IQueueCommand interface (control.h)
IQueueCommand interface queues a command for processing at a designated time. The Filter Graph Manager exposes this interface. Applications can use it to queue graph-control commands in advance.
The methods in
IQueueCommand are modeled after the IDispatch::InvokeAt method. The application specifies an interface, a method on the interface, parameters to the method, and a reference time. The Filter Graph Manager queues this information and then invokes the method at the specified time. The requested interface must inherit IDispatch and must be exposed by the Filter Graph Manager. Examples include IMediaControl, IMediaEventEx, and IMediaPosition.
When the command is queued, the filter graph manager returns a pointer to the IDeferredCommand interface. The application can use this interface to cancel or modify the command.
IQueueCommandrefer to stream time and presentation time, respectively. In the context of the Filter Graph Manager, stream time and presentation time are identical, so there is no functional difference between the two methods. Other objects could implement
IQueueCommanddifferently. For more information about stream time and presentation time, see Time and Clocks in DirectShow.
The IQueueCommand interface inherits from the IUnknown interface. IQueueCommand also has these types of members:
The IQueueCommand interface has these methods.
The InvokeAtPresentationTime method queues a method to be invoked at the specified presentation time.
The InvokeAtStreamTime method queues a method or property change for execution at a specified stream time (that is, presentation time relative to the current stream time offset).
|Minimum supported client||Windows 2000 Professional [desktop apps only]|
|Minimum supported server||Windows 2000 Server [desktop apps only]|
|Header||control.h (include Dshow.h)|