以编程方式将控件添加到表单

Question

我正在使用附加的代码在现有集合下添加另一行\行控件（单击标签时）。可能会添加相当多的行，因此我不得不使用计数器（i）多次重复代码以跟踪...

有没有更好的方法呢？

Private Sub Label10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)      Handles LblExpandSearch.Click
    If i = 0 Then

        'TextBox7
        '
        Dim TextBox7 As New TextBox
        TextBox7.Size = New Size(302, 20)
        TextBox7.Name = "TextBox7"
        TextBox7.Location = New System.Drawing.Point(60, 135)
        Me.ExpAdvancedSearch.Controls.Add(TextBox7)

        'RadioButton5
        '
        Dim RadioButton5 As New RadioButton
        RadioButton5.AutoSize = True
        RadioButton5.Checked = True
        RadioButton5.Location = New System.Drawing.Point(77, 112)
        RadioButton5.Name = "RadioButton5"
        RadioButton5.Size = New System.Drawing.Size(55, 17)
        RadioButton5.TabIndex = 48
        RadioButton5.TabStop = True
        RadioButton5.Text = "NEAR"
        RadioButton5.UseVisualStyleBackColor = True

    ElseIf i = 1 Then

        ExpAdvancedSearch.Size_ExpandedHeight = 260

        'TextBox8
        '
        Dim TextBox8 As New TextBox
        TextBox8.Size = New Size(302, 20)
        TextBox8.Name = "TextBox8"
        TextBox8.Location = New System.Drawing.Point(60, 185)
        Me.ExpAdvancedSearch.Controls.Add(TextBox8)


        'RadioButton9
        '
        Dim RadioButton9 As New RadioButton
        RadioButton9.AutoSize = True
        RadioButton9.Checked = True
        RadioButton9.Location = New System.Drawing.Point(77, 162)
        RadioButton9.Name = "RadioButton9"
        RadioButton9.Size = New System.Drawing.Size(55, 17)
        RadioButton9.TabIndex = 48
        RadioButton9.TabStop = True
        RadioButton9.Text = "NEAR"
        RadioButton9.UseVisualStyleBackColor = True

    End If

    i = i + 1
End Sub

Answer 1

嗯.. UseVisualStyleBackColor对我说'winforms'。

几点......

不要将控件全部添加到一个面板，请使用用户控件。

然后只需添加其实例。

不处理标签

中的点击事件

使用链接标签或按钮。其他任何东西=对用户意味着什么。当然，你想到了它对你有意义！现在对用户来说，这是黑白分明。

样本...

当然很少。你想要：

• 将项目放在可滚动面板中，而不是放在表单上。
• 也可能将它们添加到uc的通用列表中。
• 设置表格的最小/最大尺寸 - 允许合理的尺寸（允许任何高度> ~100）
• 设置uc和控件.Anchor属性以允许合理调整大小

uc.vb

Public Class uc
    Inherits System.Windows.Forms.UserControl

    Private components As System.ComponentModel.IContainer
    Friend WithEvents TextBox1 As System.Windows.Forms.TextBox
    Friend WithEvents LinkLabel1 As System.Windows.Forms.LinkLabel

    Public Sub New()
        MyBase.New()

        Me.TextBox1 = New System.Windows.Forms.TextBox
        Me.LinkLabel1 = New System.Windows.Forms.LinkLabel
        Me.SuspendLayout()

        Me.TextBox1.Location = New System.Drawing.Point(8, 8)
        Me.TextBox1.Name = "TextBox1"
        Me.TextBox1.Size = New System.Drawing.Size(88, 20)
        Me.TextBox1.TabIndex = 0
        Me.TextBox1.Text = "TextBox1"

        Me.LinkLabel1.Enabled = False
        Me.LinkLabel1.Location = New System.Drawing.Point(112, 8)
        Me.LinkLabel1.Name = "LinkLabel1"
        Me.LinkLabel1.Size = New System.Drawing.Size(24, 16)
        Me.LinkLabel1.TabIndex = 1
        Me.LinkLabel1.TabStop = True
        Me.LinkLabel1.Text = "add"

        Me.Controls.Add(Me.LinkLabel1)
        Me.Controls.Add(Me.TextBox1)
        Me.Name = "uc"
        Me.Size = New System.Drawing.Size(148, 36)
        Me.ResumeLayout(False)

    End Sub

    Private _addcallback As EventHandler = Nothing
    Public Property AddCallback() As EventHandler
        Get
            Return _addcallback
        End Get
        Set(ByVal Value As EventHandler)

