GenICamCallbackOnEvent.cpp

The GenICamCallbackOnEvent program is a simple example which illustrates how GenICam™ events can be used to inform an application about a certain event via a callback.

How it works:

1. Open the device by calling

   pThreadParameter->pDev->open(); 

2. Enable GenICam™ events.
3. Attach a custom callback to the ExposureEndTimestamp property that gets called whenever a property is modified.
4. Start the image acquisition in order to cause the callbacks to get triggered.

The full explanation regarding the callback usage can be found at the chapter Callbacks Triggered By GenICam™ Events .

Source code

#ifdef _MSC_VER         // is Microsoft compiler?
#   if _MSC_VER < 1300  // is 'old' VC 6 compiler?
#       pragma warning( disable : 4786 ) // 'identifier was truncated to '255' characters in the debug information'
#   endif // #if _MSC_VER < 1300
#endif // #ifdef _MSC_VER
#include <apps/Common/exampleHelper.h>
#include <iostream>
#include <mvIMPACT_CPP/mvIMPACT_acquire_GenICam.h>
 
#ifdef _WIN32
#   include <process.h>
#   include <mvDisplay/Include/mvIMPACT_acquire_display.h>
using namespace mvIMPACT::acquire::display;
#   define USE_DISPLAY
#endif // #ifdef _WIN32
 
using namespace mvIMPACT::acquire;
using namespace mvIMPACT::acquire::GenICam;
using namespace std;
 
static bool s_boTerminated = false;
 
//=============================================================================
//================= Data type definitions =====================================
//=============================================================================
//-----------------------------------------------------------------------------
struct ThreadParameter
//-----------------------------------------------------------------------------
{
    Device* pDev;
#ifdef _WIN32
    ImageDisplayWindow  displayWindow;
    explicit  ThreadParameter( Device* p ) : pDev( p ), displayWindow( "mvIMPACT_acquire sample, Device " + pDev->serial.read() ) {}
#else
    explicit  ThreadParameter( Device* p ) : pDev( p ) {}
#endif // #ifdef _WIN32
};
 
//=============================================================================
//================= Camera's property callback ================================
//=============================================================================
//-----------------------------------------------------------------------------
class EventCallback : public ComponentCallback
{
public:
    explicit EventCallback( void* pUserData = 0 ) : ComponentCallback( pUserData ) {}
 
    virtual void execute( Component& c, void* pUserData )
    {
        try
        {
            // re-generating the object/data previously attached to the callback object. This could now be used to call a certain member function e.g. to update a class instance about this event!
            EventControl* ec = reinterpret_cast<EventControl*>( pUserData );
            // Execute the followings if the component is a property.
            if( c.isProp() )
            {
                Property p( c );
                // Show the property value in console when the property value changes due to the occurrence of the event.
                cout << "Component " << c.name() << " has changed. Its current value: " << p.readS() << "us. FrameID is: " << ec->eventExposureEndFrameID.readS() << endl;
            }
        }
        catch ( const ImpactAcquireException& e )
        {
            cout << "An error occurred while retrieving the callback value. Error code: " << e.getErrorCodeAsString() << ")." << endl;
        }
    }
};
 
//-----------------------------------------------------------------------------
unsigned int __stdcall liveThread( void* pData )
//-----------------------------------------------------------------------------
{
    ThreadParameter* pThreadParameter = reinterpret_cast<ThreadParameter*>( pData );
    cout << "Initialising the device. This might take some time..." << endl;
    try
    {
        pThreadParameter->pDev->interfaceLayout.write( dilGenICam );
        pThreadParameter->pDev->open();
    }
    catch( const ImpactAcquireException& e )
    {
        // this e.g. might happen if the same device is already opened in another process...
        cout << "An error occurred while opening the device " << pThreadParameter->pDev->serial.read()
             << "(error code: " << e.getErrorCodeAsString() << ")." << endl
             << "Press [ENTER] to end the application..." << endl;
        cin.get();
        return 0;
    }
 
