slideshow/source/inc/eventqueue.hxx

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  19
  20 #ifndef INCLUDED_SLIDESHOW_SOURCE_INC_EVENTQUEUE_HXX
  21 #define INCLUDED_SLIDESHOW_SOURCE_INC_EVENTQUEUE_HXX
  22
  23 #include <canvas/elapsedtime.hxx>
  24 #include <osl/mutex.hxx>
  25
  26 #include "event.hxx"
  27
  28 #include <queue>
  29 #include <vector>
  30
  31
  32 /* Definition of ActivitiesQueue class */
  33
  34 namespace slideshow
  35 {
  36     namespace internal
  37     {
  38         /** This class handles events in a presentation. Events are
  39             time instants where e.g. effects start.
  40          */
  41         class EventQueue
  42         {
  43         public:
  44             EventQueue(
  45                 std::shared_ptr< ::canvas::tools::ElapsedTime >
  46                 const & pPresTimer );
  47
  48             ~EventQueue();
  49
  50             EventQueue(const EventQueue&) = delete;
  51             EventQueue& operator=(const EventQueue&) = delete;
  52
  53             /** Add the given event to the queue. The event is fired
  54                 at, or shortly after, its Event::getActivationTime instant.
  55              */
  56             bool addEvent( const EventSharedPtr& event );
  57
  58             /** Add the given event to the queue. The event is fired
  59                 at, or shortly after, its Event::getActivationTime instant.
  60                 The difference to addEvent() is that events added during
  61                 process() are postponed to next process().
  62              */
  63             bool addEventForNextRound( const EventSharedPtr& event );
  64
  65             /** Another way to control the order of asynchronous event
  66                 execution.  Use this method to schedule events that are to
  67                 be executed after all regular events that have no delay,
  68                 even when they schedule new regular events without delay.
  69             */
  70             bool addEventWhenQueueIsEmpty (const EventSharedPtr& rpEvent);
  71
  72             /** Process the event queue.
  73
  74                 This method executes all events whose timeout has
  75                 expired when calling this method (i.e. all events
  76                 whose scheduled time is less or equal the current
  77                 time).
  78
  79                 Check for the next available event's timeout via
  80                 nextTimeout(), or whether the queue is empty
  81                 altogether via isEmpty().
  82              */
  83             void process();
  84
  85             /** Query state of the queue
  86
  87                 @return false, if queue is empty, true otherwise
  88              */
  89             bool isEmpty() const;
  90
  91             /** Query timeout for the topmost event in the queue.
  92
  93                 @return Timeout in seconds, until the next event is
  94                 ready. The time returned here is relative to the pres
  95                 timer (i.e. the timer specified at the EventQueue
  96                 constructor). When the queue is empty (i.e. isEmpty()
  97                 returns true), the returned value is the highest
  98                 representable double value
  99                 (::std::numeric_limits<double>::max()). If the topmost
 100                 event in the queue is already pending, the timeout
 101                 returned here will actually be negative.
 102             */
 103             double nextTimeout() const;
 104
 105             /** Remove all pending events from the queue.
 106              */
 107             void clear();
 108
 109             /** Forces an empty queue, firing all events immediately
 110                 without minding any times.
 111                 @attention do only call from event loop, this calls process_()!
 112              */
 113             void forceEmpty();
 114
 115             /** Gets the queue's timer object.
 116              */
 117             std::shared_ptr< ::canvas::tools::ElapsedTime > const &
 118             getTimer() const { return mpTimer; }
 119
 120         private:
 121             mutable ::osl::Mutex      maMutex;
 122
 123             struct EventEntry
 124             {
 125                 EventSharedPtr  pEvent;
 126                 double          nTime;
 127
 128                 bool operator<( const EventEntry& ) const; // to leverage priority_queue's default compare
 129
 130                 EventEntry( EventSharedPtr const& p, double t )
 131                     : pEvent(p), nTime(t) {}
 132             };
 133
 134             typedef ::std::priority_queue< EventEntry > ImplQueueType;
 135             ImplQueueType                   maEvents;
 136             typedef ::std::vector<EventEntry> EventEntryVector;
 137             EventEntryVector                maNextEvents;
 138             ImplQueueType                   maNextNextEvents;
 139             void process_( bool bFireAllEvents );
 140
 141             // perform timing of events via relative time
 142             // measurements. The world time starts, when the
 143             // EventQueue object is created
 144             std::shared_ptr< ::canvas::tools::ElapsedTime > mpTimer;
 145         };
 146
 147     }
 148 }
 149 #endif // INCLUDED_SLIDESHOW_SOURCE_INC_EVENTQUEUE_HXX
 150
 151 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */