sync_replay_project/apps/desktop/linux/runner/my_application.cc

#include "my_application.h"

#include <stdio.h>
#include <unistd.h>

#include <flutter_linux/flutter_linux.h>
#ifdef GDK_WINDOWING_X11
#include <gdk/gdkx.h>
#endif
#ifdef GDK_WINDOWING_WAYLAND
#include <gdk/gdkwayland.h>
#endif

#include "flutter/generated_plugin_registrant.h"

struct _MyApplication {
  GtkApplication parent_instance;
  char** dart_entrypoint_arguments;
  // "starsync/window" (lib/src/platform/attention.dart).
  FlMethodChannel* window_channel;
};

G_DEFINE_TYPE(MyApplication, my_application, GTK_TYPE_APPLICATION)

// Called when first Flutter frame received.
static void first_frame_cb(MyApplication* self, FlView* view) {
  gtk_widget_show(gtk_widget_get_toplevel(GTK_WIDGET(view)));
}

// The desktop's activation token this process was started with
// (XDG_ACTIVATION_TOKEN on Wayland, DESKTOP_STARTUP_ID on X11), read
// before GTK starts and consumes it. A second start hands it to the
// running app (lib/src/platform/single_instance.dart), which brings its
// window up with it: compositors only let a window take the focus with
// a fresh token.
static gchar* launch_token = nullptr;

// Brings the window up with an activation token from another process.
static void present_with_token(GtkWindow* window, const gchar* token) {
  if (token != nullptr && token[0] != '\0') {
    GdkDisplay* display = gtk_widget_get_display(GTK_WIDGET(window));
#ifdef GDK_WINDOWING_WAYLAND
    if (GDK_IS_WAYLAND_DISPLAY(display)) {
      gdk_wayland_display_set_startup_notification_id(display, token);
    }
#endif
#ifdef GDK_WINDOWING_X11
    if (GDK_IS_X11_DISPLAY(display)) {
      gtk_window_set_startup_id(window, token);
    }
#endif
  }
  gtk_window_present(window);
}

// "starsync/window": `attention` sets the urgency hint while the window is
// not focused (focusing it clears the hint); `launchToken` is this
// process's activation token ('' when none); `present` brings the window
// up with a token (argument, may be empty); `exit` ends a second start
// that handed over (no exit handlers, see main.cc).
static void window_method_cb(FlMethodChannel* channel, FlMethodCall* call,
                             gpointer user_data) {
  GtkWindow* window = GTK_WINDOW(user_data);
  g_autoptr(FlMethodResponse) response = nullptr;
  const gchar* method = fl_method_call_get_name(call);
  if (g_strcmp0(method, "attention") == 0) {
    if (!gtk_window_is_active(window)) {
      gtk_window_set_urgency_hint(window, TRUE);
    }
    response = FL_METHOD_RESPONSE(fl_method_success_response_new(nullptr));
  } else if (g_strcmp0(method, "launchToken") == 0) {
    g_autoptr(FlValue) value =
        fl_value_new_string(launch_token != nullptr ? launch_token : "");
    response = FL_METHOD_RESPONSE(fl_method_success_response_new(value));
  } else if (g_strcmp0(method, "present") == 0) {
    FlValue* args = fl_method_call_get_args(call);
    const gchar* token = nullptr;
    if (args != nullptr && fl_value_get_type(args) == FL_VALUE_TYPE_STRING) {
      token = fl_value_get_string(args);
    }
    present_with_token(window, token);
    response = FL_METHOD_RESPONSE(fl_method_success_response_new(nullptr));
  } else if (g_strcmp0(method, "exit") == 0) {
    fflush(stdout);
    fflush(stderr);
    _exit(0);
  } else {
    response = FL_METHOD_RESPONSE(fl_method_not_implemented_response_new());
  }
  fl_method_call_respond(call, response, nullptr);
}

// Ends the process 15 s after the first close request whatever is still
// running: the app's close (lib/src/platform/app_shutdown.dart) is bounded
// to a few seconds, but a native teardown can block for good, and the
// process must never stay behind a hidden window.
static gpointer exit_watchdog(gpointer data) {
  g_usleep(15 * G_USEC_PER_SEC);
  fflush(stdout);
  fflush(stderr);
  _exit(0);
  return nullptr;
}

static gboolean window_delete_cb(GtkWidget* widget, GdkEvent* event,
                                 gpointer user_data) {
  static gboolean armed = FALSE;
  if (!armed) {
    armed = TRUE;
    g_thread_unref(g_thread_new("exit-watchdog", exit_watchdog, nullptr));
  }
  return FALSE;  // window_manager decides whether the window closes
}

static gboolean window_focus_in_cb(GtkWidget* widget, GdkEvent* event,
                                   gpointer user_data) {
  gtk_window_set_urgency_hint(GTK_WINDOW(widget), FALSE);
  return FALSE;
}

// Implements GApplication::activate.
static void my_application_activate(GApplication* application) {
  MyApplication* self = MY_APPLICATION(application);
  GtkWindow* window =
      GTK_WINDOW(gtk_application_window_new(GTK_APPLICATION(application)));