    EventControl ec( pThreadParameter->pDev );
    try
    {
        ec.eventSelector.writeS( "ExposureEnd" );
        ec.eventNotification.writeS( "On" );
    }
    catch ( const ImpactAcquireException& e )
    {
        cout << "An error occurred while setting up event control to the device " << pThreadParameter->pDev->serial.read()
             << "(error code: " << e.getErrorCodeAsString() << ").";
    }
    ImageDisplay& display = pThreadParameter->displayWindow.GetImageDisplay();
    // create an interface to the device found
    mvIMPACT::acquire::FunctionInterface fi( pThreadParameter->pDev );
    TDMR_ERROR result = DMR_NO_ERROR;
    while( ( result = static_cast<TDMR_ERROR>( fi.imageRequestSingle() ) ) == DMR_NO_ERROR ) {};
    if( result != DEV_NO_FREE_REQUEST_AVAILABLE )
    {
        cout << "'FunctionInterface.imageRequestSingle' returned with an unexpected result: " << result
             << "(" << mvIMPACT::acquire::ImpactAcquireException::getErrorCodeAsString( result ) << ")" << endl;
    }
    manuallyStartAcquisitionIfNeeded( pThreadParameter->pDev, fi );
    // run thread loop
    mvIMPACT::acquire::Request* pRequest = 0;
    // we always have to keep at least 2 images as the displayWindow module might want to repaint the image, thus we
    // can free it unless we have a assigned the displayWindow to a new buffer.
    mvIMPACT::acquire::Request* pPreviousRequest = 0;
    const unsigned int timeout_ms = 500;
 
    EventCallback eventCallback( &ec );
    // register a callback to eventExposureEndTimestamp
    eventCallback.registerComponent( ec.eventExposureEndTimestamp );
 
    while( !s_boTerminated )
    {
        // wait for results from the default capture queue
        int requestNr = fi.imageRequestWaitFor( timeout_ms );
        pRequest = fi.isRequestNrValid( requestNr ) ? fi.getRequest( requestNr ) : 0;
        if( pRequest )
        {
            if( pRequest->isOK() )
            {
                display.SetImage( pRequest );
                display.Update();
            }
            else
            {
                cout << "Error: " << pRequest->requestResult.readS() << endl;
            }
            if( pPreviousRequest )
            {
                // this image has been displayed thus the buffer is no longer needed...
                pPreviousRequest->unlock();
            }
            pPreviousRequest = pRequest;
            // send a new image request into the capture queue
            fi.imageRequestSingle();
        }
        //else
        //{
        // Please note that slow systems or interface technologies in combination with high resolution sensors
        // might need more time to transmit an image than the timeout value which has been passed to imageRequestWaitFor().
        // If this is the case simply wait multiple times OR increase the timeout(not recommended as usually not necessary
        // and potentially makes the capture thread less responsive) and rebuild this application.
        // Once the device is configured for triggered image acquisition and the timeout elapsed before
        // the device has been triggered this might happen as well.
        // The return code would be -2119(DEV_WAIT_FOR_REQUEST_FAILED) in that case, the documentation will provide
        // additional information under TDMR_ERROR in the interface reference.
        // If waiting with an infinite timeout(-1) it will be necessary to call 'imageRequestReset' from another thread
        // to force 'imageRequestWaitFor' to return when no data is coming from the device/can be captured.
        // cout << "imageRequestWaitFor failed (" << requestNr << ", " << ImpactAcquireException::getErrorCodeAsString( requestNr ) << ")"
        //   << ", timeout value too small?" << endl;
        //}
    }
    manuallyStopAcquisitionIfNeeded( pThreadParameter->pDev, fi );
    // stop the displayWindow from showing freed memory
    display.RemoveImage();
    // In this sample all the next lines are redundant as the device driver will be
    // closed now, but in a real world application a thread like this might be started
    // several times an then it becomes crucial to clean up correctly.
    // free the last potentially locked request
    if( pRequest )
    {
        pRequest->unlock();
    }
    // clear all queues
    fi.imageRequestReset( 0, 0 );
    // clean up
    eventCallback.unregisterComponent( ec.eventExposureEndTimestamp );
    return 0;
}
 
//=============================================================================
//================= Main thread ===============================================
//=============================================================================
//-----------------------------------------------------------------------------
int main( void )
//-----------------------------------------------------------------------------
{
    DeviceManager devMgr;
    Device* pDev = getDeviceFromUserInput( devMgr );
    if( !pDev )
    {
        cout << "Unable to continue! Press [ENTER] to end the application" << endl;
        cin.get();
        return 1;
    }
    cout << "Press [ENTER] to stop the acquisition thread" << endl << endl;
 
    ThreadParameter threadParam( pDev );
#ifdef _WIN32
    unsigned int dwThreadID;
    HANDLE hThread = ( HANDLE )_beginthreadex( 0, 0, liveThread, ( LPVOID )( &threadParam ), 0, &dwThreadID );
    cin.get();
    s_boTerminated = true;
    WaitForSingleObject( hThread, INFINITE );
    CloseHandle( hThread );
#else
    liveThread( &threadParam );
    cin.get();
    s_boTerminated = true;
#endif  // #ifdef _WIN32
    return 0;
}