Reduce timeline flickering

include/TimelineView.h

@@ -143,7 +143,6 @@ private:
         bool isInitialized      = false;
         bool isTimelineFinished = false;
         bool isInitialSync      = true;
-        bool isPaginationScrollPending_ = false;
 
         const int SCROLL_BAR_GAP = 400;
 

src/TimelineView.cc

@@ -85,9 +85,6 @@ TimelineView::sliderRangeChanged(int min, int max)
         if (max - scroll_area_->verticalScrollBar()->value() < SCROLL_BAR_GAP)
                 scroll_area_->verticalScrollBar()->setValue(max);
 
-        if (isPaginationScrollPending_) {
-                isPaginationScrollPending_ = false;
-
         int currentHeight = scroll_widget_->size().height();
         int diff          = currentHeight - oldHeight_;
         int newPosition   = oldPosition_ + diff;
@@ -98,7 +95,6 @@ TimelineView::sliderRangeChanged(int min, int max)
 
         scroll_area_->verticalScrollBar()->setValue(newPosition);
 }
-}
 
 void
 TimelineView::fetchHistory()
@@ -173,6 +169,9 @@ TimelineView::addBackwardsEvents(const QString &room_id, const RoomMessages &msg
         isTimelineFinished = false;
         QList<TimelineItem *> items;
 
+        scroll_widget_->adjustSize();
+        scroll_widget_->update();
+
         // Parse in reverse order to determine where we should not show sender's
         // name.
         auto ii = msgs.chunk().size();
@@ -197,7 +196,6 @@ TimelineView::addBackwardsEvents(const QString &room_id, const RoomMessages &msg
 
         prev_batch_token_       = msgs.end();
         isPaginationInProgress_ = false;
-        isPaginationScrollPending_ = true;
 
         // Exclude the top stretch.
         if (!msgs.chunk().isEmpty() && scroll_layout_->count() > 1)
@@ -465,6 +463,9 @@ TimelineView::addTimelineItem(TimelineItem *item, TimelineDirection direction)
                 scroll_layout_->addWidget(item);
         else
                 scroll_layout_->insertWidget(1, item);
+
+        scroll_widget_->adjustSize();
+        scroll_widget_->update();
 }
 
 void
@@ -488,6 +489,9 @@ TimelineView::addUserMessage(matrix::events::MessageEventType ty, const QString
         TimelineItem *view_item = new TimelineItem(ty, user_id, body, with_sender, scroll_widget_);
         scroll_layout_->addWidget(view_item);
 
+        scroll_widget_->adjustSize();
+        scroll_widget_->update();
+
         lastSender_ = user_id;
 
         PendingMessage message(txn_id, body, "", view_item);
@@ -506,6 +510,9 @@ TimelineView::addUserMessage(const QString &url, const QString &filename, int tx
         TimelineItem *view_item = new TimelineItem(image, user_id, with_sender, scroll_widget_);
         scroll_layout_->addWidget(view_item);
 
+        scroll_widget_->adjustSize();
+        scroll_widget_->update();
+
         lastSender_ = user_id;
 
         PendingMessage message(txn_id, url, "", view_item);