早上好，我在模拟器屏幕上单击“添加地点”时收到此错误
I/Choreographer(24673): Skipped 51 frames! The application may be doing too much work on its main thread.
D/EGL_emulation(24673): eglMakeCurrent: 0xf30a1410: ver 3 0 (tinfo 0xf33f8610)
D/EGL_emulation(24673): eglMakeCurrent: 0xf30a1c60: ver 3 0 (tinfo 0xf33f72b0)
D/EGL_emulation(24673): eglMakeCurrent: 0xf30a1410: ver 3 0 (tinfo 0xf33f8610)
D/MediaScannerConnection(24673): Scanned /storage/emulated/0/Android/data/com.example.GPApp/files/Pictures/4e6213df-df84-4741-b6ad-aa38b67021915812601528792428377.jpg to null
D/EGL_emulation(24673): eglMakeCurrent: 0xf30a1c60: ver 3 0 (tinfo 0xf33f72b0)
I/Choreographer(24673): Skipped 119 frames! The application may be doing too much work on its main thread.
D/EGL_emulation(24673): eglMakeCurrent: 0xf30a1410: ver 3 0 (tinfo 0xf33f8610)
I/m.example.GPAp(24673): Background young concurrent copying GC freed 2638(291KB) AllocSpace objects, 7(756KB) LOS objects, 49% free, 3269KB/6512KB, paused 3.107ms total 646.067ms
E/flutter (24673): [ERROR:flutter/lib/ui/ui_dart_state.cc(166)] Unhandled Exception: RangeError (index): Invalid value: Valid value range is empty: 0
E/flutter (24673): #0 List.[] (dart:core-patch/growable_array.dart:166:60)
E/flutter (24673): #1 LocationHelper.getPlaceAddress
package:GPApp/helpers/location_helper.dart:17
E/flutter (24673): <asynchronous suspension>
E/flutter (24673): #2 GreatPlaces.addPlace
package:GPApp/providers/great_places.dart:21
E/flutter (24673): #3 _AddPlaceScreenState._savePlace
package:GPApp/screens/add_place_screen.dart:38
E/flutter (24673): #4 _InkResponseState._handleTap
package:flutter/…/material/ink_well.dart:992
E/flutter (24673): #5 _InkResponseState.build.<anonymous closure>
package:flutter/…/material/ink_well.dart:1098
E/flutter (24673): #6 GestureRecognizer.invokeCallback
package:flutter/…/gestures/recognizer.dart:184
E/flutter (24673): #7 TapGestureRecognizer.handleTapUp
package:flutter/…/gestures/tap.dart:524
E/flutter (24673): #8 BaseTapGestureRecognizer._checkUp
package:flutter/…/gestures/tap.dart:284
E/flutter (24673): #9 BaseTapGestureRecognizer.handlePrimaryPointer
package:flutter/…/gestures/tap.dart:219
E/flutter (24673): #10 PrimaryPointerGestureRecognizer.handleEvent
package:flutter/…/gestures/recognizer.dart:477
E/flutter (24673): #11 PointerRouter._dispatch
package:flutter/…/gestures/pointer_router.dart:78
E/flutter (24673): #12 PointerRouter._dispatchEventToRoutes.<anonymous closure>
package:flutter/…/gestures/pointer_router.dart:124
E/flutter (24673): #13 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
E/flutter (24673): #14 PointerRouter._dispatchEventToRoutes
package:flutter/…/gestures/pointer_router.dart:122
E/flutter (24673): #15 PointerRouter.route
package:flutter/…/gestures/pointer_router.dart:108
E/flutter (24673): #16 GestureBinding.handleEvent
package:flutter/…/gestures/binding.dart:220
E/flutter (24673): #17 GestureBinding.dispatchEvent
package:flutter/…/gestures/binding.dart:200
E/flutter (24673): #18 GestureBinding._handlePointerEvent
package:flutter/…/gestures/binding.dart:158
E/flutter (24673): #19 GestureBinding._flushPointerEventQueue
package:flutter/…/gestures/binding.dart:104
E/flutter (24673): #20 GestureBinding._handlePointerDataPacket
package:flutter/…/gestures/binding.dart:88
E/flutter (24673): #21 _rootRunUnary (dart:async/zone.dart:1206:13)
E/flutter (24673): #22 _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter (24673): #23 _CustomZone.runUnaryGuarded (dart:async/zone.dart:1005:7)
E/flutter (24673): #24 _invoke1 (dart:ui/hooks.dart:267:10)
E/flutter (24673): #25 _dispatchPointerDataPacket (dart:ui/hooks.dart:176:5)
E/flutter (24673):
这是我的“ location_input”页面，我在其中获取“用户当前位置”并选择一个位置。
import 'package:flutter/material.dart';
import 'package:location/location.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import '../helpers/location_helper.dart';
import '../screens/map_screen.dart';
class LocationInput extends StatefulWidget {
final Function onSelectPlace;
LocationInput(this.onSelectPlace);
@override
_LocationInputState createState() => _LocationInputState();
}
class _LocationInputState extends State<LocationInput> {
String _previewImageUrl;
Future<void> _getCurrentUserLocation() async {
final locData = await Location().getLocation();
final staticMapImageUrl = LocationHelper.generateLocationPreviewImage(
latitude: locData.latitude,
