VB.NET ListBox.TopIndex属性代码示例

Private Sub RemoveTopItems()
   ' Determine if the currently selected item in the ListBox 
   ' is the item displayed at the top in the ListBox.
   If listBox1.TopIndex <> listBox1.SelectedIndex Then
      ' Make the currently selected item the top item in the ListBox.
      listBox1.TopIndex = listBox1.SelectedIndex
   End If
   ' Remove all items before the top item in the ListBox.
   Dim x As Integer
   For x = listBox1.SelectedIndex - 1 To 0 Step -1
      listBox1.Items.RemoveAt(x)
   Next x

   ' Clear all selections in the ListBox.
   listBox1.ClearSelected()
End Sub

' 导入命名空间
Imports System
Imports System.Windows.Forms


Public Class MainClass
    
    Shared Sub Main()
        Dim form1 As Form = New Form1

        Application.Run(form1)


    End Sub
End Class

Public Class Form1
    Inherits System.Windows.Forms.Form

#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

    'Form 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
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents Label2 As System.Windows.Forms.Label
    Friend WithEvents txt As System.Windows.Forms.TextBox
    Friend WithEvents pic As System.Windows.Forms.PictureBox
    Friend WithEvents lstLog As System.Windows.Forms.ListBox
    Friend WithEvents cmd As System.Windows.Forms.Button
    Friend WithEvents Label3 As System.Windows.Forms.Label

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

    '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 GroupBox1 As System.Windows.Forms.GroupBox
    Friend WithEvents Label4 As System.Windows.Forms.Label
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.txt = New System.Windows.Forms.TextBox()
        Me.Label1 = New System.Windows.Forms.Label()
        Me.Label2 = New System.Windows.Forms.Label()
        Me.lstLog = New System.Windows.Forms.ListBox()
        Me.pic = New System.Windows.Forms.PictureBox()
        Me.cmd = New System.Windows.Forms.Button()
        Me.Label3 = New System.Windows.Forms.Label()
        Me.GroupBox1 = New System.Windows.Forms.GroupBox()
        Me.Label4 = New System.Windows.Forms.Label()
        Me.GroupBox1.SuspendLayout()
        Me.SuspendLayout()
        '
        'txt
        '
        Me.txt.Location = New System.Drawing.Point(156, 20)
        Me.txt.Name = "txt"
        Me.txt.Size = New System.Drawing.Size(192, 21)
        Me.txt.TabIndex = 1
        Me.txt.Text = ""
        '
        'Label1
        '
        Me.Label1.Location = New System.Drawing.Point(6, 24)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(144, 16)
        Me.Label1.TabIndex = 2
        Me.Label1.Text = "Test keyboard events here:"
        '
        'Label2
        '
        Me.Label2.Location = New System.Drawing.Point(20, 52)
        Me.Label2.Name = "Label2"
        Me.Label2.Size = New System.Drawing.Size(128, 16)
        Me.Label2.TabIndex = 2
        Me.Label2.Text = "Test mouse events here:"
        '
        'lstLog
        '
        Me.lstLog.Anchor = (((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom) _
                    Or System.Windows.Forms.AnchorStyles.Left) _
                    Or System.Windows.Forms.AnchorStyles.Right)
        Me.lstLog.IntegralHeight = False
        Me.lstLog.Location = New System.Drawing.Point(8, 160)
        Me.lstLog.Name = "lstLog"
        Me.lstLog.Size = New System.Drawing.Size(384, 212)
        Me.lstLog.TabIndex = 0
        '
        'pic
        '
        Me.pic.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.pic.Location = New System.Drawing.Point(156, 48)
        Me.pic.Name = "pic"
        Me.pic.Size = New System.Drawing.Size(192, 48)
        Me.pic.TabIndex = 3
        Me.pic.TabStop = False
        '
        'cmd
        '
        Me.cmd.FlatStyle = System.Windows.Forms.FlatStyle.System
        Me.cmd.Location = New System.Drawing.Point(156, 100)
        Me.cmd.Name = "cmd"
        Me.cmd.Size = New System.Drawing.Size(88, 28)
        Me.cmd.TabIndex = 4
        Me.cmd.Text = "Button1"
        '
        'Label3
        '
        Me.Label3.Location = New System.Drawing.Point(24, 104)
        Me.Label3.Name = "Label3"
        Me.Label3.Size = New System.Drawing.Size(64, 24)
        Me.Label3.TabIndex = 5
        Me.Label3.Text = "Label3"
        '
        'GroupBox1
        '
        Me.GroupBox1.Anchor = ((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Left) _
                    Or System.Windows.Forms.AnchorStyles.Right)
        Me.GroupBox1.Controls.AddRange(New System.Windows.Forms.Control() {Me.Label4, Me.Label1, Me.pic, Me.txt, Me.cmd, Me.Label2})
        Me.GroupBox1.FlatStyle = System.Windows.Forms.FlatStyle.System
        Me.GroupBox1.Location = New System.Drawing.Point(8, 4)
        Me.GroupBox1.Name = "GroupBox1"
        Me.GroupBox1.Size = New System.Drawing.Size(384, 148)
        Me.GroupBox1.TabIndex = 6
        Me.GroupBox1.TabStop = False
        '
        'Label4
        '
        Me.Label4.Location = New System.Drawing.Point(92, 108)
        Me.Label4.Name = "Label4"
        Me.Label4.Size = New System.Drawing.Size(56, 16)
        Me.Label4.TabIndex = 5
        Me.Label4.Text = "And here:"
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 14)
        Me.ClientSize = New System.Drawing.Size(400, 378)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.GroupBox1, Me.Label3, Me.lstLog})
        Me.Font = New System.Drawing.Font("Tahoma", 8.25!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Name = "Form1"
        Me.Text = "Event Tracker"
        Me.GroupBox1.ResumeLayout(False)
        Me.ResumeLayout(False)

    End Sub

#End Region


    Private Sub pic_MouseEnter(ByVal sender As Object, ByVal e As System.EventArgs) Handles pic.MouseEnter, cmd.MouseEnter
        Log("Mouse Enter")
    End Sub

    Private Sub pic_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles pic.MouseMove
        log("Mouse Move: " )
    End Sub

    Private Sub Log(ByVal data As String)
        lstLog.Items.Add(data)
        Dim ItemsPerPage As Integer = lstLog.Height \ lstLog.ItemHeight
        lstLog.TopIndex = lstLog.Items.Count - ItemsPerPage
    End Sub
End Class