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// Copyright 2014 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.
import 'dart:async';
import 'dart:math';
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter_driver/driver_extension.dart';
/// This application shows empty screen until first frame timings are acquired.
void main() {
enableFlutterDriverExtension();
final Completer<List<FrameTiming>> completer = Completer<List<FrameTiming>>();
SchedulerBinding.instance.addTimingsCallback((List<FrameTiming> timings) {
completer.complete(timings);
});
runApp(Directionality(
textDirection: TextDirection.ltr,
child: _FirstFrameTimings(completer: completer),
));
}
class _FirstFrameTimings extends StatefulWidget {
const _FirstFrameTimings({
required this.completer,
});
final Completer<List<FrameTiming>> completer;
@override
_FirstFrameTimingsState createState() => _FirstFrameTimingsState();
}
class _FirstFrameTimingsState extends State<_FirstFrameTimings> {
int? _minFrameNumber;
@override
Widget build(BuildContext context) {
widget.completer.future.then(_setMinFrameNumber);
if (_minFrameNumber != null) {
return Text(
_minFrameNumber.toString(),
key: const Key('minFrameNumber'),
);
} else {
return const Text('Waiting...');
}
}
void _setMinFrameNumber(List<FrameTiming> timings) {
final int minFrameNumber = timings
.map((FrameTiming timing) => timing.frameNumber)
.reduce(min);
setState(() {
_minFrameNumber = minFrameNumber;
});
}
}