Take GL version and extensions correctly into account when binding functions

ui/gl/gl_implementation_win.cc

Index: ui/gl/gl_implementation_win.cc
diff --git a/ui/gl/gl_implementation_win.cc b/ui/gl/gl_implementation_win.cc
index 87328a306f8f4783a4535073ff5a4f215f263e17..79cb14bbbcc3eefed324074530b55295b465dd9c 100644
--- a/ui/gl/gl_implementation_win.cc
+++ b/ui/gl/gl_implementation_win.cc
@@ -17,10 +17,12 @@
 #include "base/threading/thread_restrictions.h"
 #include "base/win/windows_version.h"
 #include "ui/gl/gl_bindings.h"
+#include "ui/gl/gl_context_stub_with_extensions.h"
 #include "ui/gl/gl_egl_api_implementation.h"
 #include "ui/gl/gl_gl_api_implementation.h"
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_osmesa_api_implementation.h"
+#include "ui/gl/gl_surface_wgl.h"
 #include "ui/gl/gl_wgl_api_implementation.h"
 
 #if defined(ENABLE_SWIFTSHADER)
@@ -106,7 +108,7 @@ void GetAllowedGLImplementations(std::vector<GLImplementation>* impls) {
   impls->push_back(kGLImplementationOSMesaGL);
 }
 
-bool InitializeGLBindings(GLImplementation implementation) {
+bool InitializeStaticGLBindings(GLImplementation implementation) {
   // Prevent reinitialization with a different implementation. Once the gpu
   // unit tests have initialized with kGLImplementationMock, we don't want to
   // later switch to another GL implementation.
@@ -148,8 +150,8 @@ bool InitializeGLBindings(GLImplementation implementation) {
       AddGLNativeLibrary(library);
       SetGLImplementation(kGLImplementationOSMesaGL);
 
-      InitializeGLBindingsGL();
-      InitializeGLBindingsOSMESA();
+      InitializeStaticGLBindingsGL();
+      InitializeStaticGLBindingsOSMESA();
       break;
     }
     case kGLImplementationEGLGLES2: {
@@ -234,8 +236,8 @@ bool InitializeGLBindings(GLImplementation implementation) {
       AddGLNativeLibrary(gles_library);
       SetGLImplementation(kGLImplementationEGLGLES2);
 
-      InitializeGLBindingsGL();
-      InitializeGLBindingsEGL();
+      InitializeStaticGLBindingsGL();
+      InitializeStaticGLBindingsEGL();
 
       // These two functions take single precision float rather than double
       // precision float parameters in GLES.
@@ -244,8 +246,6 @@ bool InitializeGLBindings(GLImplementation implementation) {
       break;
     }
     case kGLImplementationDesktopGL: {
-      // When using Windows OpenGL, first try wglGetProcAddress and then
-      // Windows GetProcAddress.
       base::NativeLibrary library = base::LoadNativeLibrary(
           base::FilePath(L"opengl32.dll"), NULL);
       if (!library) {
@@ -267,14 +267,41 @@ bool InitializeGLBindings(GLImplementation implementation) {
       AddGLNativeLibrary(library);
       SetGLImplementation(kGLImplementationDesktopGL);
 
-      InitializeGLBindingsGL();
-      InitializeGLBindingsWGL();
+      // Initialize WGL bindings to be able to create a context.
+      InitializeStaticGLBindingsWGL();

[no sievers, 2014/01/14 23:16:01]

How about only looking up the symbol for wglCreateContext here manually?

That way we wouldn't have to init and clear all the other bindings for nothing
and it would simplify the comment/need for explanation.

[oetuaho-nv, 2014/01/15 15:50:25]

True. Done.

+
+      // Create a temporary GL context to bind to entry points. This is needed
+      // because wglGetProcAddress is specified to return NULL for all queries
+      // if a context is not current in MSDN documentation, and the static
+      // bindings may contain functions that need to be queried with
+      // wglGetProcAddress. OpenGL wiki further warns that other error values
+      // than NULL could also be returned from wglGetProcAddress on some
+      // implementations, so we need to clear the WGL bindings and reinitialize
+      // them after the context creation.
+      HGLRC gl_context = wglCreateContext(GLSurfaceWGL::GetDisplayDC());
+      if (!gl_context) {
+        LOG(ERROR) << "Failed to create temporary context.";
+        return false;
+      }
+      if (!wglMakeCurrent(GLSurfaceWGL::GetDisplayDC(), gl_context)) {
+        LOG(ERROR) << "Failed to make temporary GL context current.";
+        wglDeleteContext(gl_context);
+        return false;
+      }
+
+      ClearGLBindingsWGL();
+      InitializeStaticGLBindingsGL();
+      InitializeStaticGLBindingsWGL();
+
+      wglMakeCurrent(NULL, NULL);
+      wglDeleteContext(gl_context);
+
       break;
     }
     case kGLImplementationMockGL: {
       SetGLGetProcAddressProc(GetMockGLProcAddress);
       SetGLImplementation(kGLImplementationMockGL);
-      InitializeGLBindingsGL();
+      InitializeStaticGLBindingsGL();
       break;
     }
     default:
@@ -284,23 +311,29 @@ bool InitializeGLBindings(GLImplementation implementation) {
   return true;
 }
 
-bool InitializeGLExtensionBindings(GLImplementation implementation,
+bool InitializeDynamicGLBindings(GLImplementation implementation,
     GLContext* context) {
   switch (implementation) {
     case kGLImplementationOSMesaGL:
-      InitializeGLExtensionBindingsGL(context);
-      InitializeGLExtensionBindingsOSMESA(context);
+      InitializeDynamicGLBindingsGL(context);
+      InitializeDynamicGLBindingsOSMESA(context);
       break;
     case kGLImplementationEGLGLES2:
-      InitializeGLExtensionBindingsGL(context);
-      InitializeGLExtensionBindingsEGL(context);
+      InitializeDynamicGLBindingsGL(context);
+      InitializeDynamicGLBindingsEGL(context);
       break;
     case kGLImplementationDesktopGL:
-      InitializeGLExtensionBindingsGL(context);
-      InitializeGLExtensionBindingsWGL(context);
+      InitializeDynamicGLBindingsGL(context);
+      InitializeDynamicGLBindingsWGL(context);
       break;
     case kGLImplementationMockGL:
-      InitializeGLExtensionBindingsGL(context);
+      if (!context) {
+        scoped_refptr<GLContextStubWithExtensions> mock_context(
+            new GLContextStubWithExtensions());
+        mock_context->SetGLVersionString("3.0");
+        InitializeDynamicGLBindingsGL(mock_context.get());
+      } else
+        InitializeDynamicGLBindingsGL(context);
       break;
     default:
       return false;