how to blur bottom half of the screen in flutter - flutter

Question

trying to blur the bottom half of the screen as no guideline or help available.
Requirement:-
i do not want to give specific width or height in backdrop filter child container.
what is already tried:
Stack(
fit: StackFit.expand,
children: [
Image.asset("assets/images/authpage.jpg",
height: double.infinity, width: double.infinity, fit: BoxFit.fill),
Positioned(
top: 500,
child: ClipRect(
child: BackdropFilter(
filter: ImageFilter.blur(sigmaX: 5.0, sigmaY: 5.0),
child: Container(
alignment: Alignment.center,
color: Colors.black.withOpacity(0.1),
),
),
),
),
],
);
Also tried the shader mask but that will fill with colors and not the blur part.
Stack(
fit: StackFit.expand,
children: [
ShaderMask(
shaderCallback: (rect) {
return LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
colors: [Colors.white, Colors.transparent],
).createShader(Rect.fromLTRB(0, 0, rect.width, rect.height));
},
blendMode: BlendMode.dstIn,
child: Image.asset(
'assets/images/authpage.jpg',
height: 400,
fit: BoxFit.fill,
),
),
],
);

Answer 1

i have tried but its not the best
import 'package:flutter/material.dart';
class HomeScreen extends StatelessWidget {
const HomeScreen({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: [
Container(
height: MediaQuery.of(context).size.height,
decoration: BoxDecoration(
image: DecorationImage(
fit: BoxFit.cover,
image: NetworkImage(
"https://images.unsplash.com/photo-1537734796389-e1fc293cf856?ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&ixlib=rb-1.2.1&auto=format&fit=crop&w=632&q=80",
))),
// color: Colors.blue,
),
Positioned(
bottom: 0,
left: 0,
right: 0,
child: ClipRect(
child: BackdropFilter(
filter: ImageFilter.blur(sigmaX: 2.0, sigmaY: 2.0),
child: Container(
// the size where the blurring starts
height: MediaQuery.of(context).size.height * 0.4,
color: Colors.transparent,
),
),
),
),
Positioned(child: Text("data"))
],
),
);
}
}