winform input 输入数值（可以小数，负数）

    public partial class UCNumberBox : UserControl
    {
        public UCNumberBox()
        {
            InitializeComponent();
        }

        private bool _IsDecimal = true;

        /// <summary>
        /// 是否为小数,默认为小数
        /// </summary>
        public bool IsDecimal
        {
            get { return _IsDecimal; }
            set
            {
                _IsDecimal = value;

                if (!value && this.tbValue.Text.IndexOf('.') >= 0)
                {
                    tbValue.Text = tbValue.Text.Substring(0, tbValue.Text.IndexOf('.'));
                    tbValue.SelectionStart = tbValue.Text.Length;
                }
                if (value && _Precision == 0)
                {
                    _Precision = 2;
                }
            }
        }

        private int _Precision = 2;

        public int Precision
        {
            get { return _Precision; }
            set
            {
                if (value < 0)
                {
                    throw new ArgumentOutOfRangeException(nameof(Precision), "精度不能小于0");
                }
                _Precision = value;
                if (value == 0)
                {
                    _IsDecimal = false;
                }
            }
        }

        private void tbValue_KeyPress(object sender, KeyPressEventArgs e)
        {
            // 先排除非需要的字符
            if (!char.IsDigit(e.KeyChar)
                  && e.KeyChar != '.'
                  && e.KeyChar != '-'
                  && e.KeyChar != '.'
                  && e.KeyChar != '\b')
            {
                e.Handled = true;
            }

            if (e.Handled || e.KeyChar == '\b')
            {
                return;
            }

            // 去掉0开头的证书，类似：0123
            if (tbValue.Text == "0" && char.IsDigit(e.KeyChar))
            {
                if (e.KeyChar != '0')
                {
                    tbValue.Text = e.KeyChar.ToString();
                    tbValue.SelectionStart = 1;
                }
                e.Handled = true;
            }
            // 负号只能出现在第一位
            else if (tbValue.Text.Length > 0 && (e.KeyChar == '-'))
            {
                e.Handled = true;
            }
            // 排除 -0123这种
            else if (tbValue.Text == "-0" && char.IsDigit(e.KeyChar))
            {
                if (e.KeyChar != '0')
                {
                    tbValue.Text = "-" + e.KeyChar.ToString();
                    tbValue.SelectionStart = 2;
                }
                e.Handled = true;
            }

            //整数，不能出现小数点
            if (!IsDecimal && e.KeyChar == '.')
            {
                e.Handled = true;
            }
            // 小数
            else if (IsDecimal)
            {
                if (e.KeyChar == '.')
                {
                    // 替换小数点开头的=》0.
                    if (tbValue.Text.Length == 0)
                    {
                        tbValue.Text = "0.";
                        tbValue.SelectionStart = 2;
                        e.Handled = true;
                    }
                    // 不能重复插入小数点
                    else if (tbValue.Text.IndexOf('.') >= 0)
                    {
                        e.Handled = true;
                    }
                    IsInputD = !e.Handled;
                }
                if (!e.Handled && tbValue.Text.IndexOf('.') >= 0)
                {
                    // 校验小数位数
                    var ss = tbValue.Text.Split('.');
                    if (ss[1].Length >= Precision)
                    {
                        e.Handled = true;
                    }
                }
            }
        }

        private bool IsInputD = false;

        private void tbValue_TextChanged(object sender, EventArgs e)
        {
            // 在中间插入小数时，需要保证小数位数不超出指定精度
            if (IsInputD)
            {
                IsInputD = false;
                var ss = tbValue.Text.Split('.');
                if (ss[1].Length > Precision)
                {
                    var format = "".PadLeft(Precision, '0');
                    tbValue.Text = double.Parse(tbValue.Text).ToString("0." + format);
                    tbValue.SelectionStart = tbValue.Text.Length;
                }
            }
        }
    }