vb.net - GhostText 使用 VB.Net

Question

大家好，我尝试创建一个 鬼文字在文本框上使用标签。我正在使用 VB.Net2005。我用这段代码完成了这个:

Public Class frmDataEntry

    Private Sub PhantomTextLastName()
        If txtLastName.Text = "" Then
            lblLastName.Visible = True
        Else
            lblLastName.Visible = False
        End If
    End Sub

    Private Sub PhantomTextFirstName()
        If txtFirstName.Text = "" Then
            lblFirstName.Visible = True
        Else
            lblFirstName.Visible = False
        End If
    End Sub

    Private Sub PhantomTextMiddleInitial()
        If txtMiddleInitial.Text = "" Then
            lblMiddleInitial.Visible = True
        Else
            lblMiddleInitial.Visible = False
        End If
    End Sub

    Private Sub txtLastName_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtLastName.Click
        lblLastName.Text = "Last Name"
    End Sub

    Private Sub txtLastName_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txtLastName.KeyDown
        PhantomTextLastName()
    End Sub

    Private Sub txtLastName_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtLastName.TextChanged
        PhantomTextLastName()
    End Sub

    Private Sub lblLastName_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lblLastName.Click
        txtLastName.Focus()
    End Sub

    Private Sub txtFirstName_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtFirstName.Click
        lblFirstName.Text = "First Name"
    End Sub

    Private Sub txtFirstName_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txtFirstName.KeyDown
        PhantomTextFirstName()
    End Sub

    Private Sub txtFirstName_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtFirstName.TextChanged
        PhantomTextFirstName()
    End Sub

    Private Sub lblFirstName_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lblFirstName.Click
        txtFirstName.Focus()
    End Sub

    Private Sub lblMiddleInitial_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lblMiddleInitial.Click
        txtMiddleInitial.Focus()
    End Sub

    Private Sub txtMiddleInitial_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtMiddleInitial.Click
        lblMiddleInitial.Text = "Middle I."
    End Sub

    Private Sub txtMiddleInitial_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txtMiddleInitial.KeyDown
        PhantomTextMiddleInitial()
    End Sub

    Private Sub txtMiddleInitial_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtMiddleInitial.TextChanged
        PhantomTextMiddleInitial()
    End Sub
End Class

有什么办法可以减少这段代码，这样当我尝试添加另一个文本框时，我就不必重新输入一堆代码了。我有使用模块和类的基本知识，但我真的不知道如何在这个项目中应用它。我是新手，如果你有任何教程可以帮助我解决这个问题，请给我链接。在此先感谢上帝保佑。

Answer 1

创建 usercontrol .您的用户控件背后的代码可能类似于:

 Public Class GhostTextbox

    Private _ghostText As String
    Public Property GhostText As String
        Get
            Return _ghostText
        End Get
        Set(ByVal Value As String)
            _ghostText = Value
        End Set
    End Property

    Public Property ActualText As String
        Get
            Return Me.TextBox1.Text
        End Get
        Set(ByVal Value As String)
            Me.TextBox1.Text = Value
        End Set
    End Property

    Private Sub PhantomText()
        If TextBox1.Text = "" Then
            Label1.Visible = True
        Else
            Label1.Visible = False
        End If
    End Sub

    Private Sub TextBox1_Click(sender As Object, e As System.EventArgs) Handles TextBox1.Click
        Label1.Text = GhostText
    End Sub

    Private Sub TextBox1_KeyDown(sender As Object, e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyDown
        PhantomText()
    End Sub

    Private Sub TextBox1_TextChanged(sender As System.Object, e As System.EventArgs) Handles TextBox1.TextChanged
        PhantomText()
    End Sub

    Private Sub GhostTextbox_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        Label1.Text = GhostText
    End Sub
End Class

然后，使用这个自定义控件而不是仅仅使用 TextBox .您需要做的就是设置 GhostText您添加的每个新控件的属性，而不是再次重做相同的逻辑。