改进的CheckedListBox控件

这个话题似乎很早就有说了，
不过我也最近才经常接触的winform。记录之

我希望能够在CheckedListBox中实现如下的效果：

 1 1        Category.CategorysDataTable dt;            dt = new Category.CategorysDataTable();
 2 2            dt.Constraints.Add(new UniqueConstraint(dt.IDColumn));
 3 3            dt.Constraints.Add(new UniqueConstraint(dt.TableNameColumn));
 4 4            Category.CategorysRow row = dt.NewCategorysRow();
 5 5            row.ID = 1;
 6 6            row.OrginialSequence = 1;
 7 7            row.TargetSequence = 1;
 8 8            row.TableName = "TB";
 9 9            row.Flag = true;
1010            dt.AddCategorysRow(row);
1111
1212            row = dt.NewCategorysRow();
1313            row.ID = 2;
1414            row.OrginialSequence = 1;
1515            row.TargetSequence = 1;
1616            row.TableName = "TB2";
1717            row.Flag = false;
1818            dt.AddCategorysRow(row);
19            this.chklstbxTables.Items.Clear();
20            this.chklstbxTables.DataSource = dt;
21            this.chklstbxTables.DisplayMember = "TableName";
22            this.chklstbxTables.ValueMember= "Flag";

通过它，可以将CheckedListBox的复选框绑定到一个数据库的boolean型的字段上,效果如下


下面是我改造的过程

首先查了一下msdn,
http://msdn2.microsoft.com/zh-cn/library/system.windows.forms.checkedlistbox_members(VS.80).aspx
会看到如下几个属性，

DataSource

获取或设置控件的数据源。此属性与此类无关。

DisplayMember

此属性与此类无关。

ValueMember

获取或设置一个字符串，该字符串指定要从中取值的数据源的属性此属性与此类无关。

但是这三个属性是我们需要的，
使用Reflector查看了一CheckedListBox的关系
在CheckedListBox中本身已经实现了这三个属性，仅是ms使用了如下的特性，使我们不能用它了，[EditorBrowsable(EditorBrowsableState.Never), Browsable(false)]
知道了来龙去脉就好改造了，在原CheckedListBox基础上再扩展一个类ExCheckedListBox

  1using System;
  2using System.Collections.Generic;
  3using System.Text;
  4using System.ComponentModel;
  5using System.Drawing;
  6using System.Windows.Forms;
  7using System.Drawing.Design;
  8
  9namespace CustomControls
 10{
 11    /**//// <summary>
 12    /// (eraghi)
 13    /// Extended CheckedListBox with binding facilities (Value property)
 14    /// </summary>
 15    [ToolboxBitmap(typeof(CheckedListBox))]
 16    public class ExCheckedListBox : CheckedListBox
 17    {
 18        /**//// <summary>
 19        /// Default constructor
 20        /// </summary>
 21        public ExCheckedListBox()
 22        {
 23            this.CheckOnClick = true;
 24           
 25        }
 26
 27       
 28        
 29        /**//// <summary>
 30        ///    Gets or sets the property to display for this CustomControls.CheckedListBox.
 31        ///
 32        /// Returns:
 33        ///     A System.String specifying the name of an object property that is contained
 34        ///     in the collection specified by the CustomControls.CheckedListBox.DataSource
 35        ///     property. The default is an empty string ("").
 36        /// </summary>
 37        [DefaultValue("")]
 38        [TypeConverter("System.Windows.Forms.Design.DataMemberFieldConverter, System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a")]
 39        [Editor("System.Windows.Forms.Design.DataMemberFieldEditor, System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", typeof(UITypeEditor))]
 40        [Browsable(true)]
 41        public new string DisplayMember
 42        {
 43            get
 44            {
 45                return base.DisplayMember;
 46            }
 47            set
 48            {
 49                base.DisplayMember = value;
 50                
 51            }
 52        }
 53       
 54        /**//// <summary>
 55        /// Gets or sets the data source for this CustomControls.CheckedListBox.
 56        /// Returns:
 57        ///    An object that implements the System.Collections.IList or System.ComponentModel.IListSource
 58        ///    interfaces, such as a System.Data.DataSet or an System.Array. The default
 59        ///    is null.
 60        ///
 61        ///Exceptions:
 62        ///  System.ArgumentException:
 63        ///    The assigned value does not implement the System.Collections.IList or System.ComponentModel.IListSource
 64        ///    interfaces.
 65        /// </summary>
 66        [DefaultValue("")]
 67        [AttributeProvider(typeof(IListSource))]
 68        [RefreshProperties(RefreshProperties.All)]
 69        [Browsable(true)]
 70        public new object DataSource { 
 71            get 
 72            {
 73                return base.DataSource;
 74            }
 75            set 
 76            {
 77                base.DataSource = value;
 78                
 79            }
 80        }
 81        private int value;
 82        [DefaultValue(""), TypeConverter("System.Windows.Forms.Design.DataMemberFieldConverter, System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"), Editor("System.Windows.Forms.Design.DataMemberFieldEditor, System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", typeof(UITypeEditor))]
 83        [Browsable(true)]
 84        public new string ValueMember
 85        {
 86              get
 87            {
 88                /**////Gets checked items in decimal mode from binary mode
 89
 90                try
 91                {
 92                    //each item in list has a number that is binary number in decimal mode
 93                    //this number represents that number
 94                    int poweredNumber = 1;
 95                    //loop in all items of list
 96                    for (int i = 0; i < this.Items.Count; i++)
 97                    {
 98                        //if item checked and the value doesn't contains poweredNumber then
 99                        //add poweredNumber to the value
100                        if ((this.GetItemChecked(i)))
101                            this.value |= poweredNumber;
102                        //else if poweredNumber exists in the value remove from it
103                        else if ((this.value & poweredNumber) != 0)
104                            this.value -= poweredNumber;
105
106                        //raise to the power
107                        poweredNumber *= 2;
108                    }
109                }
110                catch (ArgumentException ex)
111                {
112                    throw ex;
113                }
114                catch (Exception ex)
115                {
116                    throw ex;
117                }
118
119
120                return base.ValueMember;
121            }
122            set
123            {
124                base.ValueMember = value;
125                if (base.ValueMember.ToLower() == "false")
126                    this.value = 0;
127                else
128                    this.value = 1;
129
130                try
131                {
132                    //each item in list has a number that is binary number in decimal mode
133                    //this number represents that number
134                    int poweredNumber = 1;
135                    //loop in all items of list
136                    for (int i = 0; i < this.Items.Count; i++)
137                    {
138                        //if poweredNumber exists in the value set checked on item
139                        if ((this.value & poweredNumber) != 0)
140                            this.SetItemCheckState(i, CheckState.Checked);
141                        //else remove checked from item
142                        else
143                            this.SetItemCheckState(i, CheckState.Unchecked);
144
145                        //raise to the power
146                        poweredNumber *= 2;
147                    }
148                }
149                catch (ArgumentException ex)
150                {
151                    throw ex;
152                }
153                catch (Exception ex)
154                {
155                    throw ex;
156                }
157            }
158        }
159     }
160}
161

其中控件的主要代码,这位伊郞大哥的code,link如下：
http://www.codeproject.com/cs/combobox/ExCheckedListBox.asp