Blur multiple widgets. The correct Widget tree must be: Stack > [Widget1ToBlur, Widget2ToBlur, …, Container > BackdropFilter]

blur_multiple_widgets.dart

/* Copyright (c) 2019 - Bui Minh Triet - x3cafe@gmail.com - http://fluttervn.com */
double _sigmaX = 0.0; // from 0-10
double _sigmaY = 0.0; // from 0-10
double _opacity = 0.1; // from 0-1.0
double _width = 350;
double _height = 300;

Stack(
  children: <Widget>[
    Image.asset(
      'assets/images/${images[_imageIndex]}',
      width: _width,
      height: _height,
      fit: BoxFit.cover,
    ),
    FlutterLogo(size: 80, colors: Colors.red),
    Container(
      width: _width,
      height: _height,
      child: BackdropFilter(
        filter: ImageFilter.blur(sigmaX: _sigmaX, sigmaY: _sigmaY),
        child: Container(
          color: Colors.black.withOpacity(_opacity),
        ),
      ),
    )
  ],
);