set_framegrabber_callbackT_set_framegrabber_callbackSetFramegrabberCallbackSetFramegrabberCallbackset_framegrabber_callback (Operator)

Name

set_framegrabber_callbackT_set_framegrabber_callbackSetFramegrabberCallbackSetFramegrabberCallbackset_framegrabber_callback — Register a callback function for an image acquisition device.

Signature

Description

The operator set_framegrabber_callbackset_framegrabber_callbackSetFramegrabberCallbackSetFramegrabberCallbackSetFramegrabberCallbackset_framegrabber_callback registers a callback function for the image acquisition device specified by AcqHandleAcqHandleAcqHandleAcqHandleacqHandleacq_handle. The parameter CallbackFunctionCallbackFunctionCallbackFunctionCallbackFunctioncallbackFunctioncallback_function contains a pointer to the function to register, while CallbackTypeCallbackTypeCallbackTypeCallbackTypecallbackTypecallback_type specifies to which function of the underlying API the callback should be connected.

Suggested values for CallbackTypeCallbackTypeCallbackTypeCallbackTypecallbackTypecallback_type are:

'exception':

The image acquisition has raised an exception.

'exposure_end':

The exposure of the next image has been finished.

'exposure_start':

The exposure of the next image has been started.

'transfer_end':

A new image is ready to be fetched by grab_image_asyncgrab_image_asyncGrabImageAsyncGrabImageAsyncGrabImageAsyncgrab_image_async.

Depending on the functionality of the underlying API, additional values for CallbackTypeCallbackTypeCallbackTypeCallbackTypecallbackTypecallback_type are possible. All actually supported callback types of a specific image acquisition device can be queried by calling get_framegrabber_paramget_framegrabber_paramGetFramegrabberParamGetFramegrabberParamGetFramegrabberParamget_framegrabber_param with the parameter 'available_callback_types'. For more details see the documentation of the specific image acquisition interface.

Once the callback is registered, on every occurrence of the underlying event (e.g., the notification that the exposure has finished) the specified callback function CallbackFunctionCallbackFunctionCallbackFunctionCallbackFunctioncallbackFunctioncallback_function will be called. If CallbackFunctionCallbackFunctionCallbackFunctionCallbackFunctioncallbackFunctioncallback_function is set to NULL, the corresponding callback will be unregistered.

The signature of the callback function is the following: Herror HAcqCallback(void *AcqHandle, void *Context, void *UserContext)

The first parameter of the callback function contains the handle to the image acquisition device passed in AcqHandleAcqHandleAcqHandleAcqHandleacqHandleacq_handle, the second one provides a pointer to interface-specific context data, and the third parameter is a user-specific pointer that is specified in UserContextUserContextUserContextUserContextuserContextuser_context.

Attention

For a multithreaded application all image acquisition operators (as listed in open_framegrabberopen_framegrabberOpenFramegrabberOpenFramegrabberOpenFramegrabberopen_framegrabber) are an own group in which info_framegrabberinfo_framegrabberInfoFramegrabberInfoFramegrabberInfoFramegrabberinfo_framegrabber, open_framegrabberopen_framegrabberOpenFramegrabberOpenFramegrabberOpenFramegrabberopen_framegrabber, close_framegrabberclose_framegrabberCloseFramegrabberCloseFramegrabberCloseFramegrabberclose_framegrabber and close_all_framegrabbersclose_all_framegrabbersCloseAllFramegrabbersCloseAllFramegrabbersCloseAllFramegrabbersclose_all_framegrabbers are executed exclusively.

set_framegrabber_callbackset_framegrabber_callbackSetFramegrabberCallbackSetFramegrabberCallbackSetFramegrabberCallbackset_framegrabber_callback runs in parallel with all non-exclusive operators inside and outside of this group.

Execution Information

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Processed without parallelization.

This operator modifies the state of the following input parameter:

• AcqHandleAcqHandleAcqHandleAcqHandleacqHandleacq_handle

During execution of this operator, access to the value of this parameter must be synchronized if it is used across multiple threads.

Parameters

Result

If the image acquisition device is open and the specified callback was registered successfully, the operator set_framegrabber_callbackset_framegrabber_callbackSetFramegrabberCallbackSetFramegrabberCallbackSetFramegrabberCallbackset_framegrabber_callback returns the value TRUE. Otherwise an exception is raised.

Possible Predecessors

open_framegrabberopen_framegrabberOpenFramegrabberOpenFramegrabberOpenFramegrabberopen_framegrabber, set_framegrabber_paramset_framegrabber_paramSetFramegrabberParamSetFramegrabberParamSetFramegrabberParamset_framegrabber_param

Possible Successors

grab_imagegrab_imageGrabImageGrabImageGrabImagegrab_image, grab_datagrab_dataGrabDataGrabDataGrabDatagrab_data, grab_image_startgrab_image_startGrabImageStartGrabImageStartGrabImageStartgrab_image_start, grab_image_asyncgrab_image_asyncGrabImageAsyncGrabImageAsyncGrabImageAsyncgrab_image_async, grab_data_asyncgrab_data_asyncGrabDataAsyncGrabDataAsyncGrabDataAsyncgrab_data_async, get_framegrabber_paramget_framegrabber_paramGetFramegrabberParamGetFramegrabberParamGetFramegrabberParamget_framegrabber_param

See also

open_framegrabberopen_framegrabberOpenFramegrabberOpenFramegrabberOpenFramegrabberopen_framegrabber, get_framegrabber_callbackget_framegrabber_callbackGetFramegrabberCallbackGetFramegrabberCallbackGetFramegrabberCallbackget_framegrabber_callback

Module

Foundation