sync_replay_project/apps/desktop/windows/runner/flutter_window.cpp

#include "flutter_window.h"

#include <cstdio>
#include <optional>
#include <thread>

#include <flutter/standard_method_codec.h>

#include "flutter/generated_plugin_registrant.h"

namespace {

// Ends the process after |ms| whatever is still running: the app's close
// (lib/src/platform/app_shutdown.dart) is bounded, but a native teardown
// can block for good (media_kit_video's ~VideoOutput waits on a texture
// callback the stopped engine never sends). The process must never stay
// behind a hidden window.
void ExitAfter(DWORD ms) {
  std::thread([ms] {
    ::Sleep(ms);
    fflush(nullptr);
    ::TerminateProcess(::GetCurrentProcess(), 0);
  }).detach();
}

}  // namespace

FlutterWindow::FlutterWindow(const flutter::DartProject& project)
    : project_(project) {}

FlutterWindow::~FlutterWindow() {}

bool FlutterWindow::OnCreate() {
  if (!Win32Window::OnCreate()) {
    return false;
  }

  RECT frame = GetClientArea();

  // The size here must match the window dimensions to avoid unnecessary surface
  // creation / destruction in the startup path.
  flutter_controller_ = std::make_unique<flutter::FlutterViewController>(
      frame.right - frame.left, frame.bottom - frame.top, project_);
  // Ensure that basic setup of the controller was successful.
  if (!flutter_controller_->engine() || !flutter_controller_->view()) {
    return false;
  }
  RegisterPlugins(flutter_controller_->engine());
  window_channel_ = std::make_unique<flutter::MethodChannel<flutter::EncodableValue>>(
      flutter_controller_->engine()->messenger(), "starsync/window",
      &flutter::StandardMethodCodec::GetInstance());
  window_channel_->SetMethodCallHandler(
      [this](const flutter::MethodCall<flutter::EncodableValue>& call,
             std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {
        // A second start that handed its link to the running app ends
        // here, before its window ever shows (no CRT exit, no DLL detach).
        if (call.method_name() == "exit") {
          fflush(nullptr);
          ::TerminateProcess(::GetCurrentProcess(), 0);
          return;
        }
        if (call.method_name() != "attention") {
          result->NotImplemented();
          return;
        }
        HWND hwnd = GetHandle();
        if (hwnd != nullptr && GetForegroundWindow() != hwnd) {
          // Flashes until the window comes to the front.
          FLASHWINFO info{sizeof(FLASHWINFO), hwnd, FLASHW_ALL | FLASHW_TIMERNOFG, 0, 0};
          FlashWindowEx(&info);
        }
        result->Success();
      });
  SetChildContent(flutter_controller_->view()->GetNativeWindow());

  flutter_controller_->engine()->SetNextFrameCallback([&]() {
    this->Show();
  });

  // Flutter can complete the first frame before the "show window" callback is
  // registered. The following call ensures a frame is pending to ensure the
  // window is shown. It is a no-op if the first frame hasn't completed yet.
  flutter_controller_->ForceRedraw();

  return true;
}

void FlutterWindow::OnDestroy() {
  // The engine and the plugins go now; the app released its players first.
  // Win32Window::Create runs this too, before there is an engine: only a
  // real teardown may end the process (else every start dies at 3 s).
  if (flutter_controller_) {
    ExitAfter(3000);
  }
  window_channel_ = nullptr;
  if (flutter_controller_) {
    flutter_controller_ = nullptr;
  }

  Win32Window::OnDestroy();
}

LRESULT
FlutterWindow::MessageHandler(HWND hwnd, UINT const message,
                              WPARAM const wparam,
                              LPARAM const lparam) noexcept {
  // A close request starts the app's close (players, leave), at most a
  // few seconds; past 15 s the process ends anyway.
  if (message == WM_CLOSE && !close_requested_) {
    close_requested_ = true;
    ExitAfter(15000);
  }

  // Give Flutter, including plugins, an opportunity to handle window messages.
  if (flutter_controller_) {
    std::optional<LRESULT> result =
        flutter_controller_->HandleTopLevelWindowProc(hwnd, message, wparam,
                                                      lparam);
    if (result) {
      return *result;
    }
  }

  switch (message) {
    case WM_FONTCHANGE:
      flutter_controller_->engine()->ReloadSystemFonts();
      break;
  }

  return Win32Window::MessageHandler(hwnd, message, wparam, lparam);
}