examples/glfw_drm/FlutterEmbedderGLFW.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 <cassert>
 #include <chrono>
 #include <iostream>

 #define GLFW_EXPOSE_NATIVE_EGL
 #define GLFW_INCLUDE_GLEXT

 #include <EGL/egl.h>
 #include <EGL/eglext.h>
 #include <array>
 #include <cstring>
 #include <list>
 #include <unordered_map>
 #include "GLFW/glfw3.h"
 #include "GLFW/glfw3native.h"
 #include "embedder.h"

 // This value is calculated after the window is created.
 static double g_pixelRatio = 1.0;
 static const size_t kInitialWindowWidth = 800;
 static const size_t kInitialWindowHeight = 600;
 // Maximum damage history - for triple buffering we need to store damage for
 // last two frames; Some Android devices (Pixel 4) use quad buffering.
 static const int kMaxHistorySize = 10;
 static constexpr FlutterViewId kImplicitViewId = 0;

 // Keeps track of the most recent frame damages so that existing damage can
 // be easily computed.
 std::list<FlutterRect> damage_history_;

 // Keeps track of the existing damage associated with each FBO ID
 std::unordered_map<intptr_t, FlutterRect*> existing_damage_map_;

 EGLDisplay display_;
 EGLSurface surface_;

 static_assert(FLUTTER_ENGINE_VERSION == 1,
               "This Flutter Embedder was authored against the stable Flutter "
               "API at version 1. There has been a serious breakage in the "
               "API. Please read the ChangeLog and take appropriate action "
               "before updating this assertion");

 void GLFWcursorPositionCallbackAtPhase(GLFWwindow* window,
                                        FlutterPointerPhase phase,
                                        double x,
                                        double y) {
   FlutterPointerEvent event = {};
   event.struct_size = sizeof(event);
   event.phase = phase;
   event.x = x * g_pixelRatio;
   event.y = y * g_pixelRatio;
   event.timestamp =
       std::chrono::duration_cast<std::chrono::microseconds>(
           std::chrono::high_resolution_clock::now().time_since_epoch())
           .count();
   // This example only supports a single window, therefore we assume the pointer
   // event occurred in the only view, the implicit view.
   event.view_id = kImplicitViewId;
   FlutterEngineSendPointerEvent(
       reinterpret_cast<FlutterEngine>(glfwGetWindowUserPointer(window)), &event,
       1);
 }

 void GLFWcursorPositionCallback(GLFWwindow* window, double x, double y) {
   GLFWcursorPositionCallbackAtPhase(window, FlutterPointerPhase::kMove, x, y);
 }

 void GLFWmouseButtonCallback(GLFWwindow* window,
                              int key,
                              int action,
                              int mods) {
   if (key == GLFW_MOUSE_BUTTON_1 && action == GLFW_PRESS) {
     double x, y;
     glfwGetCursorPos(window, &x, &y);
     GLFWcursorPositionCallbackAtPhase(window, FlutterPointerPhase::kDown, x, y);
     glfwSetCursorPosCallback(window, GLFWcursorPositionCallback);
   }

   if (key == GLFW_MOUSE_BUTTON_1 && action == GLFW_RELEASE) {
     double x, y;
     glfwGetCursorPos(window, &x, &y);
     GLFWcursorPositionCallbackAtPhase(window, FlutterPointerPhase::kUp, x, y);
     glfwSetCursorPosCallback(window, nullptr);
   }
 }

 static void GLFWKeyCallback(GLFWwindow* window,
                             int key,
                             int scancode,
                             int action,
                             int mods) {
   if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS) {
     glfwSetWindowShouldClose(window, GLFW_TRUE);
   }
 }

 void GLFWwindowSizeCallback(GLFWwindow* window, int width, int height) {
   FlutterWindowMetricsEvent event = {};
   event.struct_size = sizeof(event);
   event.width = width * g_pixelRatio;
   event.height = height * g_pixelRatio;
   event.pixel_ratio = g_pixelRatio;
   // This example only supports a single window, therefore we assume the event
   // occurred in the only view, the implicit view.
   event.view_id = kImplicitViewId;
   FlutterEngineSendWindowMetricsEvent(
       reinterpret_cast<FlutterEngine>(glfwGetWindowUserPointer(window)),
       &event);
 }

 // Auxiliary function used to transform a FlutterRect into the format that is
 // expected by the EGL functions (i.e. array of EGLint).
 static std::array<EGLint, 4> RectToInts(const FlutterRect rect) {
   EGLint height;
   eglQuerySurface(display_, surface_, EGL_HEIGHT, &height);

   std::array<EGLint, 4> res{
       static_cast<int>(rect.left), height - static_cast<int>(rect.bottom),
       static_cast<int>(rect.right) - static_cast<int>(rect.left),
       static_cast<int>(rect.bottom) - static_cast<int>(rect.top)};
   return res;
 }

 // Auxiliary function to union the damage regions comprised by two FlutterRect
 // element. It saves the result of this join in the rect variable.
 static void JoinFlutterRect(FlutterRect* rect, FlutterRect additional_rect) {
   rect->left = std::min(rect->left, additional_rect.left);
   rect->top = std::min(rect->top, additional_rect.top);
   rect->right = std::max(rect->right, additional_rect.right);
   rect->bottom = std::max(rect->bottom, additional_rect.bottom);
 }

 // Auxiliary function used to check if the given list of extensions contains the
 // requested extension name.
 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);
 }

 bool RunFlutter(GLFWwindow* window,
                 const std::string& project_path,
                 const std::string& icudtl_path) {
   FlutterRendererConfig config = {};
   config.type = kOpenGL;
   config.open_gl.struct_size = sizeof(config.open_gl);
   config.open_gl.make_current = [](void* userdata) -> bool {
     glfwMakeContextCurrent(static_cast<GLFWwindow*>(userdata));
     return true;
   };
   config.open_gl.clear_current = [](void*) -> bool {
     glfwMakeContextCurrent(nullptr);  // is this even a thing?
     return true;
   };
   config.open_gl.present_with_info =
       [](void* userdata, const FlutterPresentInfo* info) -> bool {
     // Free the existing damage that was allocated to this frame.
     if (existing_damage_map_[info->fbo_id] != nullptr) {
       free(existing_damage_map_[info->fbo_id]);
       existing_damage_map_[info->fbo_id] = nullptr;
     }

     // Get list of extensions.
     const char* extensions = eglQueryString(display_, EGL_EXTENSIONS);

     // Retrieve the set damage region function.
     PFNEGLSETDAMAGEREGIONKHRPROC set_damage_region_ = nullptr;
     if (HasExtension(extensions, "EGL_KHR_partial_update")) {
       set_damage_region_ = reinterpret_cast<PFNEGLSETDAMAGEREGIONKHRPROC>(
           eglGetProcAddress("eglSetDamageRegionKHR"));
     }

     // Retrieve the swap buffers with damage function.
     PFNEGLSWAPBUFFERSWITHDAMAGEEXTPROC swap_buffers_with_damage_ = nullptr;
     if (HasExtension(extensions, "EGL_EXT_swap_buffers_with_damage")) {
       swap_buffers_with_damage_ =
           reinterpret_cast<PFNEGLSWAPBUFFERSWITHDAMAGEEXTPROC>(
               eglGetProcAddress("eglSwapBuffersWithDamageEXT"));
     } else if (HasExtension(extensions, "EGL_KHR_swap_buffers_with_damage")) {
       swap_buffers_with_damage_ =
           reinterpret_cast<PFNEGLSWAPBUFFERSWITHDAMAGEEXTPROC>(
               eglGetProcAddress("eglSwapBuffersWithDamageKHR"));
     }

     if (set_damage_region_) {
       // Set the buffer damage as the damage region.
       auto buffer_rects = RectToInts(info->buffer_damage.damage[0]);
       set_damage_region_(display_, surface_, buffer_rects.data(), 1);
     }

     // Add frame damage to damage history
     damage_history_.push_back(info->frame_damage.damage[0]);
     if (damage_history_.size() > kMaxHistorySize) {
       damage_history_.pop_front();
     }

     if (swap_buffers_with_damage_) {
       // Swap buffers with frame damage.
       auto frame_rects = RectToInts(info->frame_damage.damage[0]);
       return swap_buffers_with_damage_(display_, surface_, frame_rects.data(),
                                        1);
     } else {
       // If the required extensions for partial repaint were not provided, do
       // full repaint.
       return eglSwapBuffers(display_, surface_);
     }
   };
   config.open_gl.fbo_callback = [](void*) -> uint32_t {
     return 0;  // FBO0
   };
   config.open_gl.populate_existing_damage =
       [](void* userdata, intptr_t fbo_id,
          FlutterDamage* existing_damage) -> void {
     // Given the FBO age, create existing damage region by joining all frame
     // damages since FBO was last used
     EGLint age;
     if (glfwExtensionSupported("GL_EXT_buffer_age") == GLFW_TRUE) {
       eglQuerySurface(display_, surface_, EGL_BUFFER_AGE_EXT, &age);
     } else {
       age = 4;  // Virtually no driver should have a swapchain length > 4.
     }

     existing_damage->num_rects = 1;

     // Allocate the array of rectangles for the existing damage.
     existing_damage_map_[fbo_id] = static_cast<FlutterRect*>(
         malloc(sizeof(FlutterRect) * existing_damage->num_rects));
     existing_damage_map_[fbo_id][0] =
         FlutterRect{0, 0, kInitialWindowWidth, kInitialWindowHeight};
     existing_damage->damage = existing_damage_map_[fbo_id];

     if (age > 1) {
       --age;
       // join up to (age - 1) last rects from damage history
       for (auto i = damage_history_.rbegin();
            i != damage_history_.rend() && age > 0; ++i, --age) {
         if (i == damage_history_.rbegin()) {
           if (i != damage_history_.rend()) {
             existing_damage->damage[0] = {i->left, i->top, i->right, i->bottom};
           }
         } else {
           JoinFlutterRect(&(existing_damage->damage[0]), *i);
         }
       }
     }
   };
   config.open_gl.gl_proc_resolver = [](void*, const char* name) -> void* {
     return reinterpret_cast<void*>(glfwGetProcAddress(name));
   };
   config.open_gl.fbo_reset_after_present = true;

   // This directory is generated by `flutter build bundle`.
   std::string assets_path = project_path + "/build/flutter_assets";
   FlutterProjectArgs args = {
       .struct_size = sizeof(FlutterProjectArgs),
       .assets_path = assets_path.c_str(),
       .icu_data_path =
           icudtl_path.c_str(),  // Find this in your bin/cache directory.
   };
   FlutterEngine engine = nullptr;
   FlutterEngineResult result =
       FlutterEngineRun(FLUTTER_ENGINE_VERSION, &config,  // renderer
                        &args, window, &engine);
   if (result != kSuccess || engine == nullptr) {
     std::cout << "Could not run the Flutter Engine." << std::endl;
     return false;
   }

   glfwSetWindowUserPointer(window, engine);
   GLFWwindowSizeCallback(window, kInitialWindowWidth, kInitialWindowHeight);

   return true;
 }

 void printUsage() {
   std::cout
       << "usage: embedder_example_drm <path to project> <path to icudtl.dat>"
       << std::endl;
 }

 void GLFW_ErrorCallback(int error, const char* description) {
   std::cout << "GLFW Error: (" << error << ") " << description << std::endl;
 }

 int main(int argc, const char* argv[]) {
   if (argc != 3) {
     printUsage();
     return 1;
   }

   std::string project_path = argv[1];
   std::string icudtl_path = argv[2];

   glfwSetErrorCallback(GLFW_ErrorCallback);

   int result = glfwInit();
   if (result != GLFW_TRUE) {
     std::cout << "Could not initialize GLFW." << std::endl;
     return EXIT_FAILURE;
   }

 #if defined(__linux__)
   glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_EGL_CONTEXT_API);
 #endif

   GLFWwindow* window = glfwCreateWindow(
       kInitialWindowWidth, kInitialWindowHeight, "Flutter", NULL, NULL);
   if (window == nullptr) {
     std::cout << "Could not create GLFW window." << std::endl;
     return EXIT_FAILURE;
   }

   int framebuffer_width, framebuffer_height;
   glfwGetFramebufferSize(window, &framebuffer_width, &framebuffer_height);
   g_pixelRatio = framebuffer_width / kInitialWindowWidth;

   // Get the display and surface variables.
   display_ = glfwGetEGLDisplay();
   surface_ = glfwGetEGLSurface(window);

   bool run_result = RunFlutter(window, project_path, icudtl_path);
   if (!run_result) {
     std::cout << "Could not run the Flutter engine." << std::endl;
     return EXIT_FAILURE;
   }

   glfwSetKeyCallback(window, GLFWKeyCallback);
   glfwSetWindowSizeCallback(window, GLFWwindowSizeCallback);
   glfwSetMouseButtonCallback(window, GLFWmouseButtonCallback);

   while (!glfwWindowShouldClose(window)) {
     glfwWaitEvents();
   }

   glfwDestroyWindow(window);
   glfwTerminate();

   return EXIT_SUCCESS;
 }
	// 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 <cassert>
	#include <chrono>
	#include <iostream>

	#define GLFW_EXPOSE_NATIVE_EGL
	#define GLFW_INCLUDE_GLEXT

	#include <EGL/egl.h>
	#include <EGL/eglext.h>
	#include <array>
	#include <cstring>
	#include <list>
	#include <unordered_map>
	#include "GLFW/glfw3.h"
	#include "GLFW/glfw3native.h"
	#include "embedder.h"

	// This value is calculated after the window is created.
	static double g_pixelRatio = 1.0;
	static const size_t kInitialWindowWidth = 800;
	static const size_t kInitialWindowHeight = 600;
	// Maximum damage history - for triple buffering we need to store damage for
	// last two frames; Some Android devices (Pixel 4) use quad buffering.
	static const int kMaxHistorySize = 10;
	static constexpr FlutterViewId kImplicitViewId = 0;

	// Keeps track of the most recent frame damages so that existing damage can
	// be easily computed.
	std::list<FlutterRect> damage_history_;

	// Keeps track of the existing damage associated with each FBO ID
	std::unordered_map<intptr_t, FlutterRect*> existing_damage_map_;

	EGLDisplay display_;
	EGLSurface surface_;

	static_assert(FLUTTER_ENGINE_VERSION == 1,
	"This Flutter Embedder was authored against the stable Flutter "
	"API at version 1. There has been a serious breakage in the "
	"API. Please read the ChangeLog and take appropriate action "
	"before updating this assertion");

	void GLFWcursorPositionCallbackAtPhase(GLFWwindow* window,
	FlutterPointerPhase phase,
	double x,
	double y) {
	FlutterPointerEvent event = {};
	event.struct_size = sizeof(event);
	event.phase = phase;
	event.x = x * g_pixelRatio;
	event.y = y * g_pixelRatio;
	event.timestamp =
	std::chrono::duration_cast<std::chrono::microseconds>(
	std::chrono::high_resolution_clock::now().time_since_epoch())
	.count();
	// This example only supports a single window, therefore we assume the pointer
	// event occurred in the only view, the implicit view.
	event.view_id = kImplicitViewId;
	FlutterEngineSendPointerEvent(
	reinterpret_cast<FlutterEngine>(glfwGetWindowUserPointer(window)), &event,
	1);
	}

	void GLFWcursorPositionCallback(GLFWwindow* window, double x, double y) {
	GLFWcursorPositionCallbackAtPhase(window, FlutterPointerPhase::kMove, x, y);
	}

	void GLFWmouseButtonCallback(GLFWwindow* window,
	int key,
	int action,
	int mods) {
	if (key == GLFW_MOUSE_BUTTON_1 && action == GLFW_PRESS) {
	double x, y;
	glfwGetCursorPos(window, &x, &y);
	GLFWcursorPositionCallbackAtPhase(window, FlutterPointerPhase::kDown, x, y);
	glfwSetCursorPosCallback(window, GLFWcursorPositionCallback);
	}

	if (key == GLFW_MOUSE_BUTTON_1 && action == GLFW_RELEASE) {
	double x, y;
	glfwGetCursorPos(window, &x, &y);
	GLFWcursorPositionCallbackAtPhase(window, FlutterPointerPhase::kUp, x, y);
	glfwSetCursorPosCallback(window, nullptr);
	}
	}

	static void GLFWKeyCallback(GLFWwindow* window,
	int key,
	int scancode,
	int action,
	int mods) {
	if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS) {
	glfwSetWindowShouldClose(window, GLFW_TRUE);
	}
	}

	void GLFWwindowSizeCallback(GLFWwindow* window, int width, int height) {
	FlutterWindowMetricsEvent event = {};
	event.struct_size = sizeof(event);
	event.width = width * g_pixelRatio;
	event.height = height * g_pixelRatio;
	event.pixel_ratio = g_pixelRatio;
	// This example only supports a single window, therefore we assume the event
	// occurred in the only view, the implicit view.
	event.view_id = kImplicitViewId;
	FlutterEngineSendWindowMetricsEvent(
	reinterpret_cast<FlutterEngine>(glfwGetWindowUserPointer(window)),
	&event);
	}

