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[[Engine_Development|Development]] < [[Lua_Scripting|Lua Scripting]] < {{FULLPAGENAME}}



Here are some examples of small widgets, with useful code to get you started! 



To play with each example, place the code into a "my_new_widget_name.lua" file in your Spring/LuaUI/widgets dir (create it if not already present) and run Spring with any game. Your widget should then appear ingame!



To see many more examples, check out the LuaUI/widgets directory of the games in [[Gamedev:PublicRepos|PublicRepos]]. 



Note that every widget (and gadget) must include a GetInfo() callin, but all other callins are optional.



==Example 1==

The "hello world" example, with a ticking clock.



<code><pre>

function widget:GetInfo()

   return {

      name         = "Name as shown in widget list",

      desc         = "Description as normally shown in tooltip",

      author       = "It could be you!",

      date         = "now",

      license      = "PD", -- should be compatible with Spring

      layer        = 0,

      enabled      = true

   }

end



local helloWorld = "I STARTED LOOK AT ME JIM!"

local toggle



function widget:Initialize()

   Spring.Echo(helloWorld)

end



function widget:Update()

   if (toggle == true) then

      Spring.Echo("TOCK")

      toggle = false

   else

      Spring.Echo("TICK")

      toggle = true

   end

end

</pre></code>



==Example 2==

How to make stuff happen when units do stuff.

<code><pre>

function widget:GetInfo()

   return {

      name         = "Unit Announcer",

      desc         = "Units are proud to be alive",

      author       = "Some guy",

      date         = "I don't know why we include dates",

      license      = "GPLv2 or later",

      layer        = 0,

      enabled      = true

   }

end



local machoUnits = {}



function widget:UnitCreated(unitID, unitDefID, unitTeam, builderID)

  Spring.Echo("HELLO")



  local humanName = UnitDefs[unitDefID].humanName

  local numWeapons = #UnitDefs[unitDefID].weapons

  local plural = numWeapons~=1 and "s" or ""



  Spring.Echo("I am unit " .. unitID .. ". I am a " .. humanName .. ".")

  Spring.Echo("I have " .. numWeapons .. " weapon" .. plural .. ".")

  if numWeapons>0 then

    machoUnits[unitID] = true

  end

end



function widget:UnitDestroyed(unitID, unitDefID, unitTeam, attackerID, attackerDefID, attackerTeam)

  machoUnits[unitID] = nil

end 



function widget:UnitDamaged(unitID, unitDefID, unitTeam, damage, paralyzer, weaponDefID, projectileID, attackerID, attackerDefID, attackerTeam)

  if machoUnits[unitID] then return end



  local n = math.random(3,10)

  local ow = "O"

  for i=1,n do

    ow = ow .. "W"

  end

  Spring.Echo(ow)

end

</pre></code>



==Example 3==

Something actually useful.

<code><pre>

function widget:GetInfo()

  return {

    name      = "Stop means Stop",

    desc      = "Cancels Self D orders when unit is given a stop command",

    author    = "enotseulB",

    date      = "GPL v2 or later",

    license   = "Feb 2015",

    layer     = 0,

    enabled   = true  

  }

end



local CMD_STOP = CMD.STOP



function widget:UnitCommand(unitID, unitDefID, teamID, cmdID, cmdParams, cmdOptions)

    if cmdID ~= CMD_STOP then return end

    if not unitID then return end

    if teamID ~= Spring.GetMyTeamID() then return end



    if (Spring.GetUnitSelfDTime(unitID) > 0) then

        Spring.GiveOrderToUnit(unitID, CMD.SELFD, {}, {})

    end 

end

</pre></code>

[[category: Lua]]
Lua:Tutorial GettingStarted - Revision history

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