Graffiti Board

--# Self clearing multi-monitor graffiti board
--# Connect to one or more 2+ tall monitor arrays
--# pastebin: eq9ht0wJ
--# Don't edit anything below this line
local tArgs = { ... }
local timeOutMinutes = (tArgs[1] and tonumber(tArgs[1])) and tonumber(tArgs[1]) or 15 --# how often the monitor(s) should be cleared (in minutes)
local TIMEOUT = math.ceil(timeOutMinutes * 60)          --# the value used by the countdown timer
local countdown = TIMEOUT                               --# the value displayed onscreen
local clearTimer = os.startTimer(1)                     --# start the clear monitor timer
local validColors = { [1] = true; [2] = true; [4] = true; [8] = true; [16] = true; [32] = true; [64] = true; [128] = true; [256] = true; [512] = true; [1024] = true; [2048] = true; [4096] = true; [8192] = true; [16384] = true, [32768] = true; } --# This is a reference table of the 16 valid single color values
local mon, monList, monNames, monX, monY, monCount = { }, { }, { }, { }, { }, 0 --# tables for monitors, monitor number by name, monitor name by number, monitor size (x & y), and a tracking variable for building the monitor name/number lookup lists

local function initMonitors(clearMon)                   --# function to find and wrap all color monitors that are 2 tall and 1 wide or bigger
  local bgColor, yPos                                   --# declare bgColor and yPos variables for use in monitor cataloging (so they aren't declared over and over for each monitor)
  mon = {                                               --# build the monitor table
    peripheral.find("monitor",                          --# search for monitors
      function(name, object)
        if object.isColor() then                        --# if the monitor is color then...
          object.setTextScale(0.5)                      --# set the text scale to 0.5
        else                                            --# ...otherwise...
          return false                                  --# don't add the monitor to the monitor table
        end
        monX[name], monY[name] = object.getSize()       --# get each monitor's size and save the values in the monX and monY tables
        if monY[name] > 15 then                         --# if the monitor is 16 'pixels' tall or taller then...
          object.setTextColor(colors.white)
          bgColor = object.getBackgroundColor()         --# save the current background color
          if clearMon then                              --# if clearMon is true then clear the monitor
            object.setBackgroundColor(colors.black)
            object.clear()
          end
          yPos = math.floor(monY[name] / 2) - 8         --# initialize the y position variable for drawing the color pips
          for color in pairs(validColors) do            --# cycle through the valid colors list
            yPos = yPos + 1                             --# increment the y position
            object.setBackgroundColor(color)            --# set the pip color
            object.setCursorPos(monX[name], yPos)       --# place the cursor at the far right and the y position
            object.write(" ")                           --# draw the color pip
          end
          object.setBackgroundColor(bgColor)            --# set the background color back to the color it was before drawing the color pips
          monCount = monCount + 1                       --# increment the monitor number tracking variable
          monList[name] = monCount                      --# add entry to the monitor name to number lookup table
          monNames[monCount] = name                     --# add entry to the monitor number to name lookup table
          return true                                   --# tell peripheral.find() to wrap the monitor in a new entry to the monitor table
        else                                            --# ...otherwise...
          return false                                  --# don't add the monitor to the monitor table
        end
      end
    )
  }
end

local function drawColorPips(i)                         --# function to clear a single monitor array and redraw the color pips
  local bgColor = mon[i].getBackgroundColor()           --# save the current background color
  mon[i].setBackgroundColor(colors.black)               --# set the monitor's background color to black
  mon[i].clear()                                        --# clear the monitor
  local yPos = math.floor(monY[monNames[i]] / 2) - 8    --# initialize the y position variable for drawing the color pips
  for color in pairs(validColors) do                    --# cycle through the valid colors table
    yPos = yPos + 1                                     --# increment the y position variable
    mon[i].setBackgroundColor(color)                    --# set the pip color
    mon[i].setCursorPos(monX[monNames[i]], yPos)        --# place the cursor at the far right and the y position
    mon[i].write(" ")                                   --# draw the color pip
  end
  mon[i].setBackgroundColor(bgColor)                    --# set the monitor's background color back to the color it was before clearing and drawing the color pips
end

term.setBackgroundColor(colors.black)
term.setTextColor(colors.white)
term.setCursorPos(1, 1)
term.clear()

initMonitors(true)                                      --# initialize the monitors (clearing them as they're initialized)
if not mon[1] then error("No valid monitor arrays found.  Attach one or more arrays that are at least 1 wide and 2 tall.\n", 0) end

print("Go draw!\n")
print("Time before clear: " .. tostring(countdown) .. "\n")
print("Press 'q' to quit")

while true do                                           --# start an infinite loop
  local event, data, x, y = os.pullEvent()              --# capture all events on the system for processing
  if event == "char" and data:lower() == "q" then       --# if a valid character was pressed on the keyboard and it was 'q' then...
    for i = 1, monCount do                              --# cycle through the monitor table (the table of wrapped monitors)
      mon[i].setBackgroundColor(colors.black)
      mon[i].clear()
    end
    term.clear()
    term.setCursorPos(1, 1)
    return                                              --# return from the loop (to nowhere) and thus exit the program
  elseif event == "monitor_touch" then                  --# if a monitor was touched then...
    if x == monX[data] then                             --# if the right margin of the monitor was touched then...
      local yPos = math.floor(monY[data] / 2) - 8       --# initialize the y position variable for tracking touches on the color pips
      for color in pairs(validColors) do                --# cycle through the valid colors table
        yPos = yPos + 1                                 --# increment the y position variable
        if y == yPos then                               --# if the touch y position == yPos then...
          mon[monList[data]].setBackgroundColor(color)  --# change the background color on the monitor
          break                                         --# stop the loop
        end
      end
    elseif x < monX[data] - 1 then                      --# if some part of the monitor at least one column to the left of the right hand margin is touched then...
      mon[monList[data]].setCursorPos(x, y)             --# set the monitor's cursor position to the touch position
      mon[monList[data]].write(" ")                     --# draw the 'pixel'
    end
  elseif event == "monitor_resize" then                 --# if a monitor is resized then...
    monX[data], monY[data] = mon[monList[data]].getSize() --# get the new size
    drawColorPips(monList[data])                        --# clear the monitor and redraw the color pips
  elseif event == "peripheral" or event == "peripheral_detach" then --# if a peripheral is attached or removed then...
    for i = monCount, 1, -1 do                          --# cycle through the monitor list (backwards)
      if monList[monNames[i]] then monList[monNames[i]] = nil end --# clear the monList table entry
      if monX[monNames[i]] then monX[monNames[i]] = nil end --# clear the monX table entry
      if monY[monNames[i]] then monY[monNames[i]] = nil end --# clear the monY table entry
      monNames[i] = nil                                 --# clear the monNames table entry
      mon[i] = nil                                      --# clear the monitor table entry
    end
    monCount = 0                                        --# reset the monitor count
    initMonitors()                                      --# re-initialize the monitors (don't clear the monitors)
  elseif event == "timer" and data == clearTimer then   --# if a timer event is captured and it is the monitor clear timer then...
    if countdown == 0 then                              --# if the countdown == 0 then...
      for i = 1, monCount do                            --# cycle through the monitor table (the table of wrapped monitors)
        drawColorPips(i)                                --# clear the monitor and redraw the color pips
      end
    end
    countdown = countdown ~= 0 and countdown - 1 or TIMEOUT --# decrement or reset countdown
    term.setCursorPos(20, 3)
    term.write(tostring(countdown) .. " ")
    clearTimer = os.startTimer(1)                       --# restart the monitor clear timer
  end
end