input_callback.lua

-- This simple example looks at input events to set text on the screen
-- showing one button that is being pressed.  Because it doesn't use a list
-- of text actors, if multiple buttons are pressed it will only show info for
-- the last one.

-- The Config Key/Joy screen lists all buttons in the current game mode.

-- button_text and game_button_text will be set to actors when those actors
-- are created.  These local variables exist to skip the hassle of calling
-- GetChild.
local button_text= false
local game_button_text= false
-- button_text will be used to show the button field from the input event,
-- and game_button_text will be used for the GameButton field.  These two
-- fields can be different because Stepmania has the OnlyDedicatedMenuButtons
-- preference.  That preference is intended to make it so that only the menu
-- buttons (MenuLeft, MenuRight, MenuUp, MenuDown, commonly only MenuLeft and
-- MenuRight on cabinets) can be used in menus.  If OnlyDedicatedMenuButtons
-- is false, then Left will be translated to MenuLeft, and the GameButton
-- field will be set to MenuLeft when Left on the pad is pressed.
-- This digression about menu button translation really only matters to
-- themers trying to make a good menu control scheme.  For a simfile played
-- on a cabinet, GameButton will usually be nil, because most cabinets are
-- set not to map the pads to the menu buttons.

-- Since both text actors will have their text formatted the same way, it's
-- useful to make a wrapper function to avoid duplicating the formatting.
-- When the formatting changes, say changing spaces to colons, only
-- set_button_text needs to change.
local function set_button_text(text_actor, pn, button, press_type)
   text_actor:settext(
      ToEnumShortString(pn) .. " " .. tostring(button) .. " " .. press_type)
end

-- Lua.xml lists all the parts of the event table.
local function input(event)
   -- If a button that is not mapped to any player is pressed, the
   -- PlayerNumber field will be nil.  Otherwise, it will be PLAYER_1 or
   -- PLAYER_2.
   if not event.PlayerNumber then return end
   -- The delay between FirstPress and Repeat is set by the RepeatDelay metric for the screen.
   -- The number of repeats per second is set by the RepeatRate metric.
   local press_type= ToEnumShortString(event.type)
   set_button_text(button_text, event.PlayerNumber, event.button, press_type)
   set_button_text(game_button_text, event.PlayerNumber, event.GameButton, press_type)
end

return Def.ActorFrame{
   -- The sleeper actor so this can be used in a bgchange lua file and the
   -- file won't be unloaded.  Don't do this in a screen file in a theme.
   Def.Actor{InitCommand= function(self) self:hibernate(1000) end},
   -- AddInputCallback cannot be in an InitCommand.  InitCommands happen
   -- before the screen is the top screen, so calling GetTopScreen during an
   -- InitCommand would fetch the screen that is about to be destroyed.
   OnCommand= function(self)
      SCREENMAN:GetTopScreen():AddInputCallback(input)
   end,
   Def.BitmapText{
      Font= "Common Normal", InitCommand= function(self)
         -- Since button_text is set inside an InitCommand, it occurs before the
         -- OnCommand that adds the input callback, so the input callback
         -- doesn't need to worry about whether button_text is initialized.
         button_text= self
         -- Lua is whitespace insensitive, so sticking a line break before a
         -- colon in the middle of a chain of functions is valid.
         self:xy(_screen.cx, _screen.cy-12)
         -- Colors are just tables of four numbers.  Using html strings and the
         -- color function would also work.
            :DiffuseAndStroke({.75, .75, 0, 1}, {0, 0, 0, 1})
      end
   },
   Def.BitmapText{
      Font= "Common Normal", InitCommand= function(self)
         game_button_text= self
         self:xy(_screen.cx, _screen.cy+12)
            :DiffuseAndStroke({.75, 0, .75, 1}, {0, 0, 0, 1})
      end
   },
}