スピーカーを抜き差しする方法

Question

私はVisual Studio 2013 for Visual Basicを使用しており、スピーカーがスピーカージャックに差し込まれているか、スピーカージャックから抜かれているかどうかをテストできます。出来ますか？

Answer 1

これは、デバイストポロジAPIを使用して行うことができます。 IKsJackDescriptionインターフェイスを使用して、KSJACK_DESCRIPTION構造を取得することができます。この構造には、IsConnectedのメンバーが含まれています。ただし、すべてのデバイスがケーブル存在検出をサポートしているわけではありません。

COM宣言オブジェクト

Imports System 
Imports System.Collections.Generic 
Imports System.Text 
Imports System.Runtime.InteropServices 
Imports System.IO 
Imports System.Runtime.CompilerServices 

Namespace com_test 

    Class Native 


     <DllImport("ole32.Dll")> _ 
     Public Shared Function CoCreateInstance(ByRef clsid As Guid, <MarshalAs(UnmanagedType.IUnknown)> inner As Object, context As UInteger, ByRef uuid As Guid, <MarshalAs(UnmanagedType.IUnknown)> ByRef rReturnedComObject As Object) As UInteger 
     End Function 

     '************************************************************************ 

     <DllImport("ole32.dll")> _ 
     Private Shared Function PropVariantClear(ByRef pvar As PropVariant) As Integer 
     End Function 



     Public Const DEVICE_STATE_ACTIVE As Integer = &H1 

     Public Const DEVICE_STATE_DISABLE As Integer = &H2 

     Public Const DEVICE_STATE_NOTPRESENT As Integer = &H4 

     Public Const DEVICE_STATE_UNPLUGGED As Integer = &H8 

     Public Const DEVICE_STATEMASK_ALL As Integer = &Hf 


     Public Shared PKEY_Device_FriendlyName As New PROPERTYKEY(&Ha45c254eUI, &Hdf1c, &H4efd, &H80, &H20, &H67, _ 
      &Hd1, &H46, &Ha8, &H50, &He0, 14) 




     Public Shared PKEY_AudioEndpoint_FormFactor As New PROPERTYKEY(&H1da5d803, &Hd492, &H4edd, &H8c, &H23, &He0, _ 
      &Hc0, &Hff, &Hee, &H7f, &He, 0) 



    End Class 



    Enum EndpointFormFactor 


     RemoteNetworkDevice = 0 

     Speakers = (RemoteNetworkDevice + 1) 

     LineLevel = (Speakers + 1) 

     Headphones = (LineLevel + 1) 

     Microphone = (Headphones + 1) 

     Headset = (Microphone + 1) 

     Handset = (Headset + 1) 

     UnknownDigitalPassthrough = (Handset + 1) 

     SPDIF = (UnknownDigitalPassthrough + 1) 

     DigitalAudioDisplayDevice = (SPDIF + 1) 

     UnknownFormFactor = (DigitalAudioDisplayDevice + 1) 

     EndpointFormFactor_enum_count = (UnknownFormFactor + 1) 

    End Enum 



    Enum EPcxConnectionType 


     eConnTypeUnknown = 0 

     eConnType3Point5mm 

     eConnTypeQuarter 

     eConnTypeAtapiInternal 

     eConnTypeRCA 

     eConnTypeOptical 

     eConnTypeOtherDigital 

     eConnTypeOtherAnalog 

     eConnTypeMultichannelAnalogDIN 

     eConnTypeXlrProfessional 

     eConnTypeRJ11Modem 

     eConnTypeCombination 

    End Enum 



    Enum EPcxGeoLocation 


     eGeoLocRear = &H1 

     eGeoLocFront 

     eGeoLocLeft 

     eGeoLocRight 

     eGeoLocTop 

     eGeoLocBottom 

     eGeoLocRearPanel 

     eGeoLocRiser 

     eGeoLocInsideMobileLid 

     eGeoLocDrivebay 

     eGeoLocHDMI 

     eGeoLocOutsideMobileLid 

     eGeoLocATAPI 

     eGeoLocNotApplicable 

     eGeoLocReserved6 

     EPcxGeoLocation_enum_count 

    End Enum 



    Public Enum EDataFlow 


     eRender 

     eCapture 

     eAll 

     EDataFlow_enum_count 

    End Enum 



    Public Enum ERole 


     eConsole 

     eMultimedia 

     eCommunications 

     ERole_enum_count 

    End Enum 



    Public Enum CLSCTX 


     CLSCTX_INPROC_SERVER = &H1 

     CLSCTX_INPROC_HANDLER = &H2 

     CLSCTX_LOCAL_SERVER = &H4 

     CLSCTX_REMOTE_SERVER = &H10 


     CLSCTX_SERVER = (CLSCTX_INPROC_SERVER Or CLSCTX_LOCAL_SERVER Or CLSCTX_REMOTE_SERVER) 

     CLSCTX_ALL = (CLSCTX_INPROC_HANDLER Or CLSCTX_SERVER) 

    End Enum 



    'Windows Core Audio API declarations 

    'http://www.java2s.com/Code/CSharp/Windows/SoundUtils.htm 





    <Guid("0BD7A1BE-7A1A-44DB-8397-CC5392387B5E"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)> _ 
    Public Interface IMMDeviceCollection 


     Function GetCount(ByRef pcDevices As UInteger) As Integer 

     Function Item(nDevice As UInteger, <Out, MarshalAs(UnmanagedType.[Interface])> ByRef ppDevice As Object) As Integer 

    End Interface 





    <Guid("D666063F-1587-4E43-81F1-B948E807363F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)> _ 
    Public Interface IMMDevice 



     Function Activate(ByRef iid As Guid, dwClsCtx As UInteger, pActivationParams As IntPtr, <Out, MarshalAs(UnmanagedType.[Interface])> ByRef ppInterface As Object) As Integer 



     Function OpenPropertyStore(stgmAccess As Integer, <Out, MarshalAs(UnmanagedType.[Interface])> ByRef ppProperties As Object) As Integer 



     Function GetId(ByRef ppstrId As StringBuilder) As Integer 



     Function GetState(ByRef pdwState As Integer) As Integer 

    End Interface 




    <ComImport, Guid("BCDE0395-E52F-467C-8E3D-C4579291692E")> _ 
    Class MMDeviceEnumerator 


    End Class 





    <Guid("A95664D2-9614-4F35-A746-DE8DB63617E6"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)> _ 
    Public Interface IMMDeviceEnumerator 





     Function EnumAudioEndpoints(dataFlow As EDataFlow, dwStateMask As Integer, <Out, MarshalAs(UnmanagedType.[Interface])> ByRef ppDevices As Object) As Integer 




     Function GetDefaultAudioEndpoint(dataFlow As EDataFlow, role As ERole, <Out, MarshalAs(UnmanagedType.[Interface])> ByRef ppEndpoint As Object) As Integer 



     Function GetDevice(pwstrId As String, ByRef ppDevice As IntPtr) As Integer 



     Function RegisterEndpointNotificationCallback(pClient As IntPtr) As Integer 



     Function UnregisterEndpointNotificationCallback(pClient As IntPtr) As Integer 

    End Interface 





    '*********** Property store ***************************** 



    ' https://blogs.msdn.microsoft.com/adamroot/2008/04/11/interop-with-propvariants-in-net/ 




    <ComImport, Guid("886D8EEB-8CF2-4446-8D02-CDBA1DBDCF99"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)> _ 
    Interface IPropertyStore 



     <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType := MethodCodeType.Runtime)> _ 
     Sub GetCount(<Out> ByRef cProps As UInteger) 




     <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType := MethodCodeType.Runtime)> _ 
     Sub GetAt(<[In]> iProp As UInteger, ByRef pkey As PROPERTYKEY) 




     <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType := MethodCodeType.Runtime)> _ 
     Function GetValue(<[In]> ByRef key As PROPERTYKEY, ByRef pv As PropVariant) As Integer 




     <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType := MethodCodeType.Runtime)> _ 
     Sub SetValue(<[In]> ByRef key As PROPERTYKEY, <[In]> ByRef pv As Object) 




     <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType := MethodCodeType.Runtime)> _ 
     Sub Commit() 

    End Interface 




    <StructLayout(LayoutKind.Sequential, Pack := 4)> _ 
    Structure PROPERTYKEY 


     Public fmtid As Guid 

     Public pid As UInteger 



     Public Sub New(guid As Guid, propertyId As Integer) 


