Programming Tutorial:Implementing an Input Logger - Revision history

Mellinger: /* EnvironmentExtension Class */

2026-02-02T18:10:19Z

EnvironmentExtension Class

← Older revision		Revision as of 18:10, 2 February 2026
Line 80:		Line 80:
	{		{
	public:		public:
	ThumbWheelLogger()		ThumbWheelLogger();
	~~: mLogThumbWheel(false),~~
	~~mpThumbWheelThread(nullptr)~~
	{}
	~ThumbWheelLogger() {}		~ThumbWheelLogger() {}
	void Publish() override;		void Publish() override;

Mellinger: /* EnvironmentExtension Class */

2026-02-02T18:10:01Z

EnvironmentExtension Class

← Older revision		Revision as of 18:10, 2 February 2026
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	ThumbWheelLogger()		ThumbWheelLogger()
	{		{
	PublishEnabler("LogThumbWheel");		PublishEnabler("LogThumbWheel");
	}		}
	</pre>		</pre>

Mellinger: /* EnvironmentExtension Class */

2026-02-02T18:09:30Z

EnvironmentExtension Class

← Older revision		Revision as of 18:09, 2 February 2026
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	private:		private:
	bool mLogThumbWheel;		bool mLogThumbWheel = false;
	ThumbWheelThread* mpThumbWheelThread;		ThumbWheelThread* mpThumbWheelThread = nullptr;
	};		};
	#endif // THUMBWHEEL_LOGGER_H		#endif // THUMBWHEEL_LOGGER_H
			</pre>


			In the extension component's constructor function, we communicate our ''LogThumbWheel'' parameter as a so-called enabler parameter to the framework.
			This way, the BCI2000Launcher program will be aware of our logger, and will know how to enable it at module startup:
			<pre>
			ThumbWheelLogger()
			{
			PublishEnabler("LogThumbWheel");
			}
	</pre>		</pre>

Mellinger at 09:56, 5 June 2023

2023-06-05T09:56:05Z

← Older revision		Revision as of 09:56, 5 June 2023
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	To support input logging with per-sample resolution, BCI2000 allows code to post so-called [[Programming Reference:Events\|events]] '''asynchronously''' from a separate thread, which are time-stamped internally and matched against the current data block's time stamp in order to associate them with individual samples.		To support input logging with per-sample resolution, BCI2000 allows code to post so-called [[Programming Reference:Events\|events]] '''asynchronously''' from a separate thread, which are time-stamped internally and matched against the current data block's time stamp in order to associate them with individual samples.

	In this tutorial, we will discuss how to implement input Logging for a device by polling its state in regular intervals. Generally, relying on OS events to detect changes in device state is preferred over polling; however, whether and how device state is available via OS events depends strongly on the device's driver software, and it is thus difficult to provide a valid example. Readers interested in input logging via OS events should read this tutorial first, and then proceed to the [~~http~~://{{SERVERNAME}}/tracproj/browser/trunk/src/shared/modules/signalsource/logging/KeyLogger.h key logger component's source code] for a non-polling example.		In this tutorial, we will discuss how to implement input Logging for a device by polling its state in regular intervals. Generally, relying on OS events to detect changes in device state is preferred over polling; however, whether and how device state is available via OS events depends strongly on the device's driver software, and it is thus difficult to provide a valid example. Readers interested in input logging via OS events should read this tutorial first, and then proceed to the [https://{{SERVERNAME}}/tracproj/browser/trunk/src/shared/modules/signalsource/logging/KeyLogger.h key logger component's source code] for a non-polling example.

	==Implementation==		==Implementation==

Mellinger: /* Event Interface */

2023-04-20T17:07:45Z

Event Interface

← Older revision		Revision as of 17:07, 20 April 2023
Line 26:		Line 26:

	===Event Interface===		===Event Interface===
	Using the [[Programming Reference:Events\|BCI2000 event interface]], device state may be written into [[BCI2000 Glossary#State\|BCI2000 states]] asynchronously.		Using the [[Programming Reference:Events\|BCI2000 event interface]], device state may be written into [[BCI2000 Glossary#State\|BCI2000 event states]] asynchronously.
	We will use the event interface to record the wheel's position into a state called <tt>ThumbWheelPos</tt>, writing		We will use the event interface to record the wheel's position into a state called <tt>ThumbWheelPos</tt>, writing
	<pre>		<pre>

