testing/test_gl_surface.cc - mirrors/engine - Git at Google

 // Copyright 2013 The Flutter 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 "flutter/testing/test_gl_surface.h"

 #include <EGL/egl.h>
 #include <EGL/eglext.h>
 #include <EGL/eglplatform.h>
 #include <GLES2/gl2.h>

 #include <sstream>
 #include <string>

 #include "flutter/fml/build_config.h"
 #include "flutter/fml/logging.h"
 #include "third_party/skia/include/core/SkColorSpace.h"
 #include "third_party/skia/include/core/SkColorType.h"
 #include "third_party/skia/include/core/SkSurface.h"
 #include "third_party/skia/include/gpu/gl/GrGLAssembleInterface.h"

 namespace flutter {
 namespace testing {

 static std::string GetEGLError() {
   std::stringstream stream;

   auto error = ::eglGetError();

   stream << "EGL Result: '";

   switch (error) {
     case EGL_SUCCESS:
       stream << "EGL_SUCCESS";
       break;
     case EGL_NOT_INITIALIZED:
       stream << "EGL_NOT_INITIALIZED";
       break;
     case EGL_BAD_ACCESS:
       stream << "EGL_BAD_ACCESS";
       break;
     case EGL_BAD_ALLOC:
       stream << "EGL_BAD_ALLOC";
       break;
     case EGL_BAD_ATTRIBUTE:
       stream << "EGL_BAD_ATTRIBUTE";
       break;
     case EGL_BAD_CONTEXT:
       stream << "EGL_BAD_CONTEXT";
       break;
     case EGL_BAD_CONFIG:
       stream << "EGL_BAD_CONFIG";
       break;
     case EGL_BAD_CURRENT_SURFACE:
       stream << "EGL_BAD_CURRENT_SURFACE";
       break;
     case EGL_BAD_DISPLAY:
       stream << "EGL_BAD_DISPLAY";
       break;
     case EGL_BAD_SURFACE:
       stream << "EGL_BAD_SURFACE";
       break;
     case EGL_BAD_MATCH:
       stream << "EGL_BAD_MATCH";
       break;
     case EGL_BAD_PARAMETER:
       stream << "EGL_BAD_PARAMETER";
       break;
     case EGL_BAD_NATIVE_PIXMAP:
       stream << "EGL_BAD_NATIVE_PIXMAP";
       break;
     case EGL_BAD_NATIVE_WINDOW:
       stream << "EGL_BAD_NATIVE_WINDOW";
       break;
     case EGL_CONTEXT_LOST:
       stream << "EGL_CONTEXT_LOST";
       break;
     default:
       stream << "Unknown";
   }

   stream << "' (0x" << std::hex << error << std::dec << ").";
   return stream.str();
 }

 static bool HasExtension(const char* extensions, const char* name) {
   const char* r = strstr(extensions, name);
   auto len = strlen(name);
   // check that the extension name is terminated by space or null terminator
   return r != nullptr && (r[len] == ' ' || r[len] == 0);
 }

 static void CheckSwanglekExtensions() {
   const char* extensions = ::eglQueryString(EGL_NO_DISPLAY, EGL_EXTENSIONS);
   FML_CHECK(HasExtension(extensions, "EGL_EXT_platform_base")) << extensions;
   FML_CHECK(HasExtension(extensions, "EGL_ANGLE_platform_angle_vulkan"))
       << extensions;
   FML_CHECK(HasExtension(extensions,
                          "EGL_ANGLE_platform_angle_device_type_swiftshader"))
       << extensions;
 }

 static EGLDisplay CreateSwangleDisplay() {
   CheckSwanglekExtensions();

