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

Public Class Form1
    Inherits Form

    'Entry point which delegates to C-style main Private Function
    Public Overloads Shared Sub Main()
        Main(System.Environment.GetCommandLineArgs())
    End Sub

    Private Overloads Shared Sub Main(ByVal args() As String)
        Application.EnableVisualStyles()
        Application.Run(New Form1())
    End Sub

    Private WithEvents FirstNameBox, LastNameBox As TextBox
    Private WithEvents ValidateButton As Button
    Private FlowLayout1 As FlowLayoutPanel

    Private Sub New()
    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
        ' Turn off validation when a control loses focus. This will be inherited by child
        ' controls on the form, enabling us to validate the entire form when the 
        ' button is clicked instead of one control at a time.
        Me.AutoValidate = System.Windows.Forms.AutoValidate.Disable

        FlowLayout1 = New FlowLayoutPanel()
        FlowLayout1.Dock = DockStyle.Fill

        FirstNameBox = New TextBox()
        FirstNameBox.Name = "FirstNameBox"
        FirstNameBox.Location = New Point(10, 10)
        FirstNameBox.Size = New Size(75, FirstNameBox.Size.Height)
        FirstNameBox.CausesValidation = True
        FlowLayout1.Controls.Add(FirstNameBox)

        LastNameBox = New TextBox()
        LastNameBox.Name = "LastNameBox"
        LastNameBox.Location = New Point(90, 10)
        LastNameBox.Size = New Size(75, LastNameBox.Size.Height)
        LastNameBox.CausesValidation = True
        FlowLayout1.Controls.Add(LastNameBox)

        ValidateButton = New Button()
        ValidateButton.Text = "Validate"
        ValidateButton.Location = New Point(170, 10)
        ValidateButton.Size = New Size(75, ValidateButton.Size.Height)
        FlowLayout1.Controls.Add(ValidateButton)

        Me.Text = "Test Validation"

        Me.Controls.Add(FlowLayout1)
    End Sub


    Private Sub FirstNameBox_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles FirstNameBox.Validating
        If FirstNameBox.Text.Length = 0 Then
            e.Cancel = True
        Else
            e.Cancel = False
        End If
    End Sub


    Private Sub LastNameBox_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles LastNameBox.Validating
        e.Cancel = False
    End Sub


    Private Sub ValidateButton_Click(ByVal sender As Object, ByVal e As EventArgs) Handles ValidateButton.Click
        If ValidateChildren() Then
            MessageBox.Show("Validation succeeded!")
        Else
            MessageBox.Show("Validation failed.")
        End If
    End Sub
End Class

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

Namespace ValidateChildrenWithConstraints
    _
    Class Form1
        Inherits Form

        Public Overloads Shared Sub Main(ByVal args() As String)
            Application.EnableVisualStyles()
            Application.Run(New Form1())
        End Sub

        Private Sub New()
            AddHandler Me.Load, AddressOf Form1_Load
        End Sub

        Dim WithEvents TextBox1, TextBox2, TextBox3 As TextBox
        Dim FlowPanel1 As FlowLayoutPanel
        Dim WithEvents SubTextBox1 As TextBox
        Dim WithEvents Button1 As Button

        Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
            ' Create controls on form.

            Me.Size = New Size(500, 300)
            Me.AutoValidate = AutoValidate.Disable

            TextBox1 = New TextBox()
            TextBox1.Location = New Point(20, 20)
            TextBox1.Size = New Size(75, TextBox1.Size.Height)
            TextBox1.CausesValidation = True
            Me.Controls.Add(TextBox1)

            TextBox2 = New TextBox()
            TextBox2.Location = New Point(105, 20)
            TextBox2.Size = New Size(75, TextBox2.Size.Height)
            TextBox2.CausesValidation = True
            Me.Controls.Add(TextBox2)

            TextBox3 = New TextBox()
            TextBox3.Location = New Point(190, 20)
            TextBox3.Size = New Size(75, TextBox3.Size.Height)
            TextBox3.Enabled = False
            TextBox3.CausesValidation = True
            Me.Controls.Add(TextBox3)

            Button1 = New Button()
            Button1.Text = "Click"
            Button1.Location = New Point(270, 20)
            Me.Controls.Add(Button1)

            FlowPanel1 = New FlowLayoutPanel()
            FlowPanel1.Size = New Size(400, 100)
            FlowPanel1.Dock = DockStyle.Bottom
            SubTextBox1 = New TextBox()
            SubTextBox1.CausesValidation = True
            FlowPanel1.Controls.Add(SubTextBox1)
            Me.Controls.Add(FlowPanel1)
        End Sub


        Sub SubTextBox1_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles SubTextBox1.Validating
            MessageBox.Show("SubTextBox1 Validating!")
        End Sub


        Sub TextBox1_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles TextBox1.Validating
            MessageBox.Show("TextBox1 Validating!")
        End Sub


        Sub TextBox2_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles TextBox2.Validating
            MessageBox.Show("TextBox2 Validating!")
        End Sub


        Sub TextBox3_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles TextBox3.Validating
            MessageBox.Show("TextBox3 Validating!")
        End Sub


        Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles button1.Click
            Me.ValidateChildren((ValidationConstraints.ImmediateChildren Or ValidationConstraints.Enabled))
        End Sub
    End Class
End Namespace 'ValidateChildrenWithConstraints