From 45613792bf72f56350c125b8a2eb3667ce33d69f Mon Sep 17 00:00:00 2001
From: SpiritCroc <dev@spiritcroc.de>
Date: Thu, 31 Mar 2022 11:01:00 +0200
Subject: [PATCH] Avoid loading pager before pages known

Change-Id: I427e3e5ef9a27004b7b5f5e4eb6a2f45f8141c50
---
 .../im/vector/app/features/home/HomeDetailFragment.kt |  8 ++++++++
 vector/src/main/res/layout/fragment_home_detail.xml   | 11 ++++++++---
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/vector/src/main/java/im/vector/app/features/home/HomeDetailFragment.kt b/vector/src/main/java/im/vector/app/features/home/HomeDetailFragment.kt
index 31b735dbcd..64a2f5eba7 100644
--- a/vector/src/main/java/im/vector/app/features/home/HomeDetailFragment.kt
+++ b/vector/src/main/java/im/vector/app/features/home/HomeDetailFragment.kt
@@ -36,6 +36,7 @@ import im.vector.app.R
 import im.vector.app.RoomGroupingMethod
 import im.vector.app.core.extensions.restart
 import im.vector.app.core.extensions.toMvRxBundle
+import im.vector.app.core.platform.StateView
 import im.vector.app.core.platform.VectorBaseActivity
 import im.vector.app.core.platform.VectorBaseFragment
 import im.vector.app.core.resources.ColorProvider
@@ -521,6 +522,13 @@ class HomeDetailFragment @Inject constructor(
     private fun setupViewPager(roomGroupingMethod: RoomGroupingMethod, spaces: List<RoomSummary>?, tab: HomeTab) {
         val oldAdapter = views.roomListContainerPager.adapter as? FragmentStateAdapter
         val pagingAllowed = vectorPreferences.enableSpacePager() && tab is HomeTab.RoomList
+        if (pagingAllowed && spaces == null) {
+            Timber.i("Home pager: Skip initial setup, root spaces not known yet")
+            views.roomListContainerStateView.state = StateView.State.Loading
+            return
+        } else {
+            views.roomListContainerStateView.state = StateView.State.Content
+        }
         if (DEBUG_VIEW_PAGER) Timber.i("Home pager: setup, old adapter: $oldAdapter")
         val unsafeSpaces = spaces?.map { it.roomId } ?: listOf()
         val selectedSpaceId = (roomGroupingMethod as? RoomGroupingMethod.BySpace)?.spaceSummary?.roomId
diff --git a/vector/src/main/res/layout/fragment_home_detail.xml b/vector/src/main/res/layout/fragment_home_detail.xml
index e7397648ea..2cf3bdb940 100644
--- a/vector/src/main/res/layout/fragment_home_detail.xml
+++ b/vector/src/main/res/layout/fragment_home_detail.xml
@@ -146,12 +146,17 @@
         app:layout_constraintTop_toBottomOf="@id/homeKeysBackupBanner" />
 -->
 
-    <androidx.viewpager2.widget.ViewPager2
-        android:id="@+id/roomListContainerPager"
+    <im.vector.app.core.platform.StateView
+        android:id="@+id/roomListContainerStateView"
         android:layout_width="match_parent"
         android:layout_height="0dp"
         app:layout_constraintBottom_toTopOf="@+id/bottomNavigationView"
-        app:layout_constraintTop_toBottomOf="@+id/homeKeysBackupBanner" />
+        app:layout_constraintTop_toBottomOf="@+id/homeKeysBackupBanner">
+        <androidx.viewpager2.widget.ViewPager2
+            android:id="@+id/roomListContainerPager"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent" />
+    </im.vector.app.core.platform.StateView>
 
     <com.google.android.material.bottomnavigation.BottomNavigationView
         android:id="@+id/bottomNavigationView"