add wesnoth.interface.get_items

returns all items on a locations, this allows is to
remove quite a bit of code in the dropping.lua file
of world conquest since that can now just use items.lua
instead

data/campaigns/World_Conquest/lua/game_mechanics/artifacts.lua

@@ -51,11 +51,13 @@ end
 -- place an artifact with id @a index on the map at position @a x, y.
 -- can be used from the bug console as `lua wc2_artifacts.place_item(30,20,1)`
 function artifacts.place_item(x, y, index)
-	wc2_dropping.add_item(x, y, {
-		wc2_atrifact_id = index,
+	wesnoth.wml_actions.item {
+		x = x,
+		y = y,
 		image = artifacts.get_artifact(index).icon,
 		z_order = 20,
-	})
+		wml.tag.variables { wc2_atrifact_id = index },
+	}
 end
 
 -- give te item with id @a index to unit @a unit, set @a visualize=true, to show the item pickup animation.
@@ -120,7 +122,7 @@ end
 on_event("wc2_drop_pickup", function(ec)
 	local item = wc2_dropping.current_item
 	local unit = wesnoth.get_unit(ec.x1, ec.y1)
-	if not item.wc2_atrifact_id then 
+	if not item.variables.wc2_atrifact_id then
 		return
 	end
 
@@ -135,7 +137,7 @@ on_event("wc2_drop_pickup", function(ec)
 	end
 	
 
-	local index = item.wc2_atrifact_id
+	local index = item.variables.wc2_atrifact_id
 	local filter = artifacts.get_artifact(index).filter
 	if filter and not unit:matches(filter) then
 		if is_human then
@@ -195,8 +197,8 @@ end)
 -- returns true if there is an item in the map at the given position,
 -- used to determine whether to show the artifact info menu at that position. 
 function artifacts.is_item_at(x,y)
-	for i,item in ipairs(wc2_dropping.get_entries_at_readonly(x,y)) do
-		if item.wc2_atrifact_id then
+	for i,item in ipairs(wesnoth.interface.get_items(x,y)) do
+		if item.variables.wc2_atrifact_id then
 			return true
 		end
 	end
@@ -208,9 +210,9 @@ end
 function wesnoth.wml_actions.wc2_show_item_info(cfg)
 	local x = cfg.x
 	local y = cfg.y
-	for i,item in ipairs(wc2_dropping.get_entries_at_readonly(x,y)) do
-		if item.wc2_atrifact_id then
-			local artifact_info = artifacts.get_artifact(item.wc2_atrifact_id)
+	for i,item in ipairs(wesnoth.interface.get_items(x,y)) do
+		if item.variables.wc2_atrifact_id then
+			local artifact_info = artifacts.get_artifact(item.variables.wc2_atrifact_id)
 			wesnoth.wml_actions.message {
 				scroll = false,
 				image = artifact_info.icon,

data/campaigns/World_Conquest/lua/game_mechanics/bonus.lua

@@ -43,11 +43,13 @@ function bonus.place_item(x, y, image)
 		image = image or "scenery/lighthouse.png"
 	end
 
-	wc2_dropping.add_item(x, y, {
-		wc2_is_bonus = true,
+	wesnoth.wml_actions.item {
+		x = x,
+		y = y,
 		image = image,
 		z_order = 10,
-	})
+		wml.tag.variables { wc2_is_bonus = true },
+	}
 end
 
 function bonus.remove_current_item(ec)
@@ -85,7 +87,7 @@ on_event("wc2_drop_pickup", function(ec)
 	local item = wc2_dropping.current_item
 	local side_num = wesnoth.current.side
 
