# 基本控制 > 原文： [http://zetcode.com/gui/vbwinforms/controls/](http://zetcode.com/gui/vbwinforms/controls/) Visual Basic Winforms 编程教程的这一部分将介绍基本控件。 Winforms 控件是应用的基本构建块。 Winforms 具有广泛的各种控件。 按钮，复选框，滑块，列表框等。程序员完成工作所需的一切。 在本教程的这一部分中，我们将描述几个有用的控件。 ## `Label` `Label`是用于显示文本或图像的简单控件。 它没有得到关注。 ```vb ' ZetCode Mono Visual Basic Winforms tutorial ' ' This program shows lyrics of a song ' ' author jan bodnar ' last modified May 2009 ' website www.zetcode.com Imports System.Windows.Forms Imports System.Drawing Public Class WinVBApp Inherits Form Dim lyrics As String = "Meet you downstairs in the bar and heard" & vbNewLine & _ "your rolled up sleeves and your skull t-shirt" & vbNewLine & _ "You say why did you do it with him today?" & vbNewLine & _ "and sniff me out like I was Tanqueray" & vbNewLine & _ "" & vbNewLine & _ "cause you're my fella, my guy" & vbNewLine & _ "hand me your stella and fly" & vbNewLine & _ "by the time I'm out the door" & vbNewLine & _ "you tear men down like Roger Moore" & vbNewLine & _ "" & vbNewLine & _ "I cheated myself" & vbNewLine & _ "like I knew I would" & vbNewLine & _ "I told ya, I was trouble" & vbNewLine & _ "you know that I'm no good" Public Sub New() Me.Text = "You know I'm no Good" Me.Size = New Size(300, 250) Me.InitUI Me.CenterToScreen End Sub Private Sub InitUI Dim font As New Font("Serif", 10) Dim label As New Label label.Parent = Me label.Text = lyrics label.Font = font label.Location = New Point(10, 10) label.Size = New Size (290, 290) End Sub Public Shared Sub Main Application.Run(New WinVBApp) End Sub End Class ``` 在我们的示例中，我们在标签控件中显示歌曲的歌词。 ```vb Dim lyrics As String = "Meet you downstairs in the bar and heard" & vbNewLine & _ "your rolled up sleeves and your skull t-shirt" & vbNewLine & _ ... ``` 我们定义了多行文字。 与 C# ，Python 或 Ruby 不同，没有简单的结构可以用 Visual Basic 语言创建多行文本。 若要在 Visual Basic 中创建多行文本，我们使用`vbNewLine`打印常量，`+`连接字符和`_`行终止字符。 ```vb Dim label As New Label ``` `Label`控件已创建。 ```vb label.Text = lyrics ``` 我们为标签设置文本。 ```vb Dim font As New Font("Serif", 10) ... label.Font = font ``` 标签文本的字体设置为 Serif，10px。  图：`Label` ## `CheckBox` `CheckBox`是具有两个状态的控件：开和关。 它是带有标签或图像的盒子。 如果选中了`CheckBox`，则在方框中用勾号表示。 `CheckBox`可用于在启动时显示/隐藏启动屏幕，切换工具栏的可见性等。 ```vb ' ZetCode Mono Visual Basic Winforms tutorial ' ' This program toggles the title of the ' window with the CheckBox control ' ' author jan bodnar ' last modified May 2009 ' website www.zetcode.com Imports System.Windows.Forms Imports System.Drawing Public Class WinVBApp Inherits Form Public Sub New Me.Text = "CheckBox" Me.Size = New Size(220, 170) Me.InitUI Me.CenterToScreen End Sub Private Sub InitUI Dim cb As New CheckBox cb.Parent = Me cb.Location = New Point(30, 30) cb.Text = "Show Title" cb.Checked = True AddHandler cb.CheckedChanged, AddressOf Me.OnChanged End Sub Private Sub OnChanged(ByVal sender As Object, ByVal e As EventArgs) If sender.Checked Text = "CheckBox" Else Text = "" End If End Sub Public Shared Sub Main Application.Run(New WinVBApp) End Sub End Class ``` 我们的代码示例根据窗口的状态显示或隐藏窗口的标题。 ```vb Dim cb As New CheckBox ``` `CheckBox`控件已创建。 ```vb cb.Text = "Show Title" cb.Checked = True ``` 当应用启动时，我们显示标题。 然后将`CheckBox`控件设置为选中状态。 ```vb AddHandler cb.CheckedChanged, AddressOf Me.OnChanged ``` 当我们单击`CheckBox`控件时，将触发`CheckedChanged`事件。 我们用`OnChanged`方法对这个特定事件做出反应。 ```vb If sender.Checked Text = "CheckBox" Else Text = "" End If ``` 在这里，我们切换窗口的标题。  图：`CheckBox` ## `ComboBox` `ComboBox`是一个组合了按钮或可编辑字段和下拉列表的控件。 用户可以从下拉列表中选择一个值，该列表应用户的要求出现。 如果使组合框可编辑，则组合框将包含一个可编辑字段，用户可以在其中输入值。 ```vb ' ZetCode Mono Visual Basic Winforms tutorial ' ' In this program, we use the ComboBox ' control to select an option. ' The selected option is shown in the ' Label component. ' ' author jan bodnar ' last modified May 2009 ' website www.zetcode.com Imports System.Windows.Forms Imports System.Drawing Public Class WinVBApp Inherits Form Private Dim label As Label Public Sub New Me.Text = "ComboBox" Me.Size = New Size(240, 240) Me.InitUI Me.CenterToScreen End Sub Private Sub InitUI Dim cb As New ComboBox cb.Parent = Me cb.Location = New Point(50, 30) cb.Items.AddRange(New Object() {"Ubuntu", _ "Mandriva", _ "Red Hat", _ "Fedora", _ "Gentoo"}) label = New Label label.Location = New Point(50, 140) label.Parent = Me label.Text = "..." AddHandler cb.SelectionChangeCommitted, AddressOf Me.OnChanged End Sub Private Sub OnChanged(ByVal sender As Object, ByVal e As EventArgs) label.Text = sender.Text End Sub Public Shared Sub Main Application.Run(New WinVBApp) End Sub End Class ``` 我们的代码编程示例显示了一个包含五个项目的组合框。 所选项目显示在标签控件中。 ```vb Dim cb As New ComboBox ``` `ComboBox`控件已创建。 ```vb cb.Items.AddRange(New Object() {"Ubuntu", _ "Mandriva", _ "Red Hat", _ "Fedora", _ "Gentoo"}) ``` `ComboBox`控件中充满了项目。 ```vb AddHandler cb.SelectionChangeCommitted, AddressOf Me.OnChanged ``` 如果我们从组合框中选择一个项目，则会触发`SelectionChangeCommitted`事件。 ```vb Private Sub OnChanged(ByVal sender As Object, ByVal e As EventArgs) label.Text = sender.Text End Sub ``` 在这里，将从组合框中选择的文本复制到标签。  图：`ComboBox` ## `MonthCalendar` 在下一个示例中，我们将显示`MonthCalendar`控件。 MonthCalendar 控件允许用户使用视觉显示选择日期。 ```vb ' ZetCode Mono Visual Basic Winforms tutorial ' ' In this program, we use the MonthCalendar ' control to select a date. ' The selected date is shown in the ' Label control. ' ' author jan bodnar ' last modified May 2009 ' website www.zetcode.com Imports System.Windows.Forms Imports System.Drawing Public Class WinVBApp Inherits Form Private Dim label As Label Public Sub New Me.Text = "MonthCalendar" Me.Size = New Size(240, 240) Me.InitUI Me.CenterToScreen End Sub Private Sub InitUI Dim calendar As New MonthCalendar calendar.Parent = Me calendar.Location = New Point(20, 20) label = New Label label.Location = New Point(40, 170) label.Parent = Me Dim dt As DateTime = calendar.SelectionStart label.Text = dt.Month & "/" & dt.Day & "/" & dt.Year AddHandler calendar.DateSelected, AddressOf Me.OnSel End Sub Private Sub OnSel(ByVal sender As Object, ByVal e As DateRangeEventArgs) Dim dt As DateTime = sender.SelectionStart label.Text = dt.Month & "/" & dt.Day & "/" & dt.Year End Sub Public Shared Sub Main Application.Run(New WinVBApp) End Sub End Class ``` 在示例中，我们显示了`MonthCalendar`和`Label`。 后者显示当前选择的日期。 ```vb Private Sub OnSel(ByVal sender As Object, ByVal e As DateRangeEventArgs) Dim dt As DateTime = sender.SelectionStart label.Text = dt.Month & "/" & dt.Day & "/" & dt.Year End Sub ``` 当我们从`MonthCalendar`中选择一个日期时，就会调用`OnSel`方法。 `SelectionStart`属性获取所选日期范围的开始日期。  图：`MonthCalendar` ## `TextBox` `TextBox`控件用于显示或接受某些文本。 文本可以是单行或多行。 此控件还可以进行密码屏蔽。 ```vb ' ZetCode Mono Visual Basic Winforms tutorial ' ' This program demonstrates the ' TextBox control. Text entered in the TextBox ' control is shown in a Label control. ' ' author jan bodnar ' last modified May 2009 ' website www.zetcode.com Imports System.Windows.Forms Imports System.Drawing Public Class WinVBApp Inherits Form Private Dim label As Label Public Sub New Me.Text = "TextBox" Me.Size = New Size(250, 200) Me.InitUI Me.CenterToScreen End Sub Private Sub InitUI label = New Label label.Parent = Me label.Text = "..." label.Location = New Point(60, 40) label.AutoSize = True Dim tbox As New TextBox tbox.Parent = Me tbox.Location = New Point(60, 100) AddHandler tbox.KeyUp, AddressOf Me.OnKeyUp End Sub Private Sub OnKeyUp(ByVal sender As Object, ByVal e As KeyEventArgs) Me.label.Text = sender.Text End Sub Public Shared Sub Main Application.Run(New WinVBApp) End Sub End Class ``` 本示例显示一个文本框和一个标签。 我们在文本框中键入的文本将立即显示在标签控件中。 ```vb label = New Label ... label.AutoSize = True ``` `Label`控件已创建。 `AutoSize`属性确保`Label`增长以显示文本。 ```vb Dim tbox As New TextBox ... AddHandler tbox.KeyUp, AddressOf Me.OnKeyUp ``` 我们插入`KeyUp`事件。 释放按键时，将调用`OnKeyUp`方法。 ```vb Private Sub OnKeyUp(ByVal sender As Object, ByVal e As KeyEventArgs) Me.label.Text = sender.Text End Sub ``` 在`OnKeyUp`方法中，我们使用文本框控件中的文本更新了标签控件。  图：`TextBox` 我们已经完成了 Visual Basic Winforms 教程的这一章，专门讨论基本控件。