add minimum minetest version key for contentdb

All messages sent to the displays are firstr enqueued, then "played
back" on globalstep, similar to biome_lib's deferred-generation method.

By default, no more than 10 messages will be added to the queue.  If the
queue should exceed that, old messages will be deleted to make room for
new messages.

Messages will be pulled from the queue, one item per server tick, in the
order received, and relayed to their displays, if dtime <= 0.2s.  If
dtime is greater, messages will be withheld until it decreases.

Autoscroll now limits the speed to 0.5s per step.

init.lua

@@ -2,6 +2,13 @@
 -- by Vanessa Dannenberg
 
 led_marquee = {}
+led_marquee.scheduled_messages = {}
+
+led_marquee.message_minimum_time   = tonumber(minetest.settings:get("led_marquee_message_minimum_time"))   or 0.5
+
+led_marquee.message_schedule_dtime = tonumber(minetest.settings:get("led_marquee_message_schedule_dtime")) or 0.2
+led_marquee.message_schedule_size  = tonumber(minetest.settings:get("led_marquee_message_schedule_size"))  or 10
+led_marquee.relay_timer = 0
 
 local S
 if minetest.get_modpath("intllib") then
@@ -128,7 +135,12 @@ local make_iso = function(s)
 	local s2 = ""
 	while i <= string.len(s) do
 		if string.byte(s,i) > 159 then
-			s2 = s2..string.char(get_iso(string.sub(s, i, i+1)))
+			local ciso = get_iso(string.sub(s, i, i+1))
+			if ciso >= 0 and ciso < 256 then
+				s2 = s2..string.char(ciso)
+			else
+				s2 = s2..string.char(127)
+			end
 			i = i + 2
 		else
 			s2 = s2..string.sub(s, i, i)
@@ -143,7 +155,7 @@ end
 led_marquee.set_timer = function(pos, timeout)
 	local timer = minetest.get_node_timer(pos)
 	timer:stop()
-	if not timeout or timeout < 0.2 or timeout > 5 then return false end
+	if not timeout or timeout < led_marquee.message_minimum_time or timeout > 5 then return false end
 
 	if timeout > 0 then
 		local meta = minetest.get_meta(pos)
@@ -184,7 +196,7 @@ led_marquee.scroll_text = function(pos, elapsed, skip)
 			break
 		end
 	end
-	led_marquee.display_msg(pos, channel, "/"..colorchar..string.sub(msg, f)..string.rep(" ", skip + 1))
+	led_marquee.schedule_msg(pos, channel, "/"..colorchar..string.sub(msg, f)..string.rep(" ", skip + 1))
 
 	meta:set_int("index", f)
 	if not elapsed or elapsed < 0.2 then return false end
@@ -213,6 +225,27 @@ led_marquee.decode_color = function(msg)
 
 end
 
+minetest.register_globalstep(function(dtime)
+	if dtime <= led_marquee.message_schedule_dtime
+	  and (#led_marquee.scheduled_messages) > 0 then
+		led_marquee.display_msg(
+			led_marquee.scheduled_messages[1].pos,
+			led_marquee.scheduled_messages[1].channel,
+			led_marquee.scheduled_messages[1].msg
+		)
+	end
+	table.remove(led_marquee.scheduled_messages, 1)
+end)
+
+led_marquee.schedule_msg = function(pos, channel, msg)
+	local idx = #led_marquee.scheduled_messages
+	led_marquee.scheduled_messages[idx+1] = { pos=pos, channel=channel, msg=msg }
+
+	if idx >= led_marquee.message_schedule_size then
+		table.remove(led_marquee.scheduled_messages, 1)
+	end
+end
+
 led_marquee.display_msg = function(pos, channel, msg)
 	msg = string.sub(msg, 1, 6144).." "
 	if string.sub(msg,1,1) == string.char(255) then -- treat it as incoming UTF-8
@@ -312,13 +345,13 @@ local on_digiline_receive_string = function(pos, node, channel, msg)
 				led_marquee.set_timer(pos, 0)
 				msg = string.rep(" ", 2048)
 				meta:set_string("last_msg", msg)
-				led_marquee.display_msg(pos, channel, msg)
+				led_marquee.schedule_msg(pos, channel, msg)
 				meta:set_int("index", 1)
 			elseif msg == "allon" then
 				led_marquee.set_timer(pos, 0)
 				msg = string.rep(string.char(144), 2048)
 				meta:set_string("last_msg", msg)
-				led_marquee.display_msg(pos, channel, msg)
+				led_marquee.schedule_msg(pos, channel, msg)
 				meta:set_int("index", 1)
 			elseif msg == "start_scroll" then
 				local timeout = meta:get_int("timeout")
@@ -328,7 +361,7 @@ local on_digiline_receive_string = function(pos, node, channel, msg)
 				return
 			elseif string.sub(msg, 1, 12) == "scroll_speed" then
 				local timeout = tonumber(string.sub(msg, 13))
-				led_marquee.set_timer(pos, timeout)
+				led_marquee.set_timer(pos, math.max(timeout, led_marquee.message_minimum_time))
 			elseif string.sub(msg, 1, 11) == "scroll_step" then
 				local skip = tonumber(string.sub(msg, 12))
 				led_marquee.scroll_text(pos, nil, skip)
@@ -343,7 +376,7 @@ local on_digiline_receive_string = function(pos, node, channel, msg)
 				led_marquee.set_timer(pos, 0)
 				local last_msg = meta:get_string("last_msg")
 				meta:set_string("last_msg", msg)
-				led_marquee.display_msg(pos, channel, msg)
+				led_marquee.schedule_msg(pos, channel, msg)
 				if last_msg ~= msg then
 					meta:set_int("index", 1)
 				end
@@ -358,7 +391,7 @@ local on_digiline_receive_string = function(pos, node, channel, msg)
 		end
 	elseif msg and type(msg) == "number" then
 		meta:set_string("last_msg", tostring(msg))
-		led_marquee.display_msg(pos, channel, tostring(msg))
+		led_marquee.schedule_msg(pos, channel, tostring(msg))
 		meta:set_int("index", 1)
 	end
 end
@@ -369,23 +402,17 @@ for i = 31, 255 do
 	local groups = { cracky = 2, not_in_creative_inventory = 1}
 	local light = LIGHT_MAX-2
 	local description = S("LED marquee panel ("..i..")")
-	local tiles = {
+	local leds = "led_marquee_char_"..i..".png^[mask:led_marquee_leds_on.png"
-				{ name="led_marquee_base.png", color="white"},
-				{ name="led_marquee_leds_off.png", color="white"},
-				"led_marquee_char_"..i..".png",
-			}
 
