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< LuaWML
Revision as of 05:34, 9 May 2011 by Melinath (talk | contribs) (wesnoth.show_dialog: Tried to clarify the language regarding GUIWML structures.)

This page describes the LuaWML functions and helpers for interfacing with the user.


Displays a string in the chat window and dumps it to the lua/info log domain (--log-info=scripting/lua on the command-line).

wesnoth.message "Hello World!"

The chat line header is "<Lua>" by default, but it can be changed by passing a string before the message.

wesnoth.message("Big Brother", "I'm watching you.") -- will result in "<Big Brother> I'm watching you."

See also helper.wml_error for displaying error messages.


Removes all messages from the chat window. No argument or returned values.


Creates a function proxy for lazily translating strings from the given domain.

-- #textdomain "my-campaign"
-- the comment above ensures the subsequent strings will be extracted to the proper domain
_ = wesnoth.textdomain "my-campaign"
wesnoth.set_variable("my_unit.description", _ "the unit formerly known as Hero")

The metatable of the function proxy appears as "message domain". The metatable of the translatable strings (results of the proxy) appears as "translatable string".

The translatable strings can be appended to other strings/numbers with the standard .. operator. Translation can be forced with the standard tostring operator in order to get a plain string.

wesnoth.message(string.format(tostring(_ "You gain %d gold."), amount))


Delays the engine like the [delay] tag. one argument: time to delay in milliseconds



Pops some text above a map tile.

wesnoth.float_label(unit.x, unit.y, "<span color='#ff0000'>Ouch</span>")



Highlights the given location in the game map, and the unit stationed on it if applicable.

wesnoth.hilight_hex(unit.x, unit.y)



Selects the given location in the game map.

wesnoth.select_hex(12, 34)



Scrolls the map to the given location. If true is passed as the third parameter, scrolling is disabled if the tile is hidden under the fog.

local u = wesnoth.get_units({ id = "hero" })[1]
wesnoth.scroll_to_tile(u.x, u.y)



Plays the given sound file, possibly repeating it a few more times.

wesnoth.play_sound "ambient/birds1.ogg"
wesnoth.play_sound("magic-holy-miss-3.ogg", 4) -- played 1 + 4 = 5 times



Sets the given table as an entry into the music list. See MusicListWML for the recognized attributes.

wesnoth.set_music { name = "traveling_minstrels.ogg" }

Passing no argument forces the engine to take into account all the recent changes to the music list. (Note: this is done automatically when sequences of WML commands end, so it is useful only for long events.)



Displays a dialog box described by a WML table and returns:

  • if the dialog was dismissed by a button click, the integer value associated to the button via the "return_value" keyword.
  • if the dialog was closed with the enter key, -1.
  • if the dialog was closed with the escape key, -2.

The dialog box is equivalent to the resolution section of a GUI window as described in GUIToolkitWML and must therefore contain at least the following children: [tooltip], [helptip], and [grid]. The [grid] must contain nested [row], [column] and [grid] tags which describe the layout of the window. (More information can be found in GUILayout; suffice to say that the basic structure is grid -> row -> column -> widget, where the widget is considered to be in a cell defined by the row and column of the grid. A list of widgets can be found at GUIWidgetInstanceWML.)

Two optional functions can be passed as second and third arguments; the first one is called once the dialog is created and before it is shown; the second one is called once the dialog is closed. These functions are helpful in setting the initial values of the fields and in recovering the final user values. These functions can call the #wesnoth.set_dialog_value, #wesnoth.get_dialog_value, and #wesnoth.set_dialog_callback functions for this purpose.

This function should be called in conjunction with #wesnoth.synchronize_choice, in order to ensure that only one client displays the dialog and that the other ones recover the same input values from this single client.

The example below defines a dialog with a list and two buttons on the left, and a big image on the right. The preshow function fills the list and defines a callback on it. This select callback changes the displayed image whenever a new list item is selected. The postshow function recovers the selected item before the dialog is destroyed.

