Better handling of GLX / EGL errors.

If context creation fails, try again without a shared context. Added
QPlatformOpenGLContext::isSharing() and
QPlatformOpenGLContext::isValid() to propagate whether the platform
context was successfully created with or without sharing.

Change-Id: I37080b645f531fd207946441057be6d3f6be3f6e
Reviewed-by: Jørgen Lind <jorgen.lind@nokia.com>

3 files changed, 31 insertions, 5 deletions

diff --git a/src/plugins/platforms/xcb/qglxintegration.cpp b/src/plugins/platforms/xcb/qglxintegration.cpp
index 550a5e4184..de41f862bd 100644
--- a/src/plugins/platforms/xcb/qglxintegration.cpp
+++ b/src/plugins/platforms/xcb/qglxintegration.cpp
@@ -65,13 +65,21 @@ QGLXContext::QGLXContext(QXcbScreen *screen, const QSurfaceFormat &format, QPlat
     , m_screen(screen)
     , m_context(0)
 {
-    GLXContext shareGlxContext = 0;
+    m_shareContext = 0;
     if (share)
-        shareGlxContext = static_cast<const QGLXContext*>(share)->glxContext();
+        m_shareContext = static_cast<const QGLXContext*>(share)->glxContext();
 
     GLXFBConfig config = qglx_findConfig(DISPLAY_FROM_XCB(screen),screen->screenNumber(),format);
-    m_context = glXCreateNewContext(DISPLAY_FROM_XCB(screen), config, GLX_RGBA_TYPE, shareGlxContext, TRUE);
-    m_format = qglx_surfaceFormatFromGLXFBConfig(DISPLAY_FROM_XCB(screen), config, m_context);
+
+    m_context = glXCreateNewContext(DISPLAY_FROM_XCB(screen), config, GLX_RGBA_TYPE, m_shareContext, TRUE);
+    if (!m_context && m_shareContext) {
+        // re-try without a shared glx context
+        m_shareContext = 0;
+        m_context = glXCreateNewContext(DISPLAY_FROM_XCB(screen), config, GLX_RGBA_TYPE, 0, TRUE);
+    }
+
+    if (m_context)
+        m_format = qglx_surfaceFormatFromGLXFBConfig(DISPLAY_FROM_XCB(screen), config, m_context);
 }
 
 QGLXContext::~QGLXContext()
@@ -137,4 +145,14 @@ QSurfaceFormat QGLXContext::format() const
     return m_format;
 }
 
+bool QGLXContext::isSharing() const
+{
+    return m_shareContext != 0;
+}
+
+bool QGLXContext::isValid() const
+{
+    return m_context != 0;
+}
+
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/xcb/qglxintegration.h b/src/plugins/platforms/xcb/qglxintegration.h
index 2c8fea5874..211a654c03 100644
--- a/src/plugins/platforms/xcb/qglxintegration.h
+++ b/src/plugins/platforms/xcb/qglxintegration.h
@@ -66,12 +66,15 @@ public:
     void (*getProcAddress(const QByteArray &procName)) ();
 
     QSurfaceFormat format() const;
+    bool isSharing() const;
+    bool isValid() const;
 
     GLXContext glxContext() const { return m_context; }
 
 private:
     QXcbScreen *m_screen;
     GLXContext m_context;
+    GLXContext m_shareContext;
     QSurfaceFormat m_format;
 };
 
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index a5b8aa9a35..6969124b2a 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -86,6 +86,11 @@ extern "C" {
 
 QT_BEGIN_NAMESPACE
 
+static int nullErrorHandler(Display *, XErrorEvent *)
+{
+    return 0;
+}
+
 QXcbConnection::QXcbConnection(const char *displayName)
     : m_displayName(displayName ? QByteArray(displayName) : qgetenv("DISPLAY"))
 #ifdef XCB_USE_XINPUT2_MAEMO
@@ -106,6 +111,7 @@ QXcbConnection::QXcbConnection(const char *displayName)
     m_primaryScreen = DefaultScreen(dpy);
     m_connection = XGetXCBConnection(dpy);
     XSetEventQueueOwner(dpy, XCBOwnsEventQueue);
+    XSetErrorHandler(nullErrorHandler);
     m_xlib_display = dpy;
 #ifdef XCB_USE_EGL
     EGLDisplay eglDisplay = eglGetDisplay(dpy);
@@ -1002,7 +1008,6 @@ void QXcbConnection::initializeXFixes()
         xfixes_first_event = 0;
     }
     free(xfixes_query);
-
 }
 
 void QXcbConnection::initializeXRender()