1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
// 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 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
const String _actualContent = 'Actual Content';
const String _loading = 'Loading...';
void main() {
testWidgets('deferFirstFrame/allowFirstFrame stops sending frames to engine', (WidgetTester tester) async {
expect(RendererBinding.instance.sendFramesToEngine, isTrue);
final Completer<void> completer = Completer<void>();
await tester.pumpWidget(
Directionality(
textDirection: TextDirection.ltr,
child: _DeferringWidget(
key: UniqueKey(),
loader: completer.future,
),
),
);
final _DeferringWidgetState state = tester.state<_DeferringWidgetState>(find.byType(_DeferringWidget));
expect(find.text(_loading), findsOneWidget);
expect(find.text(_actualContent), findsNothing);
expect(RendererBinding.instance.sendFramesToEngine, isFalse);
await tester.pump();
expect(find.text(_loading), findsOneWidget);
expect(find.text(_actualContent), findsNothing);
expect(RendererBinding.instance.sendFramesToEngine, isFalse);
expect(state.doneLoading, isFalse);
// Complete the future to start sending frames.
completer.complete();
await tester.idle();
expect(state.doneLoading, isTrue);
expect(RendererBinding.instance.sendFramesToEngine, isTrue);
await tester.pump();
expect(find.text(_loading), findsNothing);
expect(find.text(_actualContent), findsOneWidget);
expect(RendererBinding.instance.sendFramesToEngine, isTrue);
});
testWidgets('Two widgets can defer frames', (WidgetTester tester) async {
expect(RendererBinding.instance.sendFramesToEngine, isTrue);
final Completer<void> completer1 = Completer<void>();
final Completer<void> completer2 = Completer<void>();
await tester.pumpWidget(
Directionality(
textDirection: TextDirection.ltr,
child: Row(
children: <Widget>[
_DeferringWidget(
key: UniqueKey(),
loader: completer1.future,
),
_DeferringWidget(
key: UniqueKey(),
loader: completer2.future,
),
],
),
),
);
expect(find.text(_loading), findsNWidgets(2));
expect(find.text(_actualContent), findsNothing);
expect(RendererBinding.instance.sendFramesToEngine, isFalse);
completer1.complete();
completer2.complete();
await tester.idle();
await tester.pump();
expect(find.text(_loading), findsNothing);
expect(find.text(_actualContent), findsNWidgets(2));
expect(RendererBinding.instance.sendFramesToEngine, isTrue);
});
}
class _DeferringWidget extends StatefulWidget {
const _DeferringWidget({required Key key, required this.loader}) : super(key: key);
final Future<void> loader;
@override
State<_DeferringWidget> createState() => _DeferringWidgetState();
}
class _DeferringWidgetState extends State<_DeferringWidget> {
bool doneLoading = false;
@override
void initState() {
super.initState();
RendererBinding.instance.deferFirstFrame();
widget.loader.then((_) {
setState(() {
doneLoading = true;
RendererBinding.instance.allowFirstFrame();
});
});
}
@override
Widget build(BuildContext context) {
return doneLoading
? const Text(_actualContent)
: const Text(_loading);
}
}