Timeline: try playing with EmptyItem to fix some scroll issues

vector/src/main/java/im/vector/app/core/epoxy/TimelineEmptyItem.kt

@@ -16,6 +16,7 @@
 
 package im.vector.app.core.epoxy
 
+import androidx.core.view.updateLayoutParams
 import com.airbnb.epoxy.EpoxyAttribute
 import com.airbnb.epoxy.EpoxyModelClass
 import im.vector.app.R
@@ -25,6 +26,14 @@ import im.vector.app.features.home.room.detail.timeline.item.ItemWithEvents
 abstract class TimelineEmptyItem : VectorEpoxyModel<TimelineEmptyItem.Holder>(), ItemWithEvents {
 
     @EpoxyAttribute lateinit var eventId: String
+    @EpoxyAttribute var hidden: Boolean = true
+
+    override fun bind(holder: Holder) {
+        super.bind(holder)
+        holder.view.updateLayoutParams {
+            this.height = if (hidden) 0 else 1
+        }
+    }
 
     override fun getEventIds(): List<String> {
         return listOf(eventId)

vector/src/main/java/im/vector/app/features/home/room/detail/JumpToBottomViewVisibilityManager.kt

@@ -66,7 +66,7 @@ class JumpToBottomViewVisibilityManager(
     }
 
     private fun maybeShowJumpToBottomViewVisibility() {
-        if (layoutManager.findFirstVisibleItemPosition() != 0) {
+        if (layoutManager.findFirstVisibleItemPosition() > 1) {
             jumpToBottomView.show()
         } else {
             jumpToBottomView.hide()

vector/src/main/java/im/vector/app/features/home/room/detail/RoomDetailAction.kt

@@ -24,7 +24,6 @@ import org.matrix.android.sdk.api.session.events.model.Event
 import org.matrix.android.sdk.api.session.room.model.message.MessageStickerContent
 import org.matrix.android.sdk.api.session.room.model.message.MessageWithAttachmentContent
 import org.matrix.android.sdk.api.session.room.timeline.Timeline
-import org.matrix.android.sdk.api.session.room.timeline.TimelineEvent
 import org.matrix.android.sdk.api.session.widgets.model.Widget
 import org.matrix.android.sdk.api.util.MatrixItem
 
@@ -34,8 +33,8 @@ sealed class RoomDetailAction : VectorViewModelAction {
     data class SendSticker(val stickerContent: MessageStickerContent) : RoomDetailAction()
     data class SendMessage(val text: CharSequence, val autoMarkdown: Boolean) : RoomDetailAction()
     data class SendMedia(val attachments: List<ContentAttachmentData>, val compressBeforeSending: Boolean) : RoomDetailAction()
-    data class TimelineEventTurnsVisible(val event: TimelineEvent) : RoomDetailAction()
-    data class TimelineEventTurnsInvisible(val event: TimelineEvent) : RoomDetailAction()
+    data class TimelineEventTurnsVisible(val eventId: String) : RoomDetailAction()
+    data class TimelineEventTurnsInvisible(val eventId: String) : RoomDetailAction()
     data class LoadMoreTimelineEvents(val direction: Timeline.Direction) : RoomDetailAction()
     data class SendReaction(val targetEventId: String, val reaction: String) : RoomDetailAction()
     data class UndoReaction(val targetEventId: String, val reaction: String, val reason: String? = "") : RoomDetailAction()

vector/src/main/java/im/vector/app/features/home/room/detail/RoomDetailFragment.kt

@@ -1454,12 +1454,12 @@ class RoomDetailFragment @Inject constructor(
         return true
     }
 
-    override fun onEventVisible(event: TimelineEvent) {
-        roomDetailViewModel.handle(RoomDetailAction.TimelineEventTurnsVisible(event))
+    override fun onEventVisible(eventId: String) {
+        roomDetailViewModel.handle(RoomDetailAction.TimelineEventTurnsVisible(eventId))
     }
 