   PFNEGLGETPLATFORMDISPLAYEXTPROC egl_get_platform_display_EXT =
       reinterpret_cast<PFNEGLGETPLATFORMDISPLAYEXTPROC>(
           eglGetProcAddress("eglGetPlatformDisplayEXT"));
   FML_CHECK(egl_get_platform_display_EXT)
       << "eglGetPlatformDisplayEXT not available.";

   const EGLint display_config[] = {
       EGL_PLATFORM_ANGLE_TYPE_ANGLE,
       EGL_PLATFORM_ANGLE_TYPE_VULKAN_ANGLE,
       EGL_PLATFORM_ANGLE_DEVICE_TYPE_ANGLE,
       EGL_PLATFORM_ANGLE_DEVICE_TYPE_SWIFTSHADER_ANGLE,
       EGL_PLATFORM_ANGLE_NATIVE_PLATFORM_TYPE_ANGLE,
       EGL_PLATFORM_VULKAN_DISPLAY_MODE_HEADLESS_ANGLE,
       EGL_NONE,
   };

   return egl_get_platform_display_EXT(
       EGL_PLATFORM_ANGLE_ANGLE,
       reinterpret_cast<EGLNativeDisplayType*>(EGL_DEFAULT_DISPLAY),
       display_config);
 }

 TestGLSurface::TestGLSurface(SkISize surface_size)
     : surface_size_(surface_size) {
   display_ = CreateSwangleDisplay();
   FML_CHECK(display_ != EGL_NO_DISPLAY);

   auto result = ::eglInitialize(display_, nullptr, nullptr);
   FML_CHECK(result == EGL_TRUE) << GetEGLError();

   EGLConfig config = {0};

   EGLint num_config = 0;
   const EGLint attribute_list[] = {EGL_RED_SIZE,
                                    8,
                                    EGL_GREEN_SIZE,
                                    8,
                                    EGL_BLUE_SIZE,
                                    8,
                                    EGL_ALPHA_SIZE,
                                    8,
                                    EGL_SURFACE_TYPE,
                                    EGL_PBUFFER_BIT,
                                    EGL_CONFORMANT,
                                    EGL_OPENGL_ES2_BIT,
                                    EGL_RENDERABLE_TYPE,
                                    EGL_OPENGL_ES2_BIT,
                                    EGL_NONE};

   result = ::eglChooseConfig(display_, attribute_list, &config, 1, &num_config);
   FML_CHECK(result == EGL_TRUE) << GetEGLError();
   FML_CHECK(num_config == 1) << GetEGLError();

   {
     const EGLint onscreen_surface_attributes[] = {
         EGL_WIDTH,  surface_size_.width(),   //
         EGL_HEIGHT, surface_size_.height(),  //
         EGL_NONE,
     };

     onscreen_surface_ = ::eglCreatePbufferSurface(
         display_,                    // display connection
         config,                      // config
         onscreen_surface_attributes  // surface attributes
     );
     FML_CHECK(onscreen_surface_ != EGL_NO_SURFACE) << GetEGLError();
   }

   {
     const EGLint offscreen_surface_attributes[] = {
         EGL_WIDTH,  1,  //
         EGL_HEIGHT, 1,  //
         EGL_NONE,
     };
     offscreen_surface_ = ::eglCreatePbufferSurface(
         display_,                     // display connection
         config,                       // config
         offscreen_surface_attributes  // surface attributes
     );
     FML_CHECK(offscreen_surface_ != EGL_NO_SURFACE) << GetEGLError();
   }

   {
     const EGLint context_attributes[] = {
         EGL_CONTEXT_CLIENT_VERSION,  //
         2,                           //
         EGL_NONE                     //
     };

     onscreen_context_ =
         ::eglCreateContext(display_,           // display connection
                            config,             // config
                            EGL_NO_CONTEXT,     // sharegroup
                            context_attributes  // context attributes
         );
     FML_CHECK(onscreen_context_ != EGL_NO_CONTEXT) << GetEGLError();

     offscreen_context_ =
         ::eglCreateContext(display_,           // display connection
                            config,             // config
                            onscreen_context_,  // sharegroup
                            context_attributes  // context attributes
         );
     FML_CHECK(offscreen_context_ != EGL_NO_CONTEXT) << GetEGLError();
   }
 }

