iOS: Implement hasPendingEvents() in the event dispatcher

As we're using CFRunLoopIsWaiting() to check for the possible presence
of system events hasPendingEvents() will never return false if called
on the main thread. We assume clients will not use this function to
determine whether or not to call processEvents(), but instead use the
return value from processEvents.

Change-Id: Ifd63892c6d35bb7da204072616bfe3ee69ca1d85
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/src/platformsupport/eventdispatchers/qeventdispatcher_cf.mm b/src/platformsupport/eventdispatchers/qeventdispatcher_cf.mm
index ab26b4c1d8..6442df715a 100644
--- a/src/platformsupport/eventdispatchers/qeventdispatcher_cf.mm
+++ b/src/platformsupport/eventdispatchers/qeventdispatcher_cf.mm
@@ -460,8 +460,17 @@ void QEventDispatcherCoreFoundation::handleRunLoopActivity(CFRunLoopActivity act
 
 bool QEventDispatcherCoreFoundation::hasPendingEvents()
 {
-    qDebug() << __FUNCTION__ << "not implemented";
-    return false;
+    // There doesn't seem to be any API on iOS to peek into the other sources
+    // to figure out if there are pending non-Qt events. As a workaround, we
+    // assume that if the run-loop is currently blocking and waiting for a
+    // source to signal then there are no system-events pending. If this
+    // function is called from the main thread then the second clause
+    // of the condition will always be true, as the the run loop is
+    // never waiting in that case. The function would be more aptly named
+    // 'maybeHasPendingEvents' in our case.
+
+    extern uint qGlobalPostedEventsCount();
+    return qGlobalPostedEventsCount() || !CFRunLoopIsWaiting(CFRunLoopGetMain());
 }
 
 void QEventDispatcherCoreFoundation::wakeUp()