Add pregame timer support

LuaRules/Gadgets/start_pregame_timer.lua

@@ -0,0 +1,68 @@
+function gadget:GetInfo()
+	return {
+		name      = "Pregame Timer",
+		desc      = "Listens to server pregame timekeeping messages",
+		author    = "Sprung",
+		date      = "2024",
+		license   = "Public Domain",
+		layer     = 0,
+		enabled   = true,
+	}
+end
+
+if gadgetHandler:IsSyncedCode() then
+
+	function gadget:Initialize()
+		if Spring.GetGameFrame() > 0 then
+			gadgetHandler:RemoveGadget()
+			return
+		end
+	end
+
+	function gadget:GameStart()
+		Spring.SetGameRulesParam("pregame_timer_seconds", nil)
+		gadgetHandler:RemoveGadget()
+	end
+
+	function gadget:GotChatMsg (msg, senderID)
+		if string.find(msg, "pregame_timer_seconds") ~= 1 then
+			return
+		end
+
+		if senderID ~= 255 then -- autohost
+			return
+		end
+
+		local secondsUntilStart = tonumber(string.sub(msg, 23))
+		if not secondsUntilStart then
+			return
+		end
+
+		Spring.SetGameRulesParam("pregame_timer_seconds", secondsUntilStart)
+		SendToUnsynced("PreGameTimekeeping", secondsUntilStart)
+	end
+
+else -- unsynced
+
+	function gadget:Initialize()
+		if Spring.GetGameFrame() > 0 then
+			gadgetHandler:RemoveGadget()
+			return
+		end
+
+		gadgetHandler:AddSyncAction("PreGameTimekeeping", function (_, secondsUntilStart)
+			if Script.LuaUI("PreGameTimekeeping") then
+				Script.LuaUI.PreGameTimekeeping(secondsUntilStart)
+			end
+		end)
+	end
+
+	function gadget:GameStart()
+		gadgetHandler:RemoveGadget()
+	end
+
+	function gadget:Shutdown()
+		gadgetHandler:RemoveSyncAction("PreGameTimekeeping")
+	end
+
+end

LuaUI/Widgets/gui_epicmenu.lua

@@ -3334,6 +3334,12 @@ function widget:GameFrame(n)
 	end
 end
 
+function widget:PreGameTimekeeping(secondsUntilStart)
+	if lbl_gtime then
+		lbl_gtime:SetCaption("-"..GetTimeString(secondsUntilStart))
+	end
+end
+
 function widget:KeyPress(key, modifier, isRepeat, label)
 	if not get_key_bind_mod then
 		if key == KEYSYMS.LCTRL

LuaUI/cawidgets.lua

@@ -252,6 +252,7 @@ local flexCallIns = {
 	"UnitStructureMoved",
 	'MissileFired',
 	'MissileDestroyed',
+	"PreGameTimekeeping",
 }
 local flexCallInMap = {}
 for _, ci in ipairs(flexCallIns) do
@@ -2657,6 +2658,13 @@ function widgetHandler:Load(zip)
 	end
 end
 
+
+function widgetHandler:PreGameTimekeeping(secondsUntilStart)
+	for _,w in r_ipairs(self.PreGameTimekeepingList) do
+		w:PreGameTimekeeping(secondsUntilStart)
+	end
+end
+
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