longitude: locData.longitude,
);
setState(() {
_previewImageUrl = staticMapImageUrl;
});
widget.onSelectPlace(locData.latitude, locData.longitude);
}
Future<void> _selectOnMap() async {
final selectedLocation = await Navigator.of(context).push<LatLng>(
MaterialPageRoute(
builder: (peter) => MapScreen(
isSelecting: true,
),
),
);
if(selectedLocation == null) {
return;
}
widget.onSelectPlace(selectedLocation.latitude, selectedLocation.longitude);
}
@override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
Container(
alignment: Alignment.center,
height: 200,
width: double.infinity,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(5),
border: Border.all(
width: 1,
color: Colors.grey,
),
),
child: _previewImageUrl == null
? Text(
"No location found",
textAlign: TextAlign.center,
)
: Image.network(_previewImageUrl,
fit: BoxFit.cover, width: double.infinity),
),
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
FlatButton.icon(
label: Text(
"Current Location",
),
textColor: Theme.of(context).primaryColor,
icon: Icon(Icons.location_on),
onPressed: _getCurrentUserLocation,
),
FlatButton.icon(
label: Text(
"Select on Map",
),
textColor: Theme.of(context).primaryColor,
icon: Icon(Icons.map),
onPressed: _selectOnMap,
),
],
),
],
);
}
}
这是我实现Google插件的“ map_screen”。
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import '../models/place.dart';
class MapScreen extends StatefulWidget {
final PlaceLocation initialLocation;
final bool isSelecting;
MapScreen({
this.initialLocation = const PlaceLocation(
latitude: 37.422,
longitude: -122.084,
),
this.isSelecting = false,
});
@override
_MapScreenState createState() => _MapScreenState();
}
class _MapScreenState extends State<MapScreen> {
Completer<GoogleMapController> _controller = Completer();
LatLng _pickedLocation;
void _selectLocation(LatLng position) {
setState(() {
_pickedLocation = position;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Your Map"),
actions: <Widget>[
if (widget.isSelecting)
IconButton(
icon: Icon(Icons.check_box),
onPressed: _pickedLocation == null
? null
: () {
Navigator.of(context).pop(_pickedLocation);
},
)
],
),
body: GoogleMap(
mapType: MapType.hybrid,
initialCameraPosition: CameraPosition(
target: LatLng(
widget.initialLocation.latitude,
widget.initialLocation.longitude,
),
zoom: 16,
),
onTap: widget.isSelecting ? _selectLocation : null,
markers: _pickedLocation == null
? null
: {
Marker(
markerId: MarkerId('m1'),
position: _pickedLocation,
),
},
onMapCreated: (GoogleMapController controller) {
_controller.complete(controller);
},
),
);
}
}
这是我的“ add_place_screen”，实际上是我在数据库中保存所选位置的地方（SQLite 1）。
import 'dart:io';
import 'package:GPApp/models/place.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import '../widget/image_input.dart';
import '../providers/great_places.dart';
import '../widget/location_input.dart';
import '../models/place.dart';
class AddPlaceScreen extends StatefulWidget {
static const routeName = "add-Place";
@override
_AddPlaceScreenState createState() => _AddPlaceScreenState();
}
class _AddPlaceScreenState extends State<AddPlaceScreen> {
final _titleController = TextEditingController();
File _pickedImage;
PlaceLocation _pickedLocation;
void _selectImage(pickedImage) {
_pickedImage = pickedImage;
}
void _selectPlace (double lat, double lng) {
_pickedLocation = PlaceLocation(latitude: lat, longitude: lng);
}
void _savePlace() {
if (_titleController.text.isEmpty ||
_pickedImage == null ||
_pickedLocation == null) {
return;
}
Provider.of<GreatPlaces>(context, listen: false).addPlace(
_titleController.text,
_pickedImage,
_pickedLocation,
);
Navigator.of(context).pop();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(
"Add a New Place",
style: TextStyle(fontSize: 18.0),
),
),
body: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Expanded(
child: SingleChildScrollView(
child: Padding(
padding: const EdgeInsets.all(10),
child: Column(
children: [
TextField(
decoration: InputDecoration(labelText: "Title"),
controller: _titleController,
),
SizedBox(height: 10),
ImageInput(_selectImage),
SizedBox(height: 10),
LocationInput(_selectPlace),
],
),
),
),
),
RaisedButton.icon(
elevation: 0,
color: Theme.of(context).accentColor,
materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
onPressed: _savePlace,
icon: Icon(Icons.add),
label: Text(
"Add Place",
style: TextStyle(fontSize: 18.0),
),
),
],
),
);
}
}