在vb.net中绘制直线

我试图在按钮中使用以下代码。我想叫DrawLineFloat。我尝试调用DrawLineFloat（），但不起作用。我需要在（）中输入什么

谢谢

 Public Sub DrawLineFloat(ByVal e As PaintEventArgs)
    ' Create pen.
    Dim blackPen As New Pen(Color.Black, 3)
    ' Create coordinates of points that define line.
    Dim x1 As Single = 100.0F
    Dim y1 As Single = 100.0F
    Dim x2 As Single = 500.0F
    Dim y2 As Single = 100.0F
    ' Draw line to screen.
    e.Graphics.DrawLine(blackPen, x1, y1, x2, y2)
End Sub

尝试将空值（VB中为Nothing）传递给函数

DrawLineFloat(Nothing)

为什么不这样写呢

Public Sub DrawLine()
    ' Create pen.
    Dim blackPen As New Pen(Color.Black, 3)
    ' Create coordinates of points that define line.
    Dim x1 As Single = 100.0F
    Dim y1 As Single = 100.0F
    Dim x2 As Single = 500.0F
    Dim y2 As Single = 100.0F
    ' Draw line to screen.
    e.Graphics.DrawLine(blackPen, x1, y1, x2, y2)
End Sub

打个电话

DrawLine()

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我想你是在表单中调用它，但不是在绘画事件中。 因此，您需要创建用于绘制线的图形

    Public Sub DrawLineFloat() 
        ' Create pen. 
        Dim blackPen As New Pen(Color.Black, 3) 
        ' Create coordinates of points that define line. 
        Dim x1 As Single = 100.0F 
        Dim y1 As Single = 100.0F 
        Dim x2 As Single = 500.0F 
        Dim y2 As Single = 100.0F 
        ' Draw line to screen. 

        Dim g As Graphics = Me.CreateGraphics()
        g.DrawLine(blackPen, x1, y1, x2, y2) 

        blackPen.Dispose()

End Sub 

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还要注意的是，笔对象应该尽快处理

“它没有工作”，是否有错误，或者没有绘制任何内容？您是否已检查函数是否已执行（即必须逐步执行）？您需要在（）中传递参数。。。