Various improvements on OpenGL contexts handling

git-svn-id: https://sfml.svn.sourceforge.net/svnroot/sfml/branches/sfml2@1245 4e206d99-4929-0410-ac5d-dfc041789085

dotnet/samples/opengl/OpenGL.cs

@@ -16,9 +16,6 @@ namespace sample_opengl
             // Create main window
             RenderWindow window = new RenderWindow(new VideoMode(800, 600), "SFML.Net OpenGL");
 
-            // Activate it as the target for OpenGL calls
-            window.SetActive();
-
             // Setup event handlers
             window.Closed     += new EventHandler(OnClosed);
             window.KeyPressed += new EventHandler<KeyEventArgs>(OnKeyPressed);
@@ -79,7 +76,9 @@ namespace sample_opengl
                 // will be rendered on top of the background sprite
                 window.Flush();
 
-                // Activate the window for OpenGL calls
+                // Activate the window before using OpenGL commands.
+                // This is useless here because we have only one window which is
+                // always the active one, but don't forget it if you use multiple windows
                 window.SetActive();
 
                 // Clear depth buffer
@@ -169,8 +168,6 @@ namespace sample_opengl
         /// </summary>
         static void OnResized(object sender, SizeEventArgs e)
         {
-            RenderWindow window = (RenderWindow)sender;
-            window.SetActive();
             Gl.glViewport(0, 0, (int)e.Width, (int)e.Height);
         }
     }

dotnet/samples/window/Window.cs

@@ -15,9 +15,6 @@ namespace sample_window
             // Create the main window
             Window window = new Window(new VideoMode(640, 480, 32), "SFML.Net Window");
 
-            // Activate it as the target for OpenGL calls
-            window.SetActive();
-
             // Setup event handlers
             window.Closed     += new EventHandler(OnClosed);
             window.KeyPressed += new EventHandler<KeyEventArgs>(OnKeyPressed);
@@ -44,7 +41,9 @@ namespace sample_window
                 // Process events
                 window.DispatchEvents();
 
-                // Set the active window before using OpenGL commands
+                // Activate the window before using OpenGL commands.
+                // This is useless here because we have only one window which is
+                // always the active one, but don't forget it if you use multiple windows
                 window.SetActive();
 
                 // Clear color and depth buffer
@@ -129,8 +128,6 @@ namespace sample_window
         /// </summary>
         static void OnResized(object sender, SizeEventArgs e)
         {
-            Window window = (Window)sender;
-            window.SetActive();
             Gl.glViewport(0, 0, (int)e.Width, (int)e.Height);
         }
     }

include/SFML/Window/Context.hpp

@@ -71,6 +71,18 @@ public :
     ////////////////////////////////////////////////////////////
     void SetActive(bool active);
 
+    ////////////////////////////////////////////////////////////
+    /// \brief Make the current thread's reference context active
+    ///
+    /// This function is meant to be called internally; it is used
+    /// to deactivate the current context by activating another one
+    /// (so that we still have an active context on the current thread).
+    ///
+    /// \return True if operation was successful, false otherwise
+    ///
+    ////////////////////////////////////////////////////////////
+    static bool SetReferenceActive();
+
 private :
 
     ////////////////////////////////////////////////////////////

samples/window/Window.cpp

@@ -17,9 +17,6 @@ int main()
     // Create the main window
     sf::Window window(sf::VideoMode(640, 480, 32), "SFML Window");
 
-    // Activate it as the target for OpenGL calls
-    window.SetActive();
-
     // Create a clock for measuring the time elapsed
     sf::Clock clock;
 
@@ -56,7 +53,9 @@ int main()
                 glViewport(0, 0, event.Size.Width, event.Size.Height);
        }
 
-        // Activate the window
+        // Activate the window before using OpenGL commands.
+        // This is useless here because we have only one window which is
+        // always the active one, but don't forget it if you use multiple windows
         window.SetActive();
 
         // Clear color and depth buffer

src/SFML/Audio/AudioDevice.cpp

@@ -45,8 +45,6 @@ namespace sf
 namespace priv
 {
 ////////////////////////////////////////////////////////////
-/// Default constructor
-////////////////////////////////////////////////////////////
 AudioDevice::AudioDevice()
 {
     // Create the device
@@ -78,8 +76,6 @@ AudioDevice::AudioDevice()
 }
 