            _addcallback = Value
            LinkLabel1.Enabled = Not Value Is Nothing

        End Set
    End Property

    Private Sub LinkLabel1_LinkClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles LinkLabel1.LinkClicked
        If AddCallback Is Nothing Then Throw New ApplicationException("AddCallback not set on a uc") ' ALWAYS check for errors like this 
        _addcallback(Me, Nothing)
        AddCallback = Nothing ' gray myself out, can't insert in thie implementation
    End Sub
End Class

frm.vb

Public Class frm
    Inherits System.Windows.Forms.Form

    Private components As System.ComponentModel.IContainer
    Public Sub New()
        MyBase.New()
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(292, 266)
        Me.Name = "Form1"
        Me.Text = "Form1"
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        AddClicked(Me, Nothing)
    End Sub

    Private Sub AddClicked(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim myuc As New uc
        myuc.AddCallback = AddressOf AddClicked
        If Controls.Count > 0 Then
            myuc.Top = Controls(Controls.Count - 1).Bottom
        End If
        Me.Controls.Add(myuc)
    End Sub
End Class

Answer 2

我不知道是否有“少代码”方法，但我知道你可以使用With语句保存你的手指。

    Dim RadioButton5 As New RadioButton
    With RadioButton5
        .AutoSize = True
        .Checked = True
        .Location = New System.Drawing.Point(77, 112)
        .Name = "RadioButton5"
        .Size = New System.Drawing.Size(55, 17)
        .TabIndex = 48
        .TabStop = True
        .Text = "NEAR"
        .UseVisualStyleBackColor = True
    End With

Answer 3

如果您需要向单个页面添加无限数量的项目，则需要将这些项目存储在数组列表中，以后我们可以动态地将这些项目添加到页面中。

Imports System.Collections.Generic


Partial Class Default2
    Inherits System.Web.UI.Page

    ''# the i integer is here for helping to set the ID of the radio button 
    ''# as well as the tabindex
    Private Shared _i As Integer
    Public Shared Property i As Integer
        Get
            Return _i
        End Get
        Set(ByVal value As Integer)
            _i = value
        End Set
    End Property

    ''# we need to create an array of our control list class
    Public Shared _ctrlList As List(Of ControlList)





    ''# page load event
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not Page.IsPostBack Then
            ''# if the page is not a postback, then we need to initialize the Control List
            _ctrlList = New List(Of ControlList)
            i = 0
        End If
    End Sub



    ''# button click event
    Protected Sub button_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles button.Click

        ''# create a new RadioButton every time the button is clicked
        Dim rb As RadioButton = New RadioButton
        With rb
            .ID = "radioButton" + i.ToString
            .Checked = True
            .TabIndex = 48 + i
            .Text = "NEAR"
        End With

        ''# create a new literal every time the button is clicked
        Dim lt As Literal = New Literal
        With lt
            .ID = "literal" + i.ToString
            .Text = " <strong>my fancy text</strong><br />"
        End With

        ''# add the radio button and literal to our custom array
        _ctrlList.Add(New ControlList(rb, lt))

        ''# loop through the array and add the controls to the page
        For Each cl In _ctrlList
            LabelPlaceHolder.Controls.Add(cl.RadioBtn)
            LabelPlaceHolder.Controls.Add(cl.Litrl)
        Next

        ''# increment the i counter so that we have unique radioButton ID's
        i = i + 1
    End Sub



    ''# this is our custom Control List
    ''# the idea behind this is for us to store 
    ''# an array of Radio Buttons and literals to 
    ''# spit out onto the page
    ''# NOTE: you can add as many controls as you like 
    ''# to this list and even add static "Literals" to 
    ''# help you with your formatting (IE: DIV tags or <BR> tags
    Public Class ControlList
        Private _RadioBtn As RadioButton
        Public Property RadioBtn As RadioButton
            Get
                Return _RadioBtn
            End Get
            Set(ByVal value As RadioButton)
                _RadioBtn = value
            End Set
        End Property

        Private _Litrl As Literal
        Public Property Litrl As Literal
            Get
                Return _Litrl
            End Get
            Set(ByVal value As Literal)
                _Litrl = value
            End Set
        End Property

        Public Sub New(ByVal radioBtn As RadioButton, ByVal litrl As Literal)
            _RadioBtn = radioBtn
            _Litrl = litrl
        End Sub

    End Class


End Class

试试这个并看看它是如何工作的。您在ASPX中所需要的只是

<form id="form1" runat="server">
    <asp:PlaceHolder runat="server" id="LabelPlaceHolder" /><br />
    <asp:Button ID="button" runat="server" Text="click me" />
</form>

基本上这样做是在每次单击按钮时向页面添加一个附加控件集。您可以在页面上拥有无限数量的控件，而无需添加任何其他代码。