Pixel Canvas API

Character = {}
Character.__index = Character

function Character.create()
    local self = {}
    setmetatable(self, Character)

    self.textColor = colors.white
    self.backgroundColor = colors.black
    self.pixelMode = false
    self.character = " "
    self.pixel = {{false, false, false},{false, false, false}}
    self.invert = false
    return self
end

function Character:update()
    if self.pixelMode then
        local char = 128
        if not self.pixel[2][3] then
            char = char + (self.pixel[1][1] and 1 or 0)
            char = char + (self.pixel[2][1] and 2 or 0)
            char = char + (self.pixel[1][2] and 4 or 0)
            char = char + (self.pixel[2][2] and 8 or 0)
            char = char + (self.pixel[1][3] and 16 or 0)
            self.invert = false
        else
            char = char + (self.pixel[1][1] and 0 or 1)
            char = char + (self.pixel[2][1] and 0 or 2)
            char = char + (self.pixel[1][2] and 0 or 4)
            char = char + (self.pixel[2][2] and 0 or 8)
            char = char + (self.pixel[1][3] and 0 or 16)
            self.invert = true
        end
        self.character = string.char(char)
    end
end

function Character:draw()
    if not self.invert then
        term.setBackgroundColor(self.backgroundColor)
        term.setTextColor(self.textColor)
    else
        term.setBackgroundColor(self.textColor)
        term.setTextColor(self.backgroundColor)
    end
    term.write(self.character)
end

Canvas = {}
Canvas.__index = Canvas

function Canvas.create()
    local self = {}
    setmetatable (self, {__index=Canvas})

    self.x = 1
    self.y = 1
    self.character = {}
    local w, h = term.getSize()
    self:setSize(w, h)

    return self
end

function Canvas:setSize(width, height)
    self.__width = width
    self.__height = height
    self.character = {}
    for i=1, self.__width do
        self.character[i] = {}
        for j=1, self.__height do
            self.character[i][j] = Character.create()
        end
    end
end

function Canvas:draw()
    for j=self.y,(self.__height + self.y - 1) do
        term.setCursorPos(self.x, j)
        for i=self.x,(self.__width + self.x - 1) do
            self.character[i][j]:draw()
        end
    end
end

function Canvas:setPixel(x, y, value)
    x = x - 1
    y = y - 1
    local charX = math.floor(x / 2)
    local charY = math.floor(y / 3)
    pixelX = x - charX * 2
    pixelY = y - charY * 3
    charX = charX + 1
    charY = charY + 1
    self.character[charX][charY].pixelMode = true
    self.character[charX][charY].pixel[pixelX + 1][pixelY + 1] = value;
    self.character[charX][charY]:update()
end

function Canvas:setCharacter(x, y, char)
    self.character[charX][charY].invert = false
    self.character[charX][charY].pixelMode = false
    self.character[charX][charY].character = char;
end