      Me.fmtid = guid 


      Me.pid = CUInt(propertyId) 
     End Sub 

     Public Sub New(formatId As String, propertyId As Integer) 

      Me.New(New Guid(formatId), propertyId) 


     End Sub 


     Public Sub New(a As UInteger, b As UInteger, c As UInteger, d As UInteger, e As UInteger, f As UInteger, _ 
      g As UInteger, h As UInteger, i As UInteger, j As UInteger, k As UInteger, propertyId As Integer) 


      Me.New(New Guid(CUInt(a), CUShort(b), CUShort(c), CByte(d), CByte(e), CByte(f), _ 
       CByte(g), CByte(h), CByte(i), CByte(j), CByte(k)), propertyId) 


     End Sub 

    End Structure 




    <StructLayout(LayoutKind.Sequential)> _ 
    Public Structure PropVariant 


     Private vt As UShort 

     Private wReserved1 As UShort 

     Private wReserved2 As UShort 

     Private wReserved3 As UShort 

     Private p As IntPtr 

     Private p2 As Integer 



     Private Function GetDataBytes() As Byte() 


      Dim ret As Byte() = New Byte(IntPtr.Size + (4 - 1)) {} 

      If IntPtr.Size = 4 Then 

       BitConverter.GetBytes(p.ToInt32()).CopyTo(ret, 0) 

      ElseIf IntPtr.Size = 8 Then 

       BitConverter.GetBytes(p.ToInt64()).CopyTo(ret, 0) 
      End If 

      BitConverter.GetBytes(p2).CopyTo(ret, IntPtr.Size) 

      Return ret 

     End Function 



     Private ReadOnly Property cVal() As SByte 
      ' CHAR cVal; 

      Get 
       Return CSByte(GetDataBytes()(0)) 
      End Get 
     End Property 




     Private ReadOnly Property iVal() As Short 
      ' SHORT iVal; 

      Get 
       Return BitConverter.ToInt16(GetDataBytes(), 0) 
      End Get 
     End Property 




     Private ReadOnly Property lVal() As Integer 
      ' LONG lVal; 

      Get 
       Return BitConverter.ToInt32(GetDataBytes(), 0) 
      End Get 
     End Property 




     Private ReadOnly Property hVal() As Long 
      ' LARGE_INTEGER hVal; 

      Get 
       Return BitConverter.ToInt64(GetDataBytes(), 0) 
      End Get 
     End Property 




     Private ReadOnly Property fltVal() As Single 
      ' FLOAT fltVal; 

      Get 
       Return BitConverter.ToSingle(GetDataBytes(), 0) 
      End Get 
     End Property 




     Public ReadOnly Property Value() As Object 


      Get 


       Select Case CType(vt, VarEnum) 


        Case VarEnum.VT_I1 

         Return cVal 

        Case VarEnum.VT_I2 

         Return iVal 


        Case VarEnum.VT_I4, VarEnum.VT_INT 

         Return lVal 


        Case VarEnum.VT_UI4, VarEnum.VT_I8 

         Return hVal 

        Case VarEnum.VT_R4 

         Return fltVal 

        Case VarEnum.VT_FILETIME 
         Return DateTime.FromFileTime(hVal) 

        Case VarEnum.VT_BSTR 

         Return Marshal.PtrToStringBSTR(p) 

        Case VarEnum.VT_BLOB 

         Dim blobData As Byte() = New Byte(lVal - 1) {} 

         Dim pBlobData As IntPtr 

         If IntPtr.Size = 4 Then 



          pBlobData = New IntPtr(p2) 

         ElseIf IntPtr.Size = 8 Then 



          pBlobData = New IntPtr(BitConverter.ToInt64(GetDataBytes(), 4)) 
         Else 


          Throw New NotSupportedException() 
         End If 

         Marshal.Copy(pBlobData, blobData, 0, lVal) 

         Return blobData 

        Case VarEnum.VT_LPSTR 

         Return Marshal.PtrToStringAnsi(p) 

        Case VarEnum.VT_LPWSTR 

         Return Marshal.PtrToStringUni(p) 

        Case VarEnum.VT_UNKNOWN 

         Return Marshal.GetObjectForIUnknown(p) 