  // Use a header bar when running in GNOME as this is the common style used
  // by applications and is the setup most users will be using (e.g. Ubuntu
  // desktop).
  // If running on X and not using GNOME then just use a traditional title bar
  // in case the window manager does more exotic layout, e.g. tiling.
  // If running on Wayland assume the header bar will work (may need changing
  // if future cases occur).
  gboolean use_header_bar = TRUE;
#ifdef GDK_WINDOWING_X11
  GdkScreen* screen = gtk_window_get_screen(window);
  if (GDK_IS_X11_SCREEN(screen)) {
    const gchar* wm_name = gdk_x11_screen_get_window_manager_name(screen);
    if (g_strcmp0(wm_name, "GNOME Shell") != 0) {
      use_header_bar = FALSE;
    }
  }
#endif
  if (use_header_bar) {
    GtkHeaderBar* header_bar = GTK_HEADER_BAR(gtk_header_bar_new());
    gtk_widget_show(GTK_WIDGET(header_bar));
    gtk_header_bar_set_title(header_bar, "Starsync");
    gtk_header_bar_set_show_close_button(header_bar, TRUE);
    gtk_window_set_titlebar(window, GTK_WIDGET(header_bar));
  } else {
    gtk_window_set_title(window, "Starsync");
  }

  gtk_window_set_default_size(window, 1280, 720);

  // The window icon (X11; Wayland takes it from the .desktop file the app
  // installs for its application id).
  {
    g_autofree gchar* exe = g_file_read_link("/proc/self/exe", nullptr);
    if (exe != nullptr) {
      g_autofree gchar* dir = g_path_get_dirname(exe);
      g_autofree gchar* icon = g_build_filename(
          dir, "data", "flutter_assets", "assets", "icon", "icon_256.png",
          nullptr);
      gtk_window_set_icon_from_file(window, icon, nullptr);
    }
  }

  g_autoptr(FlDartProject) project = fl_dart_project_new();
  fl_dart_project_set_dart_entrypoint_arguments(
      project, self->dart_entrypoint_arguments);

  FlView* view = fl_view_new(project);
  GdkRGBA background_color;
  // Background defaults to black, override it here if necessary, e.g. #00000000
  // for transparent.
  gdk_rgba_parse(&background_color, "#000000");
  fl_view_set_background_color(view, &background_color);
  gtk_widget_show(GTK_WIDGET(view));
  gtk_container_add(GTK_CONTAINER(window), GTK_WIDGET(view));

  // Show the window when Flutter renders.
  // Requires the view to be realized so we can start rendering.
  g_signal_connect_swapped(view, "first-frame", G_CALLBACK(first_frame_cb),
                           self);
  gtk_widget_realize(GTK_WIDGET(view));

  // Before the plugins: window_manager's delete-event handler stops the
  // emission while the app holds the close.
  g_signal_connect(window, "delete-event", G_CALLBACK(window_delete_cb),
                   nullptr);
  fl_register_plugins(FL_PLUGIN_REGISTRY(view));

  g_autoptr(FlStandardMethodCodec) codec = fl_standard_method_codec_new();
  self->window_channel = fl_method_channel_new(
      fl_engine_get_binary_messenger(fl_view_get_engine(view)),
      "starsync/window", FL_METHOD_CODEC(codec));
  fl_method_channel_set_method_call_handler(self->window_channel,
                                            window_method_cb, window, nullptr);
  g_signal_connect(window, "focus-in-event", G_CALLBACK(window_focus_in_cb),
                   nullptr);

  gtk_widget_grab_focus(GTK_WIDGET(view));
}

// Implements GApplication::local_command_line.
static gboolean my_application_local_command_line(GApplication* application,
                                                  gchar*** arguments,
                                                  int* exit_status) {
  MyApplication* self = MY_APPLICATION(application);
  // Strip out the first argument as it is the binary name.
  self->dart_entrypoint_arguments = g_strdupv(*arguments + 1);

  g_autoptr(GError) error = nullptr;
  if (!g_application_register(application, nullptr, &error)) {
    g_warning("Failed to register: %s", error->message);
    *exit_status = 1;
    return TRUE;
  }

  g_application_activate(application);
  *exit_status = 0;

  return TRUE;
}

// Implements GApplication::startup.
static void my_application_startup(GApplication* application) {
  // MyApplication* self = MY_APPLICATION(object);

  // Perform any actions required at application startup.

  G_APPLICATION_CLASS(my_application_parent_class)->startup(application);
}

// Implements GApplication::shutdown.
static void my_application_shutdown(GApplication* application) {
  // MyApplication* self = MY_APPLICATION(object);

  // Perform any actions required at application shutdown.

  G_APPLICATION_CLASS(my_application_parent_class)->shutdown(application);
}

// Implements GObject::dispose.
static void my_application_dispose(GObject* object) {
  MyApplication* self = MY_APPLICATION(object);
  g_clear_pointer(&self->dart_entrypoint_arguments, g_strfreev);
  g_clear_object(&self->window_channel);
  G_OBJECT_CLASS(my_application_parent_class)->dispose(object);
}

static void my_application_class_init(MyApplicationClass* klass) {
  G_APPLICATION_CLASS(klass)->activate = my_application_activate;
  G_APPLICATION_CLASS(klass)->local_command_line =
      my_application_local_command_line;
  G_APPLICATION_CLASS(klass)->startup = my_application_startup;
  G_APPLICATION_CLASS(klass)->shutdown = my_application_shutdown;
  G_OBJECT_CLASS(klass)->dispose = my_application_dispose;
}

static void my_application_init(MyApplication* self) {}

MyApplication* my_application_new() {
  // Set the program name to the application ID, which helps various systems
  // like GTK and desktop environments map this running application to its
  // corresponding .desktop file. This ensures better integration by allowing
  // the application to be recognized beyond its binary name.
  g_set_prgname(APPLICATION_ID);

  // Before GTK starts (it takes these out of the environment).
  const gchar* token = g_getenv("XDG_ACTIVATION_TOKEN");
  if (token == nullptr || token[0] == '\0') token = g_getenv("DESKTOP_STARTUP_ID");
  launch_token = g_strdup(token);

  return MY_APPLICATION(g_object_new(my_application_get_type(),
                                     "application-id", APPLICATION_ID, "flags",
                                     G_APPLICATION_NON_UNIQUE, nullptr));
}