如何在 VB.Net 2010 中像 html 一样使用文本框的占位符 [英] how to use placeholder for Textbox in VB.Net 2010 like html

问题描述

我有一个表格可以进行一些数学计算.

I have a form that does some mathematical calculation.

我希望用户能够快速输入数据而不会擦除值.

I want to be able users to enter data quickly without erasing the value.

我觉得像在 html 中那样使用占位符很好

I thing its good to use placeholder like I did in html

但是我如何在 VB.Net 2010 中使用它?谢谢

but how can i use it in VB.Net 2010? Thanks

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        gtp.Text = "0.00"
        vatt.Text = "0.00"
        wht.Text = "0.00"
        npr.Text = "0.00"
    End Sub

推荐答案

如果当前值为占位符值，此代码清除文本框，否则保留输入值.

This code clears the text box if the current value is the placeholder value, otherwise it retains the input value.

Public Class Form1
Private Sub TextBox1_GotFocus(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.GotFocus
    If TextBox1.Text = "0.00" Then
        TextBox1.Text = ""
    End If
End Sub
Private Sub TextBox1_LostFocus(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.LostFocus
    If TextBox1.Text = "" Then
        TextBox1.Text = "0.00"
    End If
End Sub
End Class

如果您总是希望它清除文本框，请使用它.

If you always want it to clear the textbox then use this.

Public Class Form1
Private Sub TextBox1_GotFocus(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.GotFocus
    TextBox1.Text = ""
End Sub
Private Sub TextBox1_LostFocus(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.LostFocus
    If TextBox1.Text = "" Then
        TextBox1.Text = "0.00"
    End If
End Sub
End Class

要模拟实际的占位符，例如 HTML5 中的占位符，您需要在文本框顶部覆盖一个 label 控件，并根据 keyDown 和 LostFocus/Leave 事件，这取决于你的 VS 版本

To simulate an actual placeholder such as the one in HTML5 you'll need to overlay a label control on top of your textbox and set it's visability based on the event keyDown and LostFocus/Leave Event which will depend on your version of VS

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