IC4_QUEUESINK_CALLBACKS Struct Reference

Contains function pointers used to specify the behavior of a queue sink. More...

Data Fields

void(*	release )(void *context) Notifies the user that the sink will not call any additional callback functions.
bool(*	sink_connected )(struct IC4_SINK sink, void context, const struct IC4_IMAGE_TYPE *image_type, size_t min_buffers_required) Called when the data stream to the sink is created.
void(*	sink_disconnected )(struct IC4_SINK sink, void context) Called when the data stream to the sink is stopped.
void(*	frames_queued )(struct IC4_SINK sink, void context) Called when new images were added to the sink's queue of filled buffers.

Contains function pointers used to specify the behavior of a queue sink.

void(* frames_queued) (struct IC4_SINK *sink, void *context)

Called when new images were added to the sink's queue of filled buffers.

This callback usually calls ic4_queuesink_pop_output_buffer() to access the image buffers.

Parameters

[in]	sink	The sink object
[in]	context	The `context` parameter that was passed to ic4_queuesink_create() when the sink was created

Note: If this callback function performs a lengthy operation, it is recommended to regularly check ic4_queuesink_is_cancel_requested() to determine whether the data stream is being stopped.; The frames_queued function is executed on a dedicated thread managed by the sink.

Warning: When the data stream to ths sink is stopped, the ic4_grabber_stream_stop() call wait until this function returns. This can quickly lead to a deadlock, if code in the frames_queued callback performs an operation that unconditionally requires activity on the thread that called ic4_grabber_stream_stop.

void(* release) (void *context)

Notifies the user that the sink will not call any additional callback functions.

Any resources attached to the context parameter can be released.

Parameters

[in] context The context parameter that was passed to ic4_queuesink_create() when the sink was created

Note: The release callback function is executed on the thread that destroys the sink using the final call to ic4_sink_unref().

bool(* sink_connected) (struct IC4_SINK *sink, void *context, const struct IC4_IMAGE_TYPE *image_type, size_t min_buffers_required)

Called when the data stream to the sink is created.

Parameters

[in]	sink	The sink object
[in]	context	The `context` parameter that was passed to ic4_queuesink_create() when the sink was created
[in]	image_type	The negotiated image type that the sink will receive
[in]	min_buffers_required	The minimum number of buffers required by the device to start a stream

Returns: true, if the data stream should be created. If false is returned the call to ic4_grabber_stream_setup() will fail.

Note: min_buffers_required buffers have to be allocated and queued in order for the sink to begin operating. If the function does call ic4_queuesink_alloc_and_queue_buffers(), the required number of buffers will be created automatically after the function returns. If the function does allocate buffers, but the number is lower than required, ic4_grabber_stream_setup() will fail.; The queuesink_sink_connected function is executed on the thread that calls ic4_grabber_stream_setup().

void(* sink_disconnected) (struct IC4_SINK *sink, void *context)

Called when the data stream to the sink is stopped.

Parameters

[in]	sink	The sink object
[in]	context	The `context` parameter that was passed to ic4_queuesink_create() when the sink was created

Note: The sink_disconnected function is executed on the thread that calls ic4_grabber_stream_stop().

Warning: When the data stream to ths sink is stopped, the ic4_grabber_stream_stop() call wait until this function returns. This can quickly lead to a deadlock, if code in the sink_disconnected callback performs an operation that unconditionally requires activity on the thread that called ic4_grabber_stream_stop().