Flutter animated BackDropFilter - flutter

Question

I wanted to know if it was possible to add blur on a screen with fade in and fade out.
Do you have any idea ? I'm currently using BackDropFilter to blur my screen but it doesn't fade when appear...

Answer 1

You can animate the sigma values for blur,
TweenAnimationBuilder<double>(
tween: Tween<double>(begin: 0.0, end: 15.0),
duration: const Duration(milliseconds: 500),
builder: (_, value, child) {
return BackdropFilter(
filter: ImageFilter.blur(sigmaX: value, sigmaY: value),
child: child,
);
},
child: DecoratedBox(
decoration: BoxDecoration(
color: Colors.white.withOpacity(0.5),
),
),
https://api.flutter.dev/flutter/widgets/TweenAnimationBuilder-class.html

Answer 2

I found that I was able to animate the backDropFiter with a widget called AnimatedOpacity. You can use it as the AnimatedContainer!
Enjoy

Answer 3

Pretty much the same answer as #Damon's but including working example
class BackgroundBlurExample extends StatefulWidget {
#override
_BackgroundBlurExampleState createState() => _BackgroundBlurExampleState();
}
class _BackgroundBlurExampleState extends State<BackgroundBlurExample> {
double _begin = 10.0;
double _end = 0.0;
void _animateBlur() {
setState(() {
_begin == 10.0 ? _begin = 0.0 : _begin = 10.0;
_end == 0.0 ? _end = 10.0 : _end = 0.0;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: [
Align(
alignment: Alignment.center,
child: FlutterLogo(
size: 100,
),
),
// ... Things you want to blur above the IgnorePointer
IgnorePointer( // This is in case you want to tap things under the BackdropFilter
child: TweenAnimationBuilder<double>(
tween: Tween<double>(begin: _begin, end: _end),
duration: Duration(milliseconds: 500),
curve: Curves.easeIn,
builder: (_, value, __) {
return BackdropFilter(
filter: ImageFilter.blur(
sigmaX: value,
sigmaY: value,
),
child: Container(
width: double.maxFinite,
height: double.maxFinite,
color: Colors.transparent,
),
);
},
),
),
Align(
alignment: Alignment.bottomCenter,
child: ElevatedButton(
onPressed: _animateBlur,
child: Text('Animate'),
),
)
],
),
);
}
}