xcb: Fallback to Xlib screen when glXGetCurrentDisplay() returns NULL

Change-Id: Ie25b3fac4c0224f847c77c0515894a9df84077a2
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>

2 files changed, 11 insertions, 6 deletions

diff --git a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
index 3412f3f3fc..22e68e3db7 100644
--- a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
+++ b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
@@ -645,9 +645,12 @@ void QGLXContext::queryDummyContext()
 
     QScopedPointer<QSurface> surface;
     Display *display = glXGetCurrentDisplay();
-    const char *glxvendor = 0;
-    if (display)
-        glxvendor = glXGetClientString(display, GLX_VENDOR);
+    if (!display) {
+        // FIXME: Since Qt 5.6 we don't need to check whether primary screen is NULL
+        if (QScreen *screen = QGuiApplication::primaryScreen())
+            display = DISPLAY_FROM_XCB(static_cast<QXcbScreen *>(screen->handle()));
+    }
+    const char *glxvendor = glXGetClientString(display, GLX_VENDOR);
     if (glxvendor && !strcmp(glxvendor, "ATI")) {
         QWindow *window = new QWindow;
         window->resize(64, 64);
diff --git a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp
index cd4949af5c..a3a8aa259b 100644
--- a/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp
+++ b/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qxcbglxintegration.cpp
@@ -196,9 +196,11 @@ QPlatformOffscreenSurface *QXcbGlxIntegration::createPlatformOffscreenSurface(QO
     if (!vendorChecked) {
         vendorChecked = true;
         Display *display = glXGetCurrentDisplay();
-        const char *glxvendor = 0;
-        if (display)
-            glxvendor = glXGetClientString(display, GLX_VENDOR);
+#ifdef XCB_USE_XLIB
+        if (!display)
+            display = static_cast<Display *>(m_connection->xlib_display());
+#endif
+        const char *glxvendor = glXGetClientString(display, GLX_VENDOR);
         if (glxvendor && !strcmp(glxvendor, "ATI"))
             glxPbufferUsable = false;
     }