text: // 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.
  
  #ifndef UI_GL_GL_IMPLEMENTATION_H_
  #define UI_GL_GL_IMPLEMENTATION_H_
  
  #include <string>
  #include <vector>
  
  #include "base/files/file_path.h"
  #include "base/native_library.h"
  #include "build/build_config.h"
  #include "ui/gl/gl_export.h"
  #include "ui/gl/gl_switches.h"
  
  namespace gl {
  
  // The GL implementation currently in use.
  enum GLImplementation {
    kGLImplementationNone,
    kGLImplementationDesktopGL,
    kGLImplementationDesktopGLCoreProfile,
    kGLImplementationOSMesaGL,
    kGLImplementationAppleGL,
    kGLImplementationEGLGLES2,
    kGLImplementationMockGL
  };
  
  struct GL_EXPORT GLWindowSystemBindingInfo {
    GLWindowSystemBindingInfo();
    std::string vendor;
    std::string version;
    std::string extensions;
    bool direct_rendering;
  };
  
  #if defined(OS_WIN)
  typedef void* (WINAPI *GLGetProcAddressProc)(const char* name);
  #else
  typedef void* (*GLGetProcAddressProc)(const char* name);
  #endif
  
  // Initialize stub methods for drawing operations in the GL bindings. The
  // null draw bindings default to enabled, so that draw operations do nothing.
  GL_EXPORT void InitializeNullDrawGLBindings();
  
  // TODO(danakj): Remove this when all test suites are using null-draw.
  GL_EXPORT bool HasInitializedNullDrawGLBindings();
  
  // Filter a list of disabled_extensions from GL style space-separated
  // extension_list, returning a space separated list of filtered extensions, in
  // the same order as the input.
  GL_EXPORT std::string FilterGLExtensionList(
      const char* extension_list,
      const std::vector<std::string>& disabled_extensions);
  
  // Once initialized, instantiating this turns the stub methods for drawing
  // operations off allowing drawing will occur while the object is alive.
  class GL_EXPORT DisableNullDrawGLBindings {
   public:
    DisableNullDrawGLBindings();
    ~DisableNullDrawGLBindings();
  
   private:
    bool initial_enabled_;
  };
  
  // Set the current GL implementation.
  GL_EXPORT void SetGLImplementation(GLImplementation implementation);
  
  // Get the current GL implementation.
  GL_EXPORT GLImplementation GetGLImplementation();
  
  // Does the underlying GL support all features from Desktop GL 2.0 that were
  // removed from the ES 2.0 spec without requiring specific extension strings.
  GL_EXPORT bool HasDesktopGLFeatures();
  
  // Get the GL implementation with a given name.
  GL_EXPORT GLImplementation GetNamedGLImplementation(const std::string& name);
  
  // Get the name of a GL implementation.
  GL_EXPORT const char* GetGLImplementationName(GLImplementation implementation);
  
  // Add a native library to those searched for GL entry points.
  GL_EXPORT void AddGLNativeLibrary(base::NativeLibrary library);
  
  // Unloads all native libraries.
  GL_EXPORT void UnloadGLNativeLibraries();
  
  // Set an additional function that will be called to find GL entry points.
  // Exported so that tests may set the function used in the mock implementation.
  GL_EXPORT void SetGLGetProcAddressProc(GLGetProcAddressProc proc);
  
  // Find an entry point in the current GL implementation. Note that the function
  // may return a non-null pointer to something else than the GL function if an
  // unsupported function is queried. Spec-compliant eglGetProcAddress and
  // glxGetProcAddress are allowed to return garbage for unsupported functions,
  // and when querying functions from the EGL library supplied by Android, it may
  // return a function that prints a log message about the function being
  // unsupported.
  GL_EXPORT void* GetGLProcAddress(const char* name);
  
  // Helper for fetching the OpenGL extensions from the current context.
  // This helper abstracts over differences between the desktop OpenGL
  // core profile, and OpenGL ES and the compatibility profile.  It's
  // intended for users of the bindings, not the implementation of the
  // bindings themselves. This is a relatively expensive call, so
  // callers should cache the result.
  GL_EXPORT std::string GetGLExtensionsFromCurrentContext();
  
  // Helper for the GL bindings implementation to understand whether
  // glGetString(GL_EXTENSIONS) or glGetStringi(GL_EXTENSIONS, i) will
  // be used in the function above.
  GL_EXPORT bool WillUseGLGetStringForExtensions();
  
  // Helpers to load a library and log error on failure.
  GL_EXPORT base::NativeLibrary LoadLibraryAndPrintError(
      const base::FilePath::CharType* filename);
  GL_EXPORT base::NativeLibrary LoadLibraryAndPrintError(
      const base::FilePath& filename);
  
  }  // namespace gl
  
  #endif  // UI_GL_GL_IMPLEMENTATION_H_
  