get_framegrabber_callback — Query callback function of an image acquisition device.
The operator get_framegrabber_callback queries a callback function for the image acquisition device specified by AcqHandle. If the callback function was registered via set_framegrabber_callback before, CallbackFunction contains a pointer to it, otherwise NULL. Furthermore, UserContext contains a pointer to the user-specific context data that was set via set_framegrabber_callback (or NULL).
With the parameter CallbackType, you can select different callback types. Suggested values are:
The image acquisition has raised an exception.
The exposure of the next image has been finished.
The exposure of the next image has been started.
A new image is ready to be fetched by grab_image_async.
Depending on the functionality of the underlying API, additional values for CallbackType are possible. All actually supported callback types of a specific image acquisition device can be queried by calling get_framegrabber_param with the parameter 'available_callback_types'. For more details see the documentation of the specific image acquisition interface.
For a multithreaded application all image acquisition operators (as listed in open_framegrabber) are an own group in which info_framegrabber, open_framegrabber, close_framegrabber and close_all_framegrabbers are executed exclusively.
get_framegrabber_callback runs in parallel with all non-exclusive operators inside and outside of this group.
Handle of the acquisition device to be used.
Default value: 'transfer_end'
Suggested values: 'exception', 'exposure_end', 'exposure_start', 'transfer_end'
Pointer to the callback function.
Pointer to user-specific context data.
If the image acquisition device is open and the specified callback type is supported, the operator get_framegrabber_callback returns the value 2 (H_MSG_TRUE). Otherwise an exception is raised.
grab_image, grab_data, grab_image_start, grab_image_async, grab_data_async, set_framegrabber_param, close_framegrabber
open_framegrabber, info_framegrabber, set_framegrabber_callback