商城划线价：原价与折扣的对比标

-- 错误：原价现价各自为政，折扣标随手填
priceLabel:setString(now .. "（原价" .. origin .. "）")
tagLabel:setString("8折")

local function priceTag(origin, now)
    if origin <= now then
        return tostring(now), ""
    end
    local cut = math.floor((1 - now / origin) * 10 + 0.5)
    local tag = ""
    if cut >= 1 then
        tag = cut .. "折"
    end
    return now .. "（原价 " .. origin .. "）", tag
end