使用VB.NET开发复合控件

  1 Public Class SelectCombo
  2   Inherits System.Windows.Forms.UserControl
  3 
  4   ' Make the width of the area for the buttons 100 twips
  5   Dim mnButtonAreaWidth As Integer = 100
  6 
  7   ' Set minimum height and width for the control
  8   Dim mnMinControlWidth As Integer = 200
  9   Dim mnMinControlHeight As Integer = 200
 10 
 11 
 12 #Region " Windows Form Designer generated code "
 13 
 14   Public Sub New()
 15     MyBase.New()
 16 
 17     'This call is required by the Windows Form Designer.
 18     InitializeComponent()
 19 
 20     'Add any initialization after the InitializeComponent() call
 21 
 22   End Sub
 23 
 24   'UserControl1 overrides dispose to clean up the component list.
 25   Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
 26     If disposing Then
 27       If Not (components Is Nothing) Then
 28         components.Dispose()
 29       End If
 30     End If
 31     MyBase.Dispose(disposing)
 32   End Sub
 33 
 34   'Required by the Windows Form Designer
 35   Private components As System.ComponentModel.IContainer
 36 
 37   'NOTE: The following procedure is required by the Windows Form Designer
 38   'It can be modified using the Windows Form Designer.  
 39   'Do not modify it using the code editor.
 40   Friend WithEvents lstSource As System.Windows.Forms.ListBox
 41   Friend WithEvents btnAdd As System.Windows.Forms.Button
 42   Friend WithEvents btnAddAll As System.Windows.Forms.Button
 43   Friend WithEvents lstTarget As System.Windows.Forms.ListBox
 44   Friend WithEvents btnRemove As System.Windows.Forms.Button
 45   Friend WithEvents btnClear As System.Windows.Forms.Button
 46   <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
 47         Me.lstSource = New System.Windows.Forms.ListBox()
 48         Me.btnAdd = New System.Windows.Forms.Button()
 49         Me.btnAddAll = New System.Windows.Forms.Button()
 50         Me.btnRemove = New System.Windows.Forms.Button()
 51         Me.btnClear = New System.Windows.Forms.Button()
 52         Me.lstTarget = New System.Windows.Forms.ListBox()
 53         Me.SuspendLayout()
 54         '
 55         'lstSource
 56         '
 57         Me.lstSource.Dock = System.Windows.Forms.DockStyle.Left
 58         Me.lstSource.ItemHeight = 12
 59         Me.lstSource.Location = New System.Drawing.Point(0, 0)
 60         Me.lstSource.Name = "lstSource"
 61         Me.lstSource.Size = New System.Drawing.Size(120, 136)
 62         Me.lstSource.TabIndex = 0
 63         '
 64         'btnAdd
 65         '
 66         Me.btnAdd.Location = New System.Drawing.Point(136, 8)
 67         Me.btnAdd.Name = "btnAdd"
 68         Me.btnAdd.Size = New System.Drawing.Size(80, 24)
 69         Me.btnAdd.TabIndex = 1
 70         Me.btnAdd.Text = "Add >"
 71         '
 72         'btnAddAll
 73         '
 74         Me.btnAddAll.Location = New System.Drawing.Point(136, 40)
 75         Me.btnAddAll.Name = "btnAddAll"
 76         Me.btnAddAll.Size = New System.Drawing.Size(80, 24)
 77         Me.btnAddAll.TabIndex = 2
 78         Me.btnAddAll.Text = "Add All >>"
 79         '
 80         'btnRemove
 81         '
 82         Me.btnRemove.Location = New System.Drawing.Point(136, 72)
 83         Me.btnRemove.Name = "btnRemove"
 84         Me.btnRemove.Size = New System.Drawing.Size(80, 24)
 85         Me.btnRemove.TabIndex = 3
 86         Me.btnRemove.Text = "< Remove"
 87         '
 88         'btnClear
 89         '
 90         Me.btnClear.Location = New System.Drawing.Point(136, 104)
 91         Me.btnClear.Name = "btnClear"
 92         Me.btnClear.Size = New System.Drawing.Size(80, 24)
 93         Me.btnClear.TabIndex = 4
 94         Me.btnClear.Text = "<< Clear"
 95         '
 96         'lstTarget
 97         '
 98         Me.lstTarget.Dock = System.Windows.Forms.DockStyle.Right
 99         Me.lstTarget.ItemHeight = 12
100         Me.lstTarget.Location = New System.Drawing.Point(232, 0)
101         Me.lstTarget.Name = "lstTarget"
102         Me.lstTarget.Size = New System.Drawing.Size(120, 136)
103         Me.lstTarget.TabIndex = 5
104         '
105         'SelectCombo
106         '
107         Me.Controls.Add(Me.lstTarget)
108         Me.Controls.Add(Me.btnClear)
109         Me.Controls.Add(Me.btnRemove)
110         Me.Controls.Add(Me.btnAddAll)
111         Me.Controls.Add(Me.btnAdd)
112         Me.Controls.Add(Me.lstSource)
113         Me.Name = "SelectCombo"
114         Me.Size = New System.Drawing.Size(352, 136)
115         Me.ResumeLayout(False)
116 
117     End Sub
118 
119 #End Region
120 
121   Private Sub SelectCombo_Resize(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Resize
122     ' Check for minimum width and height.
