How to make transparent sliverappbar in flutter? - ios

Question

I'm trying to make e-commerce app in flutter.
I wanted to make Appbar transparent and have animation, so I use Sliverappbar but I can't make it transparent without scrolling down.
I tried to use stack, but it doesn't work and has error.
I want appbar transparent when it's on top and change white when I scroll down.
This is my flutter code
class _HomePageState extends State<HomePage> {
#override
Widget build(BuildContext context) {
return Scaffold(
extendBodyBehindAppBar: true,
appBar: AppBar(
backgroundColor: Colors.transparent,
elevation: 0.0,
leading: Icon(
Icons.menu,
size: 30,
),
actions: <Widget>[
IconButton(
icon: Icon(Icons.tune, color: Colors.black, size: 30),
)
],
),
body: _buildBody(),
);
}
Widget _buildBody() {
return CustomScrollView(
slivers: <Widget>[
SliverAppBar(
leading: Icon(
Icons.menu,
size: 30,
),
backgroundColor: Colors.transparent,
actions: <Widget>[
IconButton(
icon: Icon(
Icons.tune,
color: Colors.black,
size: 30,
),
)
],
floating: true,
elevation: 0.0,
snap: false,
),
SliverToBoxAdapter(
child: SizedBox(
height: MediaQuery.of(context).size.height * 0.7,
width: MediaQuery.of(context).size.width,
child: Carousel(
images: [
Image.network(
'https://i.pinimg.com/564x/83/32/37/8332374f18162612dd9f2a4af2fda794.jpg',
fit: BoxFit.cover),
Image.network(
'https://i.pinimg.com/originals/e2/8e/50/e28e5090b7193ec9b2d5b5c6dfaf501c.jpg',
fit: BoxFit.cover),
Image.network(
'https://image-cdn.hypb.st/https%3A%2F%2Fhypebeast.com%2Fwp-content%2Fblogs.dir%2F6%2Ffiles%2F2019%2F09%2Fmschf-fall-winter-lookbook-streetwear-seoul-korea-47.jpg?q=75&w=800&cbr=1&fit=max',
fit: BoxFit.cover)
],
showIndicator: false,
)),
),
SliverToBoxAdapter(
child: Padding(
padding: EdgeInsets.only(
left: 25.0, top: 20.0, right: 0.0, bottom: 20.0),
child: Text('Recommended for You',
style: TextStyle(fontWeight: FontWeight.bold, fontSize: 25)),
),
),
SliverPadding(
padding: EdgeInsets.only(left: 35.0, right: 35.0),
sliver: SliverGrid(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2,
mainAxisSpacing: 20.0,
crossAxisSpacing: 25.0,
childAspectRatio: 0.67,
),
delegate: SliverChildBuilderDelegate(
(BuildContext context, int index) {
return _buildListItem(context, index);
},
childCount: 13,
),
))
],
);

Answer 1

Best solution I can find is, instead of using SliverAppBar, use a regular AppBar in a SliverToBoxAdapter. You would set the flexibleSpace property to your Carousel, or put the AppBar and carousel into a Stack.
The flexibleSpace property, as far as I can tell, behaves differently in a SliverAppBar and a regular AppBar. It wont collapse in a regular AppBar and you also won't need to put your carousel in a FlexibleSpaceBar().
You may need to do a few additional things to get the exact look you're going for (e.g. change the elevation).

Answer 2

You can simply warp SliverAppBar with SliverOpacity widget
SliverOpacity (
opacity: 0.5,
sliver: SliverAppBar(
leading: Icon(
Icons.menu,
size: 30, ),
backgroundColor: Colors.transparent,
actions: <Widget>[
IconButton(
icon: Icon(
Icons.tune,
color: Colors.black,
size: 30,
),
)
],
floating: true,
elevation: 0.0,
snap: false,
),
)