Add usage docs and simple argument parsing.

Author: chinmaygarde

src/flutter_application.cc

@@ -6,41 +6,19 @@
 
 #include <EGL/egl.h>
 #include <sys/types.h>
-#include <unistd.h>
 
 #include <chrono>
 #include <sstream>
 #include <vector>
 
+#include "utils.h"
+
 namespace flutter {
 
 static_assert(FLUTTER_ENGINE_VERSION == 1, "");
 
 static const char* kICUDataFileName = "icudtl.dat";
 
-static std::string GetExecutableDirectory() {
-  char executable_path[1024] = {0};
-  std::stringstream stream;
-  stream << "/proc/" << getpid() << "/exe";
-  auto path = stream.str();
-  auto executable_path_size =
-      ::readlink(path.c_str(), executable_path, sizeof(executable_path));
-  if (executable_path_size <= 0) {
-    return "";
-  }
-
-  auto path_string =
-      std::string{executable_path, static_cast<size_t>(executable_path_size)};
-
-  auto found = path_string.find_last_of('/');
-
-  if (found == std::string::npos) {
-    return "";
-  }
-
-  return path_string.substr(0, found + 1);
-}
-
 static std::string GetICUDataPath() {
   auto exe_dir = GetExecutableDirectory();
   if (exe_dir == "") {
@@ -51,7 +29,7 @@ static std::string GetICUDataPath() {
 
   auto icu_path = stream.str();
 
-  if (::access(icu_path.c_str(), R_OK) != 0) {
+  if (!FileExistsAtPath(icu_path.c_str())) {
     FLWAY_ERROR << "Could not find " << icu_path << std::endl;
     return "";
   }
@@ -60,9 +38,15 @@ static std::string GetICUDataPath() {
 }
 
 FlutterApplication::FlutterApplication(
+    std::string bundle_path,
     const std::vector<std::string>& command_line_args,
     RenderDelegate& render_delegate)
     : render_delegate_(render_delegate) {
+  if (!FlutterAssetBundleIsValid(bundle_path)) {
+    FLWAY_ERROR << "Flutter asset bundle was not valid." << std::endl;
+    return;
+  }
+
   FlutterRendererConfig config = {};
   config.type = kOpenGL;
   config.open_gl.struct_size = sizeof(config.open_gl);
@@ -92,11 +76,6 @@ FlutterApplication::FlutterApplication(
     return nullptr;
   };
 
-// TODO: Pipe this in through command line args.
-#define MY_PROJECT                                                          \
-  "/usr/local/google/home/chinmaygarde/VersionControlled/flutter/examples/" \
-  "flutter_gallery/build/flutter_assets"
-
   auto icu_data_path = GetICUDataPath();
 
   if (icu_data_path == "") {
@@ -114,7 +93,7 @@ FlutterApplication::FlutterApplication(
 
   FlutterProjectArgs args = {
       .struct_size = sizeof(FlutterProjectArgs),
-      .assets_path = MY_PROJECT,
+      .assets_path = bundle_path.c_str(),
       .main_path = "",
       .packages_path = "",
       .icu_data_path = icu_data_path.c_str(),

src/flutter_application.h

@@ -26,7 +26,8 @@ class FlutterApplication {
     virtual uint32_t OnApplicationGetOnscreenFBO() = 0;
   };
 
-  FlutterApplication(const std::vector<std::string>& args,
+  FlutterApplication(std::string bundle_path,
+                     const std::vector<std::string>& args,
                      RenderDelegate& render_delegate);
 
   ~FlutterApplication();

src/main.cc

@@ -8,22 +8,68 @@
 #include <vector>
 
 #include "flutter_application.h"
+#include "utils.h"
 #include "wayland_display.h"
 
 namespace flutter {
 
-bool Main(std::vector<std::string> args) {
+static void PrintUsage() {
+  std::cerr << "Flutter Wayland Embedder" << std::endl << std::endl;
+  std::cerr << "========================" << std::endl;
+  std::cerr << "Usage: `" << GetExecutableName()
+            << " <asset_bundle_path> <flutter_flags>`" << std::endl
+            << std::endl;
+  std::cerr << R"~(
+This utility runs an instance of a Flutter application and renders using
+Wayland core protocols.
+
+The Flutter tools can be obtained at https://flutter.io/
+
+asset_bundle_path: The Flutter application code needs to be snapshotted using
+                   the Flutter tools and the assets packaged in the appropriate
+                   location. This can be done for any Flutter application by
+                   running `flutter build bundle` while in the directory of a
+                   valid Flutter project. This should package all the code and
+                   assets in the "build/flutter_assets" directory. Specify this
+                   directory as the first argument to this utility.
+
+    flutter_flags: Typically empty. These extra flags are passed directly to the
+                   Flutter engine. To see all supported flags, run
+                   `flutter_tester --help` using the test binary included in the
+                   Flutter tools.
+)~" << std::endl;
+}
+
+static bool Main(std::vector<std::string> args) {
+  if (args.size() == 0) {
+    std::cerr << "   <Invalid Arguments>   " << std::endl;
+    PrintUsage();
+    return false;
+  }
+
+  const auto asset_bundle_path = args[0];
+
+  if (!FlutterAssetBundleIsValid(asset_bundle_path)) {
+    std::cerr << "   <Invalid Flutter Asset Bundle>   " << std::endl;
+    PrintUsage();
+    return false;
+  }
+
   const size_t kWidth = 800;
   const size_t kHeight = 600;
 
