Add initial settings message to Windows embedding (flutter/engine#22323)

Sends the flutter/settings update message to the engine after starting
it. For now values other than 24-hour time preference are hard-coded,
but dark mode support can be added later.

Fixes https://github.com/flutter/flutter/issues/65590

engine/src/flutter/shell/platform/embedder/test_utils/proc_table_replacement.h

@@ -8,7 +8,9 @@
 // FlutterEngineProcTable entries (by using statics) to facilitate mocking in
 // tests of code built on top of the embedder API.
 //
-// This should *ONLY* be used in unit tests as it is leaky by design.
+// This should *ONLY* be used in unit tests as it is leaky by design. Because it
+// uses statics for the lambdas, tests using this macro are generally not safe
+// to run multiple times (e.g., using gtest_repeat).
 //
 // |proc| should be the name of an entry in FlutterEngineProcTable, such as
 // "initialize". |mock_impl| should be a lamba that replaces its implementation,

engine/src/flutter/shell/platform/windows/flutter_windows_engine.cc

@@ -8,10 +8,14 @@
 #include <iostream>
 #include <sstream>
 
+#include "flutter/shell/platform/common/cpp/client_wrapper/binary_messenger_impl.h"
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/basic_message_channel.h"
+#include "flutter/shell/platform/common/cpp/json_message_codec.h"
 #include "flutter/shell/platform/common/cpp/path_utils.h"
 #include "flutter/shell/platform/windows/flutter_windows_view.h"
 #include "flutter/shell/platform/windows/string_conversion.h"
 #include "flutter/shell/platform/windows/system_utils.h"
+#include "third_party/rapidjson/include/rapidjson/document.h"
 
 namespace flutter {
 
@@ -114,10 +118,19 @@ FlutterWindowsEngine::FlutterWindowsEngine(const FlutterProjectBundle& project)
   plugin_registrar_ = std::make_unique<FlutterDesktopPluginRegistrar>();
   plugin_registrar_->engine = this;
 
+  messenger_wrapper_ = std::make_unique<BinaryMessengerImpl>(messenger_.get());
   message_dispatcher_ =
       std::make_unique<IncomingMessageDispatcher>(messenger_.get());
   window_proc_delegate_manager_ =
       std::make_unique<Win32WindowProcDelegateManager>();
+
+  // Set up internal channels.
+  // TODO: Replace this with an embedder.h API. See
+  // https://github.com/flutter/flutter/issues/71099
+  settings_channel_ =
+      std::make_unique<BasicMessageChannel<rapidjson::Document>>(
+          messenger_wrapper_.get(), "flutter/settings",
+          &JsonMessageCodec::GetInstance());
 }
 
 FlutterWindowsEngine::~FlutterWindowsEngine() {
@@ -327,7 +340,15 @@ void FlutterWindowsEngine::SendSystemSettings() {
   embedder_api_.UpdateLocales(engine_, flutter_locale_list.data(),
                               flutter_locale_list.size());
 
-  // TODO: Send 'flutter/settings' channel settings here as well.
+  rapidjson::Document settings(rapidjson::kObjectType);
+  auto& allocator = settings.GetAllocator();
+  settings.AddMember("alwaysUse24HourFormat",
+                     Prefer24HourTime(GetUserTimeFormat()), allocator);
+  settings.AddMember("textScaleFactor", 1.0, allocator);
+  // TODO: Implement dark mode support.
+  // https://github.com/flutter/flutter/issues/54612
+  settings.AddMember("platformBrightness", "light", allocator);
+  settings_channel_->Send(settings);
 }
 
 }  // namespace flutter

engine/src/flutter/shell/platform/windows/flutter_windows_engine.h

@@ -10,6 +10,8 @@
 #include <optional>
 #include <vector>
 
+#include "flutter/shell/platform/common/cpp/client_wrapper/binary_messenger_impl.h"
+#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/basic_message_channel.h"
 #include "flutter/shell/platform/common/cpp/incoming_message_dispatcher.h"
 #include "flutter/shell/platform/embedder/embedder.h"
 #include "flutter/shell/platform/windows/flutter_project_bundle.h"
@@ -17,6 +19,7 @@
 #include "flutter/shell/platform/windows/win32_task_runner.h"
 #include "flutter/shell/platform/windows/win32_window_proc_delegate_manager.h"
 #include "flutter/shell/platform/windows/window_state.h"
+#include "third_party/rapidjson/include/rapidjson/document.h"
 
 namespace flutter {
 
@@ -134,16 +137,22 @@ class FlutterWindowsEngine {
   // The plugin messenger handle given to API clients.
   std::unique_ptr<FlutterDesktopMessenger> messenger_;
 
