CC Paint v1.1

args = {...}

local colorList = { colors.white, colors.orange, colors.magenta, colors.lightBlue, colors.black, colors.yellow, colors.lime, colors.pink, colors.gray, colors.lightGray, colors.cyan, colors.purple, colors.blue, colors.brown, colors.green, colors.red }
local pickedColor = {colors.blue, colors.red, colors.black}
local buttons = { "L", "R", "M" }
local paintSurface = {}

local colorPickingMode = 0 -- 0 = mouse, 1 = background

local backgroundColor = colors.black

function setPixel(x, y, value)
    row = paintSurface[y]
    if row == nil then
        paintSurface[y] = {}
        row = paintSurface[y]
    end

    row[x] = value
end

function getPixel(x, y)
    row = paintSurface[y]

    if row == nil then return nil end
    return row[x]
end

local colorIndexes = {}
for i=0,16 do
    colorIndexes[2^i] = i
end

local sColorIndex = "0123456789abcdef"

function exportNFP(filename)
    file = io.open(filename, "w")

    for y=1, 19 do
        for x=1,51 do
            color = getPixel(x, y)
            if color == nil then
                color = " "
            else
                --print(color)
                --os.pullEvent("char")
                color = colorIndexes[color] + 1
                color = string.sub(sColorIndex, color, color)
            end

            file:write(color)
        end
            file:write("\n")

    end

    file:close()
end

function save(filename)
    local saveFile = {}
    saveFile.version = 1.1
    saveFile.image = paintSurface

    local savingString = textutils.serialize(saveFile)

    file = io.open(filename, "w")
    file:write(savingString)
    file:close()
end

function loadNFP(filename)
    local file = fs.open(filename, "r")

    paintSurface = {}

    local y = 1

    while true do
        local line = file.readLine()
        if line == nil then break end

        for i=1, #line do
            local char = string.sub(line, i, i)

            local color = nil

            local colorNumber = string.find(sColorIndex, char)
            if colorNumber ~= nil then
                color = 2^(colorNumber - 1)
            end

            if color ~= nil then
                setPixel(i, y, color)
            end

        end

        y = y + 1
    end



    file.close()
end

function load(filename)
    local file = io.open(filename)
    local imageText = file:read("*l")
    file:close()

    local inTable = textutils.unserialize(imageText)

    if type(inTable) ~= "table" then -- We are loading NFP file
        loadNFP(filename)
        return
    end

    if inTable.version == nil then -- We are using old save format
        for k,v in pairs(inTable) do
                local x = math.floor(k / 52)
                local y = k % 52

                setPixel(x, y, v)
        end
        return
    end

    paintSurface = {}
    paintSurface = inTable.image
end

function messageDialog(message)
    term.setBackgroundColor(colors.black)
    term.clear()

    term.setCursorPos(2, 2)
    term.write(message)
    term.setCursorPos(2, 4)
    term.write("Press any key to continue...")

    os.pullEvent("key")
end

function exportDialog()
    term.setBackgroundColor(colors.black)
    term.clear()

    term.setCursorPos(2, 2)
    term.write("Enter save name:")
    term.setCursorPos(19, 2)

    local filename = read()

    exportNFP(filename)

    messageDialog("Image exported sucessfully!")
end

function saveDialog()
    term.setBackgroundColor(colors.black)
    term.clear()

    term.setCursorPos(2, 2)
    term.write("Enter save name:")
    term.setCursorPos(19, 2)

    local filename = read()

    save(filename)

    messageDialog("Image saved sucessfully!")
end


function loadDialog()
    term.setBackgroundColor(colors.black)
    term.clear()

    term.setCursorPos(2, 2)
    term.write("Enter name of the saved picture:")
    term.setCursorPos(35, 2)

    local filename = read()

    if not fs.exists(filename) then
        messageDialog("Entered file does not exist!")
        return
    end

    load(filename)

    messageDialog("Image loaded sucessfully!")
end

function colorPicked(color, button)
    if colorPickingMode == 0 then
        pickedColor[button] = color
    elseif colorPickingMode == 1 then
        backgroundColor = color
        colorPickingMode = 0
    end
end

