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EventProvider.h
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28 
29 /**
30  * @file
31  * <b>Libargus API: Event Provider API</b>
32  *
33  * @b Description: Defines the EventProvider interface.
34  */
35 
36 #ifndef _ARGUS_EVENT_PROVIDER_H
37 #define _ARGUS_EVENT_PROVIDER_H
38 
39 namespace Argus
40 {
41 
42 /**
43  * @class IEventProvider
44  *
45  * Interface for an object which generates Events (such as CaptureSession).
46  *
47  * Any generated Events are initially stored by the provider itself, and they
48  * are not copied out to public EventQueues until waitForEvents() is called.
49  * If at any time there is an event type offered by a provider that is not
50  * accepted by an active EventQueue created by that provider, all events of
51  * that type will be discarded.
52  *
53  * @ingroup ArgusCaptureSession
54  */
55 DEFINE_UUID(InterfaceID, IID_EVENT_PROVIDER, 523ed330,25dc,11e5,867f,08,00,20,0c,9a,66);
56 class IEventProvider : public Interface
57 {
58 public:
59  static const InterfaceID& id() { return IID_EVENT_PROVIDER; }
60 
61  /**
62  * Returns a list of event types that this provider can generate.
63  * @param[out] types A vector that will be populated by the available event types.
64  *
65  * @returns success/status of the call.
66  */
67  virtual Status getAvailableEventTypes(std::vector<EventType>* types) const = 0;
68 
69  /**
70  * Creates an event queue for events of the given type(s)
71  * @param[in] eventTypes The list of event types for the queue.
72  * @param[out] status An optional pointer to return success/status.
73  *
74  * @returns the new EventQueue object, or NULL on failure.
75  */
76  virtual EventQueue* createEventQueue(const std::vector<EventType>& eventTypes,
77  Status* status = NULL) = 0;
78 
79  /**
80  * Waits for and transfers any pending events from the provider to the
81  * provided queues.
82  *
83  * Ownership of all events transfered to a queue will be passed from the
84  * provider to the queue, and these event object pointers will remain
85  * valid until the queue is destroyed or until the next call to this
86  * function with that queue. In other words, any events in a queue will be
87  * destroyed when the queue is provided to another call of this function,
88  * regardless of whether or not it receives any new events, or when the
89  * queue is destroyed.
90  *
91  * If more than one given queue accepts events of the same type, only the
92  * first of these queues will receive events of that type.
93  *
94  * Any events that are not copied to queues by this function are left in
95  * the provider until they are queried using a queue receiving events of
96  * that type.
97  *
98  * If there are no pending events of the requested types at the time this
99  * function is called, it will block until one is available or a timeout
100  * occurs.
101  *
102  * @param[in] queues The list of queues to transfer events to.
103  * @param[in] timeout The maximum time (in nanoseconds) to wait for new events.
104  *
105  * @returns success/status of the call.
106  */
107  virtual Status waitForEvents(const std::vector<EventQueue*>& queues,
108  uint64_t timeout = TIMEOUT_INFINITE) = 0;
109 
110  /**
111  * Variant of waitForEvents() that waits for only one EventQueue.
112  */
113  virtual Status waitForEvents(EventQueue* queue,
114  uint64_t timeout = TIMEOUT_INFINITE) = 0;
115 
116 protected:
118 };
119 
120 } // namespace Argus
121 
122 #endif // _ARGUS_EVENT_PROVIDER_H