使用VB.NET开发复合控件

使用VB.NET开发复合控件

界面：





控件类型 名称 文本

ListBox lstSource

ListBox lstTargeg

Button btnAdd Add >

Button btnAddAll Add All >>

Button btnRemove < Remove

Button btnClear << Clear

代码如下：

Public Class SelectCombo
Inherits System.Windows.Forms.UserControl

' Make the width of the area for the buttons 100 twips
Dim mnButtonAreaWidth As Integer = 100

' Set minimum height and width for the control
Dim mnMinControlWidth As Integer = 200
Dim mnMinControlHeight As Integer = 200

#Region " Windows Form Designer generated code "

Public Sub New()
MyBase.New()

'This call is required by the Windows Form Designer.
InitializeComponent()

'Add any initialization after the InitializeComponent() call

End Sub

'UserControl1 overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub

'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer

'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
Friend WithEvents lstSource As System.Windows.Forms.ListBox
Friend WithEvents btnAdd As System.Windows.Forms.Button
Friend WithEvents btnAddAll As System.Windows.Forms.Button
Friend WithEvents lstTarget As System.Windows.Forms.ListBox
Friend WithEvents btnRemove As System.Windows.Forms.Button
Friend WithEvents btnClear As System.Windows.Forms.Button
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Me.lstSource = New System.Windows.Forms.ListBox()
Me.btnAdd = New System.Windows.Forms.Button()
Me.btnAddAll = New System.Windows.Forms.Button()
Me.btnRemove = New System.Windows.Forms.Button()
Me.btnClear = New System.Windows.Forms.Button()
Me.lstTarget = New System.Windows.Forms.ListBox()
Me.SuspendLayout()
'
'lstSource
'
Me.lstSource.Dock = System.Windows.Forms.DockStyle.Left
Me.lstSource.ItemHeight = 12
Me.lstSource.Location = New System.Drawing.Point(0, 0)
Me.lstSource.Name = "lstSource"
Me.lstSource.Size = New System.Drawing.Size(120, 136)
Me.lstSource.TabIndex = 0
'
'btnAdd
'
Me.btnAdd.Location = New System.Drawing.Point(136, 8)
Me.btnAdd.Name = "btnAdd"
Me.btnAdd.Size = New System.Drawing.Size(80, 24)
Me.btnAdd.TabIndex = 1
Me.btnAdd.Text = "Add >"
'
'btnAddAll
'
Me.btnAddAll.Location = New System.Drawing.Point(136, 40)
Me.btnAddAll.Name = "btnAddAll"
Me.btnAddAll.Size = New System.Drawing.Size(80, 24)
Me.btnAddAll.TabIndex = 2
Me.btnAddAll.Text = "Add All >>"
'
'btnRemove
'
Me.btnRemove.Location = New System.Drawing.Point(136, 72)
Me.btnRemove.Name = "btnRemove"
Me.btnRemove.Size = New System.Drawing.Size(80, 24)
Me.btnRemove.TabIndex = 3
Me.btnRemove.Text = "< Remove"
'
'btnClear
'
Me.btnClear.Location = New System.Drawing.Point(136, 104)
Me.btnClear.Name = "btnClear"
Me.btnClear.Size = New System.Drawing.Size(80, 24)
Me.btnClear.TabIndex = 4
Me.btnClear.Text = "<< Clear"
'
'lstTarget
'
Me.lstTarget.Dock = System.Windows.Forms.DockStyle.Right
Me.lstTarget.ItemHeight = 12
Me.lstTarget.Location = New System.Drawing.Point(232, 0)
Me.lstTarget.Name = "lstTarget"
Me.lstTarget.Size = New System.Drawing.Size(120, 136)
Me.lstTarget.TabIndex = 5
'
'SelectCombo
'
Me.Controls.Add(Me.lstTarget)
Me.Controls.Add(Me.btnClear)
Me.Controls.Add(Me.btnRemove)
Me.Controls.Add(Me.btnAddAll)
Me.Controls.Add(Me.btnAdd)
Me.Controls.Add(Me.lstSource)
Me.Name = "SelectCombo"
Me.Size = New System.Drawing.Size(352, 136)
Me.ResumeLayout(False)

End Sub

#End Region

Private Sub SelectCombo_Resize(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Resize
' Check for minimum width and height.
' Throw exception if new width or height too small
Dim sError As String
sError = "Attempted to make SelectCombo user control too small."

If MyBase.Size.Width < mnMinControlWidth Then
Dim eComboException As New ApplicationException(sError)
eComboException.Source = Me.ToString
End If
If MyBase.Size.Height < mnMinControlHeight Then
Dim eComboException As New ApplicationException(sError)
eComboException.Source = Me.ToString
End If

'Set source and target list boxes to appropriate width. Note that
'docking the list boxes makes their height the right size automatically.
Dim nListboxWidth As Integer
nListboxWidth = CInt(0.5 * (Me.Size.Width - mnButtonAreaWidth))
lstSource.Size = New Size(nListboxWidth, lstSource.Size.Height)
lstTarget.Size = New Size(nListboxWidth, lstSource.Size.Height)

'Now position the buttons between the list boxes.
Dim nLeftButtonPosition As Integer
nLeftButtonPosition = nListboxWidth + _
((mnButtonAreaWidth - btnAdd.Size.Width) \ 2)
btnAdd.Location = New Point(nLeftButtonPosition, btnAdd.Location.Y)
btnAddAll.Location = New Point(nLeftButtonPosition, btnAddAll.Location.Y)
btnRemove.Location = New Point(nLeftButtonPosition, btnRemove.Location.Y)
btnClear.Location = New Point(nLeftButtonPosition, btnClear.Location.Y)
End Sub

Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
Dim objItem As Object
For Each objItem In lstSource.SelectedItems
lstTarget.Items.Add(objItem)
Next objItem

End Sub

Private Sub btnAddAll_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAddAll.Click
Dim objItem As Object
For Each objItem In lstSource.Items
lstTarget.Items.Add(objItem)
Next objItem

End Sub

Private Sub btnRemove_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRemove.Click
lstTarget.Items.Clear()
End Sub

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
' Have to go through the collection in reverse
' because we are removing items.
Dim nIndex As Integer
For nIndex = lstTarget.SelectedItems.Count - 1 To 0 Step -1
lstTarget.Items.Remove(lstTarget.SelectedItems(nIndex))
Next nIndex

End Sub

Public ReadOnly Property SelectedItem(ByVal iIndex As Integer) As Object
Get
Return lstTarget.Items(iIndex)
End Get
End Property

Public ReadOnly Property SelectedCount() As Integer
Get
Return lstTarget.Items.Count
End Get
End Property

Public ReadOnly Property AvailableCount() As Integer
Get
Return lstSource.Items.Count
End Get
End Property

Public Sub Add(ByVal objItem As Object)
lstSource.Items.Add(objItem)
End Sub

Public ReadOnly Property AvailableItem(ByVal iIndex As Integer) As Object
Get
Return lstSource.Items(iIndex)
End Get
End Property

Public Sub Clear()
lstSource.Items.Clear()
lstTarget.Items.Clear()

End Sub

End Class

测试中，将控件拖入WINDOW窗体，在Form_Load事件中写入

SelectCombo1.Add("1")
SelectCombo1.Add("2")
SelectCombo1.Add("3")
SelectCombo1.Add("4")
SelectCombo1.Add("5")