 TestGLSurface::~TestGLSurface() {
   context_ = nullptr;

   auto result = ::eglDestroyContext(display_, onscreen_context_);
   FML_CHECK(result == EGL_TRUE) << GetEGLError();

   result = ::eglDestroyContext(display_, offscreen_context_);
   FML_CHECK(result == EGL_TRUE) << GetEGLError();

   result = ::eglDestroySurface(display_, onscreen_surface_);
   FML_CHECK(result == EGL_TRUE) << GetEGLError();

   result = ::eglDestroySurface(display_, offscreen_surface_);
   FML_CHECK(result == EGL_TRUE) << GetEGLError();

   result = ::eglTerminate(display_);
   FML_CHECK(result == EGL_TRUE);
 }

 const SkISize& TestGLSurface::GetSurfaceSize() const {
   return surface_size_;
 }

 bool TestGLSurface::MakeCurrent() {
   auto result = ::eglMakeCurrent(display_, onscreen_surface_, onscreen_surface_,
                                  onscreen_context_);

   if (result == EGL_FALSE) {
     FML_LOG(ERROR) << "Could not make the context current. " << GetEGLError();
   }

   return result == EGL_TRUE;
 }

 bool TestGLSurface::ClearCurrent() {
   auto result = ::eglMakeCurrent(display_, EGL_NO_SURFACE, EGL_NO_SURFACE,
                                  EGL_NO_CONTEXT);

   if (result == EGL_FALSE) {
     FML_LOG(ERROR) << "Could not clear the current context. " << GetEGLError();
   }

   return result == EGL_TRUE;
 }

 bool TestGLSurface::Present() {
   auto result = ::eglSwapBuffers(display_, onscreen_surface_);

   if (result == EGL_FALSE) {
     FML_LOG(ERROR) << "Could not swap buffers. " << GetEGLError();
   }

   return result == EGL_TRUE;
 }

 uint32_t TestGLSurface::GetFramebuffer(uint32_t width, uint32_t height) const {
   return GetWindowFBOId();
 }

 bool TestGLSurface::MakeResourceCurrent() {
   auto result = ::eglMakeCurrent(display_, offscreen_surface_,
                                  offscreen_surface_, offscreen_context_);

   if (result == EGL_FALSE) {
     FML_LOG(ERROR) << "Could not make the resource context current. "
                    << GetEGLError();
   }

   return result == EGL_TRUE;
 }

 void* TestGLSurface::GetProcAddress(const char* name) const {
   if (name == nullptr) {
     return nullptr;
   }
   auto symbol = ::eglGetProcAddress(name);
   if (symbol == NULL) {
     FML_LOG(ERROR) << "Could not fetch symbol for name: " << name;
   }
   return reinterpret_cast<void*>(symbol);
 }

 sk_sp<GrDirectContext> TestGLSurface::GetGrContext() {
   if (context_) {
     return context_;
   }

   return CreateGrContext();
 }

 sk_sp<GrDirectContext> TestGLSurface::CreateGrContext() {
   if (!MakeCurrent()) {
     return nullptr;
   }

   auto get_string =
       reinterpret_cast<PFNGLGETSTRINGPROC>(GetProcAddress("glGetString"));

   if (!get_string) {
     return nullptr;
   }

   auto c_version = reinterpret_cast<const char*>(get_string(GL_VERSION));

   if (c_version == NULL) {
     return nullptr;
   }

   GrGLGetProc get_proc = [](void* context, const char name[]) -> GrGLFuncPtr {
     return reinterpret_cast<GrGLFuncPtr>(
         reinterpret_cast<TestGLSurface*>(context)->GetProcAddress(name));
   };

   std::string version(c_version);
   auto interface = version.find("OpenGL ES") == std::string::npos
                        ? GrGLMakeAssembledGLInterface(this, get_proc)
                        : GrGLMakeAssembledGLESInterface(this, get_proc);

   if (!interface) {
     return nullptr;
   }

   context_ = GrDirectContext::MakeGL(interface);
   return context_;
 }

 sk_sp<SkSurface> TestGLSurface::GetOnscreenSurface() {
   FML_CHECK(::eglGetCurrentContext() != EGL_NO_CONTEXT);

   GrGLFramebufferInfo framebuffer_info = {};
   const uint32_t width = surface_size_.width();
   const uint32_t height = surface_size_.height();
   framebuffer_info.fFBOID = GetFramebuffer(width, height);
 #if FML_OS_MACOSX
   framebuffer_info.fFormat = 0x8058;  // GL_RGBA8
 #else
   framebuffer_info.fFormat = 0x93A1;  // GL_BGRA8;
 #endif

   GrBackendRenderTarget backend_render_target(
       width,            // width
       height,           // height
       1,                // sample count
       8,                // stencil bits
       framebuffer_info  // framebuffer info
   );

   SkSurfaceProps surface_properties(0, kUnknown_SkPixelGeometry);

   auto surface = SkSurface::MakeFromBackendRenderTarget(
       GetGrContext().get(),         // context
       backend_render_target,        // backend render target
       kBottomLeft_GrSurfaceOrigin,  // surface origin
       kN32_SkColorType,             // color type
       SkColorSpace::MakeSRGB(),     // color space
       &surface_properties,          // surface properties
       nullptr,                      // release proc
       nullptr                       // release context
   );

   if (!surface) {
     FML_LOG(ERROR) << "Could not wrap the surface while attempting to "
                       "snapshot the GL surface.";
     return nullptr;
   }

   return surface;
 }

 sk_sp<SkImage> TestGLSurface::GetRasterSurfaceSnapshot() {
   auto surface = GetOnscreenSurface();

   if (!surface) {
     FML_LOG(ERROR) << "Aborting snapshot because of on-screen surface "
                       "acquisition failure.";
     return nullptr;
   }

   auto device_snapshot = surface->makeImageSnapshot();

   if (!device_snapshot) {
     FML_LOG(ERROR) << "Could not create the device snapshot while attempting "
                       "to snapshot the GL surface.";
     return nullptr;
   }

   auto host_snapshot = device_snapshot->makeRasterImage();

   if (!host_snapshot) {
     FML_LOG(ERROR) << "Could not create the host snapshot while attempting to "
                       "snapshot the GL surface.";
     return nullptr;
   }

   return host_snapshot;
 }

 uint32_t TestGLSurface::GetWindowFBOId() const {
   return 0u;
 }

 }  // namespace testing
 }  // namespace flutter
	// Copyright 2013 The Flutter 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 "flutter/testing/test_gl_surface.h"

	#include <EGL/egl.h>
	#include <EGL/eglext.h>
	#include <EGL/eglplatform.h>
	#include <GLES2/gl2.h>

	#include <sstream>
	#include <string>

	#include "flutter/fml/build_config.h"
	#include "flutter/fml/logging.h"
	#include "third_party/skia/include/core/SkColorSpace.h"
	#include "third_party/skia/include/core/SkColorType.h"
	#include "third_party/skia/include/core/SkSurface.h"
	#include "third_party/skia/include/gpu/gl/GrGLAssembleInterface.h"

	namespace flutter {
	namespace testing {

	static std::string GetEGLError() {
	std::stringstream stream;

	auto error = ::eglGetError();

	stream << "EGL Result: '";

	switch (error) {
	case EGL_SUCCESS:
	stream << "EGL_SUCCESS";
	break;
	case EGL_NOT_INITIALIZED:
	stream << "EGL_NOT_INITIALIZED";
	break;
	case EGL_BAD_ACCESS:
	stream << "EGL_BAD_ACCESS";
	break;
	case EGL_BAD_ALLOC:
	stream << "EGL_BAD_ALLOC";
	break;
	case EGL_BAD_ATTRIBUTE:
	stream << "EGL_BAD_ATTRIBUTE";
	break;
	case EGL_BAD_CONTEXT:
	stream << "EGL_BAD_CONTEXT";
	break;
	case EGL_BAD_CONFIG:
	stream << "EGL_BAD_CONFIG";
	break;
	case EGL_BAD_CURRENT_SURFACE:
	stream << "EGL_BAD_CURRENT_SURFACE";
	break;
	case EGL_BAD_DISPLAY:
	stream << "EGL_BAD_DISPLAY";
	break;
	case EGL_BAD_SURFACE:
	stream << "EGL_BAD_SURFACE";
	break;
	case EGL_BAD_MATCH:
	stream << "EGL_BAD_MATCH";
	break;
	case EGL_BAD_PARAMETER:
	stream << "EGL_BAD_PARAMETER";
	break;
	case EGL_BAD_NATIVE_PIXMAP:
	stream << "EGL_BAD_NATIVE_PIXMAP";
	break;
	case EGL_BAD_NATIVE_WINDOW:
	stream << "EGL_BAD_NATIVE_WINDOW";
	break;
	case EGL_CONTEXT_LOST:
	stream << "EGL_CONTEXT_LOST";
	break;
	default:
	stream << "Unknown";
	}

	stream << "' (0x" << std::hex << error << std::dec << ").";
	return stream.str();
	}

	static bool HasExtension(const char* extensions, const char* name) {
	const char* r = strstr(extensions, name);
	auto len = strlen(name);
	// check that the extension name is terminated by space or null terminator
	return r != nullptr && (r[len] == ' ' \|\| r[len] == 0);
	}

	static void CheckSwanglekExtensions() {
	const char* extensions = ::eglQueryString(EGL_NO_DISPLAY, EGL_EXTENSIONS);
	FML_CHECK(HasExtension(extensions, "EGL_EXT_platform_base")) << extensions;
	FML_CHECK(HasExtension(extensions, "EGL_ANGLE_platform_angle_vulkan"))
	<< extensions;
	FML_CHECK(HasExtension(extensions,
	"EGL_ANGLE_platform_angle_device_type_swiftshader"))
	<< extensions;
	}

	static EGLDisplay CreateSwangleDisplay() {
	CheckSwanglekExtensions();

	PFNEGLGETPLATFORMDISPLAYEXTPROC egl_get_platform_display_EXT =
	reinterpret_cast<PFNEGLGETPLATFORMDISPLAYEXTPROC>(
	eglGetProcAddress("eglGetPlatformDisplayEXT"));
	FML_CHECK(egl_get_platform_display_EXT)
	<< "eglGetPlatformDisplayEXT not available.";

	const EGLint display_config[] = {
	EGL_PLATFORM_ANGLE_TYPE_ANGLE,
	EGL_PLATFORM_ANGLE_TYPE_VULKAN_ANGLE,
	EGL_PLATFORM_ANGLE_DEVICE_TYPE_ANGLE,
	EGL_PLATFORM_ANGLE_DEVICE_TYPE_SWIFTSHADER_ANGLE,
	EGL_PLATFORM_ANGLE_NATIVE_PLATFORM_TYPE_ANGLE,
	EGL_PLATFORM_VULKAN_DISPLAY_MODE_HEADLESS_ANGLE,
	EGL_NONE,
	};

	return egl_get_platform_display_EXT(
	EGL_PLATFORM_ANGLE_ANGLE,
	reinterpret_cast<EGLNativeDisplayType*>(EGL_DEFAULT_DISPLAY),
	display_config);
	}

	TestGLSurface::TestGLSurface(SkISize surface_size)
	: surface_size_(surface_size) {
	display_ = CreateSwangleDisplay();
	FML_CHECK(display_ != EGL_NO_DISPLAY);

	auto result = ::eglInitialize(display_, nullptr, nullptr);
	FML_CHECK(result == EGL_TRUE) << GetEGLError();

	EGLConfig config = {0};

	EGLint num_config = 0;
	const EGLint attribute_list[] = {EGL_RED_SIZE,
	8,
	EGL_GREEN_SIZE,
	8,
	EGL_BLUE_SIZE,
	8,
	EGL_ALPHA_SIZE,
	8,
	EGL_SURFACE_TYPE,
	EGL_PBUFFER_BIT,
	EGL_CONFORMANT,
	EGL_OPENGL_ES2_BIT,
	EGL_RENDERABLE_TYPE,
	EGL_OPENGL_ES2_BIT,
	EGL_NONE};

	result = ::eglChooseConfig(display_, attribute_list, &config, 1, &num_config);
	FML_CHECK(result == EGL_TRUE) << GetEGLError();
	FML_CHECK(num_config == 1) << GetEGLError();

