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 ;
10 10 dt.AddCategorysRow(row);
11 11
12 12 row = dt.NewCategorysRow();
13 13 row.ID = 2 ;
14 14 row.OrginialSequence = 1 ;
15 15 row.TargetSequence = 1 ;
16 16 row.TableName = " TB2 " ;
17 17 row.Flag = false ;
18 18 dt.AddCategorysRow(row);
19 this .chklstbxTables.Items.Clear();
20 this .chklstbxTables.DataSource = dt;
21 this .chklstbxTables.DisplayMember = " TableName " ;
22 this .chklstbxTables.ValueMember = " Flag " ;
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
1 using System;
2 using System.Collections.Generic;
3 using System.Text;
4 using System.ComponentModel;
5 using System.Drawing;
6 using System.Windows.Forms;
7 using System.Drawing.Design;
8
9 namespace 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
http://www.codeproject.com/cs/combobox/ExCheckedListBox.asp
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