Help! Help! Help!
Guys please help me solve this issue, i really need to solve this issues as soon as possible. The issue is seen on the Toast.dart and Armodel.dart. I have attatched the codes of both of the files. If any of the people can solve the issues it will be a great help for me. However, if possible please suggest me how do i implement OCR as i followed up the codes from Pubdev but still whenever i opens my camera it crashes.
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
class ToastContext {
BuildContext? context;
MethodChannel? _channel;
static final ToastContext _instance = ToastContext._internal();
/// Prmary Constructor for FToast
factory ToastContext() {
return _instance;
}
/// Take users Context and saves to avariable
ToastContext init(BuildContext context) {
_instance.context = context;
return _instance;
}
ToastContext._internal();
}
class Toast {
static const int lengthShort = 1;
static const int lengthLong = 3;
static const int bottom = 0;
static const int center = 1;
static const int top = 2;
static void show(String msg,
{int? duration = 1,
int? gravity = 0,
Color backgroundColor = const Color(0xAA000000),
textStyle = const TextStyle(fontSize: 15, color: Colors.white),
double backgroundRadius = 20,
bool? rootNavigator,
Border? border,
bool webShowClose = false,
Color webTexColor = const Color(0xFFffffff)}) {
if (ToastContext().context == null) {
throw Exception('Context is null, please call ToastContext.init(context) first');
}
if (kIsWeb == true) {
if (ToastContext()._channel == null) {
ToastContext()._channel = const MethodChannel('appdev/FlutterToast');
}
String toastGravity = "bottom";
if (gravity == Toast.top) {
toastGravity = "top";
} else if (gravity == Toast.center) {
toastGravity = "center";
} else {
toastGravity = "bottom";
}
final Map<String, dynamic> params = <String, dynamic>{
'msg': msg,
'duration': (duration ?? 1) * 1000,
'gravity': toastGravity,
'bgcolor': backgroundColor.toString(),
'textcolor': webTexColor.value.toRadixString(16),
'webShowClose': webShowClose,
};
ToastContext()._channel?.invokeMethod("showToast", params);
} else {
ToastView.dismiss();
ToastView.createView(msg, ToastContext().context!, duration, gravity, backgroundColor,
textStyle, backgroundRadius, border, rootNavigator);
}
}
}
class ToastView {
static final ToastView _singleton = ToastView._internal();
factory ToastView() {
return _singleton;
}
ToastView._internal();
static OverlayState? overlayState;
static OverlayEntry? _overlayEntry;
static bool _isVisible = false;
static void createView(
String msg,
BuildContext context,
int? duration,
int? gravity,
Color background,
TextStyle textStyle,
double backgroundRadius,
Border? border,
bool? rootNavigator) async {
overlayState = Overlay.of(context, rootOverlay: rootNavigator ?? false);
_overlayEntry = OverlayEntry(
builder: (BuildContext context) => ToastWidget(
widget: SizedBox(
width: MediaQuery.of(context).size.width,
child: Container(
alignment: Alignment.center,
width: MediaQuery.of(context).size.width,
child: Container(
decoration: BoxDecoration(
color: background,
borderRadius: BorderRadius.circular(backgroundRadius),
border: border,
),
margin: const EdgeInsets.symmetric(horizontal: 20),
padding: const EdgeInsets.fromLTRB(16, 10, 16, 10),
child: Text(msg, softWrap: true, style: textStyle),
)),
),
gravity: gravity),
);
_isVisible = true;
overlayState!.insert(_overlayEntry!);
await Future.delayed(Duration(seconds: duration ?? Toast.lengthShort));
dismiss();
}
static dismiss() async {
if (!_isVisible) {
return;
}
_isVisible = false;
_overlayEntry?.remove();
}
}
class ToastWidget extends StatelessWidget {
const ToastWidget({
Key? key,
