KeyDownEventHandler Delegate

Represents the method that will handle an event that has received KeyDownEventArgs data.

Syntax

Visual Basic
C#
WinRT C#
WinRT JavaScript
C++

public delegate void KeyDownEventHandler( 
   object sender,
   KeyDownEventArgs e
)

'Declaration
 
Public Delegate Sub KeyDownEventHandler( _
   ByVal sender As Object, _
   ByVal e As KeyDownEventArgs _
)

'Usage
 
Dim instance As New KeyDownEventHandler(AddressOf HandlerMethod)

public delegate void KeyDownEventHandler( 
   object sender,
   KeyDownEventArgs e
)

KeyDownEventHandler( 
   sender ,
   e 
)

public delegate void KeyDownEventHandler( 
   Object^ sender,
   KeyDownEventArgs^ e
)

Parameters

sender: The source of the event.
e: A KeyDownEventArgs object that contains the event data.

Remarks

Represents the method that will handle an event that has received KeyDownEventArgs data. When the KeyDownEvent event is raised in a toolkit object, any subscribed event handlers in your code will be called. See the Microsoft documentation on .NET Events and Delegates for more information about .NET delegates and events.

Example

Visual Basic
C#
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

Copy Code

Public _result As Boolean = False
      Public _exit As Boolean = False
      Public _form As CaptureCtrlForm = New CaptureCtrlForm()
      Public Sub KeyPressesExample()
         Dim capturectrl As CaptureCtrl = _form.CaptureCtrl
         Dim outFile As String = Path.Combine(LEAD_VARS.MediaDir, "CaptureCtrl_KeyPressesExample.avi")

         Try
            ' set a video device, use the name of your device here
            If capturectrl.VideoDevices("Analog") Is Nothing Then
               Throw New Exception("No Analog capture device available")
            End If

            capturectrl.VideoDevices("Analog").Selected = True

            ' select the MPEG4 video compressor
            capturectrl.VideoCompressors.Mpeg4.Selected = True

            ' set an audio device, use the name of your device here
            capturectrl.AudioDevices("USB").Selected = True

            ' enable preview
            capturectrl.Preview = True

            ' enable CC
            capturectrl.ClosedCaptioning = True

            ' set the target output file
            capturectrl.TargetFile = outFile

            ' subscribe to the key events
            AddHandler capturectrl.KeyDown, AddressOf KeyDown_Helper
            AddHandler capturectrl.KeyUp, AddressOf KeyUp_Helper
            AddHandler capturectrl.KeyPress, AddressOf KeyPress_Helper

            ' capture it now!
            capturectrl.StartCapture(CaptureMode.AutoFramesAndAudio)
         Catch e1 As Exception
            _result = False
         End Try

         ' we'll loop on the state and pump messages for this example.
         ' but you should not need to if running from a Windows Forms application.
         Do While _exit = False
            Application.DoEvents()
         Loop

         ' clean up event handlers
         RemoveHandler capturectrl.KeyDown, AddressOf KeyDown_Helper
         RemoveHandler capturectrl.KeyUp, AddressOf KeyUp_Helper
         RemoveHandler capturectrl.KeyPress, AddressOf KeyPress_Helper
      End Sub

      Private Sub KeyPress_Helper(ByVal sender As Object, ByVal e As Leadtools.Multimedia.KeyPressEventArgs)
         Select Case e.keyAscii
            Case CShort("p")
               ' toggle preview mode
               _form.CaptureCtrl.TogglePreview()
            Case CShort("f")
               ' toggle full screen mode
               _form.CaptureCtrl.ToggleFullScreenMode()
            Case CShort("c")
               ' toggle closed captioning
               _form.CaptureCtrl.ToggleClosedCaptioning()
            Case CShort("s")
               ' stop the capture and exit
               _form.CaptureCtrl.StopCapture()
               _exit = True
         End Select

         ' set result
         _result = True
      End Sub

      Private Sub KeyUp_Helper(ByVal sender As Object, ByVal e As KeyUpEventArgs)
         ' set result
         _result = True
      End Sub

      Public Sub KeyDown_Helper(ByVal sender As Object, ByVal e As KeyDownEventArgs)
         ' set result
         _result = True
      End Sub

Public NotInheritable Class LEAD_VARS
   Public Const MediaDir As String = "C:\Program Files (x86)\LEAD Technologies\LEADTOOLS 175\Media";
End Class

public bool _result = false;
      public bool _exit = false;
      public CaptureCtrlForm _form = new CaptureCtrlForm();
      public void KeyPressesExample()
      {
         CaptureCtrl capturectrl = _form.CaptureCtrl;
         string outFile = Path.Combine(LEAD_VARS.MediaDir,"CaptureCtrl_KeyPressesExample.avi");

         try
         {
            // set a video device, use the name of your device here
            if (capturectrl.VideoDevices["Analog"] == null)
               throw new Exception("No Analog capture device available");

            capturectrl.VideoDevices["Analog"].Selected = true;

            // select the MPEG4 video compressor
            capturectrl.VideoCompressors.Mpeg4.Selected = true;

            // set an audio device, use the name of your device here
            capturectrl.AudioDevices["USB"].Selected = true;

            // enable preview
            capturectrl.Preview = true;

            // enable CC
            capturectrl.ClosedCaptioning = true;

            // set the target output file
            capturectrl.TargetFile = outFile;

            // subscribe to the key events
            capturectrl.KeyDown += KeyDown_Helper;
            capturectrl.KeyUp += KeyUp_Helper;
            capturectrl.KeyPress += KeyPress_Helper;

            // capture it now!
            capturectrl.StartCapture(CaptureMode.AutoFramesAndAudio);
         }
         catch (Exception)
         {
            _result = false;
         }

         // we'll loop on the state and pump messages for this example.
         // but you should not need to if running from a Windows Forms application.
         while (_exit == false)
            Application.DoEvents();

         // clean up event handlers
         capturectrl.KeyDown -= KeyDown_Helper;
         capturectrl.KeyUp -= KeyUp_Helper;
         capturectrl.KeyPress -= KeyPress_Helper;
      }

      void KeyPress_Helper(object sender, Leadtools.Multimedia.KeyPressEventArgs e)
      {
         switch ((char)e.keyAscii)
         {
            case 'p':
               // toggle preview mode
               _form.CaptureCtrl.TogglePreview();
               break;
            case 'f':
               // toggle full screen mode
               _form.CaptureCtrl.ToggleFullScreenMode();
               break;
            case 'c':
               // toggle closed captioning
               _form.CaptureCtrl.ToggleClosedCaptioning();
               break;
            case 's':
               // stop the capture and exit
               _form.CaptureCtrl.StopCapture();
               _exit = true;
               break;
         }

         // set result
         _result = true;
      }

      void KeyUp_Helper(object sender, KeyUpEventArgs e)
      {
         // set result
         _result = true;
      }

      public void KeyDown_Helper(object sender, KeyDownEventArgs e)
      {
         // set result
         _result = true;
      }

static class LEAD_VARS
{
   public const string MediaDir = @"C:\Program Files (x86)\LEAD Technologies\LEADTOOLS 175\Media";
}

Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

KeyDownEventHandler Members
Leadtools.Multimedia Namespace