backguard compatibility for 0.4.16+ engines and 5.2+ and beyond

* boilerplace the minetest translation and only use format
  when is available to translate it
* uses Use MT native support for "background icons" only
  when available and if valid

README.md

@@ -12,7 +12,7 @@ position should be displayed correctly on every screen size.
 
 ## Current version
 The current version is 2.3.4.
-It works for Minetest 5.3.0 or later.
+It works for Minetest 0.4.17+ (maybe 0.4.16 too) or later.
 
 This software uses [semantic versioning](http://semver.org), as defined by version 2.0.0 of the SemVer
 standard.

init.lua

@@ -1,4 +1,27 @@
-local S = minetest.get_translator("hudbars")
+
+local S
+-- Intllib
+if minetest.get_translator ~= nil then
+	S = minetest.get_translator("ethereal") -- 5.x translation function
+else
+	if minetest.get_modpath("intllib") then
+		dofile(minetest.get_modpath("intllib") .. "/init.lua")
+		if intllib.make_gettext_pair then
+			gettext, ngettext = intllib.make_gettext_pair() -- new gettext method
+		else
+			gettext = intllib.Getter() -- old text file method
+		end
+		S = gettext
+	else -- boilerplate function
+		S = function(str, ...)
+			local args = {...}
+			return str:gsub("@%d+", function(match)
+				return args[tonumber(match:sub(2))]
+			end)
+		end
+	end
+end
+
 local N = function(s) return s end
 
 hb = {}
@@ -58,13 +81,13 @@ local function make_label(format_string, format_string_config, label, start_valu
 		if order[o] == "label" then
 			table.insert(params, label)
 		elseif order[o] == "value" then
-			if format_string_config.format_value then
+			if format_string_config.format_value and minetest.get_translator ~= nil then
 				table.insert(params, string.format(format_string_config.format_value, start_value))
 			else
 				table.insert(params, start_value)
 			end
 		elseif order[o] == "max_value" then
-			if format_string_config.format_max_value then
+			if format_string_config.format_max_value and minetest.get_translator ~= nil then
 				table.insert(params, string.format(format_string_config.format_max_value, max_value))
 			else
 				table.insert(params, max_value)
@@ -72,7 +95,7 @@ local function make_label(format_string, format_string_config, label, start_valu
 		end
 	end
 	local ret
-	if format_string_config.textdomain then
+	if format_string_config.textdomain and minetest.get_translator ~= nil then
 		ret = minetest.translate(format_string_config.textdomain, format_string, unpack(params))
 	else
 		ret = S(format_string, unpack(params))
@@ -213,6 +236,20 @@ function hb.register_hudbar(identifier, text_color, label, textures, default_sta
 					z_index = 1,
 				})
 			end
+		elseif hb.settings.bar_type == "statbar_modern" then
+			if textures.bgicon ~= nil then
+				ids.bg = player:hud_add({
+					hud_elem_type = "statbar",
+					position = pos,
+					text = textures.bgicon,
+					number = bgiconnumber,
+					alignment = {x=-1,y=-1},
+					offset = { x = offset.x, y = offset.y },
+					direction = 0,
+					size = {x=24, y=24},
+					z_index = 0,
+				})
+			end
 		end
 		local bar_image, bgicon, bar_size
 		if hb.settings.bar_type == "progress_bar" then
@@ -226,7 +263,7 @@ function hb.register_hudbar(identifier, text_color, label, textures, default_sta
 			bar_size = nil
 		elseif hb.settings.bar_type == "statbar_classic" or hb.settings.bar_type == "statbar_modern" then
 			bar_image = textures.icon
-			bgicon = textures.bgicon
+			if textures.bgicon then bgicon = textures.bgicon end
 			bar_size = {x=24, y=24}
 		end
 		ids.bar = player:hud_add({
@@ -411,6 +448,8 @@ function hb.hide_hudbar(player, identifier)
 		end
 		player:hud_change(hudtable.hudids[name].bg, "scale", {x=0,y=0})
 		player:hud_change(hudtable.hudids[name].text, "text", "")
+	elseif hb.settings.bar_type == "statbar_modern" then
+		player:hud_change(hudtable.hudids[name].bg, "number", 0)
 	end
 	player:hud_change(hudtable.hudids[name].bar, "number", 0)
 	player:hud_change(hudtable.hudids[name].bar, "item", 0)