required this.widget,
required this.gravity,
}) : super(key: key);
final Widget widget;
final int? gravity;
@override
Widget build(BuildContext context) {
return Positioned(
top: gravity == 2 ? MediaQuery.of(context).viewInsets.top 50 : null,
bottom: gravity == 0 ? MediaQuery.of(context).viewInsets.bottom 50 : null,
child: IgnorePointer(
child: Material(
color: Colors.transparent,
child: widget,
),
));
}
}
import 'package:firebase_database/firebase_database.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_mobile_vision_2/flutter_mobile_vision_2.dart';
import 'package:toast/toast.dart';
import 'arviewpage.dart';
class Armodelselect extends StatefulWidget {
@override
_ArmodelselectState createState() => _ArmodelselectState();
}
class _ArmodelselectState extends State<Armodelselect> {
int _cameraOcr = 0;
//String _textValue = "sample";
String position = "";
bool vision = false;
bool showwords = true;
bool search = false;
late String searchtext;
bool flash = false;
List<OcrText> scannedwords = [];
var DATA, DATA2, DATA3;
final databasepost = FirebaseDatabase.instance.reference();
final databasepost1 = FirebaseDatabase.instance.reference();
late OcrText selected;
@override
void initState() {
getdata();
FlutterMobileVision.start().then((x) => setState(() {
vision = true;
}));
super.initState();
}
Future<List<OcrText>> _getwords() async {
return scannedwords;
}
Future<bool> _onWillPop() async {
SystemNavigator.pop();
return false;
}
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: _onWillPop,
child: Container(
height: MediaQuery.of(context).size.height - 185.0,
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.only(topLeft: Radius.circular(75.0)),
),
child: NestedScrollView(
headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
return <Widget>[
SliverAppBar(
backgroundColor: Colors.transparent,
expandedHeight: 100,
floating: false,
pinned: false,
automaticallyImplyLeading: false,
flexibleSpace: FlexibleSpaceBar(
background:
Row(mainAxisAlignment: MainAxisAlignment.end, children: <
Widget>[
Padding(
padding: const EdgeInsets.all(10.0),
child: Container(
decoration: BoxDecoration(
color: Colors.grey[100],
border: Border.all(color: Colors.blue, width: 1.0),
borderRadius: BorderRadius.all(Radius.circular(5.0)),
boxShadow: [
BoxShadow(
blurRadius: 5,
color: Colors.black54,
offset: Offset(1, 3))
],
),
child: IconButton(
icon: Icon(
Icons.refresh,
color: Colors.blue[500],
),
onPressed: () {
setState(() {
getdata();
});
},
),
),
),
Visibility(
visible: !search,
child: Padding(
padding: const EdgeInsets.all(10.0),
child: Container(
decoration: BoxDecoration(
color: Colors.grey[100],
border: Border.all(color: Colors.blue, width: 1.0),
borderRadius:
BorderRadius.all(Radius.circular(5.0)),
boxShadow: [
BoxShadow(
blurRadius: 5,
color: Colors.black54,
offset: Offset(1, 3))
],
),
child: IconButton(
icon: Icon(
Icons.camera_alt,
color: Colors.blue[500],
),
onPressed: () {
camerarefresh();
},
),
),
),
),
Visibility(
visible: !search,
child: Padding(
padding: const EdgeInsets.all(10.0),
child: Container(
decoration: BoxDecoration(
color: Colors.grey[100],
border: Border.all(color: Colors.blue, width: 1.0),
borderRadius:
BorderRadius.all(Radius.circular(5.0)),
boxShadow: [
BoxShadow(
blurRadius: 5,
color: Colors.black54,
offset: Offset(1, 3))
],
),
child: IconButton(
icon:
Icon(flash ? Icons.flash_on : Icons.flash_off),
color: Colors.blue,
onPressed: () {
setState(() {
if (flash) {
flash = false;
} else {
flash = true;
}
});
},
),
),
),
),
Visibility(
visible: !search,
child: Padding(
padding: const EdgeInsets.all(10.0),
child: Container(
decoration: BoxDecoration(
color: Colors.grey[100],
