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KeyDownEventHandler Delegate

Summary

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

Syntax

C++/CLI

public delegate void KeyDownEventHandler( 
   object sender, 
   KeyDownEventArgs 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

using Leadtools; 
using Leadtools.MediaFoundation; 
using LeadtoolsMediaFoundationExamples.Fixtures; 
 
 
public bool _result = false; 
public bool _exit = false; 
public CaptureCtrlForm _form = new CaptureCtrlForm(false); 
 
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["USB"] == null) 
         throw new Exception("No USB capture device available"); 
 
      capturectrl.VideoDevices["USB"].Selected = true; 
 
      // set an audio device, use the name of your device here 
      capturectrl.AudioDevices["USB"].Selected = true; 
 
      // enable preview 
      capturectrl.Preview = 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.MediaFoundation.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 's': 
         // stop the capture and exit 
         _form.CaptureCtrl.StopCapture(); 
         _exit = true; 
         break; 
      case ' ': 
         // pause the capture or run if paused, this shows in the output file 
         if (_form.CaptureCtrl.State == CaptureState.Running || _form.CaptureCtrl.State == CaptureState.Pending) 
            _form.CaptureCtrl.PauseCapture(); 
         else if (_form.CaptureCtrl.State == CaptureState.Paused) 
            _form.CaptureCtrl.RunCapture(); 
         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:\LEADTOOLS23\Media"; 
}

Requirements

Target Platforms

Reference

KeyDownEventHandler Members

Leadtools.MediaFoundation Namespace

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Help Version 23.0.2024.2.29

Leadtools.MediaFoundation Assembly

Introduction

Getting Started

Namespaces

Leadtools.MediaFoundation Namespace

Leadtools.MediaFoundation.Common Namespace

Assemblies