Dammit

--[[
Scrolling input display for Capcom 6-button fighters
written by Dammit (dammit9x at hotmail dot com)
version 11/18/2009

Works with FBA, snes9x and Gens:
http://code.google.com/p/fbarr/downloads/list
http://code.google.com/p/snes9x-rr/downloads/list
http://code.google.com/p/gens-rerecording/downloads/list

The files gd.dll and lua51.dll must be with the emulator exe.
They can be found in these packages:
http://luaforge.net/frs/download.php/1594/lua-gd-2.0.33r2-win32.zip
http://luaforge.net/frs/download.php/3677/lua5_1_4_Win32_bin.zip

You may tweak the parameters above the dashed line.
Positioning is optimized for CPS1-2-3. The x[2] value must be reduced for the other emus.

You may use your own images, but their filenames must conform to "(imageset)-(gamekey).png"
For gens, the images must be in the same place as gens.exe.
For fba and snes9x, the images must be with the lua script.

Possible improvements:
save and load data in savestates: not all emus have savestate.* lua functions
add pcsx: needs better lua support
add pcejin: needs better lua support
add vba: more research needed
]]

local imageset="sf4"              --the prefix that must be on image files
local timeout=240                 --how many idle frames until old records are cleared
local buffersize=10               --how many records to show
local x={[1]=0x00,[2]=0x120}      --horizontal starting position
local y=0x20                      --vertical starting position
local dx,dy=0x10,0x10             --how far apart to space the symbols
local opacity=0.8                 --factor by which to multiply the opacity of the images
local draw={[1]=true,[2]=true}    --whether to draw each player's commands
local switch={[1]="Q",[2]="W"}    --key used to toggle each player on/off

----------------------------------------------------------------------------------------------------
require "gd"
local thisframe,lastframe,oldswitch,e,keyset,ghetto,changed={},{},{}
local inp={[1]={},[2]={}}
local idle={[1]=0,[2]=0}
local emulator={snes9x,gens,fba}
local gamekeys={
    "ul","ur","dl","dr",
    { "l",  "left", "left",        "Left"},
    { "r", "right","right",       "Right"},
    { "u",    "up",   "up",          "Up"},
    { "d",  "down", "down",        "Down"},
    {"LP",     "Y",    "X",  "Weak Punch"},
    {"MP",     "X",    "Y","Medium Punch"},
    {"HP",     "L",    "Z","Strong Punch"},
    {"LK",     "B",    "A",   "Weak Kick"},
    {"MK",     "A",    "B", "Medium Kick"},
    {"HK",     "R",    "C", "Strong Kick"},
    { "S","select", "none",       "Start"}  --taunt button
}

for index,name in ipairs(gamekeys) do --Check if all the images are present.
    local file=imageset..(name[1] or name)..".png"
    if not io.open(file,"rb") then
        print(file,"not found.")
        ghetto=true
    end
end
if ghetto then print("Falling back on ghetto mode.") end

for k,emu in pairs(emulator) do --Detect what emulator this is.
    if emu then
        keyset=k+1
        e=emu
        break
    end
    error("This script doesn't work on this emulator yet.")
end

local function toggleplayer(p)
    local nowswitch=input.get()[switch[p]] --Press the "switch" keys to toggle display for each char.
    if nowswitch and not oldswitch[p] then
        if not draw[p] then draw[p]=true
        else draw[p]=false
        end
    end
    oldswitch[p]=nowswitch
end

local function filterinput(p,f)
    for pressed,state in pairs(joypad.getdown(p)) do --Check current controller state >
        for index,name in pairs(gamekeys) do           --but ignore non-gameplay buttons.
            if pressed==name[keyset] or pressed=="P"..p.." "..tostring(name[keyset]) then
                f[name[1]]=state --FBA does not distinguish joypads, so inputs must be filtered by "P1" and "P2".
                break
            end
        end
    end
end

local function compositeinput(f)
    for _,a in pairs({"u","d"}) do --Convert individual directions to diagonals.
        for _,b in pairs({"l","r"}) do
            if f[a] and f[b] then
                f[a],f[b]=nil,nil
                f[a..b]=true
            end
        end
    end
end

local function detectchanges(f1,f2)
    changed=false
    for key,state in pairs(f2) do --If a key is pressed >
        if not f1[key] then         --that wasn't pressed last frame >
            changed=true              --then changes were made.
        end
    end
end

local function updaterecords(p,f2,i)
    if changed then                     --If changes were made >
        if idle[p]<timeout then           --and the player hasn't been idle too long>
            for record=buffersize,2,-1 do
                i[record]=i[record-1]         --then shift every old record by 1 >
            end
        else
            for record=buffersize,2,-1 do
                i[record]=nil                 --otherwise wipe out the old records.
            end
        end
        idle[p]=0                         --Reset the idle count >
        i[1]={}                           --and set current input as record 1 >
        local index=1
        for _,name in ipairs(gamekeys) do --but the order must not deviate from gamekeys.
            for key,state in pairs(f2) do
                if key==name[1] or key==name then
                    i[1][index]=key
                    index=index+1
                    break
                end
            end
        end
    else idle[p]=idle[p]+1              --Increment the idle count if nothing changed.
    end
end

local function displayrecords(p,i)
    if draw[p] then
        for line,stuff in pairs(i) do
            for index,key in pairs(i[line]) do
                if not ghetto then
                    gui.gdoverlay(x[p]+index*dx,y+line*dy,gd.createFromPng(imageset..key..".png"):gdStr(),opacity)
                else
                    gui.text(x[p]+index*dx,y+line*dy,key) --Ghetto mode displays text symbols only.
                end
            end
        end
    end
end

e.registerbefore(function()
    for player=1,2 do
        thisframe={}
        toggleplayer(player)
        filterinput(player,thisframe)
        compositeinput(thisframe)
        detectchanges(lastframe[player],thisframe)
        updaterecords(player,thisframe,inp[player])
        lastframe[player]=thisframe
    end
end)

gui.register(function()
    gui.text(0,0,"")
    for player=1,2 do
        displayrecords(player,inp[player])
    end
end)