picturebox小弟我在里面已经画图，小弟我再为其设置背景时，里面内容清空了，小弟我不想让其清空，如何设置

picturebox我在里面已经画图，我再为其设置背景时，里面内容清空了，我不想让其清空，怎么设置？
picturebox.BackColor= "#ff0000 "

------解决方案--------------------
如果仅仅是用Line，Circle等方法画图，可以再增加两个picture控件解决：
在窗体上放三个图片框，大小相同。在Picture1里面画图，另外两个起辅助作用。
Private Sub Command1_Click()
'每次画线都要同时在三个picture里面进行
Picture1.Line (100, 100)-(1000, 1000), vbBlue
Picture2.Line (100, 100)-(1000, 1000), vbBlue
Picture3.Line (100, 100)-(1000, 1000), vbBlack

Picture1.Line (800, 800)-(200, 500), vbBlue
Picture2.Line (800, 800)-(200, 500), vbBlue
Picture3.Line (800, 800)-(200, 500), vbBlack

Picture1.Circle (1000, 1000), 800, vbBlue
Picture2.Circle (1000, 1000), 800, vbBlue
Picture3.Circle (1000, 1000), 800, vbBlack
End Sub

Private Sub Command2_Click()
'换背景颜色
Picture1.BackColor = vbGreen
Picture1.PaintPicture Picture3.Image, 0, 0, , , , , , , vbSrcAnd
Picture1.PaintPicture Picture2.Image, 0, 0, , , , , , , vbSrcPaint
End Sub

Private Sub Form_Load()
Picture1.AutoRedraw = True
Picture2.AutoRedraw = True
Picture3.AutoRedraw = True
Picture2.Visible = False
Picture3.Visible = False
End Sub