X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/1df4b19481c1e4fb26b7395933d65e9fa4a506ec..a8519f6507f7b4389c0fe7dbae4ebd63120d5dd0:/include/wx/evtloop.h diff --git a/include/wx/evtloop.h b/include/wx/evtloop.h index 6841c61fd0..9ff5edbe64 100644 --- a/include/wx/evtloop.h +++ b/include/wx/evtloop.h @@ -14,6 +14,36 @@ #include "wx/utils.h" + +/* + NOTE ABOUT wxEventLoopBase::YieldFor LOGIC + ------------------------------------------ + + The YieldFor() function helps to avoid re-entrancy problems and problems + caused by out-of-order event processing + (see "wxYield-like problems" and "wxProgressDialog+threading BUG" wx-dev threads). + + The logic behind YieldFor() is simple: it analyzes the queue of the native + events generated by the underlying GUI toolkit and picks out and processes + only those matching the given mask. + + It's important to note that YieldFor() is used to selectively process the + events generated by the NATIVE toolkit. + Events syntethized by wxWidgets code or by user code are instead selectively + processed thanks to the logic built into wxEvtHandler::ProcessPendingEvents(). + In fact, when wxEvtHandler::ProcessPendingEvents gets called from inside a + YieldFor() call, wxEventLoopBase::IsEventAllowedInsideYield is used to decide + if the pending events for that event handler can be processed. + If all the pending events associated with that event handler result as "not processable", + the event handler "delays" itself calling wxEventLoopBase::DelayPendingEventHandler + (so it's moved: m_handlersWithPendingEvents => m_handlersWithPendingDelayedEvents). + Last, wxEventLoopBase::ProcessPendingEvents() before exiting moves the delayed + event handlers back into the list of handlers with pending events + (m_handlersWithPendingDelayedEvents => m_handlersWithPendingEvents) so that + a later call to ProcessPendingEvents() (possibly outside the YieldFor() call) + will process all pending events as usual. +*/ + // ---------------------------------------------------------------------------- // wxEventLoopBase: interface for wxEventLoop // ---------------------------------------------------------------------------- @@ -22,7 +52,7 @@ class WXDLLIMPEXP_BASE wxEventLoopBase { public: // trivial, but needed (because of wxEventLoopBase) ctor - wxEventLoopBase() { } + wxEventLoopBase(); // dtor virtual ~wxEventLoopBase() { } @@ -32,9 +62,18 @@ public: virtual bool IsOk() const { return true; } + // dispatch&processing + // ------------------- + // start the event loop, return the exit code when it is finished virtual int Run() = 0; + // is this event loop running now? + // + // notice that even if this event loop hasn't terminated yet but has just + // spawned a nested (e.g. modal) event loop, this would return false + bool IsRunning() const; + // exit from the loop with the given exit code virtual void Exit(int rc = 0) = 0; @@ -49,6 +88,86 @@ public: // exit the loop or -1 if timeout expired virtual int DispatchTimeout(unsigned long timeout) = 0; + // implement this to wake up the loop: usually done by posting a dummy event + // to it (can be called from non main thread) + virtual void WakeUp() = 0; + + + // pending events + // -------------- + + // process all events in the wxHandlersWithPendingEvents list -- it is necessary + // to call this function to process posted events. This happens during each + // event loop iteration in GUI mode but if there is no main loop, it may be + // also called directly. + virtual void ProcessPendingEvents(); + + // check if there are pending events on global pending event list + bool HasPendingEvents() const; + + // temporary suspends processing of the pending events + void SuspendProcessingOfPendingEvents(); + + // resume processing of the pending events previously stopped because of a + // call to SuspendProcessingOfPendingEvents() + void ResumeProcessingOfPendingEvents(); + + // called by ~wxEvtHandler to (eventually) remove the handler from the list of + // the handlers with pending events + void RemovePendingEventHandler(wxEvtHandler* toRemove); + + // adds an event handler to the list of the handlers with pending events + void AppendPendingEventHandler(wxEvtHandler* toAppend); + + // moves the event handler from the list of the handlers with pending events + //to the list of the handlers with _delayed_ pending events + void DelayPendingEventHandler(wxEvtHandler* toDelay); + + + // idle handling + // ------------- + + // make sure that idle events are sent again + virtual void WakeUpIdle(); + + // this virtual function is called when the application + // becomes idle and normally just sends wxIdleEvent to all interested + // parties + // + // it should return true if more idle events are needed, false if not + virtual bool ProcessIdle(); + + + // Yield-related hooks + // ------------------- + + // process all currently pending events right now + // + // it is an error to call Yield() recursively unless the value of + // onlyIfNeeded is true + // + // WARNING: this function is dangerous as it can lead to unexpected + // reentrancies (i.e. when called from an event handler it + // may result in calling the same event handler again), use + // with _extreme_ care or, better, don't use at all! + bool Yield(bool onlyIfNeeded = false); + virtual bool YieldFor(long eventsToProcess) = 0; + + // returns true if the main thread is inside a Yield() call + virtual bool IsYielding() const + { return m_isInsideYield; } + + // returns true if events of the given event category should be immediately + // processed inside a wxApp::Yield() call or rather should be queued for + // later processing by the main event loop + virtual bool IsEventAllowedInsideYield(wxEventCategory cat) const + { return (m_eventsToProcessInsideYield & cat) != 0; } + + // no SafeYield hooks since it uses wxWindow which is not available when wxUSE_GUI=0 + + + // active loop + // ----------- // return currently active (running) event loop, may be NULL static wxEventLoopBase *GetActive() { return ms_activeLoop; } @@ -56,15 +175,6 @@ public: // set currently active (running) event loop static void SetActive(wxEventLoopBase* loop) { ms_activeLoop = loop; } - // is this event loop running now? - // - // notice that even if this event loop hasn't terminated yet but has just - // spawned a nested (e.g. modal) event loop, this would return false - bool IsRunning() const; - - // implement this to wake up the loop: usually done by posting a dummy event - // to it (can be called from non main thread) - virtual void WakeUp() = 0; protected: // this function should be called before the event loop terminates, whether @@ -72,11 +182,26 @@ protected: // an exception thrown from inside the loop) virtual void OnExit() { } - // the pointer to currently active loop static wxEventLoopBase *ms_activeLoop; - DECLARE_NO_COPY_CLASS(wxEventLoopBase) + // the array of the handlers with pending events which needs to be processed + // inside ProcessPendingEvents() + wxEvtHandlerArray m_handlersWithPendingEvents; + + // helper array used by ProcessPendingEvents() + wxEvtHandlerArray m_handlersWithPendingDelayedEvents; + +#if wxUSE_THREADS + // this critical section protects both the lists above + wxCriticalSection m_handlersWithPendingEventsLocker; +#endif + + // Yield() helpers: + bool m_isInsideYield; + long m_eventsToProcessInsideYield; + + wxDECLARE_NO_COPY_CLASS(wxEventLoopBase); }; #if defined(__WXMSW__) || defined(__WXMAC__) || defined(__WXDFB__) || defined(__UNIX__) @@ -161,12 +286,13 @@ public: } } virtual void WakeUp() { } + virtual bool YieldFor(long eventsToProcess); protected: // the pointer to the port specific implementation class wxEventLoopImpl *m_impl; - DECLARE_NO_COPY_CLASS(wxGUIEventLoop) + wxDECLARE_NO_COPY_CLASS(wxGUIEventLoop); }; #endif // platforms