 
-////////////////////////////////////////////////////////////
-/// Destructor
 ////////////////////////////////////////////////////////////
 AudioDevice::~AudioDevice()
 {
@@ -94,8 +90,6 @@ AudioDevice::~AudioDevice()
 }
 
 
-////////////////////////////////////////////////////////////
-/// Get the unique instance of the class
 ////////////////////////////////////////////////////////////
 AudioDevice& AudioDevice::GetInstance()
 {
@@ -103,8 +97,6 @@ AudioDevice& AudioDevice::GetInstance()
 }
 
 
-////////////////////////////////////////////////////////////
-/// Get the OpenAL audio device
 ////////////////////////////////////////////////////////////
 ALCdevice* AudioDevice::GetDevice() const
 {
@@ -112,8 +104,6 @@ ALCdevice* AudioDevice::GetDevice() const
 }
 
 
-////////////////////////////////////////////////////////////
-/// Get the OpenAL format that matches the given number of channels
 ////////////////////////////////////////////////////////////
 ALenum AudioDevice::GetFormatFromChannelsCount(unsigned int channelsCount) const
 {

src/SFML/Audio/AudioDevice.hpp

@@ -37,30 +37,30 @@ namespace sf
 {
 namespace priv
 {
-
 ////////////////////////////////////////////////////////////
-/// AudioDevice is the high-level wrapper around the audio API,
+/// \brief High-level wrapper around the audio API, it manages
-/// it manages creation and destruction of the audio device and context
+///        the creation and destruction of the audio device and
-/// and stores the device capabilities
+///        context and stores the device capabilities
+///
 ////////////////////////////////////////////////////////////
 class AudioDevice
 {
 public :
 
     ////////////////////////////////////////////////////////////
-    /// Default constructor
+    /// \brief Default constructor
     ///
     ////////////////////////////////////////////////////////////
     AudioDevice();
 
     ////////////////////////////////////////////////////////////
-    /// Destructor
+    /// \brief Destructor
     ///
     ////////////////////////////////////////////////////////////
     ~AudioDevice();
 
     ////////////////////////////////////////////////////////////
-    /// Get the unique instance of the class
+    /// \brief Get the unique instance of the class
     ///
     /// \return Unique instance of the class
     ///
@@ -68,7 +68,7 @@ public :
     static AudioDevice& GetInstance();
 
     ////////////////////////////////////////////////////////////
-    /// Get the OpenAL audio device
+    /// \brief Get the OpenAL audio device
     ///
     /// \return OpenAL device (cannot be NULL)
     ///
@@ -76,9 +76,9 @@ public :
     ALCdevice* GetDevice() const;
 
     ////////////////////////////////////////////////////////////
-    /// Get the OpenAL format that matches the given number of channels
+    /// \brief Get the OpenAL format that matches the given number of channels
     ///
-    /// \param channelsCount : Number of channels
+    /// \param channelsCount Number of channels
     ///
     /// \return Corresponding format
     ///

src/SFML/Graphics/Image.cpp

@@ -407,8 +407,6 @@ bool Image::CopyScreen(RenderWindow& window, const IntRect& sourceRect)
         myNeedArrayUpdate   = true;
         myPixelsFlipped     = true;
 
-        window.SetActive(false);
-
         return true;
     }
     else

src/SFML/Graphics/Linux/RenderImageImplPBuffer.cpp

@@ -63,7 +63,7 @@ RenderImageImplPBuffer::~RenderImageImplPBuffer()
 
     // This is to make sure that another valid context is made
     // active after we destroy the P-Buffer's one
-    Context context;
+    Context::SetReferenceActive();
 }
 
 
@@ -175,22 +175,25 @@ bool RenderImageImplPBuffer::Activate(bool active)
 {
     if (active)
     {
-        if (myPBuffer && myContext && (glXGetCurrentContext() != myContext))
+        if (myPBuffer && myContext)
         {
-            // Bind the OpenGL context of the P-Buffer
+            if (glXGetCurrentContext() != myContext)
-            if (!glXMakeCurrent(myDisplay, myPBuffer, myContext))
+                return glXMakeCurrent(myDisplay, myPBuffer, myContext) != 0;
-            {
+            else
-                std::cout << "Failed to activate render image" << std::endl;
+                return true;
-                return false;
         }
+        else
+        {
+            return false;
         }
     }
     else
     {
-        // We don't actually unbind the P-Buffer, for performances reasons
+        // To deactivate the P-Buffer's context, we actually activate
+        // another one so that we make sure that there is always an
+        // active context for subsequent graphics operations
+        return Context::SetReferenceActive();
     }
-
-    return true;
 }
 
