Refactor builtin HUD (#14346)

builtin/game/hud.lua

@@ -0,0 +1,261 @@
+--[[
+Register function to easily register new builtin hud elements
+`def` is a table and contains the following fields:
+  elem_def  the HUD element definition which can be changed with hud_replace_builtin
+  events    (optional) additional event names on which the element will be updated
+            ("hud_changed" will always be used.)
+  show_elem(player, flags, id)
+            (optional) a function to decide if the element should be shown to a player
+            It is called before the element gets updated.
+  update_def(player, elem_def)
+            (optional) a function to change the elem_def before it will be used.
+            (elem_def can be changed, since the table which got set by using
+            hud_replace_builtin isn't exposed to the API.)
+  update_elem(player, id)
+            (optional) a function to change the element after it has been updated
+            (Is not called when the element is first set or recreated.)
+]]--
+
+local registered_elements = {}
+local update_events = {}
+local function register_builtin_hud_element(name, def)
+	registered_elements[name] = def
+	for _, event in ipairs(def.events or {}) do
+		update_events[event] = update_events[event] or {}
+		table.insert(update_events[event], name)
+	end
+end
+
+-- Stores HUD ids for all players
+local hud_ids = {}
+
+-- Updates one element
+-- In case the element is already added, it only calls the update_elem function from
+-- registered_elements. (To recreate the element remove it first.)
+local function update_element(player, player_hud_ids, elem_name, flags)
+	local def = registered_elements[elem_name]
+	local id = player_hud_ids[elem_name]
+
+	if def.show_elem and not def.show_elem(player, flags, id) then
+		if id then
+			player:hud_remove(id)
+			player_hud_ids[elem_name] = nil
+		end
+		return
+	end
+
+	if not id then
+		if def.update_def then
+			def.update_def(player, def.elem_def)
+		end
+
+		id = player:hud_add(def.elem_def)
+		player_hud_ids[elem_name] = id
+		return
+	end
+
+	if def.update_elem then
+		def.update_elem(player, id)
+	end
+end
+
+-- Updates all elements
+-- If to_update is specified it will only update those elements.
+local function update_hud(player, to_update)
+	local flags = player:hud_get_flags()
+	local playername = player:get_player_name()
+	hud_ids[playername] = hud_ids[playername] or {}
+	local player_hud_ids = hud_ids[playername]
+
+	if to_update then
+		for _, elem_name in ipairs(to_update) do
+			update_element(player, player_hud_ids, elem_name, flags)
+		end
+	else
+		for elem_name, _ in pairs(registered_elements) do
+			update_element(player, player_hud_ids, elem_name, flags)
+		end
+	end
+end
+
+local function player_event_handler(player, eventname)
+	assert(player:is_player())
+
+	if eventname == "hud_changed" then
+		update_hud(player)
+		return
+	end
+
+	-- Custom events
+	local to_update = update_events[eventname]
+	if to_update then
+		update_hud(player, to_update)
+	end
+end
+
+-- Returns true if successful, otherwise false,
+-- but currently the return value is not documented in the Lua API.
+function core.hud_replace_builtin(elem_name, elem_def)
+	assert(type(elem_def) == "table")
+
+	local registered = registered_elements[elem_name]
+	if not registered then
+		return false
+	end
+
+	registered.elem_def = table.copy(elem_def)
+
+	for playername, player_hud_ids in pairs(hud_ids) do
+		local player = core.get_player_by_name(playername)
+		local id = player_hud_ids[elem_name]
+		if player and id then
+			player:hud_remove(id)
+			player_hud_ids[elem_name] = nil
+			update_element(player, player_hud_ids, elem_name, player:hud_get_flags())
+		end
+	end
+	return true
+end
+
+local function cleanup_builtin_hud(player)
+	hud_ids[player:get_player_name()] = nil
+end
+
+
+-- Append "update_hud" as late as possible
+-- This ensures that the HUD is hidden when the flags are updated in this callback
+core.register_on_mods_loaded(function()
+	core.register_on_joinplayer(function(player)
+		update_hud(player)
+	end)
+end)
+core.register_on_leaveplayer(cleanup_builtin_hud)
