Lua字符长度：首字节阈值的字宽判定

-- 错误：# 数字节，汉字按三个字计
if #text > 12 then
    reject()
end

local function chsize(char)
    if char > 240 then return 4
    elseif char > 225 then return 3
    elseif char > 192 then return 2
    else return 1 end
end
local function strLen(str)
    local len, i = 0, 1
    while i <= #str do
        i = i + chsize(string.byte(str, i))
        len = len + 1
    end
    return len
end
local label = panel:getChildByName("cntText")
label:setString(tostring(strLen("侠客abc")))