 
@@ -199,10 +202,6 @@ bool RenderImageImplPBuffer::Activate(bool active)
 ////////////////////////////////////////////////////////////
 bool RenderImageImplPBuffer::UpdateTexture(unsigned int textureId)
 {
-    // Store the current active context
-    GLXDrawable currentDrawable = glXGetCurrentDrawable();
-    GLXContext currentContext = glXGetCurrentContext();
-
     if (Activate(true))
     {
         // Bind the texture
@@ -212,8 +211,8 @@ bool RenderImageImplPBuffer::UpdateTexture(unsigned int textureId)
         // Copy the rendered pixels to the image
         GLCheck(glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, myWidth, myHeight));
 
-        // Restore the previous context
+        // Deactivate the P-Buffer
-        glXMakeCurrent(myDisplay, currentDrawable, currentContext);
+        Activate(false);
 
         return true;
     }

src/SFML/Graphics/RenderWindow.cpp

@@ -48,6 +48,7 @@ RenderWindow::RenderWindow()
 ////////////////////////////////////////////////////////////
 RenderWindow::RenderWindow(VideoMode mode, const std::string& title, unsigned long style, const ContextSettings& settings)
 {
+    // Don't call the base class constructor because it contains virtual function calls
     Create(mode, title, style, settings);
 }
 
@@ -57,6 +58,7 @@ RenderWindow::RenderWindow(VideoMode mode, const std::string& title, unsigned lo
 ////////////////////////////////////////////////////////////
 RenderWindow::RenderWindow(WindowHandle handle, const ContextSettings& settings)
 {
+    // Don't call the base class constructor because it contains virtual function calls
     Create(handle, settings);
 }
 

src/SFML/Graphics/Win32/RenderImageImplPBuffer.cpp

@@ -67,7 +67,7 @@ RenderImageImplPBuffer::~RenderImageImplPBuffer()
 
     // This is to make sure that another valid context is made
     // active after we destroy the P-Buffer's one
-    Context context;
+    Context::SetReferenceActive();
 }
 
 
@@ -167,23 +167,25 @@ bool RenderImageImplPBuffer::Activate(bool active)
 {
     if (active)
     {
-        if (myDeviceContext && myContext && (wglGetCurrentContext() != myContext))
+        if (myDeviceContext && myContext)
         {
-            // Bind the OpenGL context of the P-Buffer
+            if (wglGetCurrentContext() != myContext)
-            if (!wglMakeCurrent(myDeviceContext, myContext))
+                return wglMakeCurrent(myDeviceContext, myContext) != 0;
-            {
+            else
-                std::cout << "Failed to activate render image" << std::endl;
+                return true;
-                return false;
         }
+        else
+        {
+            return false;
         }
     }
     else
     {
-        // We don't actually unbind the P-Buffer,
+        // To deactivate the P-Buffer's context, we actually activate
-        // for performances and consistency reasons
+        // another one so that we make sure that there is always an
+        // active context for subsequent graphics operations
+        return Context::SetReferenceActive();
     }
-
-    return true;
 }
 
 
@@ -192,10 +194,6 @@ bool RenderImageImplPBuffer::Activate(bool active)
 ////////////////////////////////////////////////////////////
 bool RenderImageImplPBuffer::UpdateTexture(unsigned int textureId)
 {
-    // Store the current active context
-    HDC currentDC = wglGetCurrentDC();
-    HGLRC currentContext = wglGetCurrentContext();
-
     if (Activate(true))
     {
         // Bind the texture
@@ -205,8 +203,8 @@ bool RenderImageImplPBuffer::UpdateTexture(unsigned int textureId)
         // Copy the rendered pixels to the image
         GLCheck(glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, myWidth, myHeight));
 