-	if not item.wc2_is_bonus then
+	if not item.variables.wc2_is_bonus then
 		return
 	end
 

data/campaigns/World_Conquest/lua/game_mechanics/dropping.lua

@@ -6,151 +6,27 @@ local on_event = wesnoth.require("on_event")
 
 local dropping = {}
 
-dropping.field_data = {}
-
-dropping.loc_to_index = function(x,y)
-	return (y - 1) * 1000 + x
-end
-
-dropping.index_to_loc = function(index)
-	local y_m1 = math.floor(index / 1000)
-	return index - y_m1 * 1000, y_m1 + 1
-end
-
-dropping.decorate_imagename = function(id)
-	return "wc2_item_" .. id
-end
-
-dropping.place_image = function(x, y, cfg)
-	wesnoth.add_tile_overlay(x, y, {
-		image = cfg.image,
-		team_name = cfg.team_name,
-		visible_in_fog = cfg.visible_in_fog,
-		redraw = cfg.redraw,
-		name = dropping.decorate_imagename(cfg.id),
-		z_order = cfg.z_order
-	})
-end
-
-
--- this  can be used to remove item but not to add items.
-dropping.get_entries_at_readonly = function(x,y)
-	return dropping.field_data[dropping.loc_to_index(x,y)] or {}
-end
-
-dropping.get_entries_at_readwrite = function(x,y)
-	local index = dropping.loc_to_index(x,y)
-	dropping.field_data[index] = dropping.field_data[index] or {}
-	return dropping.field_data[index]
-end
-
-dropping.remove_empty_lists = function()
-	local to_delete = {}
-	for k,v in pairs(dropping.field_data) do
-		if #v == 0 then
-			to_delete[k] = true
-		end
-	end
-	for k,v in pairs(to_delete) do
-		dropping.field_data[k] = nil
-	end
-end
-
-dropping.add_item = function(x, y, cfg)
-	table.insert(dropping.get_entries_at_readwrite(x,y), cfg)
-	cfg.id = dropping.next_id
-	dropping.next_id = dropping.next_id + 1
-	dropping.place_image(x, y, cfg)
-end
-
-dropping.remove_item = function(x, y, id)
-	local entries = dropping.get_entries_at_readwrite(x,y)
-	for i,v in ipairs(entries) do
-		if v.id == id then
-			wesnoth.remove_tile_overlay(x, y, dropping.decorate_imagename(id))
-			table.remove(entries, i)
-			break
-		end
-	end
-end
-
-dropping.remove_all_items = function(filter)
-	for k,v in pairs(dropping.field_data) do
-		local start = #v
-		local x, y = dropping.index_to_loc(k)
-		for i = start, 1, -1 do
-			if filter(v[i], x, y) then
-				wesnoth.remove_tile_overlay(x, y, dropping.decorate_imagename(v[i].id))
-				table.remove(v, i)
-			end
-		end
-	end
-end
-
 dropping.remove_current_item = function()
-	local v = dropping.current_item
 	local ec = wesnoth.current.event_context
-	wesnoth.remove_tile_overlay(ec.x1, ec.y1, dropping.decorate_imagename(v.id))
+	
+	wesnoth.interface.remove_item(ec.x1, ec.y1, dropping.current_item.name)
 	dropping.item_taken = true
 end
 
-
-wesnoth.persistent_tags.wc2_dropping.write = function(add)
-	local res = {
-		next_id = dropping.next_id,
-	}
-	for i,v in pairs(dropping.field_data) do
-		local x,y = dropping.index_to_loc(i)
-		for i2,v2 in ipairs(v) do
-			table.insert(res, wml.tag.item {
-				x = x,
-				y = y,
-				wml.tag.data (v2)
-			})
-		end
-	end		
-	add(res)
-end
--- read might not be called if there is no [dropped_items] tag found
-wesnoth.persistent_tags.wc2_dropping.read = function(cfg)
-	for item in wml.child_range(cfg, "item") do
-		local hex_list = dropping.get_entries_at_readwrite(item.x, item.y)
-		table.insert(hex_list, (wml.get_child(item, "data")))
-	end
-	dropping.next_id = cfg.next_id or 0
-	dropping.remove_empty_lists()
-end
-
 on_event("moveto", function(event_context)
 	local x = event_context.x1
 	local y = event_context.y1
-	local entries = dropping.get_entries_at_readonly(x,y)
-	local i = 1
-	while i <= #entries do
-		local v = entries[i]
-		dropping.current_item = v
+	local items = wesnoth.interface.get_items(x, y)
+	for i, item in ipairs(items) do
+		dropping.current_item = item
 		dropping.item_taken = nil
 		wesnoth.fire_event("wc2_drop_pickup", x, y)
 		if dropping.item_taken then
-			table.remove(entries, i)
-			wesnoth.remove_tile_overlay(x, y, dropping.decorate_imagename(v.id))
-			wesnoth.allow_undo(false)
-		else
-			i = i + 1
+			wesnoth.interface.remove_item(x,y, item.name)
 		end
 		dropping.current_item = nil
 		dropping.item_taken = nil
 	end
 end)
 
