企业🤖AI智能体构建引擎,智能编排和调试,一键部署,支持私有化部署方案 广告
# 小部件 > 原文: [http://zetcode.com/gui/vbgtk/widgets/](http://zetcode.com/gui/vbgtk/widgets/) 在 Visual Basic GTK# 编程教程的这一部分中,我们将介绍一些小部件。 小部件是 GUI 应用的基本构建块。 多年来,几个小部件已成为所有 OS 平台上所有工具包中的标准。 例如,按钮,复选框或滚动条。 GTK# 工具箱的理念是将小部件的数量保持在最低水平。 将创建更多专门的小部件作为自定义 GTK# 小部件。 ## `CheckButton` `CheckButton`是具有两种状态的窗口小部件:打开和关闭。 接通状态通过复选标记显示。 它用来表示一些布尔属性。 ```vb ' ZetCode Mono Visual Basic GTK# tutorial ' ' This program toggles the title of the ' window with the CheckButton widget ' ' author jan bodnar ' last modified May 2009 ' website www.zetcode.com Imports Gtk Public Class GtkVBApp Inherits Window Public Sub New MyBase.New("CheckButton") Me.InitUI Me.SetDefaultSize(250, 150) Me.SetPosition(WindowPosition.Center) AddHandler Me.DeleteEvent, AddressOf Me.OnDelete Me.ShowAll End Sub Private Sub InitUI Dim cb As New CheckButton("Show title") cb.Active = True AddHandler cb.Toggled, AddressOf Me.OnToggle Dim fix As New Fixed fix.Put(cb, 50, 50) Me.Add(fix) End Sub Sub OnToggle(ByVal sender As Object, ByVal args As EventArgs) If sender.Active Me.Title = "CheckButton" Else Title = " " End If End Sub Sub OnDelete(ByVal sender As Object, _ ByVal args As DeleteEventArgs) Application.Quit End Sub Public Shared Sub Main Application.Init Dim app As New GtkVBApp Application.Run End Sub End Class ``` 根据`CheckButton`的状态,我们将在窗口的标题栏中显示标题。 ```vb Dim cb As New CheckButton("Show title") ``` `CheckButton`小部件已创建。 ```vb cb.Active = True ``` 默认情况下标题是可见的,因此我们默认情况下选中复选按钮。 ```vb If sender.Active Me.Title = "CheckButton" Else Title = " " End If ``` 根据`CheckButton`的`Active`属性,我们显示或隐藏窗口的标题。 ![CheckButton](https://img.kancloud.cn/97/13/9713dbc55b0aa906949ef1dff66f9c77_258x178.jpg) 图:`CheckButton` ## `Label` `Label`小部件显示文本。 ```vb ' ZetCode Mono Visual Basic GTK# tutorial ' This program shows lyrics on ' the window in a label widget ' ' author jan bodnar ' last modified May 2009 ' website www.zetcode.com Imports Gtk Public Class GtkVBApp Inherits Window Dim text 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 MyBase.New("You know I'm No Good") Me.InitUI Me.SetPosition(WindowPosition.Center) Me.BorderWidth = 10 AddHandler Me.DeleteEvent, AddressOf Me.OnDelete Me.ShowAll End Sub Private Sub InitUI Dim lyrics As New Label(text) Me.Add(lyrics) End Sub Sub OnDelete(ByVal sender As Object, ByVal args As DeleteEventArgs) Application.Quit End Sub Public Shared Sub Main Application.Init Dim app As New GtkVBApp Application.Run End Sub End Class ``` 该代码示例在窗口上显示了一些歌词。 ```vb Dim text 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 Me.BorderWidth = 10 ``` `Label`周围有一些空白。 ```vb Dim lyrics As New Label(text) Me.Add(lyrics) ``` `Label`小部件已创建并添加到窗口。 ![Label Widget](https://img.kancloud.cn/48/6a/486a66d56118e51f190b8370b8a1a05c_297x258.jpg) 图:`Label`小部件 ## `Entry` `Entry`是单行文本输入字段。 该小部件用于输入文本数据。 ```vb ' ZetCode Mono Visual Basic GTK# tutorial ' ' This program demonstrates the ' Entry widget. Text entered in the Entry ' widget is shown in a Label widget. ' ' author jan bodnar ' last modified May 2009 ' website www.zetcode.com Imports Gtk Public Class GtkVBApp Inherits Window Dim label As Label Public Sub New MyBase.New("Entry") Me.InitUI Me.SetDefaultSize(250, 150) Me.SetPosition(WindowPosition.Center) AddHandler Me.DeleteEvent, AddressOf Me.OnDelete Me.ShowAll End Sub Private Sub InitUI Dim fixed As New Fixed label = New Label("...") fixed.put(label, 60, 40) Dim entry As New Entry fixed.put(entry, 60, 100) AddHandler entry.Changed, AddressOf Me.OnTextChanged Me.Add(fixed) End Sub Sub OnTextChanged(ByVal sender As Object, _ ByVal args As EventArgs) label.Text = sender.Text End Sub Sub OnDelete(ByVal sender As Object, _ ByVal args As DeleteEventArgs) Application.Quit End Sub Public Shared Sub Main Application.Init Dim app As New GtkVBApp Application.Run End Sub End Class ``` 此示例显示了条目小部件和标签。 我们输入的文本将立即显示在标签小部件中。 ```vb Dim entry As New Entry ``` `Entry`小部件已创建。 ```vb AddHandler entry.Changed, AddressOf Me.OnTextChanged ``` 如果`Entry`小部件中的文本被更改,我们将调用`OnTextChanged`方法。 ```vb Sub OnTextChanged(ByVal sender As Object, _ ByVal args As EventArgs) label.Text = sender.Text End Sub ``` 我们从`Entry`小部件获取文本并将其设置为标签。 ![Entry Widget](https://img.kancloud.cn/23/e7/23e7102e357b945fc8ecebdef1d78cb6_258x178.jpg) 图:`Entry`小部件 ## `ToggleButton` `ToggleButton`是具有两种状态的按钮。 已按下但未按下。 通过单击可以在这两种状态之间切换。 在某些情况下此功能非常合适。 ```vb ' ZetCode Mono Visual Basic GTK# tutorial ' ' This program uses toggle buttons to ' change the background color of ' a widget. ' ' author jan bodnar ' last modified May 2009 ' website www.zetcode.com Imports Gtk Public Class GtkVBApp Inherits Window Dim darea As DrawingArea Dim color As Gdk.Color Public Sub New MyBase.New("Togggle buttons") Me.InitUI Me.SetDefaultSize(350, 240) Me.SetPosition(WindowPosition.Center) AddHandler Me.DeleteEvent, AddressOf Me.OnDelete Me.ShowAll End Sub Private Sub InitUI color = New Gdk.Color(0, 0, 0) Dim redb As New ToggleButton("Red") redb.SetSizeRequest(80, 35) AddHandler redb.Toggled, AddressOf Me.OnToggled Dim greenb As New ToggleButton("Green") greenb.SetSizeRequest(80, 35) AddHandler greenb.Toggled, AddressOf Me.OnToggled Dim blueb As New ToggleButton("Blue") blueb.SetSizeRequest(80, 35) AddHandler blueb.Toggled, AddressOf Me.OnToggled darea = New DrawingArea darea.SetSizeRequest(150, 150) darea.ModifyBg(StateType.Normal, color) Dim fixed As New Fixed fixed.Put(redb, 30, 30) fixed.Put(greenb, 30, 80) fixed.Put(blueb, 30, 130) fixed.Put(darea, 150, 30) Me.Add(fixed) End Sub Private Sub OnToggled(ByVal sender As Object, _ ByVal args As EventArgs) Dim red As Integer = color.Red Dim green As Integer = color.Green Dim blue As Integer = color.Blue If sender.Label.Equals("Red") If sender.Active color.Red = 65535 Else color.Red = 0 End If End If If sender.Label.Equals("Green") If sender.Active color.Green = 65535 Else color.Green = 0 End If End If If sender.Label.Equals("Blue") If sender.Active color.Blue = 65535 Else color.Blue = 0 End If End If darea.ModifyBg(StateType.Normal, color) End Sub Sub OnDelete(ByVal sender As Object, _ ByVal args As DeleteEventArgs) Application.Quit End Sub Public Shared Sub Main Application.Init Dim app As New GtkVBApp Application.Run End Sub End Class ``` 在我们的示例中,我们显示了三个切换按钮和一个`DrawingArea`。 