-        // Restore the previous context
+        // Deactivate the P-Buffer
-        wglMakeCurrent(currentDC, currentContext);
+        Activate(false);
 
         return true;
     }

src/SFML/Window/Context.cpp

@@ -54,4 +54,11 @@ void Context::SetActive(bool active)
 }
 
 
+////////////////////////////////////////////////////////////
+bool Context::SetReferenceActive()
+{
+    return priv::ContextGL::SetReferenceActive();
+}
+
+
 } // namespace sf

src/SFML/Window/ContextGL.cpp

@@ -99,8 +99,9 @@ ContextGL::~ContextGL()
     {
         threadContext = NULL;
     }
-    else if (threadContext != NULL)
+    else if (threadContext)
     {
+        // Don't call this->SetActive(false), it would lead to a pure virtual function call
         threadContext->SetActive(true);
     }
 }
@@ -116,27 +117,41 @@ const ContextSettings& ContextGL::GetSettings() const
 ////////////////////////////////////////////////////////////
 bool ContextGL::SetActive(bool active)
 {
-    if (MakeCurrent(active))
+    if (active)
     {
-        if (active && (threadContext == 0))
+        // Activate the context
+        if (MakeCurrent())
         {
             // If this is the first context to be activated on this thread, make
             // it the reference context for the whole thread
+            if (!threadContext)
                 threadContext = this;
-        }
-        else if (!active && (threadContext != NULL) && (threadContext != this))
-        {
-            // Activate the reference context for this thread to ensure
-            // that there is always an active context for subsequent graphics operations
-            threadContext->SetActive(true);
-        }
 
             return true;
         }
+    }
     else
     {
-        return false;
+        // Deactivate the context
+        if (threadContext && (threadContext != this))
+        {
+            // To deactivate the context, we actually activate another one
+            // so that we make sure that there is always an active context
+            // for subsequent graphics operations
+            return threadContext->SetActive(true);
         }
+    }
+
+    // If we got there then something failed
+    return false;
+}
+
+
+////////////////////////////////////////////////////////////
+bool ContextGL::SetReferenceActive()
+{
+    if (threadContext)
+        return threadContext->SetActive(true);
 }
 
 

src/SFML/Window/ContextGL.hpp

@@ -129,6 +129,18 @@ public :
     ////////////////////////////////////////////////////////////
     virtual void UseVerticalSync(bool enabled) = 0;
 
+    ////////////////////////////////////////////////////////////
+    /// \brief Make the current thread's reference context active
+    ///
+    /// This function is meant to be called internally; it is used
+    /// to deactivate the current context by activating another one
+    /// (so that we still have an active context on the current thread).
+    ///
+    /// \return True if operation was successful, false otherwise
+    ///
+    ////////////////////////////////////////////////////////////
+    static bool SetReferenceActive();
+
 protected :
 
     ////////////////////////////////////////////////////////////
@@ -140,15 +152,13 @@ protected :
     ContextGL();
 
     ////////////////////////////////////////////////////////////
-    /// \brief Activate or deactivate the context as the current target
+    /// \brief Activate the context as the current target
     ///        for rendering
     ///
-    /// \param active True to activate, false to deactivate
-    ///
     /// \return True on success, false if any error happened
     ///
     ////////////////////////////////////////////////////////////
-    virtual bool MakeCurrent(bool active) = 0;
+    virtual bool MakeCurrent() = 0;
 
     ////////////////////////////////////////////////////////////
     /// \brief Evaluate a pixel format configuration

src/SFML/Window/Linux/ContextGLX.cpp

@@ -113,10 +113,8 @@ ContextGLX::~ContextGLX()
 
 
 ////////////////////////////////////////////////////////////
-bool ContextGLX::MakeCurrent(bool active)
+bool ContextGLX::MakeCurrent()
 {
-    if (active)
-    {
     if (myContext)
     {
         if (glXGetCurrentContext() != myContext)
@@ -128,14 +126,6 @@ bool ContextGLX::MakeCurrent(bool active)
     {
         return false;
     }
-    }
-    else
-    {
-        if (glXGetCurrentContext() == myContext)
-            return glXMakeCurrent(myDisplay, None, NULL) != 0;
-        else
-            return true;
-    }
 }
 
 

src/SFML/Window/Linux/ContextGLX.hpp

@@ -71,15 +71,13 @@ public :
     ~ContextGLX();
 