+core.register_playerevent(player_event_handler)
+
+
+---- Builtin HUD Elements
+
+--- Healthbar
+
+-- Cache setting
+local enable_damage = core.settings:get_bool("enable_damage")
+
+local function scale_to_hud_max(player, field)
+	-- Scale "hp" or "breath" to the hud maximum dimensions
+	local current = player["get_" .. field](player)
+	local nominal
+	if field == "hp" then -- HUD is called health but field is hp
+		nominal = registered_elements.health.elem_def.item
+	else
+		nominal = registered_elements[field].elem_def.item
+	end
+	local max_display = math.max(player:get_properties()[field .. "_max"], current)
+	return math.ceil(current / max_display * nominal)
+end
+
+register_builtin_hud_element("health", {
+	elem_def = {
+		type = "statbar",
+		position = {x = 0.5, y = 1},
+		text = "heart.png",
+		text2 = "heart_gone.png",
+		number = core.PLAYER_MAX_HP_DEFAULT,
+		item = core.PLAYER_MAX_HP_DEFAULT,
+		direction = 0,
+		size = {x = 24, y = 24},
+		offset = {x = (-10 * 24) - 25, y = -(48 + 24 + 16)},
+	},
+	events = {"properties_changed", "health_changed"},
+	show_elem = function(player, flags)
+		return flags.healthbar and enable_damage and
+				player:get_armor_groups().immortal ~= 1
+	end,
+	update_def = function(player, elem_def)
+		elem_def.item = elem_def.item or elem_def.number or core.PLAYER_MAX_HP_DEFAULT
+		elem_def.number = scale_to_hud_max(player, "hp")
+	end,
+	update_elem = function(player, id)
+		player:hud_change(id, "number", scale_to_hud_max(player, "hp"))
+	end,
+})
+
+--- Breathbar
+
+-- Stores core.after calls for every player
+local breathbar_removal_jobs = {}
+
+register_builtin_hud_element("breath", {
+	elem_def = {
+		type = "statbar",
+		position = {x = 0.5, y = 1},
+		text = "bubble.png",
+		text2 = "bubble_gone.png",
+		number = core.PLAYER_MAX_BREATH_DEFAULT * 2,
+		item = core.PLAYER_MAX_BREATH_DEFAULT * 2,
+		direction = 0,
+		size = {x = 24, y = 24},
+		offset = {x = 25, y= -(48 + 24 + 16)},
+	},
+	events = {"properties_changed", "breath_changed"},
+	show_elem = function(player, flags, id)
+		local show_breathbar = flags.breathbar and enable_damage and
+				player:get_armor_groups().immortal ~= 1
+		if id then
+			-- The element will not prematurely be removed by update_element
+			-- (but may still be instantly removed if the flag changed)
+			return show_breathbar
+		end
+		-- Don't add the element if the breath is full
+		local breath_relevant = player:get_breath() < player:get_properties().breath_max
+		return show_breathbar and breath_relevant
+	end,
+	update_def = function(player, elem_def)
+		elem_def.item = elem_def.item or elem_def.number or core.PLAYER_MAX_BREATH_DEFAULT
+		elem_def.number = scale_to_hud_max(player, "breath")
+	end,
+	update_elem = function(player, id)
+		player:hud_change(id, "number", scale_to_hud_max(player, "breath"))
+
+		local player_name = player:get_player_name()
+		local breath_relevant = player:get_breath() < player:get_properties().breath_max
+
+		if not breath_relevant then
+			if not breathbar_removal_jobs[player_name] then
+				-- The breathbar stays for some time and then gets removed.
+				breathbar_removal_jobs[player_name] = core.after(1, function()
+					local player = core.get_player_by_name(player_name)
+					local id = hud_ids[player_name].breath
+					if player and id then
+						player:hud_remove(id)
+						hud_ids[player_name].breath = nil
+					end
+					breathbar_removal_jobs[player_name] = nil
+				end)
+			end
+		else
+			-- Cancel removal
+			local job = breathbar_removal_jobs[player_name]
+			if job then
+				job:cancel()
+				breathbar_removal_jobs[player_name] = nil
+			end
+		end
+	end,
+})
+
+--- Minimap
+
+register_builtin_hud_element("minimap", {
+	elem_def = {
+		type = "minimap",
+		position = {x = 1, y = 0},
+		alignment = {x = -1, y = 1},
+		offset = {x = -10, y = 10},
+		size = {x = 256, y = 256},
+	},
+	show_elem = function(player, flags)
+		-- Don't add a minimap for clients which already have it hardcoded in C++.
+		return flags.minimap and
+				core.get_player_information(player:get_player_name()).protocol_version >= 44
+	end,
+})