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我想从网络摄像头捕获图像，我找到了一个很好的代码，唯一的问题是即使在断开网络摄像头驱动程序后网络摄像头灯仍然亮着。因此，网络摄像头似乎仍在使用中。如何调整它？

 SendMessage(hHwnd, WM_CAP_DRIVER_DISCONNECT, DeviceID, 0)
        DestroyWindow(hHwnd)

网络摄像头类

Public Class Form1
    Const WM_CAP As Short = &H400S
    Const WM_CAP_DRIVER_CONNECT As Integer = WM_CAP + 10
    Const WM_CAP_DRIVER_DISCONNECT As Integer = WM_CAP + 11
    Const WM_CAP_EDIT_COPY As Integer = WM_CAP + 30
    Public Const WM_CAP_GET_STATUS As Integer = WM_CAP + 54
    Public Const WM_CAP_DLG_VIDEOFORMAT As Integer = WM_CAP + 41
    Const WM_CAP_SET_PREVIEW As Integer = WM_CAP + 50
    Const WM_CAP_SET_PREVIEWRATE As Integer = WM_CAP + 52
    Const WM_CAP_SET_SCALE As Integer = WM_CAP + 53
    Const WS_CHILD As Integer = &H40000000
    Const WS_VISIBLE As Integer = &H10000000
    Const SWP_NOMOVE As Short = &H2S
    Const SWP_NOSIZE As Short = 1
    Const SWP_NOZORDER As Short = &H4S
    Const HWND_BOTTOM As Short = 1
    Private DeviceID As Integer = 0 ' Current device ID
    Private hHwnd As Integer ' Handle to preview window
    Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
        (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, _
        ByRef lParam As CAPSTATUS) As Boolean
    Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
       (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Boolean, _
       ByRef lParam As Integer) As Boolean
    Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
         (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, _
         ByRef lParam As Integer) As Boolean
    Declare Function SetWindowPos Lib "user32" Alias "SetWindowPos" (ByVal hwnd As Integer, _
        ByVal hWndInsertAfter As Integer, ByVal x As Integer, ByVal y As Integer, _
        ByVal cx As Integer, ByVal cy As Integer, ByVal wFlags As Integer) As Integer

    Declare Function DestroyWindow Lib "user32" (ByVal hndw As Integer) As Boolean
    Structure POINTAPI
        Dim x As Integer
        Dim y As Integer
    End Structure
        Private Sub LoadDeviceList()
        Dim strName As String = Space(100)
        Dim strVer As String = Space(100)
        Dim bReturn As Boolean
        Dim x As Short = 0
        ' 
        ' Load name of all avialable devices into the lstDevices
        '
        Do
            '
            '   Get Driver name and version
            '
            bReturn = capGetDriverDescriptionA(x, strName, 100, strVer, 100)
            '
            ' If there was a device add device name to the list
            '
            If bReturn Then lstDevices.Items.Add(strName.Trim)
            x += CType(1, Short)
        Loop Until bReturn = False
    End Sub

    Private Sub OpenPreviewWindow()
        ' Connect to device
        '
     SendMessage(hHwnd, WM_CAP_DRIVER_CONNECT, DeviceID, 0) 
       End Sub


    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        LoadDeviceList()
             End Sub


    Private Sub ClosePreviewWindow()
        '
        ' Disconnect from device
        '
        SendMessage(hHwnd, WM_CAP_DRIVER_DISCONNECT, DeviceID, 0)
        DestroyWindow(hHwnd)
    End Sub

启动和停止相机

    Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click
        DeviceID = lstDevices.SelectedIndex
        OpenPreviewWindow()
        Dim bReturn As Boolean
        Dim s As CAPSTATUS
        bReturn = SendMessage(hHwnd, WM_CAP_GET_STATUS, Marshal.SizeOf(s), s)
    End Sub

           Private Sub btnStop_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStop.Click
        ClosePreviewWindow()
          SendMessage(hHwnd, WM_CAP_DRIVER_DISCONNECT, DeviceID, 0)
    End Sub

       End Class
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