Mellinger: /* Overview */

2023-04-18T15:45:37Z

Overview

← Older revision		Revision as of 15:45, 18 April 2023
Line 6:		Line 6:
	To support input logging with per-sample resolution, BCI2000 allows code to post so-called [[Programming Reference:Events\|events]] '''asynchronously''' from a separate thread, which are time-stamped internally and matched against the current data block's time stamp in order to associate them with individual samples.		To support input logging with per-sample resolution, BCI2000 allows code to post so-called [[Programming Reference:Events\|events]] '''asynchronously''' from a separate thread, which are time-stamped internally and matched against the current data block's time stamp in order to associate them with individual samples.

	In this tutorial, we will discuss how to implement input Logging for a device by polling its state in regular intervals. Generally, relying on OS events to detect changes in device state is preferred over polling; however, whether and how device state is available via OS events depends strongly on the device's driver software, and it is thus difficult to provide a valid example. Readers interested in input logging via OS events should read this tutorial first, and then proceed to the [http://{{SERVERNAME}}/tracproj/browser/trunk/src/shared/modules/signalsource/KeyLogger.h key logger component's source code] for a non-polling example.		In this tutorial, we will discuss how to implement input Logging for a device by polling its state in regular intervals. Generally, relying on OS events to detect changes in device state is preferred over polling; however, whether and how device state is available via OS events depends strongly on the device's driver software, and it is thus difficult to provide a valid example. Readers interested in input logging via OS events should read this tutorial first, and then proceed to the [http://{{SERVERNAME}}/tracproj/browser/trunk/src/shared/modules/signalsource/logging/KeyLogger.h key logger component's source code] for a non-polling example.

	==Implementation==		==Implementation==

Mellinger at 15:34, 18 April 2023

2023-04-18T15:34:02Z

← Older revision		Revision as of 15:34, 18 April 2023
Line 169:		Line 169:

	==See also==		==See also==
	[[Programming Reference:EnvironmentExtension Class]], [[Programming Reference:~~OSThread~~ Class]], [[Programming Reference:Events]]		[[Programming Reference:EnvironmentExtension Class]], [[Programming Reference:Thread Class]], [[Programming Reference:Events]]

	[[Category:Tutorial]][[Category:Development]][[Category:Framework API]][[Category:Data Acquisition]]		[[Category:Tutorial]][[Category:Development]][[Category:Framework API]][[Category:Data Acquisition]]

Mellinger: /* EnvironmentExtension Class */

2023-04-18T15:33:20Z

EnvironmentExtension Class

← Older revision		Revision as of 15:33, 18 April 2023
Line 81:		Line 81:
	public:		public:
	ThumbWheelLogger()		ThumbWheelLogger()
	: mLogThumbWheel( false ),		: mLogThumbWheel(false),
	mpThumbWheelThread( ~~NULL~~ )		mpThumbWheelThread(nullptr)
	{}		{}
	~~virtual~~ ~ ThumbWheelLogger()		~ThumbWheelLogger() {}
	{}		void Publish() override;
	~~virtual~~ void Publish();		void Preflight() const override;
	~~virtual~~ void Preflight() const;		void Initialize() override;
	~~virtual~~ void Initialize();		void StartRun() override;
	~~virtual~~ void StartRun();		void StopRun() override;
	~~virtual~~ void StopRun();		void Halt() override;
	~~virtual~~ void Halt();

