Blackberry: Fix camera viewfinder

Enter the event loop between opening the camera and starting
the viewfinder window grabber. The latter needs a windowGroup
set, so in case the QCamera and QCameraViewfinder are constructed
directly/indirectly inside the main window constructor, we have to
wait for the top-level window of the application to be created, so
that we can retrieve the windowGroup from it.

Task-number: QTBUG-33739
Change-Id: Ib23781f0e4a2a07ba388e22debcb59b00509ed16
Reviewed-by: Rafael Roquetto <rafael.roquetto@kdab.com>
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
Reviewed-by: Tobias Koenig <tobias.koenig.qnx@kdab.com>
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

src/plugins/blackberry/camera/bbcamerasession.cpp

@@ -165,22 +165,18 @@ void BbCameraSession::setState(QCamera::State state)
             }
         } else if (state == QCamera::ActiveState) {
             if (openCamera()) {
-                applyConfiguration();
+                QMetaObject::invokeMethod(this, "applyConfiguration", Qt::QueuedConnection);
-                if (startViewFinder()) {
                 m_state = state;
             }
         }
-        }
     } else if (previousState == QCamera::LoadedState) {
         if (state == QCamera::UnloadedState) {
             closeCamera();
             m_state = state;
         } else if (state == QCamera::ActiveState) {
-            applyConfiguration();
+            QMetaObject::invokeMethod(this, "applyConfiguration", Qt::QueuedConnection);
-            if (startViewFinder()) {
             m_state = state;
         }
-        }
     } else if (previousState == QCamera::ActiveState) {
         if (state == QCamera::LoadedState) {
             stopViewFinder();
@@ -1157,6 +1153,8 @@ void BbCameraSession::applyConfiguration()
     } else if (m_captureMode & QCamera::CaptureVideo) {
         applyVideoSettings();
     }
+
+    startViewFinder();
 }
 
 static void videoRecordingStatusCallback(camera_handle_t handle, camera_devstatus_t status, uint16_t value, void *context)

src/plugins/blackberry/camera/bbcamerasession.h

@@ -176,13 +176,13 @@ private slots:
     void deviceOrientationChanged(int);
     void handleCameraPowerUp();
     void viewfinderFrameGrabbed(const QImage &image);
+    void applyConfiguration();
 
 private:
     bool openCamera();
     void closeCamera();
     bool startViewFinder();
     void stopViewFinder();
-    void applyConfiguration();
     bool startVideoRecording();
     void stopVideoRecording();