	{
	const EGLint onscreen_surface_attributes[] = {
	EGL_WIDTH, surface_size_.width(), //
	EGL_HEIGHT, surface_size_.height(), //
	EGL_NONE,
	};

	onscreen_surface_ = ::eglCreatePbufferSurface(
	display_, // display connection
	config, // config
	onscreen_surface_attributes // surface attributes
	);
	FML_CHECK(onscreen_surface_ != EGL_NO_SURFACE) << GetEGLError();
	}

	{
	const EGLint offscreen_surface_attributes[] = {
	EGL_WIDTH, 1, //
	EGL_HEIGHT, 1, //
	EGL_NONE,
	};
	offscreen_surface_ = ::eglCreatePbufferSurface(
	display_, // display connection
	config, // config
	offscreen_surface_attributes // surface attributes
	);
	FML_CHECK(offscreen_surface_ != EGL_NO_SURFACE) << GetEGLError();
	}

	{
	const EGLint context_attributes[] = {
	EGL_CONTEXT_CLIENT_VERSION, //
	2, //
	EGL_NONE //
	};

	onscreen_context_ =
	::eglCreateContext(display_, // display connection
	config, // config
	EGL_NO_CONTEXT, // sharegroup
	context_attributes // context attributes
	);
	FML_CHECK(onscreen_context_ != EGL_NO_CONTEXT) << GetEGLError();

	offscreen_context_ =
	::eglCreateContext(display_, // display connection
	config, // config
	onscreen_context_, // sharegroup
	context_attributes // context attributes
	);
	FML_CHECK(offscreen_context_ != EGL_NO_CONTEXT) << GetEGLError();
	}
	}

	TestGLSurface::~TestGLSurface() {
	context_ = nullptr;

	auto result = ::eglDestroyContext(display_, onscreen_context_);
	FML_CHECK(result == EGL_TRUE) << GetEGLError();

	result = ::eglDestroyContext(display_, offscreen_context_);
	FML_CHECK(result == EGL_TRUE) << GetEGLError();

	result = ::eglDestroySurface(display_, onscreen_surface_);
	FML_CHECK(result == EGL_TRUE) << GetEGLError();

	result = ::eglDestroySurface(display_, offscreen_surface_);
	FML_CHECK(result == EGL_TRUE) << GetEGLError();

	result = ::eglTerminate(display_);
	FML_CHECK(result == EGL_TRUE);
	}

	const SkISize& TestGLSurface::GetSurfaceSize() const {
	return surface_size_;
	}

	bool TestGLSurface::MakeCurrent() {
	auto result = ::eglMakeCurrent(display_, onscreen_surface_, onscreen_surface_,
	onscreen_context_);

	if (result == EGL_FALSE) {
	FML_LOG(ERROR) << "Could not make the context current. " << GetEGLError();
	}

	return result == EGL_TRUE;
	}

	bool TestGLSurface::ClearCurrent() {
	auto result = ::eglMakeCurrent(display_, EGL_NO_SURFACE, EGL_NO_SURFACE,
	EGL_NO_CONTEXT);

	if (result == EGL_FALSE) {
	FML_LOG(ERROR) << "Could not clear the current context. " << GetEGLError();
	}

	return result == EGL_TRUE;
	}

	bool TestGLSurface::Present() {
	auto result = ::eglSwapBuffers(display_, onscreen_surface_);

	if (result == EGL_FALSE) {
	FML_LOG(ERROR) << "Could not swap buffers. " << GetEGLError();
	}

	return result == EGL_TRUE;
	}

	uint32_t TestGLSurface::GetFramebuffer(uint32_t width, uint32_t height) const {
	return GetWindowFBOId();
	}

	bool TestGLSurface::MakeResourceCurrent() {
	auto result = ::eglMakeCurrent(display_, offscreen_surface_,
	offscreen_surface_, offscreen_context_);

	if (result == EGL_FALSE) {
	FML_LOG(ERROR) << "Could not make the resource context current. "
	<< GetEGLError();
	}