-    override fun onEventInvisible(event: TimelineEvent) {
-        roomDetailViewModel.handle(RoomDetailAction.TimelineEventTurnsInvisible(event))
+    override fun onEventInvisible(eventId: String) {
+        roomDetailViewModel.handle(RoomDetailAction.TimelineEventTurnsInvisible(eventId))
     }
 
     override fun onEncryptedMessageClicked(informationData: MessageInformationData, view: View) {

vector/src/main/java/im/vector/app/features/home/room/detail/RoomDetailViewModel.kt

@@ -1022,19 +1022,19 @@ class RoomDetailViewModel @AssistedInject constructor(
 
     private fun handleEventVisible(action: RoomDetailAction.TimelineEventTurnsVisible) {
         viewModelScope.launch(Dispatchers.Default) {
-            if (action.event.root.sendState.isSent()) { // ignore pending/local events
+            val event = timeline.getTimelineEventWithId(action.eventId) ?: return@launch
+            if (event.root.sendState.isSent()) { // ignore pending/local events
                 visibleEventsObservable.accept(action)
             }
             // We need to update this with the related m.replace also (to move read receipt)
-            action.event.annotations?.editSummary?.sourceEvents?.forEach {
+            event.annotations?.editSummary?.sourceEvents?.forEach {
                 room.getTimeLineEvent(it)?.let { event ->
-                    visibleEventsObservable.accept(RoomDetailAction.TimelineEventTurnsVisible(event))
+                    visibleEventsObservable.accept(RoomDetailAction.TimelineEventTurnsVisible(event.eventId))
                 }
             }
-
             // handle chat effects here
             if (vectorPreferences.chatEffectsEnabled()) {
-                chatEffectManager.checkForEffect(action.event)
+                chatEffectManager.checkForEffect(event)
             }
         }
     }
@@ -1194,7 +1194,9 @@ class RoomDetailViewModel @AssistedInject constructor(
                 .buffer(1, TimeUnit.SECONDS)
                 .filter { it.isNotEmpty() }
                 .subscribeBy(onNext = { actions ->
-                    val bufferedMostRecentDisplayedEvent = actions.maxByOrNull { it.event.displayIndex }?.event ?: return@subscribeBy
+                    val bufferedMostRecentDisplayedEvent = actions
+                            .mapNotNull { timeline.getTimelineEventWithId(it.eventId) }
+                            .maxByOrNull { it.displayIndex } ?: return@subscribeBy
                     val globalMostRecentDisplayedEvent = mostRecentDisplayedEvent
                     if (trackUnreadMessages.get()) {
                         if (globalMostRecentDisplayedEvent == null) {

vector/src/main/java/im/vector/app/features/home/room/detail/ScrollOnNewMessageCallback.kt

@@ -43,7 +43,6 @@ class ScrollOnNewMessageCallback(private val layoutManager: LinearLayoutManager,
             layoutManager.scrollToPosition(position)
             return
         }
-        Timber.v("On inserted $count count at position: $position")
         if (layoutManager.findFirstVisibleItemPosition() != position) {
             return
         }
@@ -51,11 +50,10 @@ class ScrollOnNewMessageCallback(private val layoutManager: LinearLayoutManager,
         val firstNewItemIds = firstNewItem.getEventIds().firstOrNull() ?: return
         val indexOfFirstNewItem = newTimelineEventIds.indexOf(firstNewItemIds)
         if (indexOfFirstNewItem != -1) {
-            Timber.v("Should scroll to position: $position")
             repeat(newTimelineEventIds.size - indexOfFirstNewItem) {
                 newTimelineEventIds.removeAt(indexOfFirstNewItem)
             }
-            layoutManager.scrollToPosition(position)
+            layoutManager.scrollToPosition(0)
         }
     }
 }