+  for (const auto& arg : args) {
+    FLWAY_ERROR << "Arg: " << arg << std::endl;
+  }
+
   WaylandDisplay display(kWidth, kHeight);
 
   if (!display.IsValid()) {
     FLWAY_ERROR << "Wayland display was not valid." << std::endl;
     return false;
   }
 
-  FlutterApplication application(args, display);
+  FlutterApplication application(asset_bundle_path, args, display);
   if (!application.IsValid()) {
     FLWAY_ERROR << "Flutter application was not valid." << std::endl;
     return false;
@@ -43,7 +89,7 @@ bool Main(std::vector<std::string> args) {
 
 int main(int argc, char* argv[]) {
   std::vector<std::string> args;
-  for (int i = 0; i < argc; ++i) {
+  for (int i = 1; i < argc; ++i) {
     args.push_back(argv[i]);
   }
   return flutter::Main(std::move(args)) ? EXIT_SUCCESS : EXIT_FAILURE;

src/utils.cc

@@ -0,0 +1,63 @@
+// Copyright 2018 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 "utils.h"
+
+#include <unistd.h>
+
+#include <sstream>
+
+namespace flutter {
+
+static std::string GetExecutablePath() {
+  char executable_path[1024] = {0};
+  std::stringstream stream;
+  stream << "/proc/" << getpid() << "/exe";
+  auto path = stream.str();
+  auto executable_path_size =
+      ::readlink(path.c_str(), executable_path, sizeof(executable_path));
+  if (executable_path_size <= 0) {
+    return "";
+  }
+  return std::string{executable_path,
+                     static_cast<size_t>(executable_path_size)};
+}
+
+std::string GetExecutableName() {
+  auto path_string = GetExecutablePath();
+  auto found = path_string.find_last_of('/');
+  if (found == std::string::npos) {
+    return "";
+  }
+  return path_string.substr(found + 1);
+}
+
+std::string GetExecutableDirectory() {
+  auto path_string = GetExecutablePath();
+  auto found = path_string.find_last_of('/');
+  if (found == std::string::npos) {
+    return "";
+  }
+  return path_string.substr(0, found + 1);
+}
+
+bool FileExistsAtPath(const std::string& path) {
+  return ::access(path.c_str(), R_OK) == 0;
+}
+
+bool FlutterAssetBundleIsValid(const std::string& bundle_path) {
+  if (!FileExistsAtPath(bundle_path)) {
+    FLWAY_ERROR << "Bundle directory does not exist." << std::endl;
+    return false;
+  }
+
+  if (!FileExistsAtPath(bundle_path + std::string{"/kernel_blob.bin"})) {
+    FLWAY_ERROR << "Kernel blob does not exist." << std::endl;
+    return false;
+  }
+
+  return true;
+}
+
+}  // namespace flutter

src/utils.h

@@ -0,0 +1,19 @@
+// Copyright 2018 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.
+
+#pragma once
+
+#include "macros.h"
+
+namespace flutter {
+
+std::string GetExecutableName();
+
+std::string GetExecutableDirectory();
+
+bool FileExistsAtPath(const std::string& path);
+
+bool FlutterAssetBundleIsValid(const std::string& bundle_path);
+
+}  // namespace flutter

src/wayland_display.cc

@@ -144,7 +144,6 @@ bool WaylandDisplay::Run() {
   }
 
   while (valid_) {
-    FLWAY_LOG << "Dispatching." << std::endl;
     wl_display_dispatch(display_);
   }
 
@@ -330,8 +329,6 @@ void WaylandDisplay::AnnounceRegistryInterface(struct wl_registry* wl_registry,
         wl_registry_bind(wl_registry, name, &wl_shell_interface, 1));
     return;
   }
-
-  FLWAY_LOG << "Unhandled Announce of: " << interface_name << std::endl;
 }
 
 void WaylandDisplay::UnannounceRegistryInterface(