        Case VarEnum.VT_DISPATCH 

         Return p 
        Case Else 


         Throw New NotSupportedException("0x" + vt.ToString("X4") + " type not supported") 


       End Select 
      End Get 
     End Property 




    End Structure 

    '***************************************************** 



    'Device Topology declarations 





    <Guid("2A07407E-6497-4A18-9787-32F79BD0D98F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)> _ 
    Public Interface IDeviceTopology 


     Function GetConnectorCount(<Out> ByRef pConnectorCount As Integer) As Integer 

     Function GetConnector(nIndex As Integer, ByRef ppConnector As IConnector) As Integer 

     Function GetSubunitCount(<Out> ByRef pCount As Integer) As Integer 

     'ISubunit 
     Function GetSubunit(nIndex As Integer, ByRef ppSubunit As Object) As Integer 

     Function GetPartById(nId As Integer, ByRef ppPart As IPart) As Integer 

     Function GetDeviceId(<Out, MarshalAs(UnmanagedType.LPWStr)> ByRef ppwstrDeviceId As String) As Integer 

     'IPartsList 
     Function GetSignalPath(pIPartFrom As IPart, pIPartTo As IPart, bRejectMixedPaths As Boolean, ppParts As Object) As Integer 

    End Interface 







    <InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("9c2c4058-23f5-41de-877a-df3af236a09e")> _ 
    Public Interface IConnector 


     Function [GetType](ByRef pType As Integer) As Integer 

     Function GetDataFlow(ByRef dataFlow As EDataFlow) As Integer 

     Function ConnectTo(<[In]> connector As IConnector) As Integer 

     Function Disconnect() As Integer 

     Function IsConnected(ByRef pbConnected As Boolean) As Integer 

     Function GetConnectedTo(<MarshalAs(UnmanagedType.[Interface])> ByRef ppConTo As Object) As Integer 

     Function GetConnectorIdConnectedTo(ByRef ppwstrConnectorId As String) As Integer 

     Function GetDeviceIdConnectedTo(ByRef ppwstrDeviceId As String) As Integer 

    End Interface 





    <Guid("AE2DE0E4-5BCA-4F2D-AA46-5D13F8FDB3A9"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)> _ 
    Public Interface IPart 


     Function GetName(ByRef ppwstrName As StringBuilder) As Integer 

     Function GetLocalId(ByRef pnId As Integer) As Integer 

     Function GetGlobalId(ByRef ppwstrGlobalId As StringBuilder) As Integer 

     Function GetPartType(ByRef pPartType As Integer) As Integer 

     Function GetSubType(ByRef pSubType As Guid) As Integer 

     Function GetControlInterfaceCount(ByRef pCount As UInteger) As Integer 



     'IControlInterface 
     Function GetControlInterface(nIndex As Integer, ByRef ppFunction As Object) As Integer 

     'IPartsList[] 
     Function EnumPartsIncoming(ByRef ppParts As Object) As Integer 

     'IPartsList[] 
     Function EnumPartsOutgoing(ByRef ppParts As Object) As Integer 



     Function GetTopologyObject(<Out, MarshalAs(UnmanagedType.[Interface])> ByRef ppTopology As Object) As Integer 






     Function Activate(dwClsContext As UInteger, ByRef refiid As Guid, <MarshalAs(UnmanagedType.[Interface])> ByRef interfacePointer As Object) As Integer 

     'IControlChangeNotify 
     Function RegisterControlChangeCallback(ByRef riid As Guid, pNofity As Object) As Integer 

     'IControlChangeNotify 
     Function UnregisterControlChangeCallback(pNotify As Object) As Integer 

    End Interface 



    <ComVisible(False)> _ 
    <ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("4509F757-2D46-4637-8E62-CE7DB944F57B")> _ 
    Public Interface IKsJackDescription 


     Function GetJackCount(ByRef jacks As UInteger) As Integer 

     Function GetJackDescription(jack As UInteger, ByRef pDescription As KSJACK_DESCRIPTION) As Integer 

