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