19.9.03 高斯模糊效果的实现

class BlurDemoPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: new Container(
        child: Stack(
          children: <Widget>[
            Positioned(
              top: 0,
              bottom: 0,
              left: 0,
              right: 0,
              child: new Image.asset(
                "static/gsy_cat.png",
                fit: BoxFit.cover,
                width: MediaQuery.of(context).size.width,
                height: MediaQuery.of(context).size.height,
              )),
            new Center(
              child: new Container(
                width: 200,
                height: 200,
                child: ClipRRect(
                  borderRadius: BorderRadius.circular(15.0),
                  child: BackdropFilter(
                    filter: ImageFilter.blur(sigmaX: 8.0, sigmaY: 8.0),
                    child: new Row(
                      mainAxisSize: MainAxisSize.max,
                      crossAxisAlignment: CrossAxisAlignment.center,
                      mainAxisAlignment: MainAxisAlignment.center,
                      children: <Widget>[
                        new Icon(Icons.ac_unit),
                        new Text("哇！！")
                      ],
                    )))))
          ],
        )));
  }
}