     ////////////////////////////////////////////////////////////
-    /// \brief Activate or deactivate the context as the current target
+    /// \brief Activate the context as the current target
     ///        for rendering
     ///
-    /// \param active True to activate, false to deactivate
-    ///
     /// \return True on success, false if any error happened
     ///
     ////////////////////////////////////////////////////////////
-    virtual bool MakeCurrent(bool active);
+    virtual bool MakeCurrent();
 
     ////////////////////////////////////////////////////////////
     /// \brief Display what has been rendered to the context so far

src/SFML/Window/Win32/ContextWGL.cpp

@@ -29,6 +29,8 @@
 #include <SFML/Window/WindowImpl.hpp>
 #include <SFML/OpenGL.hpp>
 #include <SFML/Window/glext/wglext.h>
+#include <SFML/System/Lock.hpp>
+#include <SFML/System/Mutex.hpp>
 #include <iostream>
 
 
@@ -39,19 +41,19 @@ namespace priv
 ////////////////////////////////////////////////////////////
 ContextWGL::ContextWGL(ContextWGL* shared) :
 myWindow       (NULL),
-myDC        (NULL),
+myDeviceContext(NULL),
 myContext      (NULL),
-myOwnsWindow(true)
+myOwnsWindow   (true)
 {
     // TODO : try to create a bitmap in memory instead of a dummy window
 
     // Create a dummy window (disabled and hidden)
     myWindow = CreateWindowA("STATIC", "", WS_POPUP | WS_DISABLED, 0, 0, 1, 1, NULL, NULL, GetModuleHandle(NULL), NULL);
     ShowWindow(myWindow, SW_HIDE);
-    myDC = GetDC(myWindow);
+    myDeviceContext = GetDC(myWindow);
 
     // Create the context
-    if (myDC)
+    if (myDeviceContext)
         CreateContext(shared, VideoMode::GetDesktopMode().BitsPerPixel, ContextSettings(0, 0, 0));
 
     // Activate the context
@@ -62,16 +64,16 @@ myOwnsWindow(true)
 ////////////////////////////////////////////////////////////
 ContextWGL::ContextWGL(ContextWGL* shared, const WindowImpl* owner, unsigned int bitsPerPixel, const ContextSettings& settings) :
 myWindow       (NULL),
-myDC        (NULL),
+myDeviceContext(NULL),
 myContext      (NULL),
-myOwnsWindow(false)
+myOwnsWindow   (false)
 {
     // Get the owner window and its device context
     myWindow = static_cast<HWND>(owner->GetHandle());
-    myDC = GetDC(myWindow);
+    myDeviceContext = GetDC(myWindow);
 
     // Create the context
-    if (myDC)
+    if (myDeviceContext)
         CreateContext(shared, bitsPerPixel, settings);
 
     // Activate the context
@@ -91,8 +93,8 @@ ContextWGL::~ContextWGL()
     }
 
     // Release the DC
-    if (myWindow && myDC)
+    if (myWindow && myDeviceContext)
-        ReleaseDC(myWindow, myDC);
+        ReleaseDC(myWindow, myDeviceContext);
 
     // Destroy the window if we own it
     if (myWindow && myOwnsWindow)
@@ -101,14 +103,12 @@ ContextWGL::~ContextWGL()
 
 
 ////////////////////////////////////////////////////////////
-bool ContextWGL::MakeCurrent(bool active)
+bool ContextWGL::MakeCurrent()
 {
-    if (active)
+    if (myDeviceContext && myContext)
-    {
-        if (myDC && myContext)
     {
         if (wglGetCurrentContext() != myContext)
-                return wglMakeCurrent(myDC, myContext) != 0;
+            return wglMakeCurrent(myDeviceContext, myContext) != 0;
         else
             return true;
     }
@@ -116,22 +116,14 @@ bool ContextWGL::MakeCurrent(bool active)
     {
         return false;
     }
-    }
-    else
-    {
-        if (wglGetCurrentContext() == myContext)
-            return wglMakeCurrent(NULL, NULL) != 0;
-        else
-            return true;
-    }
 }
 
 
 ////////////////////////////////////////////////////////////
 void ContextWGL::Display()
 {
-    if (myDC && myContext)
+    if (myDeviceContext && myContext)
-        SwapBuffers(myDC);
+        SwapBuffers(myDeviceContext);
 }
 
