该源代码如何把PictureBox图片保存出去?

前几天我从网上找一个可以把截取屏幕界面到PictureBox的源代码,但我去不知如何把它保存为Jpg 或Bmp文件,曾经试过用"SavePicture Picture1.Picture"但也没用,因为可能是Picture1.Picture里面是为空的.所以无法保存.请各路高手指点迷津,在下感激不已!!!
(附源代码如下)

Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function StretchBlt Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal nSrcWidth As Long, ByVal nSrcHeight As Long, ByVal dwRop As Long) As Long
-------------------------------------------------------------------------------
Private Sub Command1_Click()
Dim wScreen As Long
Dim hScreen As Long
Dim w As Long
Dim h As Long
Dim pic As PictureBox
Picture1.Cls
wScreen = Screen.Width \ Screen.TwipsPerPixelX
hScreen = Screen.Height \ Screen.TwipsPerPixelY
Picture1.ScaleMode = vbPixels
w = Picture1.ScaleWidth
h = Picture1.ScaleHeight
hdcScreen = GetDC(0)
p = StretchBlt(Picture1.hdc, 0, 0, w, h, hdcScreen, 0, 0, wScreen, hScreen, vbSrcCopy)
End Sub