Don't count m.room.member or m.room.reaction events as viewable

include/timeline/TimelineView.h

@@ -150,10 +150,16 @@ private:
         void updateLastSender(const QString &user_id, TimelineDirection direction);
         void notifyForLastEvent();
         void notifyForLastEvent(const TimelineEvent &event);
+
+        TimelineEvent findFirstViewableEvent(const std::vector<TimelineEvent> &events);
+        TimelineEvent findLastViewableEvent(const std::vector<TimelineEvent> &events);
+
         void readLastEvent() const;
         bool isScrollbarActivated() { return scroll_area_->verticalScrollBar()->value() != 0; }
         QString getLastEventId() const;
         QString getEventSender(const mtx::events::collections::TimelineEvents &event) const;
+        mtx::events::EventType getEventType(
+          const mtx::events::collections::TimelineEvents &event) const;
 
         template<class Event, class Widget>
         TimelineItem *processMessageEvent(const Event &event, TimelineDirection direction);

src/timeline/TimelineView.cc

@@ -170,7 +170,7 @@ TimelineView::addBackwardsEvents(const QString &room_id, const mtx::responses::M
         // is the first batch of messages received through /messages
         // i.e there are no other messages currently present.
         if (!topMessages_.empty() && scroll_layout_->count() == 1)
-                notifyForLastEvent(topMessages_.at(0));
+                notifyForLastEvent(findFirstViewableEvent(topMessages_));
 
         if (isVisible()) {
                 renderTopEvents(topMessages_);
@@ -313,7 +313,7 @@ TimelineView::addEvents(const mtx::responses::Timeline &timeline)
                 bottomMessages_.push_back(e);
 
         if (!bottomMessages_.empty())
-                notifyForLastEvent(bottomMessages_[bottomMessages_.size() - 1]);
+                notifyForLastEvent(findLastViewableEvent(bottomMessages_));
 
         // If the current timeline is open and there are messages to be rendered.
         if (isVisible() && !bottomMessages_.empty()) {
@@ -755,3 +755,29 @@ TimelineView::relativeWidget(TimelineItem *item, int dt) const
 
         return isOutOfBounds ? nullptr : scroll_layout_->itemAt(pos)->widget();
 }
+
+TimelineEvent
+TimelineView::findFirstViewableEvent(const std::vector<TimelineEvent> &events)
+{
+        auto it = std::find_if(events.begin(), events.end(), [this](const auto &event) {
+                return mtx::events::EventType::RoomMessage == getEventType(event);
+        });
+
+        return (it == std::end(events)) ? events.front() : *it;
+}
+
+TimelineEvent
+TimelineView::findLastViewableEvent(const std::vector<TimelineEvent> &events)
+{
+        auto it = std::find_if(events.rbegin(), events.rend(), [this](const auto &event) {
+                return mtx::events::EventType::RoomMessage == getEventType(event);
+        });
+
+        return (it == std::rend(events)) ? events.back() : *it;
+}
+
+inline mtx::events::EventType
+TimelineView::getEventType(const mtx::events::collections::TimelineEvents &event) const
+{
+        return mpark::visit([](auto msg) { return msg.type; }, event);
+}