+  // A wrapper around messenger_ for interacting with client_wrapper-level APIs.
+  std::unique_ptr<BinaryMessengerImpl> messenger_wrapper_;
+
   // Message dispatch manager for messages from engine_.
   std::unique_ptr<IncomingMessageDispatcher> message_dispatcher_;
 
   // The plugin registrar handle given to API clients.
   std::unique_ptr<FlutterDesktopPluginRegistrar> plugin_registrar_;
 
+  // The MethodChannel used for communication with the Flutter engine.
+  std::unique_ptr<BasicMessageChannel<rapidjson::Document>> settings_channel_;
+
   // A callback to be called when the engine (and thus the plugin registrar)
   // is being destroyed.
   FlutterDesktopOnPluginRegistrarDestroyed
-      plugin_registrar_destruction_callback_;
+      plugin_registrar_destruction_callback_ = nullptr;
 
   // The manager for WindowProc delegate registration and callbacks.
   std::unique_ptr<Win32WindowProcDelegateManager> window_proc_delegate_manager_;

engine/src/flutter/shell/platform/windows/flutter_windows_engine_unittests.cc

@@ -20,10 +20,81 @@ std::unique_ptr<FlutterWindowsEngine> GetTestEngine() {
   properties.icu_data_path = L"C:\\foo\\icudtl.dat";
   properties.aot_library_path = L"C:\\foo\\aot.so";
   FlutterProjectBundle project(properties);
-  return std::make_unique<FlutterWindowsEngine>(project);
+  auto engine = std::make_unique<FlutterWindowsEngine>(project);
+
+  EngineEmbedderApiModifier modifier(engine.get());
+  // Force the non-AOT path unless overridden by the test.
+  modifier.embedder_api().RunsAOTCompiledDartCode = []() { return false; };
+
+  return engine;
 }
 }  // namespace
 
+TEST(FlutterWindowsEngine, RunDoesExpectedInitialization) {
+  std::unique_ptr<FlutterWindowsEngine> engine = GetTestEngine();
+  EngineEmbedderApiModifier modifier(engine.get());
+
+  // The engine should be run with expected configuration values.
+  bool run_called = false;
+  modifier.embedder_api().Run = MOCK_ENGINE_PROC(
+      Run, ([&run_called, engine_instance = engine.get()](
+                size_t version, const FlutterRendererConfig* config,
+                const FlutterProjectArgs* args, void* user_data,
+                FLUTTER_API_SYMBOL(FlutterEngine) * engine_out) {
+        run_called = true;
+        *engine_out = reinterpret_cast<FLUTTER_API_SYMBOL(FlutterEngine)>(1);
+
+        EXPECT_EQ(version, FLUTTER_ENGINE_VERSION);
+        EXPECT_NE(config, nullptr);
+        EXPECT_EQ(user_data, engine_instance);
+        // Spot-check arguments.
+        EXPECT_STREQ(args->assets_path, "C:\\foo\\flutter_assets");
+        EXPECT_STREQ(args->icu_data_path, "C:\\foo\\icudtl.dat");
+        EXPECT_EQ(args->dart_entrypoint_argc, 0);
+        EXPECT_NE(args->platform_message_callback, nullptr);
+        EXPECT_NE(args->custom_task_runners, nullptr);
+        EXPECT_EQ(args->custom_dart_entrypoint, nullptr);
+
+        return kSuccess;
+      }));
+
+  // It should send locale info.
+  bool update_locales_called = false;
+  modifier.embedder_api().UpdateLocales = MOCK_ENGINE_PROC(
+      UpdateLocales,
+      ([&update_locales_called](auto engine, const FlutterLocale** locales,
+                                size_t locales_count) {
+        update_locales_called = true;
+
+        EXPECT_GT(locales_count, 0);
+        EXPECT_NE(locales, nullptr);
+
+        return kSuccess;
+      }));
+
+  // And it should send initial settings info.
+  bool settings_message_sent = false;
+  modifier.embedder_api().SendPlatformMessage = MOCK_ENGINE_PROC(
+      SendPlatformMessage,
+      ([&settings_message_sent](auto engine, auto message) {
+        if (std::string(message->channel) == std::string("flutter/settings")) {
+          settings_message_sent = true;
+        }
+
+        return kSuccess;
+      }));
+
+  engine->RunWithEntrypoint(nullptr);
+
+  EXPECT_TRUE(run_called);
+  EXPECT_TRUE(update_locales_called);
+  EXPECT_TRUE(settings_message_sent);
+
+  // Ensure that deallocation doesn't call the actual Shutdown with the bogus
+  // engine pointer that the overridden Run returned.
+  modifier.embedder_api().Shutdown = [](auto engine) { return kSuccess; };
+}
+
 TEST(FlutterWindowsEngine, SendPlatformMessageWithoutResponse) {
   std::unique_ptr<FlutterWindowsEngine> engine = GetTestEngine();
   EngineEmbedderApiModifier modifier(engine.get());

engine/src/flutter/shell/platform/windows/system_utils.h

@@ -31,6 +31,12 @@ std::vector<std::wstring> GetPreferredLanguages();
 // Parses a Windows language name into its components.
 LanguageInfo ParseLanguageName(std::wstring language_name);
 
