5 files changed, 47 insertions, 18 deletions

diff --git a/src/chat.cpp b/src/chat.cpp
index 162622abe..d8b577aab 100644
--- a/src/chat.cpp
+++ b/src/chat.cpp
@@ -50,6 +50,8 @@ ChatBuffer::ChatBuffer(u32 scrollback):
 
 void ChatBuffer::addLine(const std::wstring &name, const std::wstring &text)
 {
+	m_lines_modified = true;
+
 	ChatLine line(name, text);
 	m_unformatted.push_back(line);
 
@@ -72,6 +74,7 @@ void ChatBuffer::clear()
 	m_unformatted.clear();
 	m_formatted.clear();
 	m_scroll = 0;
+	m_lines_modified = true;
 }
 
 u32 ChatBuffer::getLineCount() const
@@ -99,14 +102,11 @@ void ChatBuffer::deleteOldest(u32 count)
 	u32 del_unformatted = 0;
 	u32 del_formatted = 0;
 
-	while (count > 0 && del_unformatted < m_unformatted.size())
-	{
+	while (count > 0 && del_unformatted < m_unformatted.size()) {
 		++del_unformatted;
 
 		// keep m_formatted in sync
-		if (del_formatted < m_formatted.size())
-		{
-
+		if (del_formatted < m_formatted.size()) {
 			sanity_check(m_formatted[del_formatted].first);
 			++del_formatted;
 			while (del_formatted < m_formatted.size() &&
@@ -120,6 +120,9 @@ void ChatBuffer::deleteOldest(u32 count)
 	m_unformatted.erase(m_unformatted.begin(), m_unformatted.begin() + del_unformatted);
 	m_formatted.erase(m_formatted.begin(), m_formatted.begin() + del_formatted);
 
+	if (del_unformatted > 0)
+		m_lines_modified = true;
+
 	if (at_bottom)
 		m_scroll = getBottomScrollPos();
 	else
diff --git a/src/chat.h b/src/chat.h
index aabb0821e..696d805eb 100644
--- a/src/chat.h
+++ b/src/chat.h
@@ -113,6 +113,13 @@ public:
 	// Scroll to top of buffer (oldest)
 	void scrollTop();
 
+	// Functions for keeping track of whether the lines were modified by any
+	// preceding operations
+	// If they were not changed, getLineCount() and getLine() output the same as
+	// before
+	bool getLinesModified() const { return m_lines_modified; }
+	void resetLinesModified() { m_lines_modified = false; }
+
 	// Format a chat line for the given number of columns.
 	// Appends the formatted lines to the destination array and
 	// returns the number of formatted lines.
@@ -146,6 +153,11 @@ private:
 	bool m_cache_clickable_chat_weblinks;
 	// Color of clickable chat weblinks
 	irr::video::SColor m_cache_chat_weblink_color;
+
+	// Whether the lines were modified since last markLinesUnchanged()
+	// Is always set to true when m_unformatted is modified, because that's what
+	// determines the output of getLineCount() and getLine()
+	bool m_lines_modified = true;
 };
 
 class ChatPrompt
diff --git a/src/client/game.cpp b/src/client/game.cpp
index a24ded844..6eb09adfa 100644
--- a/src/client/game.cpp
+++ b/src/client/game.cpp
@@ -804,7 +804,7 @@ private:
 		CameraOrientation *cam);
 	void handleClientEvent_CloudParams(ClientEvent *event, CameraOrientation *cam);
 
-	void updateChat(f32 dtime, const v2u32 &screensize);
+	void updateChat(f32 dtime);
 
 	bool nodePlacement(const ItemDefinition &selected_def, const ItemStack &selected_item,
 		const v3s16 &nodepos, const v3s16 &neighbourpos, const PointedThing &pointed,
@@ -2922,7 +2922,7 @@ void Game::processClientEvents(CameraOrientation *cam)
 	}
 }
 
-void Game::updateChat(f32 dtime, const v2u32 &screensize)
+void Game::updateChat(f32 dtime)
 {
 	// Get new messages from error log buffer
 	while (!m_chat_log_buf.empty())
@@ -2938,8 +2938,14 @@ void Game::updateChat(f32 dtime, const v2u32 &screensize)
 	chat_backend->step(dtime);
 
