Prevent crashing on Symbian in case EGL surface creation fails.

It is possible in environment with limited resources, that EGL
surface creation fails. When this happens, the QPainter doesn't
get properly activated, which in turn caused a crash later in
the drawing code.

Now, a check has been added into qapplication_s60.cpp to abort
window drawing immediately, if surface creation has failed. The
EGL surface is then tried to be recreated on the next time when
the window becomes visible, which usually allows the application
to recover.

In most cases, the crash happened in the function qDrawBorderPixmap,
which didn't check the validity of the QPaintEngine pointer before
accessing it. This method is analogous with the public methods of
the class QPainter where, on the other hand, availability of
QPaintEngine was always checked. To be in line, and to prevent
ptential crashes, a similar safety check and warning message have
now been added to method qDrawBorderPixmap.

Furthermore, a null-check was added to qwindowsurface_gl.cpp for the
QGLContext pointer. The same pointer was already previously
null-checked in the other branch of the same function, indicating
that the null-check is probably necessary.

Task-number: ou1cimx1#969923
Change-Id: I6d78be72b9c2308ef74b1119d8c8ec34ec015195
Reviewed-by: Jaakko Helanti <ext-jaakko.helanti@nokia.com>
Reviewed-by: Pasi Pentikäinen <ext-pasi.a.pentikainen@nokia.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/opengl/qwindowsurface_gl.cpp b/src/opengl/qwindowsurface_gl.cpp
index c39eb53..81e857f 100644
--- a/src/opengl/qwindowsurface_gl.cpp
+++ b/src/opengl/qwindowsurface_gl.cpp
@@ -693,6 +693,11 @@ void QGLWindowSurface::flush(QWidget *widget, const QRegion &rgn, const QPoint &
             }
 
             QGLContext *ctx = reinterpret_cast<QGLContext *>(parent->d_func()->extraData()->glContext);
+#ifdef Q_OS_SYMBIAN
+            if (!ctx)
+                return;
+#endif
+
             if (widget != window()) {
                 if (initializeOffscreenTexture(window()->size()))
                     qWarning() << "QGLWindowSurface: Flushing to native child widget, may lead to significant performance loss";