local helper = wesnoth.require "lua/helper.lua"
local T = helper.set_wml_tag_metatable {}
local _ = wesnoth.textdomain "wesnoth"

local dialog = {
  T.tooltip { id = "tooltip_large" },
  T.helptip { id = "tooltip_large" },
  T.grid { T.row {
    T.column { T.grid {
      T.row { T.column { horizontal_grow = true, T.listbox { id = "the_list",
        T.list_definition { T.row { T.column { horizontal_grow = true,
          T.toggle_panel { T.grid { T.row {
            T.column { horizontal_alignment = "left", T.label { id = "the_label" } },
            T.column { T.image { id = "the_icon" } }
          } } }
        } } }
      } } },
      T.row { T.column { T.grid { T.row {
        T.column { T.button { id = "ok", label = _"OK" } },
        T.column { T.button { id = "cancel", label = _"Cancel" } }
      } } } }
    } },
    T.column { T.image { id = "the_image" } }
  } }

local function preshow()
    local t = { "Ancient Lich", "Ancient Wose", "Elvish Avenger" }
    local function select()
        local i = wesnoth.get_dialog_value "the_list"
        local ut = wesnoth.unit_types[t[i]].__cfg
        wesnoth.set_dialog_value(string.gsub(ut.profile, "([^/]+)$", "transparent/%1"), "the_image")
    wesnoth.set_dialog_callback(select, "the_list")
    for i,v in ipairs(t) do
        local ut = wesnoth.unit_types[v].__cfg
        wesnoth.set_dialog_value(, "the_list", i, "the_label")
        wesnoth.set_dialog_value(ut.image, "the_list", i, "the_icon")
    wesnoth.set_dialog_value(2, "the_list")

local li = 0
local function postshow()
    li = wesnoth.get_dialog_value "the_list"

local r = wesnoth.show_dialog(dialog, preshow, postshow)
wesnoth.message(string.format("Button %d pressed. Item %d selected.", r, li))



Sets the value of a widget on the current dialog. The value is given by the first argument; its semantic depends on the type of widget it is applied to. The last argument is the id of the widget. If it does not point to a unique widget in the dialog, some discriminating parents should be given on its left, making a path that is read from left to right by the engine. The row of a list is specified by giving the id' of the list as a first argument and the 1-based row number as the next argument.

-- sets the value of a widget "bar" in the 7th row of the list "foo"
wesnoth.set_value(_"Hello world", "foo", 7, "bar")

Notes: When the row of a list does not exist, it is created. The value associated to a list is the selected row.



Gets the value of a widget on the current dialog. The arguments described the path for reaching the widget (see #wesnoth.set_dialog_value).



Sets the first argument as a callback function for the widget obtained by following the path of the other arguments (see #wesnoth.set_dialog_value). This function will be called whenever the user modifies something about the widget, so that the dialog can react to it.



Sets the WML passed as the second argument as the canvas content (index given by the first argument) of the widget obtained by following the path of the other arguments (see #wesnoth.set_dialog_value). The content of the WML table is described at GUICanvasWML.

-- draw two rectangles in the upper-left corner of the window (empty path = window widget)
wesnoth.set_dialog_canvas(2, {
    T.rectangle { x = 20, y = 20, w = 20, h = 20, fill_color= "0,0,255,255" },
    T.rectangle { x = 30, y = 30, w = 20, h = 20, fill_color = "255,0,0,255" }

The meaning of the canvas index depends on the chosen widget. It may be the disabled / enabled states of the widget, or its background / foreground planes, or... For instance, overwriting canvas 1 of the window with an empty canvas causes the window to become transparent.



Returns a proxy to the unit currently displayed in the side pane of the user interface, if any.

local name = tostring(wesnoth.get_displayed_unit().name)



This field is not a function but an associative table. It links item names to the functions that describe their content. These functions are called whenever the user interface is refreshed. The description of an item is a WML table containing [element] children. Each subtag shall contain either a text or an image field that is displayed to the user. It can also contain a tooltip field that is displayed to the user when moused over, and a "help" field that points to the help section that is displayed when the user clicks on the theme item.

Note that the wesnoth.theme_items table is originally empty and using pairs or next on it will not return the items from the current theme. Its metatable ensures that the drawing functions of existing items can be recovered though, as long as their name is known. The example below shows how to modify the unit_status item to display a custom status:

local old_unit_status = wesnoth.theme_items.unit_status
function wesnoth.theme_items.unit_status()
    local u = wesnoth.get_displayed_unit()
    if not u then return {} end
        local s = old_unit_status()
        if u.status.entangled then
            table.insert(s, { "element", {
                image = "entangled.png",
                tooltip = _"entangled: This unit is entangled. It cannot move but it can still attack."
            } })
    return s


Displays a WML message box querying a choice from the user. Attributes and options are taken from given tables (see [message]). The index of the selected option is returned.

local result = helper.get_user_choice({ speaker = "narrator" }, { "Choice 1", "Choice 2" })