在VB6下调用普通USB摄像头，如何拍照？

[myface2011]

我用VB6，在窗体里加了一个PictureBox或者Image，用来表示摄像头显示所拍摄的区域，现在加了一个按钮，拍照让拍下来的照片显示在这个PictureBox框里，我网上找了找，一旦拍摄启动，感觉是调用资源的问题，请有做过的大牛赐教！

[myface2011]

请求大牛们帮助！

[e4snake]

都不知道你怎么用的。。。。。

[myface2011]

我用了网上一段程序，如下：
.bas部分的代码

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 = 440, _
  Optional nHeight As Long = 440, _
  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

放了一个窗体，一个按钮，一个picturebox控件，窗体部分代码：
Dim Video_Handle As Long

Private Sub Command1_Click()
  Dim x As StdPicture
    Set x = CapturePicture(Video_Handle)
    SavePicture x, "c:\a1.bmp"
    PicCapture.Visible = False
    nowPic.Visible = True
    nowPic.Picture = LoadPicture("c:\a1.bmp")
    Image1.Picture = LoadPicture("c:\a1.bmp")
End Sub

Private Sub Form_Load()
   Video_Handle = CreateCaptureWindow(PicCapture.hwnd)
   nowPic.Visible = False
End Sub

Private Sub Form_Unload(Cancel As Integer)
  Disconnect Video_Handle
End Sub

执行到这两句出错：
Set x = CapturePicture(Video_Handle)
SavePicture x, "c:\a1.bmp"
提示的错误是：
runtime error "521 " can't open clipboard
不知道什么原因？

[嗷嗷叫的老马]

对于楼顶文字,我严重怀疑你是会打中文的老外,因为我看了三遍,完全没看明白你在讲什么,虽然字都认识..... 看了3楼补充,终于让我明白了: 原来你是因为这部分代码有错误 好吧,扯远了,中文语法问题我没法帮你,但VB的问题还是能帮到点的: 你的错误是"runtime error "521 " can't open clipboard",已经讲得很明白,无法打开剪贴板. 从CapturePicture()函数的实现来看,需要把截的图放到剪贴板里再取回来,才能得到一个stdPicture对象,以便保存. Public Function CapturePicture(nCaptureHandle As Long) As StdPicture Clipboard.Clear SendMessage nCaptureHandle, WM_CAP_EDIT_COPY, 0, 0 Set CapturePicture = Clipboard.GetData End Function 至于你这代码为什么无法打开剪贴板,你要跟到CapturePicture()内部去,搞清楚具体错误是在哪一行. 如果是Clipboard.Clear,那有可能是别的程序正在使用,可以尝试用一个带Sleep(100)的循环去调用这一句,没有错误的话即成功. 另外,这样的方法不好,因为你并不需要使用到剪贴板,WM_CAP_EDIT_COPY消息是方便在别的地方(例如QQ聊天窗口中)粘贴图像而使用的,你这里是为了保存到文件并显示,那使用WM_CAP_FILE_SAVEDIB消息是最合适不过的了. 这里给你一个封装:

Function capFileSaveDIB(ByVal hCapWnd As Long, ByVal FilePath As String) As Boolean
   capFileSaveDIB = SendMessageAsString(hCapWnd, WM_CAP_FILE_SAVEDIB, 0&, FilePath)
End Function

'调用:
if not capFileSaveDIB(Video_Handle,"C:\a1.bmp") then
    Msgbox "保存失败!"
end if

[SHPMEX]

我的错误是 “380”无效属性值

[litaoa]

在获取视频的时候和获取别的窗体的时候用的API是不一样的，以前我测试过用普能API不能截取播放的影片的图，后来没再试过。 用暴风和QQ可以实现。暂没发现是什么原理。