请问在.net里面怎么实现在picturebox里面画线啊？我在窗体里面可以实现，但是picturebox里不可以，为什么？

不可能不可以的，如下：

void PictureBox_Paint(object sender, PaintEventArgs e)
        {
            var g = Pb.CreateGraphics();
            g.SmoothingMode = SmoothingMode.AntiAlias;
            g.Clear(Pb.BackColor);
            g.DrawLine(new Pen(Color.Black, 2f), 0, 0, Pb.Width, Pb.Height);
        }

 

我也遇到过同样问题  但是我的程序是从VB6.0中移植过来的  但是PictureBox控件的不能升级

我是新手，今天刚好看到一篇类似的教程，借用下：

Private Sub btnDrawborder_Click(sender As Object, e As EventArgs) Handles btnDrawborder.Click
        Dim objGraphics As Graphics
        objGraphics = Me.CreateGraphics
        objGraphics.Clear(System.Drawing.SystemColors.Control)
        objGraphics.DrawRectangle(System.Drawing.Pens.Red, picShowPicture.Left - 1, _
                                    picShowPicture.Top - 1, picShowPicture.Height + 1, _
                                    picShowPicture.Width + 1)
        objGraphics.Dispose()
    End Sub

希望能对你有帮助