How to create custom InlineSpans in Flutter? - flutter

Question

How can I reuse pieces of code of InlineSpan type (e.g. TextSpan, WidgetSpan).
For example,
Text.rich(
TextSpan(
children: [
WidgetSpan(...), // code I like to reuse
... // other stuff
],
),
)
Of course I can write a function, that gives me this InlineSpan, like this:
InlineSpan myCustomWidgetSpan() {
return WidgetSpan(...);
}
This is technically ok, but usually I reuse parts of code by creating a class that extends some other Flutter class (like StatelessWidget or StatefulWidget).
I think that there should be some more idiomatic approach to this. So what are the best practices for reusing code that produces InlineSpan?

Answer 1

You can copy paste run full code below
You can use package https://pub.dev/packages/span_builder
code snippet
final spans = SpanBuilder("The quick brown fox")
.apply(TextSpan(text: "brown", style: TextStyle(fontWeight: FontWeight.bold)))
.apply(TextSpan(text: "🦊"), whereText: "fox")
.build();
Text.rich(
TextSpan(
children: spans
),
),
working demo
full code
import 'package:flutter/material.dart';
import 'package:span_builder/span_builder.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
final spans = SpanBuilder("The quick brown fox")
.apply(TextSpan(text: "brown", style: TextStyle(fontWeight: FontWeight.bold)))
.apply(TextSpan(text: "🦊"), whereText: "fox")
.build();
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text.rich(
TextSpan(
children: spans
),
),
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}