call "readMessage" when the latest item is shown.

app/src/main/java/chat/rocket/android/fragment/chatroom/RoomFragment.java

@@ -28,6 +28,7 @@ import chat.rocket.android.helper.LoadMoreScrollListener;
 import chat.rocket.android.helper.LogcatIfError;
 import chat.rocket.android.helper.OnBackPressListener;
 import chat.rocket.android.helper.RecyclerViewAutoScrollManager;
+import chat.rocket.android.helper.RecyclerViewScrolledToBottomListener;
 import chat.rocket.android.helper.TextUtils;
 import chat.rocket.android.layouthelper.chatroom.MessageFormManager;
 import chat.rocket.android.layouthelper.chatroom.MessageListAdapter;
@@ -157,6 +158,8 @@ public class RoomFragment extends AbstractChatRoomFragment
       }
     };
     listView.addOnScrollListener(scrollListener);
+    listView.addOnScrollListener(
+        new RecyclerViewScrolledToBottomListener(layoutManager, 1, this::markAsReadIfNeeded));
 
     setupSideMenu();
     setupMessageComposer();

app/src/main/java/chat/rocket/android/helper/RecyclerViewScrolledToBottomListener.java

+package chat.rocket.android.helper;
+
+import android.os.Handler;
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+
+/**
+ * ScrollListener for detecting scrolled on the bottom of the RecyclerView.
+ */
+public class RecyclerViewScrolledToBottomListener extends RecyclerView.OnScrollListener {
+
+  /**
+   * callback.
+   */
+  public interface Callback {
+    void onScrolledToBottom();
+  }
+
+  private final LinearLayoutManager layoutManager;
+  private final int thresholdPosition;
+  private final Handler handler;
+  private final Callback callback;
+
+  /**
+   * Trigger callback if the bottom item position > thresholdPosition.
+   */
+  public RecyclerViewScrolledToBottomListener(LinearLayoutManager layoutManager,
+                                              int thresholdPosition, Callback callback) {
+    this.layoutManager = layoutManager;
+    this.thresholdPosition = thresholdPosition;
+    this.callback = callback;
+
+    this.handler = new Handler() {
+      @Override
+      public void handleMessage(android.os.Message msg) {
+        onScrollEnd();
+      }
+    };
+  }
+
+
+  @Override
+  public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
+    super.onScrolled(recyclerView, dx, dy);
+    handler.removeMessages(0);
+    handler.sendEmptyMessageDelayed(0, 120);
+  }
+
+  private void onScrollEnd() {
+    if (layoutManager.getReverseLayout()) {
+      if (layoutManager.findFirstVisibleItemPosition() <= thresholdPosition) {
+        doCallback();
+      }
+    } else {
+      if (layoutManager.findLastVisibleItemPosition() >= thresholdPosition) {
+        doCallback();
+      }
+    }
+  }
+
+  private void doCallback() {
+    if (callback != null) {
+      callback.onScrolledToBottom();
+    }
+  }
+}
+