123     ' Throw exception if new width or height too small 
124     Dim sError As String
125     sError = "Attempted to make SelectCombo user control too small."
126 
127     If MyBase.Size.Width < mnMinControlWidth Then
128       Dim eComboException As New ApplicationException(sError)
129       eComboException.Source = Me.ToString
130     End If
131     If MyBase.Size.Height < mnMinControlHeight Then
132       Dim eComboException As New ApplicationException(sError)
133       eComboException.Source = Me.ToString
134     End If
135 
136     'Set source and target list boxes to appropriate width. Note that
137     'docking the list boxes makes their height the right size automatically.
138     Dim nListboxWidth As Integer
139     nListboxWidth = CInt(0.5 * (Me.Size.Width - mnButtonAreaWidth))
140     lstSource.Size = New Size(nListboxWidth, lstSource.Size.Height)
141     lstTarget.Size = New Size(nListboxWidth, lstSource.Size.Height)
142 
143     'Now position the buttons between the list boxes. 
144     Dim nLeftButtonPosition As Integer
145     nLeftButtonPosition = nListboxWidth + _
146            ((mnButtonAreaWidth - btnAdd.Size.Width) \ 2)
147     btnAdd.Location = New Point(nLeftButtonPosition, btnAdd.Location.Y)
148     btnAddAll.Location = New Point(nLeftButtonPosition, btnAddAll.Location.Y)
149     btnRemove.Location = New Point(nLeftButtonPosition, btnRemove.Location.Y)
150     btnClear.Location = New Point(nLeftButtonPosition, btnClear.Location.Y)
151   End Sub
152 
153   Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
154     Dim objItem As Object
155     For Each objItem In lstSource.SelectedItems
156       lstTarget.Items.Add(objItem)
157     Next objItem
158 
159   End Sub
160 
161   Private Sub btnAddAll_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAddAll.Click
162     Dim objItem As Object
163     For Each objItem In lstSource.Items
164       lstTarget.Items.Add(objItem)
165     Next objItem

166 
167   End Sub
168 
169   Private Sub btnRemove_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRemove.Click
170     lstTarget.Items.Clear()
171   End Sub
172 
173   Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
174     ' Have to go through the collection in reverse
175     ' because we are removing items.
176     Dim nIndex As Integer
177     For nIndex = lstTarget.SelectedItems.Count - 1 To 0 Step -1
178       lstTarget.Items.Remove(lstTarget.SelectedItems(nIndex))
179     Next nIndex
180 
181   End Sub
182 
183   Public ReadOnly Property SelectedItem(ByVal iIndex As Integer) As Object
184     Get
185       Return lstTarget.Items(iIndex)
186     End Get
187   End Property
188 
189   Public ReadOnly Property SelectedCount() As Integer
190     Get
191       Return lstTarget.Items.Count
192     End Get
193   End Property
194 
195   Public ReadOnly Property AvailableCount() As Integer
196     Get
197       Return lstSource.Items.Count
198     End Get
199   End Property
200 
201   Public Sub Add(ByVal objItem As Object)
202     lstSource.Items.Add(objItem)
203   End Sub
204 
205   Public ReadOnly Property AvailableItem(ByVal iIndex As Integer) As Object
206     Get
207       Return lstSource.Items(iIndex)
208     End Get
209   End Property
210 
211   Public Sub Clear()
212     lstSource.Items.Clear()
213     lstTarget.Items.Clear()
214 
215   End Sub
216 
217 End Class