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super.initState();
controller = AnimationController(
duration: const Duration(milliseconds: 2000),
vsync: this,
);
curve = CurvedAnimation(parent: controller, curve: Curves.easeIn);
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: GestureDetector(
onDoubleTap: () {
if (controller.isCompleted) {
controller.reverse();
} else {
controller.forward();
}
},
child: RotationTransition(
turns: curve,
child: const FlutterLogo(size: 200),
),
),
),
);
}
}<code_end>
<topic_end>
<topic_start>
Listviews and adapters
<topic_end>
<topic_start>
What is the equivalent to a ListView in Flutter?
The equivalent to a ListView in Flutter is … a ListView!In a Xamarin.Forms ListView, you create a ViewCell
and possibly a DataTemplateSelectorand pass it into the ListView,
which renders each row with what your
DataTemplateSelector or ViewCell returns.
However, you often have to make sure you turn on Cell Recycling
otherwise you will run into memory issues and slow scrolling speeds.Due to Flutter’s immutable widget pattern,
you pass a list of widgets to your ListView,
and Flutter takes care of making sure that scrolling is fast and smooth.
<code_start>import 'package:flutter/material.dart';
void main() {
runApp(const SampleApp());
}
class SampleApp extends StatelessWidget {
/// This widget is the root of your application.
const SampleApp({super.key});
@override
Widget build(BuildContext context) {
return const MaterialApp(
title: 'Sample App',
home: SampleAppPage(),
);
}
}
class SampleAppPage extends StatelessWidget {
const SampleAppPage({super.key});
List<Widget> _getListData() {
return List<Widget>.generate(
100,
(index) => Padding(
padding: const EdgeInsets.all(10),
child: Text('Row $index'),
),
);
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: const Text('Sample App')),
body: ListView(children: _getListData()),
);
}
}<code_end>
<topic_end>
<topic_start>
How do I know which list item has been clicked?
In Xamarin.Forms, the ListView has an ItemTapped method
to find out which item was clicked.
There are many other techniques you might have used
such as checking when SelectedItem or EventToCommand
behaviors change.In Flutter, use the touch handling provided by the passed-in widgets.
<code_start>import 'dart:developer' as developer;
import 'package:flutter/material.dart';
void main() {
runApp(const SampleApp());
}
class SampleApp extends StatelessWidget {
// This widget is the root of your application.
const SampleApp({super.key});
@override
Widget build(BuildContext context) {
return const MaterialApp(
title: 'Sample App',
home: SampleAppPage(),
);
}
}