From dd31b41f08ced4860cb06d4d87189b97328b98fb Mon Sep 17 00:00:00 2001
From: "Stefanos A." <stapostol@gmail.com>
Date: Tue, 17 Dec 2013 21:24:25 +0100
Subject: [PATCH] Load opengl32.dll before gdi32.dll

According to
http://stackoverflow.com/questions/199016/wglcreatecontext-in-c-sharp-failing-but-not-in-managed-c,
opengl32.dll must be loaded before gdi32.dll. Affect issue #19.
---
 Source/OpenTK/Platform/Windows/WinFactory.cs   | 20 ++++++++++++++++++++
 Source/OpenTK/Platform/Windows/WinGLContext.cs | 17 ++---------------
 2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/Source/OpenTK/Platform/Windows/WinFactory.cs b/Source/OpenTK/Platform/Windows/WinFactory.cs
index b0fc822..5435018 100644
--- a/Source/OpenTK/Platform/Windows/WinFactory.cs
+++ b/Source/OpenTK/Platform/Windows/WinFactory.cs
@@ -34,6 +34,7 @@ namespace OpenTK.Platform.Windows
 {
     using Graphics;
     using OpenTK.Input;
+    using System.Runtime.InteropServices;
 
     class WinFactory : IPlatformFactory 
     {
@@ -41,6 +42,9 @@ namespace OpenTK.Platform.Windows
         readonly object SyncRoot = new object();
         IInputDriver2 inputDriver;
 
+        internal static IntPtr OpenGLHandle { get; private set; }
+        const string OpenGLName = "OPENGL32.DLL";
+
         public WinFactory()
         {
             if (System.Environment.OSVersion.Version.Major <= 4)
@@ -48,6 +52,11 @@ namespace OpenTK.Platform.Windows
                 throw new PlatformNotSupportedException("OpenTK requires Windows XP or higher");
             }
 
+            // Dynamically load opengl32.dll in order to use the extension loading capabilities of Wgl.
+            // Note: opengl32.dll must be loaded before gdi32.dll, otherwise strange failures may occur
+            // (such as "error: 2000" when calling wglSetPixelFormat or slowness/lag on specific GPUs).
+            LoadOpenGL();
+
             if (System.Environment.OSVersion.Version.Major >= 6)
             {
                 if (Toolkit.Options.EnableHighResolution)
@@ -60,6 +69,17 @@ namespace OpenTK.Platform.Windows
             }
         }
 
+        static void LoadOpenGL()
+        {
+            OpenGLHandle = Functions.LoadLibrary(OpenGLName);
+            if (OpenGLHandle == IntPtr.Zero)
+            {
+                throw new ApplicationException(String.Format("LoadLibrary(\"{0}\") call failed with code {1}",
+                    OpenGLName, Marshal.GetLastWin32Error()));
+            }
+            Debug.WriteLine(String.Format("Loaded opengl32.dll: {0}", OpenGLHandle));
+        }
+
         #region IPlatformFactory Members
 
         public virtual INativeWindow CreateNativeWindow(int x, int y, int width, int height, string title, GraphicsMode mode, GameWindowFlags options, DisplayDevice device)
diff --git a/Source/OpenTK/Platform/Windows/WinGLContext.cs b/Source/OpenTK/Platform/Windows/WinGLContext.cs
index a534d92..bfe4c9d 100644
--- a/Source/OpenTK/Platform/Windows/WinGLContext.cs
+++ b/Source/OpenTK/Platform/Windows/WinGLContext.cs
@@ -30,9 +30,6 @@ namespace OpenTK.Platform.Windows
         static readonly object LoadLock = new object();
         static readonly object SyncRoot = new object();
 
-        static IntPtr opengl32Handle;
-        const string opengl32Name = "OPENGL32.DLL";
-
         bool vsync_supported;
 
         readonly WinGraphicsMode ModeSelector;
@@ -43,16 +40,6 @@ namespace OpenTK.Platform.Windows
         {
             lock (LoadLock)
             {
-                // Dynamically load opengl32.dll in order to use the extension loading capabilities of Wgl.
-                if (opengl32Handle == IntPtr.Zero)
-                {
-                    opengl32Handle = Functions.LoadLibrary(opengl32Name);
-                    if (opengl32Handle == IntPtr.Zero)
-                        throw new ApplicationException(String.Format("LoadLibrary(\"{0}\") call failed with code {1}",
-                                                                     opengl32Name, Marshal.GetLastWin32Error()));
-                    Debug.WriteLine(String.Format("Loaded opengl32.dll: {0}", opengl32Handle));
-                }
-
                 // We need to create a temp context in order to load
                 // wgl extensions (e.g. for multisampling or GL3).
                 // We cannot rely on OpenTK.Platform.Wgl until we
@@ -341,7 +328,7 @@ namespace OpenTK.Platform.Windows
             IntPtr address = Wgl.GetProcAddress(function_string);
             if (!IsValid(address))
             {
-                address = Functions.GetProcAddress(opengl32Handle, function_string);
+                address = Functions.GetProcAddress(WinFactory.OpenGLHandle, function_string);
             }
             return address;
         }
@@ -351,7 +338,7 @@ namespace OpenTK.Platform.Windows
             IntPtr address = Wgl.GetProcAddress(function_string);
             if (!IsValid(address))
             {
-                address = Functions.GetProcAddress(opengl32Handle, function_string);
+                address = Functions.GetProcAddress(WinFactory.OpenGLHandle, function_string);
             }
             return address;
         }
-- 
2.7.4