Question

我正在尝试在按钮中使用以下代码。我想调用DrawLineFloat。我试过调用DrawLineFloat（）但它没有用。我需要输入什么？（）？

由于

 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

Answer 1

我想你是在一个表单中调用它，但不是在Paint事件中。因此，您需要创建用于绘制线条的图形

    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

另请注意，Pen对象应尽快处理

Answer 2

为什么不写

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

并调用

DrawLine()

Answer 3

尝试将null值（VB中的Nothning）传递给函数。

DrawLineFloat(Nothing)

在vb.net中绘制线条

3 个答案: