Add a ZeroItem to avoid automatic scroll when the breadcrumbs are updated from another client

vector/src/main/java/im/vector/riotx/core/epoxy/ZeroItem.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2019 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.riotx.core.epoxy
+
+import com.airbnb.epoxy.EpoxyModelClass
+import im.vector.riotx.R
+
+/**
+ * Item of size (0, 0).
+ * It can be useful to avoid automatic scroll of RecyclerView with Epoxy controller, when the first valuable item changes.
+ */
+@EpoxyModelClass(layout = R.layout.item_zero)
+abstract class ZeroItem : VectorEpoxyModel<ZeroItem.Holder>() {
+
+    class Holder : VectorEpoxyHolder()
+}

vector/src/main/java/im/vector/riotx/features/home/room/breadcrumbs/BreadcrumbsController.kt

@@ -19,6 +19,7 @@ package im.vector.riotx.features.home.room.breadcrumbs
 import android.view.View
 import com.airbnb.epoxy.EpoxyController
 import im.vector.matrix.android.api.util.toMatrixItem
+import im.vector.riotx.core.epoxy.zeroItem
 import im.vector.riotx.core.utils.DebouncedClickListener
 import im.vector.riotx.features.home.AvatarRenderer
 import javax.inject.Inject
@@ -45,9 +46,13 @@ class BreadcrumbsController @Inject constructor(
     override fun buildModels() {
         val safeViewState = viewState ?: return
 
+        // Add a ZeroItem to avoid automatic scroll when the breadcrumbs are updated from another client
+        zeroItem {
+            id("top")
+        }
+
         // An empty breadcrumbs list can only be temporary because when entering in a room,
         // this one is added to the breadcrumbs
-
         safeViewState.asyncBreadcrumbs.invoke()
                 ?.forEach {
                     breadcrumbsItem {

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

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<View xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="0dp"
+    android:layout_height="0dp" />