	// Auxiliary function used to transform a FlutterRect into the format that is
	// expected by the EGL functions (i.e. array of EGLint).
	static std::array<EGLint, 4> RectToInts(const FlutterRect rect) {
	EGLint height;
	eglQuerySurface(display_, surface_, EGL_HEIGHT, &height);

	std::array<EGLint, 4> res{
	static_cast<int>(rect.left), height - static_cast<int>(rect.bottom),
	static_cast<int>(rect.right) - static_cast<int>(rect.left),
	static_cast<int>(rect.bottom) - static_cast<int>(rect.top)};
	return res;
	}

	// Auxiliary function to union the damage regions comprised by two FlutterRect
	// element. It saves the result of this join in the rect variable.
	static void JoinFlutterRect(FlutterRect* rect, FlutterRect additional_rect) {
	rect->left = std::min(rect->left, additional_rect.left);
	rect->top = std::min(rect->top, additional_rect.top);
	rect->right = std::max(rect->right, additional_rect.right);
	rect->bottom = std::max(rect->bottom, additional_rect.bottom);
	}

	// Auxiliary function used to check if the given list of extensions contains the
	// requested extension name.
	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);
	}

	bool RunFlutter(GLFWwindow* window,
	const std::string& project_path,
	const std::string& icudtl_path) {
	FlutterRendererConfig config = {};
	config.type = kOpenGL;
	config.open_gl.struct_size = sizeof(config.open_gl);
	config.open_gl.make_current = [](void* userdata) -> bool {
	glfwMakeContextCurrent(static_cast<GLFWwindow*>(userdata));
	return true;
	};
	config.open_gl.clear_current = [](void*) -> bool {
	glfwMakeContextCurrent(nullptr); // is this even a thing?
	return true;
	};
	config.open_gl.present_with_info =
	[](void* userdata, const FlutterPresentInfo* info) -> bool {
	// Free the existing damage that was allocated to this frame.
	if (existing_damage_map_[info->fbo_id] != nullptr) {
	free(existing_damage_map_[info->fbo_id]);
	existing_damage_map_[info->fbo_id] = nullptr;
	}

	// Get list of extensions.
	const char* extensions = eglQueryString(display_, EGL_EXTENSIONS);

	// Retrieve the set damage region function.
	PFNEGLSETDAMAGEREGIONKHRPROC set_damage_region_ = nullptr;
	if (HasExtension(extensions, "EGL_KHR_partial_update")) {
	set_damage_region_ = reinterpret_cast<PFNEGLSETDAMAGEREGIONKHRPROC>(
	eglGetProcAddress("eglSetDamageRegionKHR"));
	}

	// Retrieve the swap buffers with damage function.
	PFNEGLSWAPBUFFERSWITHDAMAGEEXTPROC swap_buffers_with_damage_ = nullptr;
	if (HasExtension(extensions, "EGL_EXT_swap_buffers_with_damage")) {
	swap_buffers_with_damage_ =
	reinterpret_cast<PFNEGLSWAPBUFFERSWITHDAMAGEEXTPROC>(
	eglGetProcAddress("eglSwapBuffersWithDamageEXT"));
	} else if (HasExtension(extensions, "EGL_KHR_swap_buffers_with_damage")) {
	swap_buffers_with_damage_ =
	reinterpret_cast<PFNEGLSWAPBUFFERSWITHDAMAGEEXTPROC>(
	eglGetProcAddress("eglSwapBuffersWithDamageKHR"));
	}

	if (set_damage_region_) {
	// Set the buffer damage as the damage region.
	auto buffer_rects = RectToInts(info->buffer_damage.damage[0]);
	set_damage_region_(display_, surface_, buffer_rects.data(), 1);
	}

	// Add frame damage to damage history
	damage_history_.push_back(info->frame_damage.damage[0]);
	if (damage_history_.size() > kMaxHistorySize) {
	damage_history_.pop_front();
	}

	if (swap_buffers_with_damage_) {
	// Swap buffers with frame damage.
	auto frame_rects = RectToInts(info->frame_damage.damage[0]);
	return swap_buffers_with_damage_(display_, surface_, frame_rects.data(),
	1);
	} else {
	// If the required extensions for partial repaint were not provided, do
	// full repaint.
	return eglSwapBuffers(display_, surface_);
	}
	};
	config.open_gl.fbo_callback = [](void*) -> uint32_t {
	return 0; // FBO0
	};
	config.open_gl.populate_existing_damage =
	[](void* userdata, intptr_t fbo_id,
	FlutterDamage* existing_damage) -> void {
	// Given the FBO age, create existing damage region by joining all frame
	// damages since FBO was last used
	EGLint age;
	if (glfwExtensionSupported("GL_EXT_buffer_age") == GLFW_TRUE) {
	eglQuerySurface(display_, surface_, EGL_BUFFER_AGE_EXT, &age);
	} else {
	age = 4; // Virtually no driver should have a swapchain length > 4.
	}

	existing_damage->num_rects = 1;

