Merge branch 'qt_event_loop' of https://github.com/GeoTeric/wxWidgets

Use QEventLoop for wxEventLoop implementation in wxQt to fix several
issues with wxEventLoop, notably avoid "QApplication::exec is already
running" errors.

See https://github.com/wxWidgets/wxWidgets/pull/1165

include/wx/qt/evtloop.h

@@ -9,6 +9,7 @@
 #define _WX_QT_EVTLOOP_H_
 
 class QTimer;
+class QEventLoop;
 
 class WXDLLIMPEXP_CORE wxQtEventLoopBase : public wxEventLoopBase
 {
@@ -16,13 +17,15 @@ public:
     wxQtEventLoopBase();
     ~wxQtEventLoopBase();
 
-    virtual int DoRun();
+    virtual int DoRun() wxOVERRIDE;
-    virtual void ScheduleExit(int rc = 0);
+    virtual void ScheduleExit(int rc = 0) wxOVERRIDE;
-    virtual bool Pending() const;
+    virtual bool Pending() const wxOVERRIDE;
-    virtual bool Dispatch();
+    virtual bool Dispatch() wxOVERRIDE;
-    virtual int DispatchTimeout(unsigned long timeout);
+    virtual int DispatchTimeout(unsigned long timeout) wxOVERRIDE;
-    virtual void WakeUp();
+    virtual void WakeUp() wxOVERRIDE;
-    virtual void DoYieldFor(long eventsToProcess);
+    virtual void DoYieldFor(long eventsToProcess) wxOVERRIDE;
+
+    void ScheduleIdleCheck();
 
 #if wxUSE_EVENTLOOP_SOURCE
     virtual wxEventLoopSource *AddSourceForFD(int fd, wxEventLoopSourceHandler *handler, int flags);
@@ -30,6 +33,7 @@ public:
 protected:
 
 private:
+    QEventLoop *m_qtEventLoop;
     QTimer *m_qtIdleTimer;
     
     wxDECLARE_NO_COPY_CLASS(wxQtEventLoopBase);

src/qt/evtloop.cpp

@@ -17,6 +17,7 @@
 #include <QtCore/QAbstractEventDispatcher>
 #include <QtCore/QSocketNotifier>
 #include <QtCore/QTimer>
+#include <QtCore/QEventLoop>
 
 #include <QtWidgets/QApplication>
 
@@ -40,14 +41,13 @@ wxQtIdleTimer::wxQtIdleTimer( wxQtEventLoopBase *eventLoop )
 
     connect( this, &QTimer::timeout, this, &wxQtIdleTimer::idle );
     setSingleShot( true );
-    start( 0 );
 }
 
 bool wxQtIdleTimer::eventFilter( QObject *WXUNUSED( watched ), QEvent *WXUNUSED( event ) )
 {
     // Called for each Qt event, start with timeout 0 (run as soon as idle)
     if ( !isActive() )
-        start( 0 );
+        m_eventLoop->ScheduleIdleCheck();
 
     return false; // Continue handling the event
 }
@@ -60,7 +60,7 @@ void wxQtIdleTimer::idle()
 
     // Send idle event
     if ( m_eventLoop->ProcessIdle() )
-        start( 0 );
+        m_eventLoop->ScheduleIdleCheck();
 }
 
 wxQtEventLoopBase::wxQtEventLoopBase()
@@ -78,10 +78,15 @@ wxQtEventLoopBase::wxQtEventLoopBase()
     // Pass all events to the idle timer, so it can be restarted each time
     // an event is received
     qApp->installEventFilter( m_qtIdleTimer );
+
+
+    m_qtEventLoop = new QEventLoop;
 }
 
 wxQtEventLoopBase::~wxQtEventLoopBase()
 {
+    qApp->removeEventFilter(m_qtIdleTimer);
+    delete m_qtEventLoop;
     delete m_qtIdleTimer;
 }
 
@@ -89,44 +94,31 @@ void wxQtEventLoopBase::ScheduleExit(int rc)
 {
     wxCHECK_RET( IsInsideRun(), wxT("can't call ScheduleExit() if not started") );
     m_shouldExit = true;
-    QCoreApplication::exit( rc );
+    m_qtEventLoop->exit(rc);
 }
 
 int wxQtEventLoopBase::DoRun()
 {
-    int ret;
+    const int ret = m_qtEventLoop->exec();
-
-    // This is placed inside of a loop to take into account nested event loops
-    while ( !m_shouldExit )
-    {
-        // This will print Qt warnins if app already started:
-        // "QCoreApplication::exec: The event loop is already running"
-        // TODO: check the loopLevel (nested) like in wxGTK
-        ret = QCoreApplication::exec();
-        // process pending events (if exec was started previously)
-        // TODO: use a real new QEventLoop() ?
-        QCoreApplication::processEvents();
-    }
     OnExit();
     return ret;
 }
 
 bool wxQtEventLoopBase::Pending() const
 {
-    return QCoreApplication::hasPendingEvents();
+    QAbstractEventDispatcher *instance = QAbstractEventDispatcher::instance();
+    return instance->hasPendingEvents();
 }
 
 bool wxQtEventLoopBase::Dispatch()
 {
-    QCoreApplication::processEvents();
+    m_qtEventLoop->processEvents();
-
     return true;
 }
 
 int wxQtEventLoopBase::DispatchTimeout(unsigned long timeout)
 {
-    QCoreApplication::processEvents( QEventLoop::AllEvents, timeout );
+    m_qtEventLoop->processEvents(QEventLoop::AllEvents, timeout);
-
     return true;
 }
 
@@ -146,6 +138,12 @@ void wxQtEventLoopBase::DoYieldFor(long eventsToProcess)
     wxEventLoopBase::DoYieldFor(eventsToProcess);
 }
 
+void wxQtEventLoopBase::ScheduleIdleCheck()
+{
+    if ( IsInsideRun() )
+        m_qtIdleTimer->start(0);
+}
+
 #if wxUSE_EVENTLOOP_SOURCE
 
 template <void (wxEventLoopSourceHandler::*function)()>