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/TimelineEventController.kt

@@ -85,8 +85,8 @@ class TimelineEventController @Inject constructor(private val dateFormatter: Vec
             ReadReceiptsCallback,
             PreviewUrlCallback {
         fun onLoadMore(direction: Timeline.Direction)
-        fun onEventInvisible(event: TimelineEvent)
-        fun onEventVisible(event: TimelineEvent)
+        fun onEventInvisible(eventId: String)
+        fun onEventVisible(eventId: String)
         fun onRoomCreateLinkClicked(url: String)
         fun onEncryptedMessageClicked(informationData: MessageInformationData, view: View)
         fun onImageMessageClicked(messageImageContent: MessageImageInfoContent, mediaData: ImageContentRenderer.Data, view: View)
@@ -144,7 +144,6 @@ class TimelineEventController @Inject constructor(private val dateFormatter: Vec
     private var unreadState: UnreadState = UnreadState.Unknown
     private var positionOfReadMarker: Int? = null
     private var eventIdToHighlight: String? = null
-    private var previousModelsSize = 0
 
     var callback: Callback? = null
     var timeline: Timeline? = null
@@ -341,7 +340,7 @@ class TimelineEventController @Inject constructor(private val dateFormatter: Vec
         updateUTDStates(event, nextEvent)
         val eventModel = timelineItemFactory.create(event, nextEvent, eventIdToHighlight, callback).also {
             it.id(event.localId)
-            it.setOnVisibilityStateChanged(TimelineEventVisibilityStateChangedListener(callback, event))
+            it.setOnVisibilityStateChanged(TimelineEventVisibilityStateChangedListener(callback, event.eventId))
         }
         val addDaySeparator = if (hasReachedInvite && hasUTD) {
             true

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/helper/TimelineControllerInterceptorHelper.kt

@@ -19,6 +19,7 @@ package im.vector.app.features.home.room.detail.timeline.helper
 import com.airbnb.epoxy.EpoxyModel
 import com.airbnb.epoxy.VisibilityState
 import im.vector.app.core.epoxy.LoadingItem_
+import im.vector.app.core.epoxy.TimelineEmptyItem
 import im.vector.app.core.epoxy.TimelineEmptyItem_
 import im.vector.app.features.call.webrtc.WebRtcCallManager
 import im.vector.app.features.home.room.detail.UnreadState
@@ -59,12 +60,27 @@ class TimelineControllerInterceptorHelper(private val positionOfReadMarker: KMut
         val showHiddenEvents = vectorPreferences.shouldShowHiddenEvents()
         var index = 0
         val firstUnreadEventId = (unreadState as? UnreadState.HasUnread)?.firstUnreadEventId
+        var prevWasHidden = false
+        var onlyHidden = true
         // Then iterate on models so we have the exact positions in the adapter
         modelsIterator.forEach { epoxyModel ->
+            if (epoxyModel is TimelineEmptyItem && !prevWasHidden) {
+                prevWasHidden = true
+                modelsIterator.remove()
+                val emptyItem = TimelineEmptyItem_()
+                        .id("not_hidden_${epoxyModel.id()}")
+                        .eventId(epoxyModel.eventId)
+                        .hidden(false)
+                        .setOnVisibilityStateChanged(TimelineEventVisibilityStateChangedListener(callback, epoxyModel.eventId))
+                modelsIterator.add(emptyItem)
+            } else if (epoxyModel !is TimelineEmptyItem) {
+                onlyHidden = false
+                prevWasHidden = false
+            }
             if (epoxyModel is ItemWithEvents) {
                 epoxyModel.getEventIds().forEach { eventId ->
                     adapterPositionMapping[eventId] = index
-                    if (eventId == firstUnreadEventId) {
+                    if (eventId == firstUnreadEventId && !onlyHidden) {
                         modelsIterator.addReadMarkerItem(callback)
                         index++
                         positionOfReadMarker.set(index)
@@ -88,6 +104,7 @@ class TimelineControllerInterceptorHelper(private val positionOfReadMarker: KMut
         add(readMarker)
         // Use next as we still have some process to do before the next iterator loop
         next()
+        previous()
     }
 