    End Interface 




    <StructLayout(LayoutKind.Sequential)> _ 
    Public Structure KSJACK_DESCRIPTION 


     Public ChannelMapping As UInteger 

     Public Color As UInteger 

     Public ConnectionType As UInteger 

     Public GeoLocation As UInteger 

     Public GenLocation As UInteger 

     Public PortConnection As UInteger 

     Public IsConnected As UInteger 

    End Structure 


End Namespace 

---

例現在のデフォルトデバイスのジャック情報についての情報を取得する方法を

Imports System 
Imports System.Collections.Generic 
Imports System.Data 
Imports System.Text 
Imports System.Windows.Forms 
Imports System.Runtime.InteropServices 
Imports System.ComponentModel 

Namespace com_test 
    Public Partial Class Form1 
     Inherits Form 

     'displays device 
     Private Function PrintDevice(dev As IMMDevice) As String 
      Dim propertyStore As IPropertyStore = Nothing 
      Dim pDeviceTopology As IDeviceTopology = Nothing 
      Dim pConnFrom As IConnector = Nothing 
      Dim pConnTo As IConnector = Nothing 
      Dim pPart As IPart = Nothing 
      Dim pJackDesc As IKsJackDescription = Nothing 
      Dim desc As New KSJACK_DESCRIPTION() 

      Dim res As New StringBuilder(300) 
      Dim o As Object = Nothing 

      Dim state As Integer = 0 
      Dim con_count As UInteger = 0 

      Try 
       'device name 
       'STGM_READ 
       dev.OpenPropertyStore(0, o) 
       propertyStore = TryCast(o, IPropertyStore) 

       Dim friendlyName As New PropVariant() 
       propertyStore.GetValue(Native.PKEY_Device_FriendlyName, friendlyName) 
       res.AppendLine(friendlyName.Value.ToString()) 


       'form factor 
       Dim FormFactor As New PropVariant() 
       propertyStore.GetValue(Native.PKEY_AudioEndpoint_FormFactor, FormFactor) 
       Dim f As EndpointFormFactor = EndpointFormFactor.UnknownFormFactor 
       [Enum].TryParse(Of EndpointFormFactor)(FormFactor.Value.ToString(), f) 
       res.AppendLine("Form factor: " + f.ToString()) 

       dev.GetState(state) 

       Dim str As String = "" 
       Select Case state 
        Case Native.DEVICE_STATE_DISABLE 
         str = ("Disabled") 
         Exit Select 
        Case Native.DEVICE_STATE_NOTPRESENT 
         str = ("Not present") 
         Exit Select 
        Case Native.DEVICE_STATE_UNPLUGGED 
         str = ("Unplugged") 
         Exit Select 
       End Select 
       If str <> "" Then 
        res.AppendLine(str) 
       End If 


       ' DEVICE TOPOLOGY 

       Dim iidDeviceTopology As New Guid("2A07407E-6497-4A18-9787-32F79BD0D98F") 
       dev.Activate(iidDeviceTopology, CUInt(CLSCTX.CLSCTX_ALL), IntPtr.Zero, o) 
       pDeviceTopology = TryCast(o, IDeviceTopology) 

       pDeviceTopology.GetConnector(0, pConnFrom) 

       Try 
        o = Nothing 
        pConnFrom.GetConnectedTo(o) 
        pConnTo = TryCast(o, IConnector) 

        pPart = CType(pConnTo, IPart) 
        'QueryInterface 
        Dim iidKsJackDescription As New Guid("4509F757-2D46-4637-8E62-CE7DB944F57B") 
        pPart.Activate(CUInt(CLSCTX.CLSCTX_INPROC_SERVER), iidKsJackDescription, o) 
        pJackDesc = CType(o, IKsJackDescription) 

        If pJackDesc IsNot Nothing Then 
         con_count = 0 
         pJackDesc.GetJackCount(con_count) 
         If con_count > 0 Then 
          Dim sb As StringBuilder 

          'display jacks 
          For i As UInteger = 0 To con_count - 1 
           pJackDesc.GetJackDescription(i, desc) 

           sb = New StringBuilder(100) 
           Dim con_type As EPcxConnectionType = CType(desc.ConnectionType, EPcxConnectionType) 
           Dim loc As EPcxGeoLocation = CType(desc.GeoLocation, EPcxGeoLocation) 
           res.Append("* ") 

