animate widgets based on condition in scaffold body - flutter

Question

I have a widget, with a scaffold. His body is x widget, how do I animate in the y widget on the body instead of the x widget?
The widgets are like:
Scaffold(
body: condition ? X() : Y(),
)
When the condition goes from true to false or false to true, I want the Y or X widget to animate in. How can I do this?

Answer 1

You can change the Offset values to get your desired result
class Test extends StatefulWidget {
#override
_TestState createState() => _TestState();
}
class _TestState extends State<Test>
with SingleTickerProviderStateMixin {
bool condition;
AnimationController _controller;
Animation<Offset> _offsetAnimation;
#override
void initState() {
condition = false;
_controller = AnimationController(
duration: const Duration(seconds: 1),
vsync: this,
);
_offsetAnimation =
Tween<Offset>(begin: Offset(0.0, -5.0), end: Offset.zero)
.animate(CurvedAnimation(
curve: Curves.linear,
parent: _controller,
));
super.initState();
}
#override
void dispose() {
_controller.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: InkWell(
onTap: () {
setState(() {
condition = true;
});
_controller.forward();
},
child: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Container(
color: Colors.red,
width: 200,
height: 200,
),
if (condition)
SlideTransition(
position: _offsetAnimation,
child: Container(
color: Colors.green,
width: 100,
height: 100,
),
),
],
),
),
),
);
}
}