Map adjustment

local startX, startY, mapX, mapY
local function dragMap(event)
    self = event.target
    if event.phase == "began" then
        startX, startY = self.viewX, self.viewY
        mapX, mapY = self.x, self.y
    elseif actor == nil and event.phase == "moved" then
        local dX, dY = event.x - event.xStart, event.y - event.yStart
        self:View(startX + math.floor(dX / size), startY + math.floor(dY / size))
        self.x, self.y = (mapX + dX) % size, (mapY + dY) % size
    end
end