Timeline : scroll to show new message

app/src/main/java/im/vector/riotredesign/core/platform/DefaultListUpdateCallback.kt

@@ -0,0 +1,22 @@
+package im.vector.riotredesign.core.platform
+
+import android.support.v7.util.ListUpdateCallback
+
+interface DefaultListUpdateCallback : ListUpdateCallback {
+
+    override fun onChanged(position: Int, count: Int, tag: Any?) {
+        //no-op
+    }
+
+    override fun onMoved(position: Int, count: Int) {
+        //no-op
+    }
+
+    override fun onInserted(position: Int, count: Int) {
+        //no-op
+    }
+
+    override fun onRemoved(position: Int, count: Int) {
+        //no-op
+    }
+}

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

@@ -33,6 +33,7 @@ class RoomDetailFragment : RiotFragment() {
     private val matrix by inject<Matrix>()
     private val currentSession = matrix.currentSession
     private var roomId by FragmentArgumentDelegate<String>()
+
     private lateinit var timelineEventController: TimelineEventController
     private lateinit var room: Room
 
@@ -59,8 +60,10 @@ class RoomDetailFragment : RiotFragment() {
 
     private fun setupRecyclerView() {
         val layoutManager = LinearLayoutManager(context, LinearLayoutManager.VERTICAL, true)
+        val listUpdateCallback = ScrollOnNewMessageCallback(layoutManager)
         recyclerView.layoutManager = layoutManager
         timelineEventController = TimelineEventController(riotActivity)
+        timelineEventController.addModelBuildListener { it.dispatchTo(listUpdateCallback) }
         recyclerView.setController(timelineEventController)
     }
 
@@ -82,4 +85,4 @@ class RoomDetailFragment : RiotFragment() {
         timelineEventController.requestModelBuild()
     }
 
-}
+}

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

@@ -0,0 +1,14 @@
+package im.vector.riotredesign.features.home.room.detail
+
+import android.support.v7.widget.LinearLayoutManager
+import im.vector.riotredesign.core.platform.DefaultListUpdateCallback
+
+class ScrollOnNewMessageCallback(private val layoutManager: LinearLayoutManager) : DefaultListUpdateCallback {
+
+    override fun onInserted(position: Int, count: Int) {
+        if (layoutManager.findFirstVisibleItemPosition() == 0) {
+            layoutManager.scrollToPosition(0)
+        }
+    }
+
+}