 	if i == 31 then
-		tiles = {
+		leds ={
-			{ name="led_marquee_base.png", color="white"},
+			name = "led_marquee_char_31.png^[mask:led_marquee_leds_on_cursor.png",
-			{ name="led_marquee_leds_off.png", color="white"},
-				{
-				name = "led_marquee_char_31.png",
 			animation = {type = "vertical_frames", aspect_w = 32, aspect_h = 32, length = 0.75}
 		}
-		}
 	end
 
+	local wimage
+
 	if i == 32 then
 		groups = {cracky = 2}
 		light = nil
@@ -397,7 +424,11 @@ for i = 31, 255 do
 		description = description,
 		drawtype = "mesh",
 		mesh = "led_marquee.obj",
-		tiles = tiles,
+		tiles = {
+			{ name = "led_marquee_base.png", color = "white" },
+			{ name = "led_marquee_leds_off.png", color = "white" }
+		},
+		overlay_tiles = { "", leds },
 		inventory_image = wimage,
 		wield_image = wimage,
 		palette="led_marquee_palette.png",
@@ -412,6 +443,11 @@ for i = 31, 255 do
 			reset_meta(pos)
 		end,
 		on_receive_fields = function(pos, formname, fields, sender)
+			local name = sender:get_player_name()
+			if minetest.is_protected(pos, name) and not minetest.check_player_privs(name, {protection_bypass=true}) then
+				minetest.record_protection_violation(pos, name)
+				return
+			end
 			if (fields.channel) then
 				minetest.get_meta(pos):set_string("channel", fields.channel)
 			end

mod.conf

@@ -1 +1,2 @@
 name = led_marquee
+min_minetest_version = 5.2.0

models/led_marquee.obj

@@ -21,10 +21,6 @@ v -0.500000 -0.453125 0.468750
 v -0.500000 -0.453125 -0.468750
 v -0.500000 -0.437500 -0.484375
 v -0.500000 -0.437500 -0.500000
-v 0.500000 -0.449125 -0.468750
-v -0.500000 -0.449125 -0.468750
-v -0.500000 -0.449125 0.468750
-v 0.500000 -0.449125 0.468750
 vt 0.681855 0.961799
 vt 0.723891 0.992824
 vt 0.723891 0.000000
@@ -69,10 +65,6 @@ vt 0.000000 0.000000
 vt 1.000000 0.000000
 vt 1.000000 1.000000
 vt 0.000000 1.000000
-vt 0.000000 0.000000
-vt 1.000000 0.000000
-vt 1.000000 1.000000
-vt 0.000000 1.000000
 vn 1.0000 0.0000 0.0000
 vn 0.0000 -1.0000 -0.0000
 vn -1.0000 0.0000 0.0000
@@ -106,7 +98,5 @@ f 7/26/8 6/38/8 19/19/8
 f 19/19/6 6/38/6 5/20/6
 f 15/22/6 10/39/6 9/23/6
 f 8/25/7 17/40/7 16/24/7
-g Cube_Cube_LEDs_Cube_Cube_LEDs_leds_off
+g Cube_Cube_LEDs_Cube_Cube_LEDs_base_led_marquee_leds_off.png
 f 1/41/6 2/42/6 3/43/6 4/44/6
-g Cube_Cube_LEDs_Cube_Cube_LEDs_leds_on
-f 21/45/6 22/46/6 23/47/6 24/48/6