border: Border.all(color: Colors.blue, width: 1.0),
borderRadius:
BorderRadius.all(Radius.circular(5.0)),
boxShadow: [
BoxShadow(
blurRadius: 5,
color: Colors.black54,
offset: Offset(1, 3))
],
),
child: IconButton(
icon: Icon(
Icons.list,
color: Colors.blue[500],
),
onPressed: () {
setState(() {
if (showwords) {
showwords = false;
} else {
showwords = true;
}
});
},
),
),
),
),
Padding(
padding: const EdgeInsets.all(10.0),
child: Container(
decoration: BoxDecoration(
color: Colors.grey[100],
border: Border.all(color: Colors.blue, width: 1.0),
borderRadius: BorderRadius.all(Radius.circular(5.0)),
boxShadow: [
BoxShadow(
blurRadius: 5,
color: Colors.black54,
offset: Offset(1, 3))
],
),
child: IconButton(
icon: Icon(
Icons.search,
color: Colors.blue[500],
),
onPressed: () {
setState(() {
if (search) {
search = false;
} else {
search = true;
}
});
},
),
),
),
Visibility(
visible: search,
child: Expanded(
child: Padding(
padding: const EdgeInsets.all(10.0),
child: TextField(
decoration: InputDecoration(
labelText: "Keyword",
border: OutlineInputBorder()),
onChanged: (text) {
setState(() {
searchtext = text;
});
}),
),
),
),
]),
),
)
];
},
body: Container(
padding: EdgeInsets.fromLTRB(50, 10, 0, 0),
child: FutureBuilder(
future: _getwords(),
builder: (BuildContext context, AsyncSnapshot snapshot) {
if (search) {
return Center(
child: RaisedButton(
color: Color(0xFF21BFBD),
onPressed: () {
searchbutton(searchtext);
},
child: Text("Build Model"),
),
);
} else if (scannedwords.length == 0 || !showwords) {
return Container();
} else if (scannedwords.length == 1) {
wordselected(scannedwords[0]);
return Container();
} else {
return Container(
child: ListView.builder(
scrollDirection: Axis.vertical,
shrinkWrap: true,
itemCount: scannedwords.length,
itemBuilder: (BuildContext context, int index) {
return Padding(
padding: const EdgeInsets.all(8.0),
child: GestureDetector(
onTap: () {
wordselected(scannedwords[index]);
},
child: Container(
decoration: BoxDecoration(
color: Colors.grey[100],
border: Border.all(
color: Colors.blue, width: 2.0),
borderRadius:
BorderRadius.all(Radius.circular(5.0)),
boxShadow: [
BoxShadow(
blurRadius: 5,
color: Colors.black54,
offset: Offset(1, 3))
],
),
padding: EdgeInsets.all(10),
child: Center(
child: Text(
processword(
scannedwords[index].value.toString(),
),
style: TextStyle(
color: Colors.black,
fontWeight: FontWeight.w400,
fontSize: 30,
),
),
),
),
),
);
}),
);
}
}),
),
),
),
);
}
//functions:::::::::::::::
Future<void> camerarefresh() async {
_read();
}
//read live words from camera
_read() async {
try {
print(" $_cameraOcr");
scannedwords = await FlutterMobileVision.read(
camera: 0,
flash: flash,
waitTap: true,
autoFocus: true,
multiple: true,
showText: true,
fps: 30,
);
Future.delayed(Duration(seconds: 1), () {
setState(() {});
});
} catch (e) {
showToast("failed to recognize text");
}
}
//method when ocr word list is shown
Future<void> wordselected(OcrText word) async {
String name = word.value.toString().toLowerCase();
if (!checkname(name, DATA2['available'])) {
showToast("Ar data not available check after sometime");
changerequestword(name, DATA2['requested']);
} else {
print("${DATA[name]['image']}");
objmodel modeldes = new objmodel(
name,
DATA[name]['size'].toString().split(","),
DATA[name]['image'],
DATA[name]['explain'],
DATA[name]['type']);
Future.delayed(Duration(seconds: 2), () {
vision = false;
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => arviewpage(modeldes),
),
);
});
}
}
//for search keyword button method implementation
Future<void> searchbutton(String word) async {
String name = word.toLowerCase();
print(DATA[0]);
if (!checkname(name, DATA2['available'])) {
