Add fallback support rendering proposed in MSC3676

matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/session/room/model/relation/RelationContent.kt

@@ -26,8 +26,8 @@ interface RelationContent {
     val option: Int?
 
     /**
-     * This flag indicates that the message should be displayed in the main
-     * timeline as a reply if needed
+     * This flag indicates that the message should be rendered as a reply
+     * fallback, when isFallingBack = false
      */
     val isFallingBack: Boolean?
 }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/send/LocalEchoEventFactory.kt

@@ -355,6 +355,7 @@ internal class LocalEchoEventFactory @Inject constructor(
                     RelationDefaultContent(
                             type = RelationType.THREAD,
                             eventId = it,
+                            isFallingBack = true,
                             inReplyTo = ReplyToContent(eventId = localEchoRepository.getLatestThreadEvent(it))
                     )
                 }
@@ -398,6 +399,7 @@ internal class LocalEchoEventFactory @Inject constructor(
                     RelationDefaultContent(
                             type = RelationType.THREAD,
                             eventId = it,
+                            isFallingBack = true,
                             inReplyTo = ReplyToContent(eventId = localEchoRepository.getLatestThreadEvent(it))
                     )
                 }
@@ -428,6 +430,7 @@ internal class LocalEchoEventFactory @Inject constructor(
                     RelationDefaultContent(
                             type = RelationType.THREAD,
                             eventId = it,
+                            isFallingBack = true,
                             inReplyTo = ReplyToContent(eventId = localEchoRepository.getLatestThreadEvent(it))
                     )
                 }
@@ -448,6 +451,7 @@ internal class LocalEchoEventFactory @Inject constructor(
                     RelationDefaultContent(
                             type = RelationType.THREAD,
                             eventId = it,
+                            isFallingBack = true,
                             inReplyTo = ReplyToContent(eventId = localEchoRepository.getLatestThreadEvent(it))
                     )
                 }

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/sync/handler/room/ThreadsAwarenessHandler.kt

@@ -162,7 +162,7 @@ internal class ThreadsAwarenessHandler @Inject constructor(
                              eventEntity: EventEntity? = null): String? {
         event ?: return null
         roomId ?: return null
-        if (lightweightSettingsStorage.areThreadMessagesEnabled()) return null
+        if (lightweightSettingsStorage.areThreadMessagesEnabled() && !isReplyEvent(event)) return null
         handleRootThreadEventsIfNeeded(realm, roomId, eventEntity, event)
         if (!isThreadEvent(event)) return null
         val eventPayload = if (!event.isEncrypted()) {
@@ -387,6 +387,16 @@ internal class ThreadsAwarenessHandler @Inject constructor(
     private fun getPreviousEventOrRoot(event: Event): String? =
             event.content.toModel<MessageRelationContent>()?.relatesTo?.inReplyTo?.eventId
 
+    /**
+     * Returns if we should html inject the current event.
+     */
+    private fun isReplyEvent(event: Event): Boolean {
+        return isThreadEvent(event) && !isFallingBack(event) && getPreviousEventOrRoot(event) != null
+    }
+
+    private fun isFallingBack(event: Event): Boolean =
+            event.content.toModel<MessageRelationContent>()?.relatesTo?.isFallingBack == true
+
     @Suppress("UNCHECKED_CAST")
     private fun getValueFromPayload(payload: JsonDict?, key: String): String? {
         val content = payload?.get("content") as? JsonDict

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

@@ -506,7 +506,10 @@ class TimelineViewModel @AssistedInject constructor(
 
     private fun handleSendSticker(action: RoomDetailAction.SendSticker) {
         val content = initialState.rootThreadEventId?.let {
-            action.stickerContent.copy(relatesTo = RelationDefaultContent(RelationType.THREAD, it))
+            action.stickerContent.copy(relatesTo = RelationDefaultContent(
+                    type = RelationType.THREAD,
+                    isFallingBack = true,
+                    eventId = it))
         } ?: action.stickerContent
 
         room.sendEvent(EventType.STICKER, content.toContent())

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

@@ -40,7 +40,8 @@
         android:id="@+id/additionalTopSpace"
         android:layout_height="12dp"
         android:layout_width="0dp"
-        android:layout_toEndOf="@id/messageStartGuideline" />
+        android:layout_toEndOf="@id/messageStartGuideline"
+        tools:ignore="MissingConstraints" />
 
     <TextView
         android:id="@+id/messageTimeView"