+// Returns the user's system time format string.
+std::wstring GetUserTimeFormat();
+
+// Returns true if the time_format is set to use 24 hour time.
+bool Prefer24HourTime(std::wstring time_format);
+
 }  // namespace flutter
 
 #endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_SYSTEM_UTILS_H_

engine/src/flutter/shell/platform/windows/system_utils_unittests.cc

@@ -71,5 +71,22 @@ TEST(SystemUtils, ParseLanguageNameWithThreeCharacterLanguage) {
   EXPECT_TRUE(info.script.empty());
 }
 
+TEST(SystemUtils, GetUserTimeFormat) {
+  // The value varies based on machine; just ensure that something is returned.
+  EXPECT_FALSE(GetUserTimeFormat().empty());
+}
+
+TEST(SystemUtils, Prefer24HourTimeHandlesEmptyFormat) {
+  EXPECT_FALSE(Prefer24HourTime(L""));
+}
+
+TEST(SystemUtils, Prefer24HourTimeHandles12Hour) {
+  EXPECT_FALSE(Prefer24HourTime(L"h:mm:ss tt"));
+}
+
+TEST(SystemUtils, Prefer24HourTimeHandles24Hour) {
+  EXPECT_TRUE(Prefer24HourTime(L"HH:mm:ss"));
+}
+
 }  // namespace testing
 }  // namespace flutter

engine/src/flutter/shell/platform/windows/system_utils_win32.cc

@@ -90,4 +90,20 @@ LanguageInfo ParseLanguageName(std::wstring language_name) {
   return info;
 }
 
+std::wstring GetUserTimeFormat() {
+  // Rather than do the call-allocate-call-free dance, just use a sufficiently
+  // large buffer to handle any reasonable time format string.
+  const int kBufferSize = 100;
+  wchar_t buffer[kBufferSize];
+  if (::GetLocaleInfoEx(LOCALE_NAME_USER_DEFAULT, LOCALE_STIMEFORMAT, buffer,
+                        kBufferSize) == 0) {
+    return std::wstring();
+  }
+  return std::wstring(buffer, kBufferSize);
+}
+
+bool Prefer24HourTime(std::wstring time_format) {
+  return time_format.find(L"H") != std::wstring::npos;
+}
+
 }  // namespace flutter

engine/src/flutter/testing/run_tests.py

@@ -97,8 +97,11 @@ def RunEngineExecutable(build_dir, executable_name, filter, flags=[], cwd=buildr
 def RunCCTests(build_dir, filter):
   print("Running Engine Unit-tests.")
 
-  shuffle_flags = [
+  # Not all of the engine unit tests are designed to be run more than once.
+  non_repeatable_shuffle_flags = [
     "--gtest_shuffle",
+  ]
+  shuffle_flags = non_repeatable_shuffle_flags + [
     "--gtest_repeat=2",
   ]
 
@@ -115,7 +118,7 @@ def RunCCTests(build_dir, filter):
     RunEngineExecutable(build_dir, 'embedder_unittests', filter, shuffle_flags)
     RunEngineExecutable(build_dir, 'embedder_proctable_unittests', filter, shuffle_flags)
   else:
-    RunEngineExecutable(build_dir, 'flutter_windows_unittests', filter, shuffle_flags)
+    RunEngineExecutable(build_dir, 'flutter_windows_unittests', filter, non_repeatable_shuffle_flags)
 
     RunEngineExecutable(build_dir, 'client_wrapper_windows_unittests', filter, shuffle_flags)
 
@@ -150,14 +153,14 @@ def RunCCTests(build_dir, filter):
   # These unit-tests are Objective-C and can only run on Darwin.
   if IsMac():
     RunEngineExecutable(build_dir, 'flutter_channels_unittests', filter, shuffle_flags)
-    RunEngineExecutable(build_dir, 'flutter_desktop_darwin_unittests', filter, shuffle_flags)
+    RunEngineExecutable(build_dir, 'flutter_desktop_darwin_unittests', filter, non_repeatable_shuffle_flags)
 
   # https://github.com/flutter/flutter/issues/36296
   if IsLinux():
     RunEngineExecutable(build_dir, 'txt_unittests', filter, shuffle_flags)
 
   if IsLinux():
-    RunEngineExecutable(build_dir, 'flutter_linux_unittests', filter, shuffle_flags)
+    RunEngineExecutable(build_dir, 'flutter_linux_unittests', filter, non_repeatable_shuffle_flags)
 
 
 def RunEngineBenchmarks(build_dir, filter):