showToast("Ar data not available check after sometime");
changerequestword(name, DATA2['requested']);
} else {
print("image${DATA[name]['image']}");
objmodel modeldes = new objmodel(
name,
DATA[name]['size'].toString().split(","),
DATA[name]['image'],
DATA[name]['explain'],
DATA[name]['type']);
Future.delayed(Duration(seconds: 2), () {
vision = false;
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => arviewpage(modeldes),
),
);
});
}
}
//check if the word exist in the available,requested word list
bool checkname(String word, String list) {
var listc = list.split(",");
for (int i = 0; i < listc.length; i ) {
if (listc[i] == word) {
return true;
}
}
return false;
}
//make wordfrequency change request to firebase database
changerequestword(String word, String list) {
if (checkname(word, list)) {
int count = int.parse(DATA3[word]);
count = count 1;
databasepost.child("wordfrequency").update({
"$word": "$count",
});
} else {
databasepost.child("wordfrequency").update({
"$word": "1",
});
if (list == "") {
databasepost1.child("wordlist").update({
"requested": "${word}",
});
} else {
databasepost1.child("wordlist").update({
"requested": "${list},${word}",
});
}
}
}
String processword(String word) {
String postword = "";
word.runes.forEach((int rune) {
var character = new String.fromCharCode(rune);
if (character == " ") {
postword = postword " ";
} else {
postword = postword character;
}
});
var w = postword.split("\n");
postword = "";
for (int i = 0; i < w.length; i ) {
postword = postword w[i] " ";
}
return postword.trim();
}
//toast method
void showToast(String text) {
Toast.show(text,
textStyle: context, duration: Toast.lengthLong, gravity: Toast.bottom);
}
//get url for image from database
Future<void> getdata() async {
final reference =
await FirebaseDatabase.instance.reference().child("datamodel");
reference.once().then((DatabaseEvent snap) {
DATA = snap.snapshot;
});
final reference2 =
await FirebaseDatabase.instance.reference().child("wordlist");
reference2.once().then((DatabaseEvent snap) {
DATA2 = snap.snapshot;
});
final reference3 =
await FirebaseDatabase.instance.reference().child("wordfrequency");
reference3.once().then((DatabaseEvent snap) {
DATA3 = snap.snapshot;
});
}
}
class objmodel {
var size;
String name, img_url, type, explain;
objmodel(this.name, this.size, this.img_url, this.explain, this.type);
}
E/flutter ( 6018): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: Exception: Context is null, please call ToastContext.init(context) first
E/flutter ( 6018): #0 Toast.show (package:toast/toast.dart:42:7)
E/flutter ( 6018): #1 _ArmodelselectState.showToast (package:flutter_auth_ui/screens/armodelselect.dart:456:11)
E/flutter ( 6018): #2 _ArmodelselectState._read (package:flutter_auth_ui/screens/armodelselect.dart:344:7)
E
CodePudding user response：
I think you should call this code in your main function.
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
ToastContext().init(context);//-> This part
return new MaterialApp(
title: 'Flutter Demo',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: new MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
CodePudding user response：
Because in your Toast class, you have:
if (ToastContext().context == null) {
throw Exception('Context is null, please call ToastContext.init(context) first');
}
So it is obvious that if your context is null, there will be an exception thrown. And in the code you have posted, there is no any .init(...) method called to set the context of ToastContext class?
You have to call init method of the ToastContext class wherever you are initializing the page. Better to call it in the initState, or wherever BUT before using it!