C# 定义用户控件并添加属性（制作一个限定输入的文本框）

   用用户控件是我们常用的，刚搞了这方面，也记录一下。

   这里做了一个限定输入与提示的文本框：

   1.第一步：新建一个控件库项目或者直接在建好的项目右键添加：用户控件

   

 2.第二步：从工具箱里面拖动一个文本框，然后写代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace ControlText1
{
    [ToolboxBitmap(@"E/Images/Logo.Icon")]   //添加图标
    public partial class UserControl1 : UserControl
    {
        public UserControl1()
        {
            InitializeComponent();
        }
        //添加最小值属性
        protected int _userControlMinLenght1;

        public int UserControlMinLenght1
        {
            get { return _userControlMinLenght1; }
            set
            {
                if (value > 0)
                {
                    this.txtTest.MaxLength = value;
                    this._userControlMinLenght1 = value;
                }
                else
                {
                    _userControlMinLenght1 = 0;
                }
            }
        }
        //添加最大值属性
        protected int _userControlMaxLenght1;

        public int UserControlMaxLenght1
        {
            get { return _userControlMaxLenght1; }
            set
            {
                if (value > 0)
                {
                    this.txtTest.MaxLength = value;
                    this._userControlMaxLenght1 = value;
                }
                else
                {
                    _userControlMaxLenght1 = 10;
                }
            }
        }

        /// <summary>
        /// 该控件停止操作时发生
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void txtTest_Leave(object sender, EventArgs e)
        {
            try
            {

                int a = Convert.ToInt32(txtTest.Text);
                //文本框的最大值与最小值限定
                if (a < _userControlMinLenght1 || a > _userControlMaxLenght1)
                {
                    txtTest.Text = "输入有误";
                    txtTest.Font = new System.Drawing.Font(Font.FontFamily, 11, FontStyle.Italic);
                    txtTest.BackColor = ColorTranslator.FromHtml("#f7e7e7");
                }
            }
            catch (Exception)
            {
                txtTest.Text = "输入有误";
                txtTest.Font = new System.Drawing.Font(Font.FontFamily, 11, FontStyle.Italic);
                txtTest.BackColor = Color.Gray;
            }
        }
        /// <summary>
        /// 鼠标按下发生
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void txtTest_MouseDown(object sender, MouseEventArgs e)
        {
            txtTest.Text = null;
            txtTest.BackColor = Color.White;  
        }
    }
}

3.收工测试，（没问题）
这样为控件添加了两个属性：最大值与最小值，这么文本框用起来就方便多了。