Fix formspec lag when settings scrollbar is moved

mods/apis/ctf_settings/init.lua

@@ -43,37 +43,72 @@ function ctf_settings.get(player, setting)
 	return value == "" and info.default or value
 end
 
+-- This Function MIT by Rubenwardy
+--- Creates a scrollbaroptions for a scroll_container
+--
+-- @param visible_l the length of the scroll_container and scrollbar
+-- @param total_l length of the scrollable area
+-- @param scroll_factor as passed to scroll_container
+local function make_scrollbaroptions_for_scroll_container(visible_l, total_l, scroll_factor)
+
+	assert(total_l >= visible_l)
+
+	local thumb_size = (visible_l / total_l) * (total_l - visible_l)
+
+	local max = total_l - visible_l
+
+	return ("scrollbaroptions[min=0;max=%f;thumbsize=%f]"):format(max / scroll_factor, thumb_size / scroll_factor)
+end
+
 minetest.register_on_mods_loaded(function()
 	sfinv.register_page("ctf_settings:settings", {
 		title = "Settings",
 		get = function(self, player, context)
 			local setting_list = {}
 			local lastypos = -0.5
 
+			if not context then
+				context = {}
+			end
+
+			if not context.setting then
+				context.setting = {}
+			end
+
 			for k, setting in ipairs(ctf_settings.settings_list) do
 				local settingdef = ctf_settings.settings[setting]
 
+				if not context.setting[setting] then
+					context.setting[setting] = ctf_settings.get(player, setting)
+				end
+
 				if settingdef.type == "bool" then
 					setting_list[k] = {
 						"checkbox[0,%f;%s;%s;%s]tooltip[%s;%s]",
 						lastypos,
 						setting,
 						settingdef.label or setting,
-						ctf_settings.get(player, setting),
+						context.setting[setting],
 						setting,
 						settingdef.description or HumanReadable(setting)
 					}
 
 					lastypos = lastypos + 0.5
 				elseif settingdef.type == "list" then
+					local max_len = 0
+
+					for _, val in pairs(settingdef.list) do
+						max_len = math.max(val:len(), max_len)
+					end
+
 					lastypos = lastypos + 0.3
 					setting_list[k] = {
 						"dropdown[0,%f;%f;%s;%s;%d]tooltip[0,%f;%f,0.6;%s]",
 						lastypos,
-						FORMSIZE.x/1.7,
+						math.max(FORMSIZE.x / 2, math.min(FORMSIZE.x - SCROLLBAR_W + 2, 0.5 + (max_len * 0.23))),
 						setting,
 						settingdef.list,
-						ctf_settings.get(player, setting),
+						context.setting[setting],
 						--label
 						lastypos,
 						(FORMSIZE.x/1.7) - 0.3,
@@ -91,12 +126,12 @@ minetest.register_on_mods_loaded(function()
 				},
 				ctf_gui.list_to_formspec_str(setting_list),
 				"scroll_container_end[]",
-				{"scrollbaroptions[max=%d]", math.ceil((lastypos - 3.833) * 11.538)},
+				make_scrollbaroptions_for_scroll_container(FORMSIZE.y + 0.7, math.max(lastypos+1, FORMSIZE.y + 0.7), 0.1),
 				{"scrollbar[%f,-0.1;%f,%f;vertical;settings_scrollbar;%f]",
 					FORMSIZE.x - SCROLLBAR_W,
 					SCROLLBAR_W,
 					FORMSIZE.y,
-					context and context.settings_scrollbar or 0
+					context.settings_scrollbar or 0
 				},
 			}
 
@@ -112,24 +147,30 @@ minetest.register_on_mods_loaded(function()
 					if setting.type == "bool" then
 						local newvalue = value == "true" and "true" or "false"
 
-						ctf_settings.set(player, field, newvalue)
+						if context.setting[field] ~= newvalue then
+							context.setting[field] = newvalue
+							ctf_settings.set(player, field, newvalue)
 
-						if setting.on_change then
-							setting.on_change(player, newvalue)
+							if setting.on_change then
+								setting.on_change(player, newvalue)
+							end
+
+							refresh = true
 						end
 					elseif setting.type == "list" then
 						local idx = table.indexof(setting.list, value)
 
-						if idx ~= -1 then
+						if idx ~= -1 and context.setting[field] ~= tostring(idx) then
+							context.setting[field] = tostring(idx)
 							ctf_settings.set(player, field, tostring(idx))
 
 							if setting.on_change then
-								setting.on_change(player, idx)
+								setting.on_change(player, tostring(idx))
 							end
+
+							refresh = true
 						end
 					end
-
-					refresh = true
 				end
 			end