Avoid eventloop recursion in touch event handling.

The eventloop recursion in the threaded render loop
was there to preempt any pending event to make sure
we worked with as recent as possible input events. The
benefit of this was never verified.

The recursion after the actual flush was to fix animations
which were constantly started during touch events, such
as a behavior tracking the mouse point. This is fixed
differently.

Event loop recursion is always dangerous, so we're
doing what we can to avoid it.

Change-Id: I120b2e98350e3b9068153415a671408773fbc769
Reviewed-by: Michael Brasser <michael.brasser@live.com>

1 files changed, 2 insertions, 10 deletions

diff --git a/src/quick/scenegraph/qsgthreadedrenderloop.cpp b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
index a74a51146e..793a247427 100644
--- a/src/quick/scenegraph/qsgthreadedrenderloop.cpp
+++ b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
@@ -1066,17 +1066,9 @@ void QSGThreadedRenderLoop::polishAndSync(Window *w, bool inExpose)
     }
 
     // Flush pending touch events.
-    // First we force flushing of the windowing system events, so that we're
-    // working with the latest possible data. This can trigger event processing
-    // which in turn can stop rendering this window, so verify that before
-    // proceeding. Then we flush the touch event and as that also does event
-    // processing, verify again that we still are active and rendering.
-    QWindowSystemInterface::flushWindowSystemEvents();
+    QQuickWindowPrivate::get(window)->flushDelayedTouchEvent();
+    // The delivery of the event might have caused the window to stop rendering
     w = windowFor(m_windows, window);
-    if (w) {
-        QQuickWindowPrivate::get(window)->flushDelayedTouchEvent();
-        w = windowFor(m_windows, window);
-    }
     if (!w || !w->thread || !w->thread->window) {
         qCDebug(QSG_LOG_RENDERLOOP) << "- removed after event flushing, abort";
         killTimer(w->timerId);