function handleMenuClick(x, y, button)
    if y == 3 then -- Color picker
        for k,v in pairs(colorList) do
            colorStartX = (k - 1) * 2 + 1
            if x >= colorStartX and x <= colorStartX + 2 then
                colorPicked(v, button)
                break
            end
        end
    elseif y == 5 then -- Color options
        if x >= 21 and x <= 22 then --Background
            colorPickingMode = 1
        end
    elseif y == 17 then -- Buttons
        if x >= 34 and x <= 39 then -- EXIT button
            term.setBackgroundColor(colors.black)
            term.setCursorPos(1,1)
            term.clear()

            return false
        elseif x >= 2 and x <= 6 then -- NEW button
            paintSurface = {}
            return
        elseif x >= 12 and x <= 17 then -- SAVE button
            saveDialog()
            return
        elseif x >= 23 and x <= 28 then -- LOAD button
            loadDialog()
            return
        end
    elseif y == 19 then -- Second row of buttons
        if x >= 2 and x <= 13 then -- EXPORT button
            exportDialog()
            return
        end
    end

    return true
end

function showMenu()
    term.setBackgroundColor(colors.black)

    while true do
        term.clear()

        term.setCursorPos(2,1)
        term.write("Color Picker:")

        local colorX = 2
        for k,v in pairs(colorList) do
            term.setCursorPos(colorX, 3)
            term.setBackgroundColor(v)
            term.write("||")

            colorX = colorX + 2
        end

        colorX = colorX + 4

        for i=1,3 do
            term.setCursorPos(colorX, 3)
            term.setBackgroundColor(pickedColor[i])
            term.write("||")

            term.setCursorPos(colorX, 2)
            term.setBackgroundColor(colors.black)
            term.write(buttons[i])

            colorX = colorX + 2

        end

        term.setBackgroundColor(colors.black)

        term.setCursorPos(2, 5)
        term.write("Background Color: ")
        term.setCursorPos(21, 5)
        if colorPickingMode == 1 then
            term.write("?")
        else
            term.setBackgroundColor(backgroundColor)
            term.write("||")
            term.setBackgroundColor(colors.black)
        end

        term.setCursorPos(2, 14)
        term.write("Options:")

        term.setCursorPos(2, 17)
        term.write("[NEW]")

        term.setCursorPos(12, 17)
        term.write("[SAVE]")

        term.setCursorPos(23, 17)
        term.write("[LOAD]")

        term.setCursorPos(34, 17)
        term.write("[EXIT]")

        term.setCursorPos(2, 19)
        term.write("[EXPORT NFP]")


        while true do
            event, button, x, y = os.pullEvent()

            if event == "mouse_click" then -- Handle clicks
                local returned = handleMenuClick(x, y, button)
                if returned == false then return false end -- We got exit. Terminate everything
                if returned == nil then return true end -- We got no return. Just close down menu.

                break
            elseif event == "key" and button == 57 then -- Return to painting if space is pressed
                return true
            end
        end
    end
end

function initPaintingSurface()
    term.setBackgroundColor(backgroundColor)
    term.clear()

    -- Load everything from saved image
    for y,row in pairs(paintSurface) do
        for x,color in pairs(row) do
            term.setBackgroundColor(color)

            term.setCursorPos(x, y)
            term.write(" ")

        end
    end
end

if args[1] ~= nil and fs.exists(args[1]) then
    load(args[1])
end

initPaintingSurface()

while true do
    event, key, x, y = os.pullEvent()

    if event == "mouse_click" then
        local color = pickedColor[key]
        if color == nil then
            pickedColor = color[3]
        end

        setPixel(x, y, color)
        term.setBackgroundColor(color)
        term.setCursorPos(x, y)
        term.write(" ")
        --print(x .. " " .. y)
    elseif event == "key" and key == 57 then
        if not showMenu() then break end
        initPaintingSurface()
    end
end