Capturing Image Data In More Complex Applications

To capture an image an instance of the class mvIMPACT::acquire::FunctionInterface must be created. This class can be constructed by passing a pointer to the mvIMPACT::acquire::Device object obtained from the mvIMPACT::acquire::DeviceManager to the class constructor.

The function interface class provides access to most of the devices executable functions, while most of the settings (e.g. the exposure time or the trigger mode) are implemented as properties (see e.g. mvIMPACT::acquire::Property for details).

//-----------------------------------------------------------------------------
int main(int argc, char* argv[])
//-----------------------------------------------------------------------------
{
  mvIMPACT::acquire::DeviceManager devMgr;
  if( devMgr.deviceCount() == 0 )
  {
    cout << "No device found! Unable to continue!" << endl;
    char ch = getch();
    return 0;
  }
  cout << "Initializing the device. This might take some time..." << endl;
  // create an interface to the first device found
  mvIMPACT::acquire::Device* pDev = devMgr[0];
  try
  {
    pDev->open();
  }
  catch(mvIMPACT::acquire::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(error code: " << e.errCode()
         << "). Press any key to end the application..." << endl;
    char ch = getch();
    return 0;
  }
  mvIMPACT::acquire::FunctionInterface fi( pDev );
  // send a request to the default request queue of the device and wait for the result.
  fi.imageRequestSingle();
  // Start the acquisition manually if this was requested(this is to prepare the framework for data capture and tell the device to start streaming data)
  if( pDev->acquisitionStartStopBehaviour.read() == assbUser )
  {
    TDMR_ERROR result = DMR_NO_ERROR;
    if( ( result = static_cast<TDMR_ERROR>(fi.acquisitionStart()) ) != DMR_NO_ERROR )
    {
      cout << "'FunctionInterface.acquisitionStart' returned with an unexpected result: " << result
          << "(" << ImpactAcquireException::getErrorCodeAsString( result ) << ")" << endl;
    }
  }
  // wait for results from the default capture queue
  int requestNr = fi.imageRequestWaitFor( -1 );
  // check if the image has been captured without any problems
  if( !fi.isRequestNrValid( requestNr ) )
  {
    // If the error code is -2119(DEV_WAIT_FOR_REQUEST_FAILED), the documentation will provide
    // additional information under TDMR_ERROR in the interface reference
    cout << "imageRequestWaitFor failed (" << requestNr << ", " << ImpactAcquireException::getErrorCodeAsString( requestNr ) << ")"
         << ", timeout value too small?" << endl;
  }
  const mvIMPACT::acquire::Request* pRequest = fi.getRequest(requestNr);
  if( !pRequest->isOK() )
  {
    cout << "ERROR! Request result: " << pRequest->requestResult.readS() << endl;
    return 0;
  }
  // everything went well. Do whatever you like with the result
  const int width = pRequest->imageWidth.read();
  // unlock the buffer to let the framework know that you no longer need this buffer
  fi.imageRequestUnlock( requestNr );
  return 0;
}

This sample contains everything the user needs to do to capture one image including all initialization work and error handling for every source of error one can think of.

Note

A much more specific summary of the available sample applications can be found at the Typical Usage Scenarios And Example Applications page.

Several example applications will provide an even better understanding of the interface.

The GenICam™ vs. DeviceSpecific Interface Layout chapter will provide more details on how to work with properties.