-on_event("preload", function()
-	dropping.next_id = dropping.next_id or 0
-	for k,v in pairs(dropping.field_data) do
-		local x,y = dropping.index_to_loc(k)
-		for i, cfg in ipairs(v) do
-			dropping.place_image(x, y, cfg)
-		end
-	end
-end)
-
 return dropping

data/lua/wml/items.lua

@@ -2,7 +2,14 @@ local wml_actions = wesnoth.wml_actions
 
 local scenario_items = (wesnoth.require "location_set").create()
 local next_item_name = 0
+
 local function add_overlay(x, y, cfg)
+
+	if not cfg.name then
+		cfg.name = "item_" .. tostring(next_item_name)
+		next_item_name = next_item_name + 1
+	end
+
 	wesnoth.interface.add_hex_overlay(x, y, cfg)
 	local items = scenario_items:get(x, y)
 	if not items then
@@ -20,6 +27,7 @@ local function add_overlay(x, y, cfg)
 			redraw = cfg.redraw,
 			name = cfg.name,
 			z_order = cfg.z_order,
+			wml.tag.variables(wml.get_child(cfg, "variables") or {}),
 		})
 end
 
@@ -40,6 +48,28 @@ function wesnoth.interface.remove_item(x, y, name)
 	end
 end
 
+function wesnoth.interface.get_items(x, y)
+	local res = {}
+	local items = scenario_items:get(x, y) or {}
+	for i = 1,#items do
+		local cfg = items[i]
+		-- make a copy, since modifying these values (except variabels) wouldn't work anyways.
+		table.insert( res, {
+			x = cfg.x, y = cfg.y,
+			image = cfg.image,
+			halo = cfg.halo,
+			team_name = cfg.team_name,
+			filter_team = cfg.filter_team,
+			visible_in_fog = cfg.visible_in_fog,
+			redraw = cfg.redraw,
+			name = cfg.name,
+			z_order = cfg.z_order,
+			variables = wml.get_child(cfg, "variables"),
+		})
+	end
+	return res
+end
+
 function wesnoth.persistent_tags.item.write(add)
 	for x,y,v in scenario_items:iter() do
 		for i,w in ipairs(v) do
@@ -53,6 +83,7 @@ function wesnoth.persistent_tags.next_item_name.write(add)
 end
 
 function wesnoth.persistent_tags.item.read(cfg)
+	if not cfg.name then cfg.name = "" end
 	add_overlay(cfg.x, cfg.y, cfg)
 end
 
@@ -60,13 +91,11 @@ function wesnoth.persistent_tags.next_item_name.read(cfg)
 	next_item_name = cfg.next_item_name or next_item_name
 end
 
+
+-- returns the 'name' of an item, this can be used as an id to remove the iten later.
 function wml_actions.item(cfg)
 	local locs = wesnoth.get_locations(cfg)
 	cfg = wml.parsed(cfg)
-	if not cfg.name then
-		cfg.name = "item_" .. tostring(next_item_name)
-		next_item_name = next_item_name + 1
-	end
 	if not cfg.image and not cfg.halo then
 		wml.error "[item] missing required image= and halo= attributes."
 	end