Take GL version and extensions correctly into account when binding functions

ui/gl/gl_implementation_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <vector>
 
 #include "base/at_exit.h"
 #include "base/base_paths.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/native_library.h"
 #include "base/path_service.h"
 #include "base/strings/stringprintf.h"
 #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)
 #include "software_renderer.h"
 #endif
 
 namespace gfx {
 
 namespace {
 
@@ skipping 65 matching lines @@
     AddTraceEventFunc add_trace_event_func);
 
 }  // namespace
 
 void GetAllowedGLImplementations(std::vector<GLImplementation>* impls) {
   impls->push_back(kGLImplementationEGLGLES2);
   impls->push_back(kGLImplementationDesktopGL);
   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.
   if (GetGLImplementation() != kGLImplementationNone)
     return true;
 
   // Allow the main thread or another to initialize these bindings
   // after instituting restrictions on I/O. Going forward they will
   // likely be used in the browser process on most platforms. The
   // one-time initialization cost is small, between 2 and 5 ms.
@@ skipping 21 matching lines @@
       if (!get_proc_address) {
         DLOG(ERROR) << "OSMesaGetProcAddress not found.";
         base::UnloadNativeLibrary(library);
         return false;
       }
 
       SetGLGetProcAddressProc(get_proc_address);
       AddGLNativeLibrary(library);
       SetGLImplementation(kGLImplementationOSMesaGL);
 
-      InitializeGLBindingsGL();
-      InitializeGLBindingsOSMESA();
+      InitializeStaticGLBindingsGL();
+      InitializeStaticGLBindingsOSMESA();
       break;
     }
     case kGLImplementationEGLGLES2: {
       base::FilePath module_path;
       if (!PathService::Get(base::DIR_MODULE, &module_path))
         return false;
 
       // Attempt to load the D3DX shader compiler using the default search path
       // and if that fails, using an absolute path. This is to ensure these DLLs
       // are loaded before ANGLE is loaded in case they are not in the default
@@ skipping 64 matching lines @@
         base::UnloadNativeLibrary(egl_library);
         base::UnloadNativeLibrary(gles_library);
         return false;
       }
 
       SetGLGetProcAddressProc(get_proc_address);
       AddGLNativeLibrary(egl_library);
       AddGLNativeLibrary(gles_library);
       SetGLImplementation(kGLImplementationEGLGLES2);
 
-      InitializeGLBindingsGL();
-      InitializeGLBindingsEGL();
+      InitializeStaticGLBindingsGL();
+      InitializeStaticGLBindingsEGL();
 
       // These two functions take single precision float rather than double
       // precision float parameters in GLES.
       ::gfx::g_driver_gl.fn.glClearDepthFn = MarshalClearDepthToClearDepthf;
       ::gfx::g_driver_gl.fn.glDepthRangeFn = MarshalDepthRangeToDepthRangef;
       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) {
         DVLOG(1) << "opengl32.dll not found";
         return false;
       }
 
       GLGetProcAddressProc get_proc_address =
           reinterpret_cast<GLGetProcAddressProc>(
               base::GetFunctionPointerFromNativeLibrary(
                   library, "wglGetProcAddress"));
       if (!get_proc_address) {
         LOG(ERROR) << "wglGetProcAddress not found.";
         base::UnloadNativeLibrary(library);
         return false;
       }
 
       SetGLGetProcAddressProc(get_proc_address);
       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:
       return false;
   }
 
   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;
   }
 
   return true;
 }
 
 void InitializeDebugGLBindings() {
   InitializeDebugGLBindingsEGL();
@@ skipping 17 matching lines @@
       return GetGLWindowSystemBindingInfoWGL(info);
     case kGLImplementationEGLGLES2:
       return GetGLWindowSystemBindingInfoEGL(info);
     default:
       return false;
   }
   return false;
 }
 
 }  // namespace gfx