画圆 圆心为（350,250）半径为200

Public Class Form1
    Private Sub Form1_Paint(ByVal sender As Object,ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
        Dim gr As Graphics = Me.CreateGraphics
        gr.DrawEllipse(Pens.Green,350,250,50,50)
        gr.Dispose()
    End Sub
End Class

画椭圆 和窗体相同大的椭圆

Public Class Form1
    Private Sub Form1_Paint(ByVal sender As Object,ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
        Dim gr As Graphics = Me.CreateGraphics
        gr.DrawEllipse(Pens.Red,Me.ClientSize.Width,Me.ClientSize.Height)
        gr.Dispose()
    End Sub
End Class

画椭圆 改 （跟随窗体大小改变）

Public Class Form1
    Private Sub Form1_Resize(ByVal sender As Object,ByVal e As System.EventArgs) Handles Me.Resize
        Me.Refresh() '刷新
        Dim gr As Graphics = Me.CreateGraphics
        gr.DrawEllipse(Pens.Red,Me.ClientSize.Height)
        gr.Dispose()
    End Sub
End Class

画两点之间的线 例如 （100,30）到（500,300）之间的线

Public Class Form1
    Private Sub Form1_Paint(ByVal sender As Object,ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
        Dim gr As Graphics = Me.CreateGraphics
        gr.DrawLine(Pens.Red,100,30,500,300)
        gr.Dispose()
    End Sub
End Class

图片的水平和垂直翻转

Public Class Form1
    Private Sub Form1_Paint(ByVal sender As Object,ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
        Dim gr As Graphics = Me.CreateGraphics
        Dim img As Image = Image.FromFile("C:\Users\lenovo\Downloads\1.jpg")
        gr.DrawImage(img,100)
        gr.DrawImage(img,220,-100) '垂直翻转
        gr.DrawImage(img,230,-100,100) '水平翻转
        gr.Dispose()
    End Sub
End Class

绘制正方形

Public Class Form1
    Private Sub Form1_Paint(ByVal sender As Object,ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
        Dim gr As Graphics = Me.CreateGraphics
        gr.DrawRectangle(Pens.Red,130,300,300)
        gr.Dispose()
    End Sub
End Class