text stringlengths 1 474 |
|---|
An excerpt displays the initial line(s) of text in a paragraph, |
and handles the overflow text, often using an ellipsis.In Flutter, use the maxLines property of a Text widget |
to specify the number of lines to include in the excerpt, |
and the overflow property for handling overflow text. |
<topic_end> |
<topic_start>Flutter for Xamarin.Forms developers |
This document is meant for Xamarin.Forms developers |
looking to apply their existing knowledge |
to build mobile apps with Flutter. |
If you understand the fundamentals of the Xamarin.Forms framework, |
then you can use this document as a jump start to Flutter development.Your Android and iOS knowledge and skill set |
are valuable when building with Flutter, |
because Flutter relies on the native operating system configurations, |
similar to how you would configure your native Xamarin.Forms projects. |
The Flutter Frameworks is also similar to how you create a single UI, |
that is used on multiple platforms.This document can be used as a cookbook by jumping around |
and finding questions that are most relevant to your needs.<topic_end> |
<topic_start> |
Project setup |
<topic_end> |
<topic_start> |
How does the app start? |
For each platform in Xamarin.Forms, |
you call the LoadApplication method, |
which creates a new application and starts your app.In Flutter, the default main entry point is |
main where you load your Flutter app. |
<code_start>void main() { |
runApp(const MyApp()); |
}<code_end> |
In Xamarin.Forms, you assign a Page to the |
MainPage property in the Application class.In Flutter, “everything is a widget”, even the application itself. |
The following example shows MyApp, a simple application Widget. |
<code_start>class MyApp extends StatelessWidget { |
/// This widget is the root of your application. |
const MyApp({super.key}); |
@override |
Widget build(BuildContext context) { |
return const Center( |
child: Text( |
'Hello World!', |
textDirection: TextDirection.ltr, |
), |
); |
} |
}<code_end> |
<topic_end> |
<topic_start> |
How do you create a page? |
Xamarin.Forms has many types of pages; |
ContentPage is the most common. |
In Flutter, you specify an application widget that holds your root page. |
You can use a MaterialApp widget, which supports Material Design, |
or you can use a CupertinoApp widget, which supports an iOS-style app, |
or you can use the lower level WidgetsApp, |
which you can customize in any way you want.The following code defines the home page, a stateful widget. |
In Flutter, all widgets are immutable, |
but two types of widgets are supported: Stateful and Stateless. |
Examples of a stateless widget are titles, icons, or images.The following example uses MaterialApp, |
which holds its root page in the home property. |
<code_start>class MyApp extends StatelessWidget { |
/// This widget is the root of your application. |
const MyApp({super.key}); |
@override |
Widget build(BuildContext context) { |
return const MaterialApp( |
title: 'Flutter Demo', |
home: MyHomePage(title: 'Flutter Demo Home Page'), |
); |
} |
}<code_end> |
From here, your actual first page is another Widget, |
in which you create your state.A Stateful widget, such as MyHomePage below, consists of two parts. |
The first part, which is itself immutable, creates a State object |
that holds the state of the object. The State object persists over |
the life of the widget. |
<code_start>class MyHomePage extends StatefulWidget { |
const MyHomePage({super.key, required this.title}); |
final String title; |
@override |
State<MyHomePage> createState() => _MyHomePageState(); |
}<code_end> |
The State object implements the build() method for the stateful widget.When the state of the widget tree changes, call setState(), |
which triggers a build of that portion of the UI. |
Make sure to call setState() only when necessary, |
and only on the part of the widget tree that has changed, |
or it can result in poor UI performance. |
<code_start>class _MyHomePageState extends State<MyHomePage> { |
int _counter = 0; |
void _incrementCounter() { |
setState(() { |
_counter++; |
}); |
} |
@override |
Widget build(BuildContext context) { |
return Scaffold( |
appBar: AppBar( |
// Take the value from the MyHomePage object that was created by |
// the App.build method, and use it to set the appbar title. |
title: Text(widget.title), |
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