Cocoa: Fix qmlscene flicker on startup.

The SG render thread was racing window creation in
the GUI thread, which would cause flicker if the
window won the race and was shown before the SG
thread had a frame ready.

Send a synchronous expose event before showing the
window - this will wait for the SG render thread.

In addition, don't defer NSwindow creation. The GL
context setup is done before the window is shown
and needs a fully created window.

New API: QWindowSystemInterface::handleSynchronousExposeEvent
Retire: QWindowSystemInterface::handleExposeEvent

Change-Id: I0bb46089d16ec4882aaac8db67b57d15e0f51531
Reviewed-on: http://codereview.qt.nokia.com/3399
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@nokia.com>

5 files changed, 10 insertions, 7 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 78785a8527..ef04fc4238 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -121,8 +121,10 @@ void QCocoaWindow::setVisible(bool visible)
         if (window()->transientParent())
             setGeometry(window()->geometry());
 
+        // Make sure the QWindow has a frame ready before we show the NSWindow.
+        QWindowSystemInterface::handleSynchronousExposeEvent(window(), QRect(QPoint(), geometry().size()));
+
         [m_nsWindow makeKeyAndOrderFront:nil];
-        QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(), geometry().size()));
     } else {
         [m_nsWindow orderOut:nil];
     }
@@ -319,7 +321,7 @@ QNSWindow * QCocoaWindow::createWindow()
         panel = [[NSPanel alloc] initWithContentRect:frame
                                    styleMask:m_windowAttributes
                                    backing:NSBackingStoreBuffered
-                                   defer:YES];
+                                   defer:NO]; // see window case below
 //  ### crashes
 //        [panel setFloatingPanel:needFloating];
 //        [panel setWorksWhenModal:worksWhenModal];
@@ -330,7 +332,8 @@ QNSWindow * QCocoaWindow::createWindow()
         window  = [[QNSWindow alloc] initWithContentRect:frame
                                             styleMask:(NSResizableWindowMask | NSClosableWindowMask | NSMiniaturizableWindowMask | NSTitledWindowMask)
                                             backing:NSBackingStoreBuffered
-                                            defer:YES];
+                                            defer:NO]; // Deferring window creation breaks OpenGL (the GL context is set up
+                                                       // before the window is shown and needs a proper window.).
         break;
     }
 
diff --git a/src/plugins/platforms/wayland/qwaylandwindow.cpp b/src/plugins/platforms/wayland/qwaylandwindow.cpp
index f685dae729..48da7b537e 100644
--- a/src/plugins/platforms/wayland/qwaylandwindow.cpp
+++ b/src/plugins/platforms/wayland/qwaylandwindow.cpp
@@ -125,7 +125,7 @@ void QWaylandWindow::attach(QWaylandBuffer *buffer)
     mBuffer = buffer;
     if (mSurface) {
         wl_surface_attach(mSurface, buffer->buffer(),0,0);
-        QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(), geometry().size()));
+        QWindowSystemInterface::handleSynchronousExposeEvent(window(), QRect(QPoint(), geometry().size()));
     }
 }
 
diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index 95b770f043..8e10ae694a 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -902,7 +902,7 @@ void QWindowsWindow::handleWmPaint(HWND hwnd, UINT,
         if (QWindowsContext::verboseIntegration)
             qDebug() << __FUNCTION__ << this << window() << updateRect;
 
-        QWindowSystemInterface::handleExposeEvent(window(), QRegion(updateRect));
+        QWindowSystemInterface::handleSynchronousExposeEvent(window(), QRegion(updateRect));
         clearFlag(WithinWmPaint);
         m_hdc = 0;
         EndPaint(hwnd, &ps);
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index a8ffc5832a..c60e066ed9 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -472,7 +472,7 @@ void QXcbConnection::handleXcbEvent(xcb_generic_event_t *event)
 
     switch (response_type) {
     case XCB_EXPOSE:
-        HANDLE_PLATFORM_WINDOW_EVENT(xcb_expose_event_t, window, handleExposeEvent);
+        HANDLE_PLATFORM_WINDOW_EVENT(xcb_expose_event_t, window, handleSynchronousExposeEvent);
     case XCB_BUTTON_PRESS:
         HANDLE_PLATFORM_WINDOW_EVENT(xcb_button_press_event_t, event, handleButtonPressEvent);
     case XCB_BUTTON_RELEASE:
diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 0f3d1d57d1..db8d37e817 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -1074,7 +1074,7 @@ QXcbEGLSurface *QXcbWindow::eglSurface() const
 void QXcbWindow::handleExposeEvent(const xcb_expose_event_t *event)
 {
     QRect rect(event->x, event->y, event->width, event->height);
-    QWindowSystemInterface::handleExposeEvent(window(), rect);
+    QWindowSystemInterface::handleSynchronousExposeEvent(window(), rect);
 }
 
 void QXcbWindow::handleClientMessageEvent(const xcb_client_message_event_t *event)