编程：如何检测是否有程序在用摄象头？

[jf110]

如题：
如何检测是否有程序在用摄象头？

[tzwsoho]

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

Sub Get_CaptureWindow(Optional ByVal nm As Long = 0)
'建立一个可抽取的窗口
'nm 为,若不只一个抽取装置的话,指定装置代号
CapHWnd = capCreateCaptureWindow("", WS_CHILD Or WS_VISIBLE, 0, 0, 160, 120, Screen.ActiveForm.hwnd, 0)
Call Connect_CaptureDriver(nm)
End Sub

Function Connect_CaptureDriver(ByVal nDriverIndex As Long) As Boolean
'链接到抽取装置
Dim retVal As Boolean
Dim Caps As CAPDRIVERCAPS
Dim I As Long
'Debug.Assert (nDriverIndex < 10) And (nDriverIndex >= 0)
'链接到抽取窗口的界面
retVal = SendMessage_Long(CapHWnd, WM_CAP_DRIVER_CONNECT, nDriverIndex, 0&)
If retVal = False Then Exit Function
'返回抽取界面的能力
retVal = SendMessage_Any(CapHWnd, WM_CAP_DRIVER_GET_CAPS, Len(Caps), Caps)
'设置每毫秒预览的速度
Call Set_PreviewRate(CapHWnd, 66) '15 FPS
'激活摄影机的预览图像
Call Set_Preview
'重新调整抽取窗口为全部占满图像
Call ResizeCaptureWindow
Connect_CaptureDriver = True
End Function

用这个创建一个视频窗口，创建失败的话应该就是使用中了吧…………没测试过…………

[jf110]

这是普通的做法，但是有个特殊的情况

当一个程序已经打开了摄象头，我的程序再打开的话，
SendMessage_Long(CapHWnd, WM_CAP_DRIVER_CONNECT, nDriverIndex, 0&)
到这步的时候，会先跳出一个视频源的对话框，一定要把这个对话框关闭以后，然后才能得到返回值


很是郁闷啊。。。。。。

[cangwu_lee]

這個 API capDriverConnect，看看

[jf110]

capDriverConnect，没有这个API，这是一个被定义的函数，内容就是
SendMessage_Long(CapHWnd, WM_CAP_DRIVER_CONNECT, nDriverIndex, 0&)