Ensure that wxApp::Yield is always processing pending event by creating a

temporary event loop if needed.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@53607 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/evtloop.h

@@ -198,4 +198,32 @@ private:
     wxEventLoop *m_evtLoopOld;
 };
 
+#if wxABI_VERSION >= 20808
+class wxEventLoopGuarantor
+{
+public:
+    wxEventLoopGuarantor()
+    {
+        m_evtLoopNew = NULL;
+        if (!wxEventLoop::GetActive())
+        {
+            m_evtLoopNew = new wxEventLoop;
+            wxEventLoop::SetActive(m_evtLoopNew);
+        }
+    }
+
+    ~wxEventLoopGuarantor()
+    {
+        if (m_evtLoopNew)
+        {
+            wxEventLoop::SetActive(NULL);
+            delete m_evtLoopNew;
+        }
+    }
+
+private:
+    wxEventLoop *m_evtLoopNew;
+};
+#endif // wxABI_VERSION >= 20805
+
 #endif // _WX_EVTLOOP_H_

src/dfb/app.cpp

@@ -137,7 +137,8 @@ bool wxApp::Yield(bool onlyIfNeeded)
 
     wxLog::Suspend();
 
-    if ( wxEventLoop::GetActive() )
+    // A guarentee that there will be an active event loop:
+    wxEventLoopGuarantor dummyLoopIfNeeded;
     wxEventLoop::GetActive()->Yield();
 
     // it's necessary to call ProcessIdle() to update the frames sizes which

src/mgl/app.cpp

@@ -74,11 +74,10 @@ bool wxApp::Yield(bool onlyIfNeeded)
 
     wxLog::Suspend();
 
-    if ( wxEventLoop::GetActive() )
-    {
+    // A guarentee that there will be an active event loop:
+    wxEventLoopGuarantor dummyLoopIfNeeded;
     while (wxEventLoop::GetActive()->Pending())
         wxEventLoop::GetActive()->Dispatch();
-    }
 
     /* it's necessary to call ProcessIdle() to update the frames sizes which
        might have been changed (it also will update other things set from

src/motif/app.cpp

@@ -437,6 +437,7 @@ bool wxApp::Yield(bool onlyIfNeeded)
 
     s_inYield = true;
 
+    wxEventLoopGuarantor dummyLoopIfNeeded;
     while (wxTheApp && wxTheApp->Pending())
         wxTheApp->Dispatch();
 

src/msw/app.cpp

@@ -702,6 +702,7 @@ bool wxApp::Yield(bool onlyIfNeeded)
 
     // we don't want to process WM_QUIT from here - it should be processed in
     // the main event loop in order to stop it
+    wxEventLoopGuarantor dummyLoopIfNeeded;
     MSG msg;
     while ( PeekMessage(&msg, (HWND)0, 0, 0, PM_NOREMOVE) &&
             msg.message != WM_QUIT )

src/os2/app.cpp

@@ -551,6 +551,7 @@ bool wxApp::Yield(bool onlyIfNeeded)
     // We want to go back to the main message loop
     // if we see a WM_QUIT. (?)
     //
+    wxEventLoopGuarantor dummyLoopIfNeeded;
     while (::WinPeekMsg(vHab, &vMsg, (HWND)NULL, 0, 0, PM_NOREMOVE) && vMsg.msg != WM_QUIT)
     {
 #if wxUSE_THREADS

src/x11/app.cpp

@@ -796,13 +796,7 @@ bool wxApp::Yield(bool onlyIfNeeded)
 
         // Make sure we have an event loop object,
         // or Pending/Dispatch will fail
-        wxEventLoop* eventLoop = wxEventLoop::GetActive();
-        wxEventLoop* newEventLoop = NULL;
-        if (!eventLoop)
-        {
-            newEventLoop = new wxEventLoop;
-            wxEventLoop::SetActive(newEventLoop);
-        }
+        wxEventLoopGuarantor dummyLoopIfNeeded;
 
         // Call dispatch at least once so that sockets
         // can be tested
@@ -816,12 +810,6 @@ bool wxApp::Yield(bool onlyIfNeeded)
 #endif
         ProcessIdle();
 
-        if (newEventLoop)
-        {
-            wxEventLoop::SetActive(NULL);
-            delete newEventLoop;
-        }
-
         s_inYield = false;
     }
 

version-script.in

@@ -31,6 +31,7 @@
         *TimeZone*Make*;
         *wxBitmapButton*OnFocusChange*;
         *wxDocManager*MakeNewDocumentName*;
+        *wxEventLoopGuarantor*;
         *wxGridBagSizer*AdjustForOverflow*;
         *wxRemotelyScrolledTreeCtrl*DoCalcScrolledPosition*;
         *wxRemotelyScrolledTreeCtrl*SetScrollbar*;