Add placehoders for paged room list

vector/src/main/java/im/vector/app/features/home/room/list/RoomSummaryItemPlaceHolder.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2021 New Vector Ltd
+ *
+ * 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
+ *
+ * http://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 im.vector.app.features.home.room.list
+
+import com.airbnb.epoxy.EpoxyModelClass
+import im.vector.app.R
+import im.vector.app.core.epoxy.VectorEpoxyHolder
+import im.vector.app.core.epoxy.VectorEpoxyModel
+
+@EpoxyModelClass(layout = R.layout.item_room_placeholder)
+abstract class RoomSummaryItemPlaceHolder : VectorEpoxyModel<RoomSummaryItemPlaceHolder.Holder>() {
+    class Holder : VectorEpoxyHolder()
+}

vector/src/main/java/im/vector/app/features/home/room/list/RoomSummaryPagedController.kt

@@ -24,7 +24,7 @@ import org.matrix.android.sdk.api.session.room.model.RoomSummary
 
 class RoomSummaryPagedController(
         private val roomSummaryItemFactory: RoomSummaryItemFactory
-) : PagedListEpoxyController<RoomSummary> (
+) : PagedListEpoxyController<RoomSummary>(
         // Important it must match the PageList builder notify Looper
         modelBuildingHandler = createUIHandler()
 ), CollapsableControllerExtension {
@@ -39,12 +39,12 @@ class RoomSummaryPagedController(
         }
 
     override var collapsed = false
-    set(value) {
-        if (field != value) {
-            field = value
-            requestForcedModelBuild()
+        set(value) {
+            if (field != value) {
+                field = value
+                requestForcedModelBuild()
+            }
         }
-    }
 
     override fun addModels(models: List<EpoxyModel<*>>) {
         if (collapsed) {
@@ -56,19 +56,7 @@ class RoomSummaryPagedController(
 
     override fun buildItemModel(currentPosition: Int, item: RoomSummary?): EpoxyModel<*> {
         // for place holder if enabled
-        item ?: return roomSummaryItemFactory.createRoomItem(
-                roomSummary = RoomSummary(
-                        roomId = "null_item_pos_$currentPosition",
-                        name = "",
-                        encryptionEventTs = null,
-                        isEncrypted = false,
-                        typingUsers = emptyList()
-                ),
-                selectedRoomIds = emptySet(),
-                onClick = null,
-                onLongClick = null
-        )
-
+        item ?: return RoomSummaryItemPlaceHolder_().apply { id(currentPosition) }
         return roomSummaryItemFactory.create(item, roomChangeMembershipStates.orEmpty(), emptySet(), listener)
     }
 }

vector/src/main/java/im/vector/app/features/home/room/list/SpaceRoomListSectionBuilder.kt

@@ -20,6 +20,7 @@ import androidx.annotation.StringRes
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.liveData
+import androidx.paging.PagedList
 import com.airbnb.mvrx.Async
 import im.vector.app.AppStateHandler
 import im.vector.app.R
@@ -52,6 +53,13 @@ class SpaceRoomListSectionBuilder(
         val onUdpatable: (UpdatableLivePageResult) -> Unit
 ) : RoomListSectionBuilder {
 
+    val pagedListConfig = PagedList.Config.Builder()
+            .setPageSize(10)
+            .setInitialLoadSizeHint(20)
+            .setEnablePlaceholders(true)
+            .setPrefetchDistance(10)
+            .build()
+
     override fun buildSections(mode: RoomListDisplayMode): List<RoomsSection> {
         val sections = mutableListOf<RoomsSection>()
         val activeSpaceAwareQueries = mutableListOf<RoomListViewModel.ActiveSpaceQueryUpdater>()
@@ -322,8 +330,8 @@ class SpaceRoomListSectionBuilder(
                                     }
                                 }
                                 RoomListViewModel.SpaceFilterStrategy.NONE       -> roomQueryParams
-                            }
-
+                            },
+                            pagedListConfig
                     ).also {
                         when (spaceFilterStrategy) {
                             RoomListViewModel.SpaceFilterStrategy.NORMAL     -> {

vector/src/main/res/layout/item_room_placeholder.xml

@@ -0,0 +1,79 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/itemRoomLayout"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:background="?riotx_background"
+    android:clickable="true"
+    android:focusable="true"
+    android:foreground="?attr/selectableItemBackground">
+
+
+    <FrameLayout
+        android:id="@+id/roomAvatarContainer"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="8dp"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent">
+
+        <ImageView
+            android:id="@+id/roomAvatarImageView"
+            android:layout_width="56dp"
+            android:layout_height="56dp"
+            android:importantForAccessibility="no"
+            android:src="@drawable/header_panel_round_background" />
+
+    </FrameLayout>
+
+    <!-- Margin bottom does not work, so I use space -->
+    <Space
+        android:id="@+id/roomAvatarBottomSpace"
+        android:layout_width="0dp"
+        android:layout_height="12dp"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@id/roomAvatarContainer"
+        tools:layout_marginStart="20dp" />
+
+
+    <View
+        android:id="@+id/roomNameView"
+        android:layout_width="wrap_content"
+        android:layout_height="15dp"
+        android:layout_marginStart="@dimen/layout_horizontal_margin"
+        android:layout_marginTop="12dp"
+        android:layout_marginEnd="70dp"
+        android:background="@drawable/rounded_rect_shape_8"
+        app:layout_constrainedWidth="true"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.0"
+        app:layout_constraintHorizontal_chainStyle="packed"
+        app:layout_constraintStart_toEndOf="@id/roomAvatarContainer"
+        app:layout_constraintTop_toTopOf="parent" />
+
+
+    <View
+        android:id="@+id/roomTypingView"
+        android:layout_width="0dp"
+        android:layout_height="30dp"
+        android:layout_marginTop="8dp"
+        android:layout_marginEnd="8dp"
+        android:background="@drawable/rounded_rect_shape_8"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="@+id/roomNameView"
+        app:layout_constraintTop_toBottomOf="@+id/roomNameView" />
+
+
+    <View
+        android:id="@+id/roomDividerView"
+        android:layout_width="0dp"
+        android:layout_height="1dp"
+        android:background="?riotx_header_panel_border_mobile"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>