From d31583dc2dcbc42403a34bb7e9acbcb7db87ed09 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lukas=20Br=C3=BCbach?= <Bruebach.Lukas@bdosecurity.de>
Date: Wed, 12 Aug 2026 01:16:14 +0200
Subject: [PATCH] Implement stick-to-bottom flag

---
 .../widgets/server/chat_view/chat_view.cpp    | 31 ++++++++++++++-----
 .../widgets/server/chat_view/chat_view.h      |  4 ++-
 2 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/cockatrice/src/interface/widgets/server/chat_view/chat_view.cpp b/cockatrice/src/interface/widgets/server/chat_view/chat_view.cpp
index 64812b4a4..5b567e77e 100644
--- a/cockatrice/src/interface/widgets/server/chat_view/chat_view.cpp
+++ b/cockatrice/src/interface/widgets/server/chat_view/chat_view.cpp
@@ -51,6 +51,9 @@ ChatView::ChatView(TabSupervisor *_tabSupervisor, AbstractGame *_game, bool _sho
     setTextInteractionFlags(Qt::TextSelectableByMouse | Qt::LinksAccessibleByMouse);
     setOpenLinks(false);
     connect(this, &ChatView::anchorClicked, this, &ChatView::openLink);
+
+    connect(verticalScrollBar(), &QScrollBar::rangeChanged, this, &ChatView::onScrollBarRangeChanged);
+    connect(verticalScrollBar(), &QScrollBar::valueChanged, this, &ChatView::onScrollBarValueChanged);
 }
 
 void ChatView::adjustColorsToPalette()
@@ -149,7 +152,7 @@ void ChatView::appendHtml(const QString &html)
     bool atBottom = verticalScrollBar()->value() >= verticalScrollBar()->maximum();
     prepareBlock().insertHtml(html);
     if (atBottom) {
-        verticalScrollBar()->setValue(verticalScrollBar()->maximum());
+        scrollToBottom();
     }
 }
 
@@ -167,7 +170,7 @@ void ChatView::appendHtmlServerMessage(const QString &html, bool optionalIsBold,
 
     prepareBlock().insertHtml(htmlText);
     if (atBottom) {
-        verticalScrollBar()->setValue(verticalScrollBar()->maximum());
+        scrollToBottom();
     }
 }
 
@@ -327,6 +330,8 @@ void ChatView::appendMessage(QString message,
         }
     }
 
+    // ChatHistory messages are only ever sent once per room, right after joining, before the user can
+    // interact with the view. Always scroll to the bottom so the whole history is visible on join.
     if (atBottom || messageType.testFlag(Event_RoomSay::ChatHistory)) {
         scrollToBottom();
     }
@@ -334,14 +339,24 @@ void ChatView::appendMessage(QString message,
 
 void ChatView::scrollToBottom()
 {
+    // The document layout, and therefore the scrollbar range, may be updated asynchronously (e.g. while
+    // the chat history is loaded into a view that has not been laid out yet). Setting the value once is
+    // not enough: keep stickToBottom set so any later range change scrolls to the new maximum as well.
+    stickToBottom = true;
     verticalScrollBar()->setValue(verticalScrollBar()->maximum());
+}
 
-    if (!scrollToBottomPending) {
-        scrollToBottomPending = true;
-        QTimer::singleShot(0, this, [this] {
-            scrollToBottomPending = false;
-            verticalScrollBar()->setValue(verticalScrollBar()->maximum());
-        });
+void ChatView::onScrollBarRangeChanged()
+{
+    if (stickToBottom) {
+        verticalScrollBar()->setValue(verticalScrollBar()->maximum());
+    }
+}
+
+void ChatView::onScrollBarValueChanged(int value)
+{
+    if (value < verticalScrollBar()->maximum()) {
+        stickToBottom = false;
     }
 }
 
diff --git a/cockatrice/src/interface/widgets/server/chat_view/chat_view.h b/cockatrice/src/interface/widgets/server/chat_view/chat_view.h
index 447bb33aa..e722ab1c1 100644
--- a/cockatrice/src/interface/widgets/server/chat_view/chat_view.h
+++ b/cockatrice/src/interface/widgets/server/chat_view/chat_view.h
@@ -60,7 +60,7 @@ private:
     QStringList highlightedWords;
     bool evenNumber;
     bool showTimestamps;
-    bool scrollToBottomPending = false;
+    bool stickToBottom = false;
     HoveredItemType hoveredItemType;
     QString hoveredContent;
     QAction *messageClicked;
@@ -89,6 +89,8 @@ private slots:
     void actMessageClicked();
     void adjustColorsToPalette();
     void refreshBlockColors();
+    void onScrollBarRangeChanged();
+    void onScrollBarValueChanged(int value);
 
 public:
     ChatView(TabSupervisor *_tabSupervisor, AbstractGame *_game, bool _showTimestamps, QWidget *parent = nullptr);