 
@@ -180,7 +172,7 @@ void ContextWGL::CreateContext(ContextWGL* shared, unsigned int bitsPerPixel, co
         int   formats[128];
 	    UINT  nbFormats;
 	    float floatAttributes[] = {0, 0};
-	    bool  isValid = wglChoosePixelFormatARB(myDC, intAttributes, floatAttributes, sizeof(formats) / sizeof(*formats), formats, &nbFormats) != 0;
+	    bool  isValid = wglChoosePixelFormatARB(myDeviceContext, intAttributes, floatAttributes, sizeof(formats) / sizeof(*formats), formats, &nbFormats) != 0;
         if (!isValid || (nbFormats == 0))
         {
             if (mySettings.AntialiasingLevel > 2)
@@ -190,7 +182,7 @@ void ContextWGL::CreateContext(ContextWGL* shared, unsigned int bitsPerPixel, co
                           << mySettings.AntialiasingLevel << " antialiasing levels ; trying with 2 levels" << std::endl;
 
                 mySettings.AntialiasingLevel = intAttributes[1] = 2;
-	            isValid = wglChoosePixelFormatARB(myDC, intAttributes, floatAttributes, sizeof(formats) / sizeof(*formats), formats, &nbFormats) != 0;
+	            isValid = wglChoosePixelFormatARB(myDeviceContext, intAttributes, floatAttributes, sizeof(formats) / sizeof(*formats), formats, &nbFormats) != 0;
             }
 
             if (!isValid || (nbFormats == 0))
@@ -211,7 +203,7 @@ void ContextWGL::CreateContext(ContextWGL* shared, unsigned int bitsPerPixel, co
                 PIXELFORMATDESCRIPTOR attributes;
                 attributes.nSize    = sizeof(attributes);
                 attributes.nVersion = 1;
-                DescribePixelFormat(myDC, formats[i], sizeof(attributes), &attributes);
+                DescribePixelFormat(myDeviceContext, formats[i], sizeof(attributes), &attributes);
 
                 // Evaluate the current configuration
                 int color = attributes.cRedBits + attributes.cGreenBits + attributes.cBlueBits + attributes.cAlphaBits;
@@ -243,7 +235,7 @@ void ContextWGL::CreateContext(ContextWGL* shared, unsigned int bitsPerPixel, co
         descriptor.cStencilBits = static_cast<BYTE>(mySettings.StencilBits);
 
         // Get the pixel format that best matches our requirements
-        bestFormat = ChoosePixelFormat(myDC, &descriptor);
+        bestFormat = ChoosePixelFormat(myDeviceContext, &descriptor);
         if (bestFormat == 0)
         {
             std::cerr << "Failed to find a suitable pixel format for device context -- cannot create OpenGL context" << std::endl;
@@ -255,12 +247,12 @@ void ContextWGL::CreateContext(ContextWGL* shared, unsigned int bitsPerPixel, co
     PIXELFORMATDESCRIPTOR actualFormat;
     actualFormat.nSize    = sizeof(actualFormat);
     actualFormat.nVersion = 1;
-    DescribePixelFormat(myDC, bestFormat, sizeof(actualFormat), &actualFormat);
+    DescribePixelFormat(myDeviceContext, bestFormat, sizeof(actualFormat), &actualFormat);
     mySettings.DepthBits   = actualFormat.cDepthBits;
     mySettings.StencilBits = actualFormat.cStencilBits;
 
     // Set the chosen pixel format
-    if (!SetPixelFormat(myDC, bestFormat, &actualFormat))
+    if (!SetPixelFormat(myDeviceContext, bestFormat, &actualFormat))
     {
         std::cerr << "Failed to set pixel format for device context -- cannot create OpenGL context" << std::endl;
         return;
@@ -279,13 +271,13 @@ void ContextWGL::CreateContext(ContextWGL* shared, unsigned int bitsPerPixel, co
             WGL_CONTEXT_MINOR_VERSION_ARB, 0,
             0, 0
         };
-        myContext = wglCreateContextAttribsARB(myDC, sharedContext, attributes);
+        myContext = wglCreateContextAttribsARB(myDeviceContext, sharedContext, attributes);
     }
 