我们将区域的背景色设置为黑色。 切换按钮将切换颜色值的红色,绿色和蓝色部分。 背景颜色取决于我们按下的切换按钮。 ```vb color = New Gdk.Color(0, 0, 0) ``` 这是将使用切换按钮更新的颜色值。 ```vb Dim redb As New ToggleButton("Red") redb.SetSizeRequest(80, 35) AddHandler redb.Toggled, AddressOf Me.OnToggled ``` `ToggleButton`小部件已创建。 我们将其大小设置为`80x35`像素。 每个切换按钮具有相同的处理器方法。 ```vb darea = New DrawingArea darea.SetSizeRequest(150, 150) darea.ModifyBg(StateType.Normal, color) ``` `DrawingArea`小部件是显示颜色的小部件,由切换按钮混合。 开始时,它显示为黑色。 ```vb If sender.Label.Equals("Red") If sender.Active color.Red = 65535 Else color.Red = 0 End If End If ``` 我们根据`Active`属性的值更新颜色的红色部分。 ```vb darea.ModifyBg(StateType.Normal, color) ``` 我们更新`DrawingArea`小部件的颜色。 ![ToggleButton widget](https://img.kancloud.cn/a0/75/a075fbddc467a04bdeb06209b44cf5d2_358x268.jpg) 图:`ToggleButton` widget ## `ComboBox` `ComboBox`是一个小部件,允许用户从选项列表中进行选择。 ```vb ' ZetCode Mono Visual Basic GTK# tutorial ' ' In this program, we use the ComboBox ' widget to select an option. ' The selected option is shown in the ' Label widget ' ' author jan bodnar ' last modified May 2009 ' website www.zetcode.com Imports Gtk Public Class GtkVBApp Inherits Window Dim lbl As Label Public Sub New MyBase.New("ComboBox") Me.InitUI Me.SetDefaultSize(350, 240) Me.SetPosition(WindowPosition.Center) AddHandler Me.DeleteEvent, AddressOf Me.OnDelete Me.ShowAll End Sub Private Sub InitUI Dim distros() As String = New String() { _ "Ubuntu", _ "Mandriva", _ "Red Hat", _ "Fedora", _ "Gentoo" _ } Dim fixed As New Fixed Dim cb As New ComboBox(distros) AddHandler cb.Changed, AddressOf Me.OnChanged lbl = New Label("...") fixed.Put(cb, 50, 40) fixed.Put(lbl, 50, 140) Me.Add(fixed) End Sub Private Sub OnChanged(ByVal sender As Object, _ ByVal args As EventArgs) lbl.Text = sender.ActiveText End Sub Sub OnDelete(ByVal sender As Object, _ ByVal args As DeleteEventArgs) Application.Quit End Sub Public Shared Sub Main Application.Init Dim app As New GtkVBApp Application.Run End Sub End Class ``` 该示例显示了一个组合框和一个标签。 组合框具有六个选项的列表。 这些是 Linux Distros 的名称。 标签窗口小部件显示了从组合框中选择的选项。 ```vb Dim distros() As String = New String() { _ "Ubuntu", _ "Mandriva", _ "Red Hat", _ "Fedora", _ "Gentoo" _ } ``` 这是一个字符串数组,将显示在`ComboBox`小部件中。 ```vb Dim cb As New ComboBox(distros) ``` `ComboBox`小部件已创建。 构造器将字符串数组作为参数。 ```vb Private Sub OnChanged(ByVal sender As Object, _ ByVal args As EventArgs) lbl.Text = sender.ActiveText End Sub ``` 在`OnChanged`方法内部,我们从组合框中获取选定的文本并将其设置为标签。 ![ComboBox](https://img.kancloud.cn/d9/13/d913607b6932e168c2c845c3ae02e736_358x268.jpg) 图:`ComboBox` 在本章中,我们使用 Visual Basic 语言展示了 GTK# 编程库的一些基本小部件。