vb.net picturebox控件 绘制曲线

大家都知道,vb.net封装了GDI,但是你死活找不到像vb6一样简单的代码

vb6是这样的:

Dim x1 As Integer
Dim x2 As Integer
Dim y1 As Integer
Dim y2 As Integer
Dim flag As Boolean

Private Sub Picture1_MouseDown(button As Integer, shift As Integer, x As Single, y As Single)
    flag = True
    x1 = x
    y1 = y
    Picture1.Line (x1, y1)-(x1 + 1, y1 + 1)
End Sub

Private Sub Picture1_MouseMove(button As Integer, shift As Integer, x As Single, y As Single)

    If flag = False Then
        Exit Sub
    End If
    
    If flag = True Then
        x2 = x
        y2 = y
        Picture1.Line (x1, y1)-(x2, y2)
        x1 = x2
        y1 = y2
    End If
    
End Sub
Private Sub Picture1_MouseUp(button As Integer, shift As Integer, x As Single, y As Single)
    flag = False
End Sub

而vb.net是这样的

Dim x1 As Integer
    Dim x2 As Integer
    Dim y1 As Integer
    Dim y2 As Integer
    Dim flag As Boolean = False
Private Sub PictureBox1_MouseDown(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseDown
        flag = True
        x1 = e.X
        y1 = e.Y
        x2 = e.X
        y2 = e.Y
    End Sub

    Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove
        If flag = True Then
            x1 = e.X
            y1 = e.Y
            Dim Graph As Graphics
            Graph = Graphics.FromImage(PictureBox1.Image)
            PictureBox1.CreateGraphics.DrawLine(p, New Point(x1, y1), New Point(x2, y2))
            x2 = e.X
            y2 = e.Y
        End If
    End Sub

    Private Sub PictureBox1_MouseUp(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseUp
        flag = False
    End Sub

 现在终于明白了吧

那么如何清除呢?

vb6

Picture1.Cls

vb.net

PictureBox1.CreateGraphics.Clear(BackColor)

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