     // If the OpenGL 3.0 context failed, create a regular OpenGL 1.x context
     if (!myContext)
     {
-        myContext = wglCreateContext(myDC);
+        myContext = wglCreateContext(myDeviceContext);
         if (!myContext)
         {
             std::cerr << "Failed to create an OpenGL context for this window" << std::endl;
@@ -295,6 +287,10 @@ void ContextWGL::CreateContext(ContextWGL* shared, unsigned int bitsPerPixel, co
         // Share this context with others
         if (sharedContext)
         {
+            // wglShareLists doesn't seem to be thread-safe
+            static Mutex mutex;
+            Lock lock(mutex);
+
             if (!wglShareLists(sharedContext, myContext))
                 std::cerr << "Failed to share the OpenGL context" << std::endl;
         }

src/SFML/Window/Win32/ContextWGL.hpp

@@ -70,15 +70,13 @@ public :
     ~ContextWGL();
 
     ////////////////////////////////////////////////////////////
-    /// \brief Activate or deactivate the context as the current target
+    /// \brief Activate the context as the current target
     ///        for rendering
     ///
-    /// \param active True to activate, false to deactivate
-    ///
     /// \return True on success, false if any error happened
     ///
     ////////////////////////////////////////////////////////////
-    virtual bool MakeCurrent(bool active);
+    virtual bool MakeCurrent();
 
     ////////////////////////////////////////////////////////////
     /// \brief Display what has been rendered to the context so far
@@ -123,7 +121,7 @@ private :
     // Member data
     ////////////////////////////////////////////////////////////
     HWND  myWindow;        ///< Window to which the context is attached
-    HDC   myDC;         ///< Device context of the window
+    HDC   myDeviceContext; ///< Device context of the window
     HGLRC myContext;       ///< OpenGL context
     bool  myOwnsWindow;    ///< Did we create the host window?
 };

src/SFML/Window/Window.cpp

@@ -27,7 +27,6 @@
 ////////////////////////////////////////////////////////////
 #include <SFML/Window/Window.hpp>
 #include <SFML/Window/ContextGL.hpp>
-#include <SFML/Window/Context.hpp>
 #include <SFML/Window/WindowImpl.hpp>
 #include <SFML/System/Sleep.hpp>
 #include <iostream>
@@ -127,16 +126,9 @@ void Window::Create(VideoMode mode, const std::string& title, unsigned long styl
         style |= Style::Titlebar;
 
     // Recreate the window implementation
-    delete myWindow;
     myWindow = priv::WindowImpl::New(mode, title, style);
 
-    // Make sure another context is bound, so that:
-    // - the context creation can request OpenGL extensions if necessary
-    // - myContext can safely be destroyed (it's no longer bound)
-    Context context;
-
     // Recreate the context
-    delete myContext;
     myContext = priv::ContextGL::New(myWindow, mode.BitsPerPixel, settings);
 
     // Perform common initializations
@@ -147,17 +139,13 @@ void Window::Create(VideoMode mode, const std::string& title, unsigned long styl
 ////////////////////////////////////////////////////////////
 void Window::Create(WindowHandle handle, const ContextSettings& settings)
 {
-    // Recreate the window implementation
+    // Destroy the previous window implementation
     Close();
+
+    // Recreate the window implementation
     myWindow = priv::WindowImpl::New(handle);
 
-    // Make sure another context is bound, so that:
-    // - the context creation can request OpenGL extensions if necessary
-    // - myContext can safely be destroyed (it's no longer bound)
-    Context context;
-
     // Recreate the context
-    delete myContext;
     myContext = priv::ContextGL::New(myWindow, VideoMode::GetDesktopMode().BitsPerPixel, settings);
 
     // Perform common initializations
@@ -325,6 +313,7 @@ bool Window::SetActive(bool active) const
     }
     else
     {
+        std::cerr << "Trying to activate the window, but it doesn't have a valid context" << std::endl;
         return false;
     }
 }
@@ -349,11 +338,8 @@ void Window::Display()
     myClock.Reset();
 
     // Display the backbuffer on screen
-    if (SetActive(true))
+    if (SetActive())
-    {
         myContext->Display();
-        SetActive(false);
-    }
 }
 
 
@@ -435,7 +421,7 @@ void Window::Initialize()
     myLastFrameTime = 0.f;
 
     // Activate the window
-    SetActive(true);
+    SetActive();
 
     // Notify the derived class
     OnCreate();