X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/1df4b19481c1e4fb26b7395933d65e9fa4a506ec..86ac84b8ce086e6bbda58f422d41f84268606e35:/include/wx/evtloop.h

diff --git a/include/wx/evtloop.h b/include/wx/evtloop.h
index 6841c61fd0..8bea93090a 100644
--- a/include/wx/evtloop.h
+++ b/include/wx/evtloop.h
@@ -12,8 +12,38 @@
 #ifndef _WX_EVTLOOP_H_
 #define _WX_EVTLOOP_H_
 
+#include "wx/event.h"
 #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() { }
@@ -31,10 +61,22 @@ public:
     // using it
     virtual bool IsOk() const { return true; }
 
+    // returns true if this is the main loop
+    bool IsMain() const;
+
+
+    // 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;
 
@@ -49,34 +91,77 @@ 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;
+
+
+    // 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; }
 
     // set currently active (running) event loop
-    static void SetActive(wxEventLoopBase* loop) { ms_activeLoop = loop; }
+    static void SetActive(wxEventLoopBase* 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
     // this happens normally (because of Exit() call) or abnormally (because of
     // an exception thrown from inside the loop)
-    virtual void OnExit() { }
-
+    virtual void OnExit();
 
     // the pointer to currently active loop
     static wxEventLoopBase *ms_activeLoop;
 
-    DECLARE_NO_COPY_CLASS(wxEventLoopBase)
+    // YieldFor() helpers:
+    bool m_isInsideYield;
+    long m_eventsToProcessInsideYield;
+
+    wxDECLARE_NO_COPY_CLASS(wxEventLoopBase);
 };
 
 #if defined(__WXMSW__) || defined(__WXMAC__) || defined(__WXDFB__) || defined(__UNIX__)
@@ -161,12 +246,13 @@ 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