Added code

SFML-2.4.2/include/SFML/Window/GlResource.hpp

@@ -0,0 +1,103 @@
+////////////////////////////////////////////////////////////
+//
+// SFML - Simple and Fast Multimedia Library
+// Copyright (C) 2007-2017 Laurent Gomila (laurent@sfml-dev.org)
+//
+// This software is provided 'as-is', without any express or implied warranty.
+// In no event will the authors be held liable for any damages arising from the use of this software.
+//
+// Permission is granted to anyone to use this software for any purpose,
+// including commercial applications, and to alter it and redistribute it freely,
+// subject to the following restrictions:
+//
+// 1. The origin of this software must not be misrepresented;
+//    you must not claim that you wrote the original software.
+//    If you use this software in a product, an acknowledgment
+//    in the product documentation would be appreciated but is not required.
+//
+// 2. Altered source versions must be plainly marked as such,
+//    and must not be misrepresented as being the original software.
+//
+// 3. This notice may not be removed or altered from any source distribution.
+//
+////////////////////////////////////////////////////////////
+
+#ifndef SFML_GLRESOURCE_HPP
+#define SFML_GLRESOURCE_HPP
+
+////////////////////////////////////////////////////////////
+// Headers
+////////////////////////////////////////////////////////////
+#include <SFML/Window/Export.hpp>
+#include <SFML/System/NonCopyable.hpp>
+
+
+namespace sf
+{
+
+class Context;
+
+////////////////////////////////////////////////////////////
+/// \brief Base class for classes that require an OpenGL context
+///
+////////////////////////////////////////////////////////////
+class SFML_WINDOW_API GlResource
+{
+protected:
+
+    ////////////////////////////////////////////////////////////
+    /// \brief Default constructor
+    ///
+    ////////////////////////////////////////////////////////////
+    GlResource();
+
+    ////////////////////////////////////////////////////////////
+    /// \brief Destructor
+    ///
+    ////////////////////////////////////////////////////////////
+    ~GlResource();
+
+    ////////////////////////////////////////////////////////////
+    /// \brief Empty function for ABI compatibility, use acquireTransientContext instead
+    ///
+    ////////////////////////////////////////////////////////////
+    static void ensureGlContext();
+
+    ////////////////////////////////////////////////////////////
+    /// \brief RAII helper class to temporarily lock an available context for use
+    ///
+    ////////////////////////////////////////////////////////////
+    class SFML_WINDOW_API TransientContextLock : NonCopyable
+    {
+    public:
+        ////////////////////////////////////////////////////////////
+        /// \brief Default constructor
+        ///
+        ////////////////////////////////////////////////////////////
+        TransientContextLock();
+
+        ////////////////////////////////////////////////////////////
+        /// \brief Destructor
+        ///
+        ////////////////////////////////////////////////////////////
+        ~TransientContextLock();
+
+    private:
+        Context* m_context; ///< Temporary context, in case we needed to create one
+    };
+};
+
+} // namespace sf
+
+
+#endif // SFML_GLRESOURCE_HPP
+
+////////////////////////////////////////////////////////////
+/// \class sf::GlResource
+/// \ingroup window
+///
+/// This class is for internal use only, it must be the base
+/// of every class that requires a valid OpenGL context in
+/// order to work.
+///
+////////////////////////////////////////////////////////////