在richtextbox中每行输入字符数量的限制。（不完全！）

Imports System.ComponentModel

Public Class myrichtextbox

    Inherits System.Windows.Forms.RichTextBox

 

 

 

 

#Region " Windows 窗体设计器生成的代码 "

 

 

 

 

    Public Sub New()

        MyBase.New()

 

 

 

 

        '该调用是 Windows 窗体设计器所必需的。

        InitializeComponent()

 

 

 

 

        '在 InitializeComponent() 调用之后添加任何初始化

        Me.Text = ""

    End Sub

 

 

 

 

    'UserControl 重写 dispose 以清理组件列表。

    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

 

 

 

 

    'Windows 窗体设计器所必需的

    Private components As System.ComponentModel.IContainer

 

 

 

 

    '注意：以下过程是 Windows 窗体设计器所必需的

    '可以使用 Windows 窗体设计器修改此过程。

    '不要使用代码编辑器修改它。

    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

        components = New System.ComponentModel.Container()

    End Sub

 

 

 

 

#End Region

    Private row As Integer ‘行号

    Private row_length As Integer ‘每行最大输入数

    <Browsable(True), Description("每行的字符数"), DefaultValue(CByte(10))> _

   Public Property set_num() As Integer

        Get

            Return row_length

        End Get

        Set(ByVal Value As Integer)

            row_length = IIf(Value = 0, 10, Value)

        End Set

    End Property

   

    Public Function s(ByVal row As Integer) As Integer

        If Me.Text.Length = 0 Then Exit Function '如果没有输入时，第一个输入是没有行的

        'MessageBox.Show(Me.Text.Length, "111")

        'MessageBox.Show(CStr(Me.Text.Length))

        If Me.Lines(row).Length >= row_length - 1 Then ‘一般输入9个，第10个为回车符

            Return -1

        End If

        Return 0

    End Function

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)

        Select Case m.Msg

            Case &H102    '按键

                'MessageBox.Show(111)

                Dim KeyAsc As Integer = m.WParam.ToInt32

                MessageBox.Show(CStr(KeyAsc))

                If s(row) = -1 Then

                    If Not (KeyAsc = 10 OrElse KeyAsc = 13) Then '按了回车符，换行符是否超行的处理

                        Return

                    End If

                End If

 

 

 

 

        End Select

        MyBase.WndProc(m)

    End Sub

 

 

 

 

    Private Sub myrichtextbox_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.TextChanged

        'MessageBox.Show(Me.Text.Length)

        row = Me.Lines.GetLength(0) - 1

    End Sub

 

 

 

 

    'Private Sub myrichtextbox_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles MyBase.KeyPress

 

 

 

 

    '    MessageBox.Show("哈哈")

    'End Sub

End Class