Unity文本截取长度，超出部分使用省略号代替

/// <summary>文字长度截取(超出部分使用...代替)</summary>
        public static string InterceptionLength(string str, int length)
        {
            if (string.IsNullOrEmpty(str)) return null;
            if (str.Length <= length) return str;

            string temp = null;

            float count=0;

            for (int i = 0; i < str.Length; i++)
            {
                if(str[i].Equals('@')|| str[i].Equals('￥') || str[i].Equals('%'))
                {
                    count += 1;
                }
                else
                {
                    if (str[i] > 127) count += 1;
                    else count += 0.5f;
                }
            
                if (count - length > -0.5f)
                {
                    break;
                }
                else temp += str[i];
            }

            return temp+="...";
        }