VB.net关于Textbox文本控件全选的小技巧

#Region "搜索框的全选"

 

    Dim counter As Integer = 0 '点击次数

    Dim isSelectAll As Boolean = False '是否全选

    Dim selectPoint As Integer = 0  '当前光标位置

 

    Private Sub TextBox1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.Click

        counter += 1

 

        If counter = 1 Then '判断是否首次点击

            selectPoint = TextBox1.SelectionStart

            TextBox1.SelectAll()

            isSelectAll = True

        ElseIf counter > 1 Then

            If TextBox1.SelectionLength = 0 Then '判断选择字符的长度是否为0

                If TextBox1.SelectionStart = selectPoint Then '判断是否点击上次同一位置

                    If isSelectAll = True Then

                        isSelectAll = False

                    Else

                        TextBox1.SelectAll()

                        isSelectAll = True

                    End If

                Else

                    If TextBox1.SelectionStart = TextBox1.TextLength AndAlso isSelectAll = False Then '判断光标位置在最末

                        TextBox1.SelectAll()

                        isSelectAll = True

                    Else

                        selectPoint = TextBox1.SelectionStart '不是上次同一位置，则记录当前位置

                        isSelectAll = False

                    End If

 

                End If

            End If

        End If

    End Sub

 

    Private Sub TextBox1_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.LostFocus

        counter = 0

    End Sub

 

    Private Sub TextBox1_DoubleClick(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.DoubleClick

        isSelectAll = True

    End Sub

 

#End Region