	private:		private:
Line 104:		Line 103:
	void ThumbWheelLogger::Publish()		void ThumbWheelLogger::Publish()
	{		{
	if( OptionalParameter( "LogThumbWheel" ) > 0 )		if (OptionalParameter("LogThumbWheel") > 0)
	{		{
	BEGIN_PARAMETER_DEFINITIONS		BEGIN_PARAMETER_DEFINITIONS
Line 121:		Line 120:
	void ThumbWheelLogger::Preflight() const		void ThumbWheelLogger::Preflight() const
	{		{
	if( OptionalParameter( "LogThumbWheel" ) > 0 )		if (OptionalParameter("LogThumbWheel") > 0)
	if( ThumbOK != ThumbWheelInit() )		if(ThumbOK != ThumbWheelInit())
	bcierr << "ThumbWheel device unavailable" ~~<< endl~~;		bcierr << "ThumbWheel device unavailable";
	}		}
	</pre>		</pre>
Line 130:		Line 129:
	void ThumbWheelLogger::Initialize()		void ThumbWheelLogger::Initialize()
	{		{
	mLogThumbWheel = ( OptionalParameter( "LogThumbWheel" ) > 0 );		mLogThumbWheel = (OptionalParameter("LogThumbWheel") > 0);
	}		}
	</pre>		</pre>
Line 137:		Line 136:
	void ThumbWheelLogger::StartRun()		void ThumbWheelLogger::StartRun()
	{		{
	if( mLogThumbWheel )		if(mLogThumbWheel)
	{		{
	mpThumbWheelThread = new ThumbWheelThread;		mpThumbWheelThread = new ThumbWheelThread;
Line 148:		Line 147:
	void ThumbWheelLogger::StopRun()		void ThumbWheelLogger::StopRun()
	{		{
	if( mpThumbWheelThread ~~!= NULL~~ )		if (mpThumbWheelThread)
	{		{
	~~OSEvent terminateEvent;~~		mpThumbWheelThread->Terminate();
	mpThumbWheelThread->Terminate~~( &terminateEvent );~~
	~~terminateEvent->Wait~~();
	delete mpThumbWheelThread;		delete mpThumbWheelThread;
	mpThumbWheelThread = ~~NULL~~;		mpThumbWheelThread = nullptr;
	}		}
	}		}
Line 166:		Line 163:
	</pre>		</pre>
	Finally, to make sure there exists an object of our <tt>ThumbWheelLogger</tt> class, we use the <tt>Extension</tt> macro at the top of its <tt>.cpp</tt> file:		Finally, to make sure there exists an object of our <tt>ThumbWheelLogger</tt> class, we use the <tt>Extension</tt> macro at the top of its <tt>.cpp</tt> file:
	Extension( ThumbWheelLogger );		Extension(ThumbWheelLogger);

	==Finished==		==Finished==

Mellinger: /* Thread Interface */

2023-04-18T15:28:16Z

Thread Interface

← Older revision		Revision as of 15:28, 18 April 2023
Line 35:		Line 35:

	===Thread Interface===		===Thread Interface===
	In order to observe the wheel's state independently of BCI2000's processing of data blocks, we create a thread that polls wheel state in regular intervals. We will use BCI2000's [[Programming Reference:~~OSThread~~ Class\|~~OSThread~~ class]] to implement that separate thread.		In order to observe the wheel's state independently of BCI2000's processing of data blocks, we create a thread that polls wheel state in regular intervals. We will use BCI2000's [[Programming Reference:Thread Class\|Thread class]] to implement that separate thread.
	<pre>		<pre>
	#include "~~OSThread~~.h"		#include "Thread.h"
	#include "ThumbWheel.h"		#include "ThumbWheel.h"

	class ThumbThread : public ~~OSThread~~		class ThumbThread : public Thread
	{		{
	ThumbThread()		ThumbThread()
	{}		{}
	~~virtual~~ ~ThumbThread()		~ThumbThread()
	{}		{}
	~~virtual~~ int ~~Execute~~()		int OnExecute() override
	{		{
	if( ThumbOK == ThumbWheelInit() )		if( ThumbOK == ThumbWheelInit() )
	{		{
	int lastWheelPos = -1;		int lastWheelPos = -1;
	while( !~~IsTerminating~~() )		while( !Terminating() )
	{		{
	~~Sleep~~( 1 );		ThreadUtils::SleepForMs( 1 );
	int curWheelPos = ThumbWheelGetPos();		int curWheelPos = ThumbWheelGetPos();
	if( curWheelPos != lastWheelPos )		if( curWheelPos != lastWheelPos )

Mellinger: /* EnvironmentExtension Class */

2011-06-10T14:37:21Z

EnvironmentExtension Class

← Older revision		Revision as of 14:37, 10 June 2011
Line 150:		Line 150:
	if( mpThumbWheelThread != NULL )		if( mpThumbWheelThread != NULL )
	{		{
	mpThumbWheelThread->Terminate();		OSEvent terminateEvent;
	~~while( !mpThumbWheelThread~~->~~IsTerminated() )~~		mpThumbWheelThread->Terminate( &terminateEvent );
	~~Sleep~~( 1 );		terminateEvent->Wait();
	delete mpThumbWheelThread;		delete mpThumbWheelThread;
	mpThumbWheelThread = NULL;		mpThumbWheelThread = NULL;