在VB.net中刷新或重画picturebox

我试图在我的vb应用程序中查看youtube验证码，但我不知道如何刷新/重画图片框。youtube验证码在，每次我刷新页面时验证码都在更改。如何使用vb.net中的按钮或计时器更改验证码。下面是我用来将验证码加载到picturebox的代码

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 
        captchaBox.ImageLocation = "http://www.youtube.com/cimg" 
    End Sub

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我尝试使用captchaBox.Refresh（），但它不起作用。我希望有人能帮助我。thx

刷新只是重新绘制控件，它不会再次检索图像。您需要重置ImageLocation属性才能使其工作。例如，使用计时器：

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    captchaBox.ImageLocation = "http://www.youtube.com/cimg"
    Timer1.Enabled = True
    Timer1.Interval = 1000
End Sub

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
    captchaBox.ImageLocation = "http://www.youtube.com/cimg"
End Sub

试试这个：

Private Sub Form1_Load() Handles MyBase.Load
    Timer1.Start()
    PictureBox1.ImageLocation = "http://www.youtube.com/cimg"
End Sub

Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
    PictureBox1.Image = Nothing
    PictureBox1.ImageLocation = "http://www.youtube.com/cimg"
End Sub