我正在尝试在FlexibleSpaceBar中创建一个带有谷歌地图的固定ScrollView。
有一个包含SliverAppBar和正文内容的NestedScrollView。在SliverAppBar中,有一个谷歌地图小部件,应用栏占据了整个设备视图。还有一个FloatingActionButton,按下时应滚动到视图底部,显示NestedScrollView的正文内容,并将地图移到应用栏和反之亦然。这在技术上可以实现,如果有人想看看它的样子,这里有一些代码:
@override
State<MapPage> createState() => MapPageState();
}
const LatLng _coordinates = LatLng(37.43296265331129, -122.08832357078792);
class MapPageState extends State<MapPage> with SingleTickerProviderStateMixin {
ScrollController _scrollController;
Completer<GoogleMapController> _controller = Completer();
double _scrollExtent;
bool _buttonState;
static final CameraPosition _kGooglePlex = CameraPosition(
target: _coordinates,
zoom: 14.4746,
);
@override
void initState() {
_buttonState = true;
_scrollController = ScrollController(initialScrollOffset: 0.0);
super.initState();
}
@override
void dispose() {
_scrollController.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
_scrollExtent = MediaQuery.of(context).size.height;
return Scaffold(
floatingActionButton: FloatingActionButton(
child: Icon(Icons.keyboard_arrow_down),
backgroundColor: Colors.white,
foregroundColor: Colors.red,
onPressed: (){
if(_buttonState){
_scrollController.animateTo(_scrollExtent, duration: Duration(seconds: 1), curve: Curves.fastOutSlowIn);
_buttonState = false;
}
else{
_scrollController.animateTo(-_scrollExtent, duration: Duration(seconds: 1), curve: Curves.fastOutSlowIn);
_buttonState = true;
}
},
),
body: NestedScrollView(
controller: _scrollController,
headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
return <Widget>[
SliverAppBar(
expandedHeight: MediaQuery.of(context).size.height,
floating: false,
pinned: true,
flexibleSpace: FlexibleSpaceBar(
title: Text("Title",
style: TextStyle(
color: Colors.white,
fontSize: 16.0,
)),
background: GoogleMap(
mapType: MapType.normal,
initialCameraPosition: _kGooglePlex,
markers: _createMarker(),
onMapCreated: (GoogleMapController controller) {
_controller.complete(controller);
},
),
),
),
];
},
body: Container(
padding: EdgeInsets.all(24.0),
child: Text(
'Content'),
),
),
);
}
Set<Marker> _createMarker() {
return <Marker>[
Marker(
markerId: MarkerId("marker_1"),
position: _coordinates,
infoWindow: InfoWindow(title: 'Marker"'),
),
].toSet();
}
}
重要的部分在这里:
NestedScrollView(
controller: _scrollController,
headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
return <Widget>[
SliverAppBar(
expandedHeight: MediaQuery.of(context).size.height,
floating: false,
pinned: true,
flexibleSpace: FlexibleSpaceBar(
title: Text("Title",
style: TextStyle(
color: Colors.white,
fontSize: 16.0,
)),
background: GoogleMap(
mapType: MapType.normal,
initialCameraPosition: _kGooglePlex,
markers: _createMarker(),
onMapCreated: (GoogleMapController controller) {
_controller.complete(controller);
},
),
),
),
];
},
有3个问题:
- 我不知道如何防止用户使用手势滚动。
我希望它只能通过滚动控制器进行控制。我已经尝试将NestedScrollView的物理属性设置为NeverScrollableScrollPhysics(),但没有任何效果。
- 可滚动小部件中的地图手势检测表现奇怪。
您无法正确拖动它,似乎只能通过轻触实现。例如,在ListView中,使用NeverScrollable physics时可以正常工作。
- 每次在应用栏中重新构建时似乎会导致某种内存泄漏,并且我会收到下一个警告。
E/flutter (10644): #0 _AsyncCompleter.complete (dart:async/future_impl.dart:39:31)
E/flutter (10644): #1 MapPageState.build.<anonymous closure>.<anonymous closure> (package:flutter_app/map_page2.dart:83:35)
E/flutter (10644): #2 _GoogleMapState.onPlatformViewCreated (package:google_maps_flutter/src/google_map.dart:259:14)
E/flutter (10644): <asynchronous suspension>
E/flutter (10644): #3 AndroidViewController._create (package:flutter/src/services/platform_views.dart:599:15)
...
如果有人能为此提供帮助或知道这种实现的示例,我将不胜感激。