From 775a7c7bd4f9d61ac872f7c285f25b6d48b22c09 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Mlynari=C4=8D?= <mlykotom@google.com>
Date: Mon, 23 May 2022 14:51:48 +0200
Subject: [PATCH] Add ForYou feed scrolling state

Change-Id: Ia371c564e4ff723fbeaca741d278174bd6db0dd8
---
 .../feature/foryou/ForYouScreen.kt            | 25 ++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/feature-foryou/src/main/java/com/google/samples/apps/nowinandroid/feature/foryou/ForYouScreen.kt b/feature-foryou/src/main/java/com/google/samples/apps/nowinandroid/feature/foryou/ForYouScreen.kt
index 2ab82c054..b29a3b6e0 100644
--- a/feature-foryou/src/main/java/com/google/samples/apps/nowinandroid/feature/foryou/ForYouScreen.kt
+++ b/feature-foryou/src/main/java/com/google/samples/apps/nowinandroid/feature/foryou/ForYouScreen.kt
@@ -45,6 +45,7 @@ import androidx.compose.foundation.lazy.grid.GridCells
 import androidx.compose.foundation.lazy.grid.LazyHorizontalGrid
 import androidx.compose.foundation.lazy.grid.items
 import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.foundation.shape.CornerSize
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.icons.Icons
@@ -63,6 +64,7 @@ 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
@@ -86,6 +88,7 @@ import com.google.samples.apps.nowinandroid.core.model.data.NewsResource
 import com.google.samples.apps.nowinandroid.core.model.data.NewsResourceType.Video
 import com.google.samples.apps.nowinandroid.core.model.data.SaveableNewsResource
 import com.google.samples.apps.nowinandroid.core.model.data.Topic
+import com.google.samples.apps.nowinandroid.core.ui.JankMetricEffect
 import com.google.samples.apps.nowinandroid.core.ui.LoadingWheel
 import com.google.samples.apps.nowinandroid.core.ui.NewsResourceCardExpanded
 import com.google.samples.apps.nowinandroid.core.ui.component.NiaFilledButton
@@ -95,8 +98,10 @@ import com.google.samples.apps.nowinandroid.core.ui.component.NiaTopAppBar
 import com.google.samples.apps.nowinandroid.core.ui.icon.NiaIcons
 import com.google.samples.apps.nowinandroid.core.ui.theme.NiaTheme
 import com.google.samples.apps.nowinandroid.core.ui.theme.NiaTypography
-import kotlin.math.floor
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.flow.combine
 import kotlinx.datetime.Instant
+import kotlin.math.floor
 
 @Composable
 fun ForYouRoute(
@@ -166,7 +171,25 @@ fun ForYouScreen(
                     else -> floor(maxWidth / 300.dp).toInt().coerceAtLeast(1)
                 }
 
+                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()
+                }
+
                 LazyColumn(
+                    state = lazyListState,
                     modifier = Modifier.fillMaxSize(),
                 ) {
                     InterestsSelection(