事件查看器

Application: The.Application.Name.exe
 Framework Version: v4.0.30319
 Description: The process was terminated due to an unhandled exception.
 Exception Info: System.IO.FileNotFoundException
 Stack:

   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(
      System.Object,System.Delegate,System.Object,Int32,System.Delegate)

   at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(
      System.Windows.Threading.DispatcherPriority,System.TimeSpan,Int32)

   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr,IntPtr,IntPtr)

   at MS.Win32.UnsafeNativeMethods.DispatchMessage(System.Windows.Interop.MSG ByRef)

   at System.Windows.Threading.Dispatcher.PushFrameImpl(
      System.Windows.Threading.DispatcherFrame)

   at System.Windows.Threading.Dispatcher.PushFrame(
      System.Windows.Threading.DispatcherFrame)

   at System.Windows.Threading.Dispatcher.Run()

   at System.Windows.Application.RunDispatcher(System.Object)

   at System.Windows.Application.RunInternal(System.Windows.Window)

   at System.Windows.Application.Run(System.Windows.Window)

   at The.Application.Name.Main()

BtnUseDesktop_Click

private void BtnUseDesktop_Click(object sender,RoutedEventArgs e)
{
    AvSwitcher switcher = new AvSwitcher();
    this.RunAsyncTask(() => 
        switcher.SwitchToDesktop(this.windowSyncSvc.ActiveLyncWindowHandle));
}

Click事件调用的AvSwitcher

public class AvSwitcher
{
    private DeviceLocationSvc deviceLocationSvc;
    private UIAutomationSvc uiAutomationSvc;
    private WindowMovingSvc windowMovingSvc;
    private ManualResetEvent manualResetEvent;
    private Modality audioVideo;
    public static bool IsSwitching { get; set; }

    public AvSwitcher()
    {            
        this.deviceLocationSvc = new DeviceLocationSvc();
        this.uiAutomationSvc = new UIAutomationSvc();
        this.windowMovingSvc = new WindowMovingSvc();
    }

    public void SwitchToDesktop(IntPtr activeLyncConvWindowHandle)
    {
        this.BeginHold(DeviceLocation.Desktop,activeLyncConvWindowHandle);
    }

    public void SwitchToWall(IntPtr activeLyncConvWindowHandle)
    {
        this.BeginHold(DeviceLocation.Wall,activeLyncConvWindowHandle);
    }

    private Conversation GetLyncConversation()
    {
        Conversation conv = null;
        if (LyncClient.GetClient() != null)
        {
            conv = LyncClient.GetClient().ConversationManager.Conversations.FirstOrDefault();
        }

        return conv;
    }

    private void BeginHold(DeviceLocation targetLocation,IntPtr activeLyncConvWindowHandle)
    {
        AvSwitcher.IsSwitching = true;

        // make sure the class doesn't dispose of itself
        this.manualResetEvent = new ManualResetEvent(false);

        Conversation conv = this.GetLyncConversation();
        if (conv != null)
        {
            this.audioVideo = conv.Modalities[ModalityTypes.AudioVideo];
            ModalityState modalityState = this.audioVideo.State;

            if (modalityState == ModalityState.Connected)
            {
                this.HoldCallAndThenDoTheSwitching(targetLocation,activeLyncConvWindowHandle);
            }
            else
            {
                this.DoTheSwitching(targetLocation,activeLyncConvWindowHandle);
            }
        }
    }

    private void HoldCallAndThenDoTheSwitching(
        DeviceLocation targetLocation,IntPtr activeLyncConvWindowHandle)
    {
        try
        {
            this.audioVideo.BeginHold(
                this.BeginHold_callback,new AsyncStateValues()
                {
                    TargetLocation = targetLocation,ActiveLyncConvWindowHandle = activeLyncConvWindowHandle
                });
            this.manualResetEvent.WaitOne();
        }
        catch (UnauthorizedAccessException)
        {
            // the call is already on hold
            this.DoTheSwitching(targetLocation,activeLyncConvWindowHandle);
        }
    }

    private void BeginHold_callback(IAsyncResult ar)
    {
        if (ar.IsCompleted)
        {
            DeviceLocation targetLocation = ((AsyncStateValues)ar.AsyncState).TargetLocation;
            IntPtr activeLyncConvWindowHandle = 
                ((AsyncStateValues)ar.AsyncState).ActiveLyncConvWindowHandle;
            this.DoTheSwitching(targetLocation,activeLyncConvWindowHandle);
        }

        Thread.Sleep(2000); // is this necessary
        this.audioVideo.BeginRetrieve(this.BeginRetrieve_callback,null);
    }

    private void DoTheSwitching(DeviceLocation targetLocation,IntPtr activeLyncConvWindowHandle)
    {
        DeviceLocationSvc.TargetDevices targetDevices = 
            this.deviceLocationSvc.GetTargetDevices(targetLocation);

        this.SwitchScreenUsingWinApi(targetDevices.Screen,activeLyncConvWindowHandle);
        this.SwitchVideoUsingLyncApi(targetDevices.VideoDevice);
        this.SwitchAudioUsingUIAutomation(
            targetDevices.MicName,targetDevices.SpeakersName,activeLyncConvWindowHandle);

        AvSwitcher.IsSwitching = false;
    }

    private void SwitchScreenUsingWinApi(Screen targetScreen,IntPtr activeLyncConvWindowHandle)
    {
        if (activeLyncConvWindowHandle != IntPtr.Zero)
        {
            WindowPosition wp = 
                this.windowMovingSvc.GetTargetWindowPositionFromScreen(targetScreen);
            this.windowMovingSvc.MoveTheWindowToTargetPosition(activeLyncConvWindowHandle,wp);
        }
    }

    private void SwitchVideoUsingLyncApi(VideoDevice targetVideoDevice)
    {
        if (targetVideoDevice != null)
        {
            LyncClient.GetClient().DeviceManager.ActiveVideoDevice = targetVideoDevice;
        }
    }

    private void SwitchAudioUsingUIAutomation(
        string targetMicName,string targetSpeakersName,IntPtr activeLyncConvWindowHandle)
    {
        if (targetMicName != null && targetSpeakersName != null)
        {
            AutomationElement lyncConvWindow = 
                AutomationElement.FromHandle(activeLyncConvWindowHandle);

            AutomationElement lyncOptionsWindow =
                this.uiAutomationSvc.OpenTheLyncOptionsWindowFromTheConvWindow(lyncConvWindow);

            this.uiAutomationSvc.SelectTheTargetMic(lyncOptionsWindow,targetMicName);

            this.uiAutomationSvc.SelectTheTargetSpeakers(lyncOptionsWindow,targetSpeakersName);

            this.uiAutomationSvc.InvokeOkayButton(lyncOptionsWindow);
        }
    }

    private void BeginRetrieve_callback(IAsyncResult ar)
    {
        this.audioVideo.EndRetrieve(ar);
        this.manualResetEvent.Set(); // allow the program to exit
    }

    private class AsyncStateValues
    {
        internal DeviceLocation TargetLocation { get; set; }

        internal IntPtr ActiveLyncConvWindowHandle { get; set; }
    }
}