 	// Display all messages in a static text element
-	m_game_ui->setChatText(chat_backend->getRecentChat(),
-		chat_backend->getRecentBuffer().getLineCount());
+	auto &buf = chat_backend->getRecentBuffer();
+	if (buf.getLinesModified()) {
+		buf.resetLinesModified();
+		m_game_ui->setChatText(chat_backend->getRecentChat(), buf.getLineCount());
+	}
+
+	// Make sure that the size is still correct
+	m_game_ui->updateChatSize();
 }
 
 void Game::updateCamera(u32 busy_time, f32 dtime)
@@ -3861,9 +3867,7 @@ void Game::updateFrame(ProfilerGraph *graph, RunStats *stats, f32 dtime,
 		Get chat messages from client
 	*/
 
-	v2u32 screensize = driver->getScreenSize();
-
-	updateChat(dtime, screensize);
+	updateChat(dtime);
 
 	/*
 		Inventory
@@ -3957,6 +3961,8 @@ void Game::updateFrame(ProfilerGraph *graph, RunStats *stats, f32 dtime,
 	/*
 		Profiler graph
 	*/
+	v2u32 screensize = driver->getScreenSize();
+
 	if (m_game_ui->m_flags.show_profiler_graph)
 		graph->draw(10, screensize.Y - 10, driver, g_fontengine->getFont());
 
diff --git a/src/client/gameui.cpp b/src/client/gameui.cpp
index 9b77cf6ff..ecb8e0ec4 100644
--- a/src/client/gameui.cpp
+++ b/src/client/gameui.cpp
@@ -227,7 +227,13 @@ void GameUI::showTranslatedStatusText(const char *str)
 
 void GameUI::setChatText(const EnrichedString &chat_text, u32 recent_chat_count)
 {
+	setStaticText(m_guitext_chat, chat_text);
 
+	m_recent_chat_count = recent_chat_count;
+}
+
+void GameUI::updateChatSize()
+{
 	// Update gui element size and position
 	s32 chat_y = 5;
 
@@ -238,15 +244,15 @@ void GameUI::setChatText(const EnrichedString &chat_text, u32 recent_chat_count)
 
 	const v2u32 &window_size = RenderingEngine::getWindowSize();
 
-	core::rect<s32> chat_size(10, chat_y,
-		window_size.X - 20, 0);
+	core::rect<s32> chat_size(10, chat_y, window_size.X - 20, 0);
 	chat_size.LowerRightCorner.Y = std::min((s32)window_size.Y,
-		m_guitext_chat->getTextHeight() + chat_y);
+			m_guitext_chat->getTextHeight() + chat_y);
 
-	m_guitext_chat->setRelativePosition(chat_size);
-	setStaticText(m_guitext_chat, chat_text);
+	if (chat_size == m_current_chat_size)
+		return;
+	m_current_chat_size = chat_size;
 
-	m_recent_chat_count = recent_chat_count;
+	m_guitext_chat->setRelativePosition(chat_size);
 }
 
 void GameUI::updateProfiler()
diff --git a/src/client/gameui.h b/src/client/gameui.h
index cb460b1c3..2eb2488e6 100644
--- a/src/client/gameui.h
+++ b/src/client/gameui.h
@@ -89,6 +89,7 @@ public:
 		return m_flags.show_chat && m_recent_chat_count != 0 && m_profiler_current_page == 0;
 	}
 	void setChatText(const EnrichedString &chat_text, u32 recent_chat_count);
+	void updateChatSize();
 
 	void updateProfiler();
 
@@ -122,6 +123,7 @@ private:
 
 	gui::IGUIStaticText *m_guitext_chat = nullptr; // Chat text
 	u32 m_recent_chat_count = 0;
+	core::rect<s32> m_current_chat_size{0, 0, 0, 0};
 
 	gui::IGUIStaticText *m_guitext_profiler = nullptr; // Profiler text
 	u8 m_profiler_current_page = 0;