           Select Case con_type 
            Case EPcxConnectionType.eConnType3Point5mm 
             sb.Append("Jack 3.5 mm ") 
             Exit Select 
            Case EPcxConnectionType.eConnTypeAtapiInternal 
             sb.Append("ATAPI jack") 
             Exit Select 
            Case EPcxConnectionType.eConnTypeRCA 
             sb.Append("RCA jack") 
             Exit Select 
            Case EPcxConnectionType.eConnTypeQuarter 
             sb.Append("1/2 in. jack ") 
             Exit Select 
            Case EPcxConnectionType.eConnTypeOtherAnalog 
             sb.Append("Analog jack ") 
             Exit Select 
            Case EPcxConnectionType.eConnTypeOtherDigital 
             sb.Append("Digital jack ") 
             Exit Select 
            Case Else 
             sb.Append(con_type.ToString() + " ") 
             Exit Select 
           End Select 

           sb.Append("- " + loc.ToString()) 
           'jack location 
           res.Append(sb.ToString()) 

           If desc.IsConnected = 0 Then 
            res.AppendLine(": Disconnected") 
           Else 
            res.AppendLine(": Connected") 


           End If 
           'end for 
          Next 
         Else 
          res.AppendLine("* No jacks") 

         End If 
        Else 
         res.AppendLine("* Unable to get jacks") 
        End If 



       Catch ex As COMException 
        If CUInt(ex.HResult) = &H80070490UI Then 
         'E_NOTFOUND 
         res.AppendLine("Disconnected") 
        Else 
         res.AppendLine("COM error while getting jacks: " + ex.Message) 
        End If 
       Catch ex As Exception 
        res.AppendLine("Error while getting jacks: " + ex.Message) 

       End Try 
      Finally 
       'clean up resources     
       If dev IsNot Nothing Then 
        Marshal.ReleaseComObject(dev) 
       End If 
       If propertyStore IsNot Nothing Then 
        Marshal.ReleaseComObject(propertyStore) 
       End If 

       If pDeviceTopology IsNot Nothing Then 
        Marshal.ReleaseComObject(pDeviceTopology) 
        pDeviceTopology = Nothing 
       End If 
       If pConnFrom IsNot Nothing Then 
        Marshal.ReleaseComObject(pConnFrom) 
        pConnFrom = Nothing 
       End If 
       If pConnTo IsNot Nothing Then 
        Marshal.ReleaseComObject(pConnTo) 
        pConnTo = Nothing 
       End If 
       If pPart IsNot Nothing Then 
        Marshal.ReleaseComObject(pPart) 
        pPart = Nothing 
       End If 
       If pJackDesc IsNot Nothing Then 
        Marshal.ReleaseComObject(pJackDesc) 
        pJackDesc = Nothing 
       End If 
      End Try 

      Return res.ToString() 
     End Function 


     Public Sub New() 
      InitializeComponent() 
     End Sub 

     Private Sub button_Click(sender As Object, e As EventArgs) 
      Dim devenum As New MMDeviceEnumerator() 
      'Create enumerator 
      Dim deviceEnumerator As IMMDeviceEnumerator = CType(devenum, IMMDeviceEnumerator) 

      Dim defDevice As IMMDevice = Nothing 
      Dim propertyStore As IPropertyStore = Nothing 

      Try 
       Dim o As Object = Nothing 

       ' * get default device *     
       deviceEnumerator.GetDefaultAudioEndpoint(EDataFlow.eRender, ERole.eConsole, o) 
       defDevice = TryCast(o, IMMDevice) 

       textBox1.Text = "Default sound device: " + Environment.NewLine + Environment.NewLine 

       textBox1.Text += PrintDevice(defDevice) 
      Catch ex As Exception 
       MessageBox.Show(ex.ToString()) 
      Finally 
       'clean up resources 
       If devenum IsNot Nothing Then 
        Marshal.ReleaseComObject(devenum) 
       End If 
       If deviceEnumerator IsNot Nothing Then 
        Marshal.ReleaseComObject(deviceEnumerator) 
       End If 
       If defDevice IsNot Nothing Then 
        Marshal.ReleaseComObject(defDevice) 
       End If 
       If propertyStore IsNot Nothing Then 
        Marshal.ReleaseComObject(propertyStore) 
       End If 
      End Try 
     End Sub 


    End Class 
End Namespace