	// Allocate the array of rectangles for the existing damage.
	existing_damage_map_[fbo_id] = static_cast<FlutterRect*>(
	malloc(sizeof(FlutterRect) * existing_damage->num_rects));
	existing_damage_map_[fbo_id][0] =
	FlutterRect{0, 0, kInitialWindowWidth, kInitialWindowHeight};
	existing_damage->damage = existing_damage_map_[fbo_id];

	if (age > 1) {
	--age;
	// join up to (age - 1) last rects from damage history
	for (auto i = damage_history_.rbegin();
	i != damage_history_.rend() && age > 0; ++i, --age) {
	if (i == damage_history_.rbegin()) {
	if (i != damage_history_.rend()) {
	existing_damage->damage[0] = {i->left, i->top, i->right, i->bottom};
	}
	} else {
	JoinFlutterRect(&(existing_damage->damage[0]), *i);
	}
	}
	}
	};
	config.open_gl.gl_proc_resolver = [](void, const char name) -> void* {
	return reinterpret_cast<void*>(glfwGetProcAddress(name));
	};
	config.open_gl.fbo_reset_after_present = true;

	// This directory is generated by `flutter build bundle`.
	std::string assets_path = project_path + "/build/flutter_assets";
	FlutterProjectArgs args = {
	.struct_size = sizeof(FlutterProjectArgs),
	.assets_path = assets_path.c_str(),
	.icu_data_path =
	icudtl_path.c_str(), // Find this in your bin/cache directory.
	};
	FlutterEngine engine = nullptr;
	FlutterEngineResult result =
	FlutterEngineRun(FLUTTER_ENGINE_VERSION, &config, // renderer
	&args, window, &engine);
	if (result != kSuccess \|\| engine == nullptr) {
	std::cout << "Could not run the Flutter Engine." << std::endl;
	return false;
	}

	glfwSetWindowUserPointer(window, engine);
	GLFWwindowSizeCallback(window, kInitialWindowWidth, kInitialWindowHeight);

	return true;
	}

	void printUsage() {
	std::cout
	<< "usage: embedder_example_drm <path to project> <path to icudtl.dat>"
	<< std::endl;
	}

	void GLFW_ErrorCallback(int error, const char* description) {
	std::cout << "GLFW Error: (" << error << ") " << description << std::endl;
	}

	int main(int argc, const char* argv[]) {
	if (argc != 3) {
	printUsage();
	return 1;
	}

	std::string project_path = argv[1];
	std::string icudtl_path = argv[2];

	glfwSetErrorCallback(GLFW_ErrorCallback);

	int result = glfwInit();
	if (result != GLFW_TRUE) {
	std::cout << "Could not initialize GLFW." << std::endl;
	return EXIT_FAILURE;
	}

	#if defined(__linux__)
	glfwWindowHint(GLFW_CONTEXT_CREATION_API, GLFW_EGL_CONTEXT_API);
	#endif

	GLFWwindow* window = glfwCreateWindow(
	kInitialWindowWidth, kInitialWindowHeight, "Flutter", NULL, NULL);
	if (window == nullptr) {
	std::cout << "Could not create GLFW window." << std::endl;
	return EXIT_FAILURE;
	}

	int framebuffer_width, framebuffer_height;
	glfwGetFramebufferSize(window, &framebuffer_width, &framebuffer_height);
	g_pixelRatio = framebuffer_width / kInitialWindowWidth;

	// Get the display and surface variables.
	display_ = glfwGetEGLDisplay();
	surface_ = glfwGetEGLSurface(window);

	bool run_result = RunFlutter(window, project_path, icudtl_path);
	if (!run_result) {
	std::cout << "Could not run the Flutter engine." << std::endl;
	return EXIT_FAILURE;
	}

	glfwSetKeyCallback(window, GLFWKeyCallback);
	glfwSetWindowSizeCallback(window, GLFWwindowSizeCallback);
	glfwSetMouseButtonCallback(window, GLFWmouseButtonCallback);

	while (!glfwWindowShouldClose(window)) {
	glfwWaitEvents();
	}

	glfwDestroyWindow(window);
	glfwTerminate();

	return EXIT_SUCCESS;
	}