How to make text transition by animation upon button press? - flutter

Question

Currently, when opacity = 0 & button is pressed, opacity becomes one. But I would like the button also having the function to turn opacity to zero and back to one when opacity is already one.
How can this be made possible ? Thanks
Im thinking it has something to do with tween? Eg. When the button is pressed, the opacity of the quote turns to zero and back to 1 (duration of one second).
But Im not sure how to write that.
Attached below is the main chunk of the code that's involved in this action:
double opacity1 = 0.0;
String quoteCat1 = List1[Random().nextInt(List1.length)];
void generateConvoTopic1() {
setState(() {
quoteCat1 = List1[Random().nextInt(List1.length)];
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
...
body: ...
AnimatedOpacity(
opacity: opacity1,
duration: Duration(seconds: 1),
child:Text(quoteCat1),
]),
...
ElevatedButton(
...
onPressed: () {
generatequoteCat1();
opacity1 = 1.0;
opacity2 = 0.0;
opacity3 = 0.0;
},),
...

Answer 1

If you only want to switch between two values, you could use a boolean and make your button switch its value. In the toggleOpacity function is also an example of how to animate back the function as #Aayush said using a Future.delayed.
Now if you want more complex animations, or infinite ones, you should use an animationController to have full control of it
See example:
class Demo extends StatefulWidget {
Demo({Key key, this.title}) : super(key: key);
final String title;
#override
_DemoState createState() => _DemoState();
}
class _DemoState extends State<Demo> {
bool visible = true;
var animateBack=false;
void toggleOpacity() {
setState(() {
visible = !visible;
});
if(animateBack)
Future.delayed(Duration(seconds: 1)).then((value) {
setState(() {
visible = !visible;
});
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: AnimatedOpacity(
opacity: visible ? 1 : 0,
duration: Duration(seconds: 1),
child: Text(
'Now you see me',
),
),
),
floatingActionButton: FloatingActionButton(
onPressed: toggleOpacity,
child: Icon(visible?Icons.wb_sunny:Icons.wb_sunny_outlined),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}