GenICamCallbackOnEvent.cs

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

   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

using mv.impact.acquire;
using mv.impact.acquire.examples.helper;
using mv.impact.acquire.GenICam;
using System;
using System.Threading;
 
namespace GenICamCallbackOnEvent
{
    public class EventCallback : ComponentCallback
    {
        public EventCallback(Object pUserData) : base(pUserData) { }
        // Please carefully read the documentation of the base class (mv.impact.acquire.ComponentCallback) and the documentation of the 
        // mv.impact.acquire.ComponentCallback.execute function in particular to avoid unpleasant surprises!
        public override void execute(Component c, Object 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 = (EventControl)pUserData;
                // Execute the followings if the component is a property.
                if (c.isProp)
                {
                    Property p = new Property(c.hObj);
                    // Show the property value in console when the property value changes due to the occurrence of the event.
                    Console.WriteLine("Component " + c.name + " has changed. Its current value: " + p.readS() + "us. FrameID is: " + ec.eventExposureEndFrameID.readS());
                }
            }
            catch (ImpactAcquireException e)
            {
                Console.WriteLine("An error occurred while retrieving the callback value. Error code: " + e.Message + ").");
            }
        }
 
        static void Main(string[] args)
        {
            mv.impact.acquire.LibraryPath.init(); // this will add the folders containing unmanaged libraries to the PATH variable.
            Device pDev = DeviceAccess.getDeviceFromUserInput();
            if (pDev == null)
            {
                Console.WriteLine("Unable to continue! Press any key to end the program.");
                Console.Read();
                Environment.Exit(1);
            }
 
            Console.WriteLine("Initialising the device. This might take some time...");
            try
            {
                pDev.open();
            }
            catch (ImpactAcquireException e)
            {
                // this e.g. might happen if the same device is already opened in another process...
                Console.WriteLine("An error occurred while opening the device " + pDev.serial +
                    "(error code: " + e.Message + "). Press any key to end the application...");
                Console.ReadLine();
                Environment.Exit(1);
            }
 
            EventControl ec = new EventControl(pDev);
            try
            {
                ec.eventSelector.writeS("ExposureEnd");
                ec.eventNotification.writeS("On");
            }
            catch (ImpactAcquireException e)
            {
                Console.WriteLine("An error occurred while setting up event control to the device " + pDev.serial.read()
                        + "(error code: " + e.Message + ").");
            }
 
#if USE_DISPLAY
            ImageDisplayWindow window = new ImageDisplayWindow(String.Format("mvIMPACT_acquire sample, Device {0}", pDev.serial.read()));
#endif // #if USE_DISPLAY
            bool terminated = false;
            Console.WriteLine("Press [ENTER] to end the application");
            EventCallback eventCallback = new EventCallback(ec);
            // register a callback to eventExposureEndTimestamp
            eventCallback.registerComponent(ec.eventExposureEndTimestamp);
 
            Thread thread = new Thread(delegate ()
            {
                // create an interface to the device found
                FunctionInterface fi = new FunctionInterface(pDev);
                // Send all requests to the capture queue. There can be more than 1 queue for some devices, but for this sample
                // we will work with the default capture queue. If a device supports more than one capture or result
                // queue, this will be stated in the manual. If nothing is mentioned about it, the device supports one
                // queue only. This loop will send all requests currently available to the driver. To modify the number of requests
                // use the property mv.impact.acquire.SystemSettings.requestCount at runtime (note that some devices will
                // only allow to modify this parameter while NOT streaming data!) or the property
                // mv.impact.acquire.Device.defaultRequestCount BEFORE opening the device.
                TDMR_ERROR result = TDMR_ERROR.DMR_NO_ERROR;
                while ((result = (TDMR_ERROR)fi.imageRequestSingle()) == TDMR_ERROR.DMR_NO_ERROR) { };
                if (result != TDMR_ERROR.DEV_NO_FREE_REQUEST_AVAILABLE)
                {
                    Console.WriteLine("'FunctionInterface.imageRequestSingle' returned with an unexpected result: {0}({1})", result, ImpactAcquireException.getErrorCodeAsString(result));
                }
                DeviceAccess.manuallyStartAcquisitionIfNeeded(pDev, fi);
                // run thread loop
                Request pRequest = null;
                // we always have to keep at least 2 images as the display module might want to repaint the image, thus we
                // cannot free it unless we have a assigned the display to a new buffer.
                Request pPreviousRequest = null;
                int timeout_ms = 500;
                int requestNr = Device.INVALID_ID;
                while (!terminated)
                {
                    // wait for results from the default capture queue
                    requestNr = fi.imageRequestWaitFor(timeout_ms);
                    pRequest = fi.isRequestNrValid(requestNr) ? fi.getRequest(requestNr) : null;
                    if (pRequest != null)
                    {
                        if (pRequest.isOK)
                        {
#if USE_DISPLAY
#   if CLR_AT_LEAST_3_DOT_5
                            // Extension methods are not supported by CLR versions smaller than 3.5 and this next function
                            // is therefore not available then.
                            window.imageDisplay.SetImage(pRequest);
#   else
                            // If extension methods are not available, the following function can be used instead. It is
                            // not as convenient and will only work for some pixel formats. For more complex pixel formats
                            // use other overloads of this method
                            window.imageDisplay.SetImage(pRequest.imageData.read(), pRequest.imageWidth.read(), pRequest.imageHeight.read(), pRequest.imageBytesPerPixel.read() * 8, pRequest.imageLinePitch.read());
#   endif
                            window.imageDisplay.Update();
#endif // #if USE_DISPLAY
                        }
                        else
                        {
                            Console.WriteLine("Error: {0}", pRequest.requestResult.readS());
                        }
                        if (pPreviousRequest != null)
                        {
                            // 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.
                    // Console.WriteLine("imageRequestWaitFor failed ({0}, {1}), timeout value too small?", requestNr, ImpactAcquireException.getErrorCodeAsString(requestNr));
                    //}
                }
                DeviceAccess.manuallyStopAcquisitionIfNeeded(pDev, fi);
#if USE_DISPLAY
                // stop the display from showing freed memory
                window.imageDisplay.RemoveImage();
#endif // #if USE_DISPLAY
                // 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 != null)
                {
                    pRequest.unlock();
                }
                // clear all queues
                fi.imageRequestReset(0, 0);
            });
            thread.Start();
            Console.ReadLine();
            terminated = true;
            // clean up
            eventCallback.unregisterComponent(ec.eventExposureEndTimestamp);
            thread.Join();
#if USE_DISPLAY
            window.Dispose();
#endif // #if USE_DISPLAY
        }
    }
}