	return result == EGL_TRUE;
	}

	void* TestGLSurface::GetProcAddress(const char* name) const {
	if (name == nullptr) {
	return nullptr;
	}
	auto symbol = ::eglGetProcAddress(name);
	if (symbol == NULL) {
	FML_LOG(ERROR) << "Could not fetch symbol for name: " << name;
	}
	return reinterpret_cast<void*>(symbol);
	}

	sk_sp<GrDirectContext> TestGLSurface::GetGrContext() {
	if (context_) {
	return context_;
	}

	return CreateGrContext();
	}

	sk_sp<GrDirectContext> TestGLSurface::CreateGrContext() {
	if (!MakeCurrent()) {
	return nullptr;
	}

	auto get_string =
	reinterpret_cast<PFNGLGETSTRINGPROC>(GetProcAddress("glGetString"));

	if (!get_string) {
	return nullptr;
	}

	auto c_version = reinterpret_cast<const char*>(get_string(GL_VERSION));

	if (c_version == NULL) {
	return nullptr;
	}

	GrGLGetProc get_proc = [](void* context, const char name[]) -> GrGLFuncPtr {
	return reinterpret_cast<GrGLFuncPtr>(
	reinterpret_cast<TestGLSurface*>(context)->GetProcAddress(name));
	};

	std::string version(c_version);
	auto interface = version.find("OpenGL ES") == std::string::npos
	? GrGLMakeAssembledGLInterface(this, get_proc)
	: GrGLMakeAssembledGLESInterface(this, get_proc);

	if (!interface) {
	return nullptr;
	}

	context_ = GrDirectContext::MakeGL(interface);
	return context_;
	}

	sk_sp<SkSurface> TestGLSurface::GetOnscreenSurface() {
	FML_CHECK(::eglGetCurrentContext() != EGL_NO_CONTEXT);

	GrGLFramebufferInfo framebuffer_info = {};
	const uint32_t width = surface_size_.width();
	const uint32_t height = surface_size_.height();
	framebuffer_info.fFBOID = GetFramebuffer(width, height);
	#if FML_OS_MACOSX
	framebuffer_info.fFormat = 0x8058; // GL_RGBA8
	#else
	framebuffer_info.fFormat = 0x93A1; // GL_BGRA8;
	#endif

	GrBackendRenderTarget backend_render_target(
	width, // width
	height, // height
	1, // sample count
	8, // stencil bits
	framebuffer_info // framebuffer info
	);

	SkSurfaceProps surface_properties(0, kUnknown_SkPixelGeometry);

	auto surface = SkSurface::MakeFromBackendRenderTarget(
	GetGrContext().get(), // context
	backend_render_target, // backend render target
	kBottomLeft_GrSurfaceOrigin, // surface origin
	kN32_SkColorType, // color type
	SkColorSpace::MakeSRGB(), // color space
	&surface_properties, // surface properties
	nullptr, // release proc
	nullptr // release context
	);

	if (!surface) {
	FML_LOG(ERROR) << "Could not wrap the surface while attempting to "
	"snapshot the GL surface.";
	return nullptr;
	}

	return surface;
	}

	sk_sp<SkImage> TestGLSurface::GetRasterSurfaceSnapshot() {
	auto surface = GetOnscreenSurface();

	if (!surface) {
	FML_LOG(ERROR) << "Aborting snapshot because of on-screen surface "
	"acquisition failure.";
	return nullptr;
	}

	auto device_snapshot = surface->makeImageSnapshot();

	if (!device_snapshot) {
	FML_LOG(ERROR) << "Could not create the device snapshot while attempting "
	"to snapshot the GL surface.";
	return nullptr;
	}

	auto host_snapshot = device_snapshot->makeRasterImage();

	if (!host_snapshot) {
	FML_LOG(ERROR) << "Could not create the host snapshot while attempting to "
	"snapshot the GL surface.";
	return nullptr;
	}

	return host_snapshot;
	}

	uint32_t TestGLSurface::GetWindowFBOId() const {
	return 0u;
	}

	} // namespace testing
	} // namespace flutter