     private fun MutableListIterator<EpoxyModel<*>>.removeCallItemIfNeeded(
@@ -105,6 +122,7 @@ class TimelineControllerInterceptorHelper(private val positionOfReadMarker: KMut
             val emptyItem = TimelineEmptyItem_()
                     .id(epoxyModel.id())
                     .eventId(epoxyModel.attributes.informationData.eventId)
+                    .hidden(false)
             add(emptyItem)
         }
         callIds.add(callId)

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/helper/TimelineVisibilityStateChangedListeners.kt

@@ -32,14 +32,14 @@ class ReadMarkerVisibilityStateChangedListener(private val callback: TimelineEve
 }
 
 class TimelineEventVisibilityStateChangedListener(private val callback: TimelineEventController.Callback?,
-                                                  private val event: TimelineEvent)
+                                                  private val eventId: String)
     : VectorEpoxyModel.OnVisibilityStateChangedListener {
 
     override fun onVisibilityStateChanged(visibilityState: Int) {
         if (visibilityState == VisibilityState.VISIBLE) {
-            callback?.onEventVisible(event)
+            callback?.onEventVisible(eventId)
         } else if (visibilityState == VisibilityState.INVISIBLE) {
-            callback?.onEventInvisible(event)
+            callback?.onEventInvisible(eventId)
         }
     }
 }
@@ -50,9 +50,9 @@ class MergedTimelineEventVisibilityStateChangedListener(private val callback: Ti
 
     override fun onVisibilityStateChanged(visibilityState: Int) {
         if (visibilityState == VisibilityState.VISIBLE) {
-            events.forEach { callback?.onEventVisible(it) }
+            events.forEach { callback?.onEventVisible(it.eventId) }
         } else if (visibilityState == VisibilityState.INVISIBLE) {
-            events.forEach { callback?.onEventInvisible(it) }
+            events.forEach { callback?.onEventInvisible(it.eventId) }
         }
     }
 }

vector/src/main/java/im/vector/app/features/home/room/detail/timeline/item/BlankItem.kt

@@ -1,26 +0,0 @@
-/*
- * 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.app.features.home.room.detail.timeline.item
-
-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_timeline_event_blank_stub)
-abstract class BlankItem : VectorEpoxyModel<BlankItem.BlankHolder>() {
-    class BlankHolder : VectorEpoxyHolder()
-}

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

@@ -3,7 +3,6 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    android:background="?riotx_background"
     android:padding="8dp">
 
     <View
@@ -12,16 +11,15 @@
         android:layout_gravity="center_vertical"
         android:layout_marginStart="8dp"
         android:layout_marginEnd="8dp"
-        android:background="?riotx_header_panel_background" />
+        android:background="?riotx_list_bottom_sheet_divider_color" />
 
     <TextView
         android:id="@+id/itemDayTextView"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_gravity="center"
-        android:background="?riotx_background"
-        android:paddingStart="32dp"
-        android:paddingEnd="32dp"
+        android:background="?android:attr/windowBackground"
+        android:paddingHorizontal="24dp"
         android:textColor="?riotx_header_panel_text_secondary"
         android:textSize="15sp"
         tools:text="@tools:sample/date/day_of_week" />

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

@@ -2,7 +2,6 @@
 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    android:background="?riotx_background"
     android:padding="8dp">
 
     <View
@@ -17,10 +16,9 @@
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_gravity="center"
-        android:background="?riotx_background"
+        android:background="?android:attr/windowBackground"
         android:fontFamily="sans-serif-medium"
-        android:paddingStart="8dp"
-        android:paddingEnd="8dp"
+        android:paddingHorizontal="16dp"
         android:text="@string/timeline_unread_messages"
         android:textColor="@color/notification_accent_color"
         android:textSize="15sp" />