-
  override fun onCreate(savedInstanceState: Bundle?) {
  super.onCreate(savedInstanceState)
 
@@ -51,15 +51,11 @@ class MainActivity : ComponentActivity() {
 
  override fun onResume() {
  super.onResume()
- isTrackingEnabled(true)
+ lazyStats.get().isTrackingEnabled = true
  }
 
  override fun onPause() {
  super.onPause()
- isTrackingEnabled(false)
- }
-
- private fun isTrackingEnabled(enabled: Boolean) {
- lazyStats.get().isTrackingEnabled = enabled
+ lazyStats.get().isTrackingEnabled = false
  }
 }

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

@@ -67,7 +67,6 @@ import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination
 fun NiaApp(windowSizeClass: WindowSizeClass) {
  NiaTheme {
  val navController = rememberNavController()
-
  val niaTopLevelNavigation = remember(navController) {
  NiaTopLevelNavigation(navController)
  }

build-logic/convention/build.gradle.kts

@@ -69,5 +69,9 @@ gradlePlugin {
  id = "nowinandroid.spotless"
  implementationClass = "SpotlessConventionPlugin"
  }
+ register("firebase-perf") {
+ id = "nowinandroid.firebase-perf"
+ implementationClass = "FirebasePerfConventionPlugin"
+ }
  }
 }

build-logic/convention/src/main/kotlin/FirebasePerfConventionPlugin.kt

@@ -0,0 +1,29 @@
+/*
+ * 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.
+ */
+
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+
+class FirebasePerfConventionPlugin : Plugin<Project> {
+ override fun apply(target: Project) {
+ with(target) {
+ pluginManager.findPlugin("com.google.firebase.firebase-perf").apply {
+ version = "1.4.1"
+ }
+ }
+ }
+
+}

core-ui/src/main/java/com/google/samples/apps/nowinandroid/core/ui/JankStatsExtensions.kt

@@ -16,12 +16,14 @@
 
 package com.google.samples.apps.nowinandroid.core.ui
 
+import androidx.compose.foundation.gestures.ScrollableState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.DisposableEffectResult
 import androidx.compose.runtime.DisposableEffectScope
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.snapshotFlow
 import androidx.compose.ui.platform.LocalView
 import androidx.metrics.performance.PerformanceMetricsState
 import androidx.metrics.performance.PerformanceMetricsState.MetricsStateHolder
@@ -71,3 +73,18 @@ fun JankMetricDisposableEffect(
  reportMetric(this, metrics)
  }
 }
+
+@Composable
+fun TrackScrollJank(scrollableState: ScrollableState, stateName: String) {
+ JankMetricEffect(scrollableState) { metricsHolder ->
+ snapshotFlow { scrollableState.isScrollInProgress }.collect { isScrollInProgress ->
+ metricsHolder.state?.apply {
+ if (isScrollInProgress) {
+ addState(stateName, "Scrolling=true")
+ } else {
+ removeState(stateName)
+ }
+ }
+ }
+ }
+}

feature-foryou/src/main/java/com/google/samples/apps/nowinandroid/feature/foryou/AuthorsCarousel.kt

@@ -38,7 +38,6 @@ import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.remember
-import androidx.compose.runtime.snapshotFlow
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -57,9 +56,7 @@ import com.google.samples.apps.nowinandroid.core.designsystem.icon.NiaIcons
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.NiaTheme
 import com.google.samples.apps.nowinandroid.core.model.data.Author
 import com.google.samples.apps.nowinandroid.core.model.data.FollowableAuthor
-import com.google.samples.apps.nowinandroid.core.ui.JankMetricEffect
-import kotlinx.coroutines.flow.collect
-import kotlinx.coroutines.flow.combine
+import com.google.samples.apps.nowinandroid.core.ui.TrackScrollJank
 
 @Composable
 fun AuthorsCarousel(
@@ -69,21 +66,7 @@ fun AuthorsCarousel(
 ) {
  val lazyListState = rememberLazyListState()
 
- JankMetricEffect(lazyListState) { metricsHolder ->
- combine(
- snapshotFlow { lazyListState.isScrollInProgress },
- snapshotFlow { lazyListState.firstVisibleItemIndex }
- ) { isScrollInProgress, firstVisibleItemIndex ->
- if (isScrollInProgress) {
- metricsHolder.state?.addState(
- "ForYou:AuthorsCarousel:Scrolling",
- "Index=$firstVisibleItemIndex"
- )
- } else {
- metricsHolder.state?.removeState("ForYou:AuthorsCarousel:Scrolling")
- }
- }.collect()
- }
+ TrackScrollJank(lazyListState, "ForYou:AuthorsCarousel")
 
  LazyRow(modifier, lazyListState) {
  items(items = authors, key = { item -> item.author.id }) { followableAuthor ->

feature-foryou/src/main/java/com/google/samples/apps/nowinandroid/feature/foryou/ForYouScreen.kt

@@ -63,7 +63,6 @@ import androidx.compose.material3.windowsizeclass.WindowWidthSizeClass
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.snapshotFlow
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
@@ -93,11 +92,9 @@ import com.google.samples.apps.nowinandroid.core.model.data.SaveableNewsResource
 import com.google.samples.apps.nowinandroid.core.model.data.previewAuthors
 import com.google.samples.apps.nowinandroid.core.model.data.previewNewsResources
 import com.google.samples.apps.nowinandroid.core.model.data.previewTopics
-import com.google.samples.apps.nowinandroid.core.ui.JankMetricEffect
 import com.google.samples.apps.nowinandroid.core.ui.NewsResourceCardExpanded
+import com.google.samples.apps.nowinandroid.core.ui.TrackScrollJank
 import kotlin.math.floor
-import kotlinx.coroutines.flow.collect
-import kotlinx.coroutines.flow.combine
 
 @Composable
 fun ForYouRoute(
@@ -168,21 +165,7 @@ fun ForYouScreen(
  }
 
  val lazyListState = rememberLazyListState()
- JankMetricEffect(lazyListState) { metricsHolder ->
- combine(
- snapshotFlow { lazyListState.isScrollInProgress },
- snapshotFlow { lazyListState.firstVisibleItemIndex },
- ) { isScrollInProgress, firstVisibleItemIndex ->
- if (isScrollInProgress) {
- metricsHolder.state?.addState(
- "ForYou:Feed:Scrolling",
- "index=$firstVisibleItemIndex"
- )
- } else {
- metricsHolder.state?.removeState("ForYou:Feed:Scrolling")
- }
- }.collect()
- }
+ TrackScrollJank(lazyListState, "ForYou:Feed")
 
  LazyColumn(
  state = lazyListState,
@@ -311,21 +294,8 @@ private fun TopicSelection(
  modifier: Modifier = Modifier
 ) {
  val lazyGridState = rememberLazyGridState()
- JankMetricEffect(lazyGridState) { metricsHolder ->
- combine(
- snapshotFlow { lazyGridState.isScrollInProgress },
- snapshotFlow { lazyGridState.firstVisibleItemIndex },
- ) { isScrollInProgress, firstVisibleItemIndex ->
- if (isScrollInProgress) {
- metricsHolder.state?.addState(
- "ForYou:TopicSelection:Scrolling",
- "index=$firstVisibleItemIndex"
- )
- } else {
- metricsHolder.state?.removeState("ForYou:TopicSelection:Scrolling")
- }
- }.collect()
- }
+
+ TrackScrollJank(scrollableState = lazyGridState, stateName = "ForYou:TopicSelection")
 
  LazyHorizontalGrid(
  state = lazyGridState,