一个自定义的数字输入框控件

一个自定义的数字输入框控件

        项目开发中经常会用到只允许输入数字的文本框控件。虽然很多第三方控商已经提供了不少此类优秀的控件，但是我们为什么就不能自已动手也来DIY一把呢。以下就是本人的一个小例子：

        我的设计思路是在用户每次敲击键盘时对键入的字符进行校验以过滤不合法的字符。在文本框失去焦点时再对录入的数据进行一次校验以符合预定的格式。以下是该控件的实现代码。

  1using System;
  2using System.Collections.Generic;
  3using System.ComponentModel;
  4using System.Drawing;
  5using System.Data;
  6using System.Text;
  7using System.Windows.Forms;
  8
  9namespace Nelson.ControlLibrary
 10{
 11    public partial class NumberBox : System.Windows.Forms.TextBox
 12    {
 13        public NumberBox()
 14        {
 15            InitializeComponent();
 16        }
 17
 18        自定义成员#region 自定义成员
 19        private int maxIntegerLength = 10;
 20        private int minIntegerLength = 0;
 21        private int maxDecimalLength = 4;
 22        private int minDecimalLength = 0;
 23        private int integerLength;
 24        private int decimalLength;
 25        #endregion
 26
 27        自定义属性#region 自定义属性
 28        /**//// <summary>
 29        /// 最大整数位数
 30        /// </summary>
 31        public int MaxIntegerLength
 32        {
 33            get
 34            {
 35                return maxIntegerLength;
 36            }
 37            set
 38            {
 39                if (value >= 0 && value >= minIntegerLength)
 40                {
 41                    maxIntegerLength = value;
 42                }
 43                else
 44                {
 45                    throw new Exception("最大整数位数不应小于最小整数位数");
 46                }
 47            }
 48        }
 49
 50        /**//// <summary>
 51        /// 最小整数位数
 52        /// </summary>
 53        public int MinIntegerLength
 54        {
 55            get
 56            {
 57                return minIntegerLength;
 58            }
 59            set
 60            {
 61                if (value >= 0 && value <= maxIntegerLength)
 62                {
 63                    minIntegerLength = value;
 64                }
 65                else
 66                {
 67                    throw new Exception("最小整数位数不应大于最大整数位数");
 68                }
 69            }
 70        }
 71
 72        /**//// <summary>
 73        /// 最大小数位数
 74        /// </summary>
 75        public int MaxDecimalLength
 76        {
 77            get
 78            {
 79                return maxDecimalLength;
 80            }
 81            set
 82            {
 83                if (value >= 0 && value >= minDecimalLength)
 84                {
 85                    maxDecimalLength = value;
 86                }
 87                else
 88                {
 89                    throw new Exception("最大小数位数不应小于最小小数位数");
 90                }
 91            }
 92        }
 93
 94        /**//// <summary>
 95        /// 最小小数位数
 96        /// </summary>
 97        public int MinDecimalLength
 98        {
 99            get
100            {
101                return minDecimalLength;
102            }
103            set
104            {
105                if (value >= 0 && value <= maxDecimalLength)
106                {
107                    minDecimalLength = value;
108                }
109                else
110                {
111                    throw new Exception("最小小数位数不应大于最大小数位数");
112                }
113            }
114        }
115        #endregion
116
117        重写方法#region 重写方法
118        protected override void OnKeyPress(KeyPressEventArgs e)
119        {
120            int editIndex = SelectionStart;         //获取当前编辑位
121
122            if (e.KeyChar == (char)Keys.Back) return;   //放行"退格"键
123
124            if (e.KeyChar.Equals('.') || Char.IsNumber(e.KeyChar)) //过滤非数字与非小数点
125            {
126                if (Text.IndexOf(".") > -1)     //是否存在小数点
127                {
128                    //禁止重复输入小数点
129                    if (e.KeyChar.Equals('.'))
130                    {
131                        e.Handled = true;
132                        return;
133                    }
134                    else
135                    {
136                        if (SelectedText.Length > 0)
137                        {
138                            return;
139                        }
140
141                        integerLength = Text.IndexOf(".");
142                        decimalLength = Text.Length - integerLength - 1;
143
144                        //控制最大小数位数
145                        if (decimalLength >= maxDecimalLength && editIndex > Text.IndexOf("."))
146                        {
147                            e.Handled = true;
148                            return;
149                        }
150
151                        //控制最大整数位数
152                        if (integerLength >= maxIntegerLength && editIndex <= Text.IndexOf("."))
153                        {
154                            e.Handled = true;
155                            return;
156                        }
157                    }
158                }
159                else
160                {  
161                    //控制最大整数位数
162                    integerLength = Text.Length;
163                    if (integerLength == maxIntegerLength && !e.KeyChar.Equals('.'))
164                    {
165                        e.Handled = true;
166                    }
167                }
168            }
169            else
170            {
171                e.Handled = true;
172            }
173
174            base.OnKeyPress(e);
175        }
176
177
178        protected override void OnLeave(EventArgs e)
179        {
180            if (Text == null || Text == "") return;
181
182            Text = Text.TrimStart('0');
183
184            //取整数位数与小数位数
185            if (Text.IndexOf(".") == -1)
186            {
187                integerLength = Text.Length;
188                decimalLength = 0;
189            }
190            else
191            {
192                integerLength = Text.IndexOf(".");
193                decimalLength = Text.Length - integerLength - 1;
194                
195                //验证小数位数是否符合最小值(不足补零)            
196                if (decimalLength < minDecimalLength)
197                {
198                    Text = Text.PadRight(integerLength + minDecimalLength + 1, '0');
199                }
200            }
201
202            //整数未输自动补零
203            if (integerLength == 0)
204            {
205                Text = "0" + Text;
206            }
207
208            //验证整数位数是否符合最小值
209            if (integerLength < minIntegerLength)
210            {
211                Focus();
212                Select(0, integerLength);
213            }
214
215            //验证整数位数是否符合最大值
216            if (integerLength > maxIntegerLength)
217            {
218                Focus();
219                Select(0, integerLength);
220            }
221            base.OnLeave(e);
222        }
223        #endregion
224    }
225}
226