Fixes #25545: wait to draw Pocket until after first frame

app/src/main/java/org/mozilla/fenix/FeatureFlags.kt

@@ -87,7 +87,7 @@ object FeatureFlags {
     /**
      * Enables the Task Continuity enhancements.
      */
-    val taskContinuityFeature = Config.channel.isDebug
+    val taskContinuityFeature = Config.channel.isNightlyOrDebug
 
     /**
      * Enables the Unified Search feature.

app/src/main/java/org/mozilla/fenix/components/appstate/AppAction.kt

@@ -27,6 +27,11 @@ import org.mozilla.fenix.gleanplumb.MessagingState
  */
 sealed class AppAction : Action {
     data class UpdateInactiveExpanded(val expanded: Boolean) : AppAction()
+
+    /**
+     * Updates whether the first frame of the homescreen has been [drawn].
+     */
+    data class UpdateFirstFrameDrawn(val drawn: Boolean) : AppAction()
     data class AddNonFatalCrash(val crash: NativeCodeCrash) : AppAction()
     data class RemoveNonFatalCrash(val crash: NativeCodeCrash) : AppAction()
     object RemoveAllNonFatalCrashes : AppAction()

app/src/main/java/org/mozilla/fenix/components/appstate/AppState.kt

@@ -28,6 +28,7 @@ import org.mozilla.fenix.gleanplumb.MessagingState
  *
  * @property inactiveTabsExpanded A flag to know if the Inactive Tabs section of the Tabs Tray
  * should be expanded when the tray is opened.
+ * @property firstFrameDrawn Flag indicating whether the first frame of the homescreen has been drawn.
  * @property nonFatalCrashes List of non-fatal crashes that allow the app to continue being used.
  * @property collections The list of [TabCollection] to display in the [HomeFragment].
  * @property expandedCollections A set containing the ids of the [TabCollection] that are expanded
@@ -50,6 +51,7 @@ import org.mozilla.fenix.gleanplumb.MessagingState
  */
 data class AppState(
     val inactiveTabsExpanded: Boolean = false,
+    val firstFrameDrawn: Boolean = false,
     val nonFatalCrashes: List<NativeCodeCrash> = emptyList(),
     val collections: List<TabCollection> = emptyList(),
     val expandedCollections: Set<Long> = emptySet(),

app/src/main/java/org/mozilla/fenix/components/appstate/AppStoreReducer.kt

@@ -26,6 +26,9 @@ internal object AppStoreReducer {
     fun reduce(state: AppState, action: AppAction): AppState = when (action) {
         is AppAction.UpdateInactiveExpanded ->
             state.copy(inactiveTabsExpanded = action.expanded)
+        is AppAction.UpdateFirstFrameDrawn -> {
+            state.copy(firstFrameDrawn = action.drawn)
+        }
         is AppAction.AddNonFatalCrash ->
             state.copy(nonFatalCrashes = state.nonFatalCrashes + action.crash)
         is AppAction.RemoveNonFatalCrash ->

app/src/main/java/org/mozilla/fenix/home/HomeFragment.kt

@@ -28,6 +28,7 @@ import androidx.constraintlayout.widget.ConstraintSet.TOP
 import androidx.coordinatorlayout.widget.CoordinatorLayout
 import androidx.core.content.ContextCompat
 import androidx.core.view.isVisible
+import androidx.core.view.doOnPreDraw
 import androidx.core.view.updateLayoutParams
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
@@ -385,11 +386,13 @@ class HomeFragment : Fragment() {
 
         displayWallpaperIfEnabled()
 
+        binding.root.doOnPreDraw {
+            requireComponents.appStore.dispatch(AppAction.UpdateFirstFrameDrawn(drawn = true))
+        }
         // DO NOT MOVE ANYTHING BELOW THIS addMarker CALL!
         requireComponents.core.engine.profiler?.addMarker(
             MarkersFragmentLifecycleCallbacks.MARKER_NAME, profilerStartTime, "HomeFragment.onCreateView",
         )
-
         return binding.root
     }
 

app/src/main/java/org/mozilla/fenix/home/pocket/PocketCategoriesViewHolder.kt

@@ -49,11 +49,16 @@ class PocketCategoriesViewHolder(
             composeView.resources.getDimensionPixelSize(R.dimen.home_item_horizontal_margin)
         composeView.setPadding(horizontalPadding, 0, horizontalPadding, 0)
 
+        val homeScreenReady = components.appStore
+            .observeAsComposableState { state -> state.firstFrameDrawn }.value ?: false
+
         val categories = components.appStore
             .observeAsComposableState { state -> state.pocketStoriesCategories }.value
         val categoriesSelections = components.appStore
             .observeAsComposableState { state -> state.pocketStoriesCategoriesSelections }.value
 
+        // See the detailed comment in PocketStoriesViewHolder for reasoning behind this change.
+        if (!homeScreenReady) return
         Column {
             Spacer(Modifier.height(24.dp))
 

app/src/main/java/org/mozilla/fenix/home/pocket/PocketStoriesViewHolder.kt

@@ -52,9 +52,22 @@ class PocketStoriesViewHolder(
     override fun Content() {
         val horizontalPadding = dimensionResource(R.dimen.home_item_horizontal_margin)
 
+        val homeScreenReady = components.appStore
+            .observeAsComposableState { state -> state.firstFrameDrawn }.value ?: false
+
         val stories = components.appStore
             .observeAsComposableState { state -> state.pocketStories }.value
 
+        /* This was originally done to address this perf issue:
+         * https://github.com/mozilla-mobile/fenix/issues/25545 for details.
+         * It was determined that Pocket content was becoming available before the first frame was
+         * rendered more regularly. Including Pocket in the first render pass significantly
+         * increases time-to-render in lower-end devices. By waiting until the first frame has
+         * rendered, the perceived performance should increase since the app becomes active more
+         * quickly. This was intended as a workaround until the Compose upgrade was completed and a
+         * more robust solution could be investigated.
+         */
+        if (!homeScreenReady) return
         LaunchedEffect(stories) {
             // We should report back when a certain story is actually being displayed.
             // Cannot do it reliably so for now we'll just mass report everything as being displayed.

app/src/main/res/layout/top_placeholder_item.xml

@@ -2,6 +2,10 @@
 <!-- This Source Code Form is subject to the terms of the Mozilla Public
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- RecyclerViews will focus the first element that is focusable. This prevents views below
+the top from being scrolled to unintentionally. -->
 <View xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
-    android:layout_height="0dp"/>
+    android:layout_height="0dp"
+    android:focusable="true" />