Entry Point

Program Entry

When the project creates an executable, the entry point of the project is located in main(), where the default is given as:

void main(){
  runApp(const MyApp());
}

This can be find in lib/main.dart along with other source code.

info

Inside the main() function, there is the runApp() function which bootstrap the application by initializing the framework and attaching the root widget the render tree. This is perform by:

void runApp(Widget app) {
  final WidgetsBinding binding = WidgetsFlutterBinding.ensureInitialized();
  _runWidget(binding.wrapWithDefaultView(app), binding, 'runApp');
}

WidgetsFlutterBinding.ensureInitialized(); creates the binders required (GestureBinding, RendererBinding, SchedulerBinding, WidgetsBinding)
This binding is pass into _runWidget
The widget (app) passed in will be wrapped with a View widget, this widget will now be the root widget and be rendered through the RendererBinding
This now calls the mount() function which recursively adds the child elements and instantiates RenderObject for each RenderObjectWidget.
SchedulerBinding.scheduleFrame() hooks into window.onDrawFrame
The event loop will now initialize, each loop will update render objects and draw schedule frames.

Program Entry​

Program Entry