fix(chatlog): fix stick to bottom behavior

This commit fixes the behavior when a message is received while the
chatlog is scrolled to the bottom. With this change, the chatlog will
stick to the bottom when it is scrolled all the way down. If it is
somewhere in the middle (e.g. for search) the chatlog will not change
its position.

src/chatlog/chatlog.cpp

@@ -407,10 +407,9 @@ void ChatLog::insertChatlineAtBottom(const QList<ChatLine::Ptr>& newLines)
 
     layout(lines.last()->getRow(), lines.size(), useableWidth());
 
-    if (visibleLines.size() > 1) {
-        startResizeWorker(visibleLines[1]);
-    } else {
-        startResizeWorker();
+    // redo layout only when scrolled down
+    if(stickToBottom()) {
+        startResizeWorker(true);
     }
 }
 
@@ -463,9 +462,9 @@ void ChatLog::insertChatlinesOnTop(const QList<ChatLine::Ptr>& newLines)
 
     // redo layout
     if (visibleLines.size() > 1) {
-        startResizeWorker(visibleLines[1]);
+        startResizeWorker(stickToBottom(), visibleLines[1]);
     } else {
-        startResizeWorker();
+        startResizeWorker(stickToBottom());
     }
 
 }
@@ -481,7 +480,7 @@ void ChatLog::scrollToBottom()
     verticalScrollBar()->setValue(verticalScrollBar()->maximum());
 }
 
-void ChatLog::startResizeWorker(ChatLine::Ptr anchorLine)
+void ChatLog::startResizeWorker(bool stick, ChatLine::Ptr anchorLine)
 {
     if (lines.empty()) {
         isScroll = true;
@@ -491,11 +490,11 @@ void ChatLog::startResizeWorker(ChatLine::Ptr anchorLine)
     // (re)start the worker
     if (!workerTimer->isActive()) {
         // these values must not be reevaluated while the worker is running
-        if (anchorLine) {
-            workerAnchorLine = anchorLine;
-            workerStb = false;
+        workerStb = stick;
+        if (stick) {
+            workerAnchorLine = ChatLine::Ptr();
         } else {
-            workerStb = stickToBottom();
+            workerAnchorLine = anchorLine;
         }
     }
 
@@ -765,7 +764,7 @@ int ChatLog::getNumRemove() const
 
 void ChatLog::forceRelayout()
 {
-    startResizeWorker();
+    startResizeWorker(stickToBottom());
 }
 
 void ChatLog::checkVisibility(bool causedWheelEvent)
@@ -834,7 +833,7 @@ void ChatLog::resizeEvent(QResizeEvent* ev)
     bool stb = stickToBottom();
 
     if (ev->size().width() != ev->oldSize().width()) {
-        startResizeWorker();
+        startResizeWorker(stb);
         stb = false; // let the resize worker handle it
     }
 
@@ -901,8 +900,9 @@ QRectF ChatLog::calculateSceneRect() const
 {
     qreal bottom = (lines.empty() ? 0.0 : lines.last()->sceneBoundingRect().bottom());
 
-    if (typingNotification.get() != nullptr)
+    if (typingNotification.get() != nullptr) {
         bottom += typingNotification->sceneBoundingRect().height() + lineSpacing;
+    }
 
     return QRectF(-margins.left(), -margins.top(), useableWidth(),
                   bottom + margins.bottom() + margins.top());

src/chatlog/chatlog.h

@@ -105,7 +105,7 @@ protected:
     void updateSceneRect();
     void checkVisibility(bool causedWheelEvent = false);
     void scrollToBottom();
-    void startResizeWorker(ChatLine::Ptr anchorLine = nullptr);
+    void startResizeWorker(bool stick, ChatLine::Ptr anchorLine = nullptr);
 
     virtual void mouseDoubleClickEvent(QMouseEvent* ev) final override;
     virtual void mousePressEvent(QMouseEvent* ev) final override;