Make sure the GLFW example compiles. (#30442)

BUILD.gn

@@ -79,6 +79,11 @@ group("flutter") {
     "//flutter/sky",
   ]
 
+  # Ensure the example for a sample embedder compiles.
+  if (is_mac || is_linux) {
+    public_deps += [ "//flutter/examples/glfw" ]
+  }
+
   # If enbaled, compile the SDK / snapshot.
   if (!is_fuchsia) {
     public_deps += [ "//flutter/lib/snapshot:generate_snapshot_bins" ]

DEPS

@@ -102,7 +102,7 @@ allowed_hosts = [
 ]
 
 deps = {
-  'src': 'https://github.com/flutter/buildroot.git' + '@' + '88c2c61d323e3141849611b2d7fd4ac14103c61f',
+  'src': 'https://github.com/flutter/buildroot.git' + '@' + '4660f4a166979c64ff56f6b856b44ccc1dba5c63',
 
    # Fuchsia compatibility
    #

examples/glfw/BUILD.gn

@@ -0,0 +1,14 @@
+# 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.
+
+executable("glfw") {
+  output_name = "embedder_example"
+
+  sources = [ "FlutterEmbedderGLFW.cc" ]
+
+  deps = [
+    "//flutter/shell/platform/embedder:embedder",
+    "//third_party/glfw",
+  ]
+}

examples/glfw/FlutterEmbedderGLFW.cc

@@ -89,15 +89,15 @@ bool RunFlutter(GLFWwindow* window,
   config.type = kOpenGL;
   config.open_gl.struct_size = sizeof(config.open_gl);
   config.open_gl.make_current = [](void* userdata) -> bool {
-    glfwMakeContextCurrent((GLFWwindow*)userdata);
+    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 = [](void* userdata) -> bool {
-    glfwSwapBuffers((GLFWwindow*)userdata);
+    glfwSwapBuffers(static_cast<GLFWwindow*>(userdata));
     return true;
   };
   config.open_gl.fbo_callback = [](void*) -> uint32_t {
@@ -116,7 +116,10 @@ bool RunFlutter(GLFWwindow* window,
   FlutterEngineResult result =
       FlutterEngineRun(FLUTTER_ENGINE_VERSION, &config,  // renderer
                        &args, window, &engine);
-  assert(result == kSuccess && engine != nullptr);
+  if (result != kSuccess || engine == nullptr) {
+    std::cout << "Could not run the Flutter Engine." << std::endl;
+    return false;
+  }
 
   glfwSetWindowUserPointer(window, engine);
   GLFWwindowSizeCallback(window, kInitialWindowWidth, kInitialWindowHeight);
@@ -125,7 +128,7 @@ bool RunFlutter(GLFWwindow* window,
 }
 
 void printUsage() {
-  std::cout << "usage: flutter_glfw <path to project> <path to icudtl.dat>"
+  std::cout << "usage: embedder_example <path to project> <path to icudtl.dat>"
             << std::endl;
 }
 
@@ -145,25 +148,33 @@ int main(int argc, const char* argv[]) {
   glfwSetErrorCallback(GLFW_ErrorCallback);
 
   int result = glfwInit();
-  assert(result == GLFW_TRUE);
+  if (result != GLFW_TRUE) {
+    std::cout << "Could not initialize GLFW." << std::endl;
+    return EXIT_FAILURE;
+  }
 
   GLFWwindow* window = glfwCreateWindow(
       kInitialWindowWidth, kInitialWindowHeight, "Flutter", NULL, NULL);
-  assert(window != nullptr);
+  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;
 
   bool runResult = RunFlutter(window, project_path, icudtl_path);
-  assert(runResult);
+  if (!runResult) {
+    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)) {
-    std::cout << "Looping..." << std::endl;
     glfwWaitEvents();
   }
 

shell/platform/embedder/BUILD.gn

@@ -24,6 +24,10 @@ shell_gpu_configuration("embedder_gpu_configuration") {
 
 _framework_binary_subpath = "Versions/A/FlutterEmbedder"
 
+config("embedder_header_config") {
+  include_dirs = [ "." ]
+}
+
 # Template for the embedder build. Used to allow building it multiple times with
 # different flags.
 template("embedder_source_set") {
@@ -108,6 +112,7 @@ template("embedder_source_set") {
 
     public_configs += [
       ":embedder_gpu_configuration_config",
+      ":embedder_header_config",
       "//flutter:config",
     ]
   }