OpenGL: Don't request a context version higher than is supported

The function wglCreateContextAttribsARB will fail if we request a
context version higher than is supported. We therefore upper-bound the
requested version by the version of the static context. This results
in context creation succeeding and having the closest possible match
to the requested format.

The xcb qpa plugin is modified to operate similarly to the windows
plugin in that it now creates a "static" context which is used to
limit the versions of contexts requested by the user.

Change-Id: I277ad7cc82edfdf7b9d8502ad921c8175feb1a4a
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/src/plugins/platforms/xcb/qxcbintegration.h b/src/plugins/platforms/xcb/qxcbintegration.h
index 7f7c52372c..669a0d00f6 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.h
+++ b/src/plugins/platforms/xcb/qxcbintegration.h
@@ -51,6 +51,11 @@ class QXcbConnection;
 class QAbstractEventDispatcher;
 class QXcbNativeInterface;
 
+#if !defined(QT_NO_OPENGL) && defined(XCB_USE_GLX)
+class QOpenGLDefaultContextInfo;
+class QXcbScreen;
+#endif
+
 class QXcbIntegration : public QPlatformIntegration
 {
 public:
@@ -92,6 +97,10 @@ public:
     QStringList themeNames() const;
     QPlatformTheme *createPlatformTheme(const QString &name) const;
 
+#if !defined(QT_NO_OPENGL) && defined(XCB_USE_GLX)
+    void removeDefaultOpenGLContextInfo(QXcbScreen *screen);
+#endif
+
 private:
     QList<QXcbConnection *> m_connections;
 
@@ -101,6 +110,10 @@ private:
     QScopedPointer<QPlatformInputContext> m_inputContext;
     QAbstractEventDispatcher *m_eventDispatcher;
 
+#if !defined(QT_NO_OPENGL) && defined(XCB_USE_GLX)
+    mutable QHash<QXcbScreen *, QOpenGLDefaultContextInfo *> m_defaultContextInfos;
+#endif
+
 #ifndef QT_NO_ACCESSIBILITY
     QScopedPointer<QPlatformAccessibility> m_accessibility;
 #endif