VB使用摄像头拍照

运用这段简单的代码，可以用VB轻松地打开摄像头拍照，改动后可实现后台拍照！模块代码
Private Declare Function capCreateCaptureWindow Lib "avicap32.dll" _  
  Alias "capCreateCaptureWindowA" ( _ 
  ByVal lpszWindowName As String, _  
  ByVal dwStyle As Long, _  
  ByVal x As Long, _  
  ByVal y As Long, _  
  ByVal nWidth As Long, _  
  ByVal nHeight As Long, _  
  ByVal hWndParent As Long, _  
  ByVal nID As Long) As Long

Private Const WS_CHILD = &H40000000
Private Const WS_VISIBLE = &H10000000
Private Const WM_USER = &H400
Private Const WM_CAP_START = &H400
Private Const WM_CAP_EDIT_COPY = (WM_CAP_START + 30)
Private Const WM_CAP_DRIVER_CONNECT = (WM_CAP_START + 10)
Private Const WM_CAP_SET_PREVIEWRATE = (WM_CAP_START + 52)
Private Const WM_CAP_SET_OVERLAY = (WM_CAP_START + 51)
Private Const WM_CAP_SET_PREVIEW = (WM_CAP_START + 50)
Private Const WM_CAP_DRIVER_DISCONNECT = (WM_CAP_START + 11)
Private Declare Function SendMessage Lib "user32" _  
  Alias "SendMessageA" ( _
  ByVal hwnd As Long, _
  ByVal wMsg As Long, _ 
  ByVal wParam As Long, _
  lParam As Any) As Long

Private Preview_Handle As Long
Public Function CreateCaptureWindow( _
  hWndParent As Long, _
  Optional x As Long = 0, _ 
  Optional y As Long = 0, _ 
  Optional nWidth As Long = 320, _ 
  Optional nHeight As Long = 240, _ 
  Optional nCameraID As Long = 0) As Long  

Preview_Handle = capCreateCaptureWindow("Video", _ 
   WS_CHILD + WS_VISIBLE, x, y, _  
   nWidth, nHeight, hWndParent, 1)  
SendMessage Preview_Handle, WM_CAP_DRIVER_CONNECT, nCameraID, 0 
 SendMessage Preview_Handle, WM_CAP_SET_PREVIEWRATE, 30, 0 
 SendMessage Preview_Handle, WM_CAP_SET_OVERLAY, 1, 0 
 SendMessage Preview_Handle, WM_CAP_SET_PREVIEW, 1, 0 
 CreateCaptureWindow = Preview_Handle
End Function

Public Function CapturePicture(nCaptureHandle As Long) As StdPicture 
 Clipboard.Clear 
 SendMessage nCaptureHandle, WM_CAP_EDIT_COPY, 0, 0 
 Set CapturePicture = Clipboard.GetData
End Function

Public Sub Disconnect(nCaptureHandle As Long, _  
  Optional nCameraID = 0)  
SendMessage nCaptureHandle, WM_CAP_DRIVER_DISCONNECT, _   
 nCameraID, 0
End Sub

'在form上添加一个PictureBox,名称改为PicCapture,一个按钮,名称为Command1。
Dim Video_Handle As Long
Private Sub Form_Load()
    Video_Handle = CreateCaptureWindow(PicCapture.hwnd)
End Sub
Private Sub Command1_Click()
    Dim x As StdPicture  
  Set x = CapturePicture(Video_Handle)  
  SavePicture x, "c:\a.bmp"'拍照保存
End Sub
Private Sub Form_Unload(Cancel As Integer) 
   Disconnect Video_Handle
End Sub