flutter_full_screen_scanner 1.0.5 
flutter_full_screen_scanner: ^1.0.5 copied to clipboard
A production-ready, federated Flutter plugin for high-performance, full-screen continuous barcode and QR code scanning.
example/lib/main.dart
import 'dart:math' as math;
import 'package:flutter/material.dart';
import 'package:flutter_full_screen_scanner/flutter_full_screen_scanner.dart';
import 'package:image_picker/image_picker.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Scanner Demo',
theme: ThemeData.dark(useMaterial3: true),
home: const ScannerScreen(),
);
}
}
class ScannerScreen extends StatefulWidget {
const ScannerScreen({super.key});
@override
State<ScannerScreen> createState() => _ScannerScreenState();
}
class _ScannerScreenState extends State<ScannerScreen> {
final ScannerController _controller = ScannerController();
final List<ScannerResult> _scannedHistory = [];
final Map<String, Map<String, dynamic>> _liveBarcodes = {};
final ImagePicker _picker = ImagePicker();
ScannerResult? _lastScannedResult;
DateTime? _lastScanTime;
@override
void dispose() {
_controller.dispose();
super.dispose();
}
Future<void> _scanFromGallery() async {
final XFile? image = await _picker.pickImage(source: ImageSource.gallery);
if (image != null) {
// Pause camera while parsing gallery image
await _controller.pause();
final results = await _controller.scanImage(image.path);
if (results.isNotEmpty && mounted) {
setState(() {
_scannedHistory.insertAll(0, results);
_lastScannedResult = results.first;
_lastScanTime = DateTime.now();
});
showDialog(
context: context,
builder: (ctx) => AlertDialog(
title: const Text('Gallery Scan Success'),
content: Text('Found ${results.length} barcode(s).'),
actions: [
TextButton(
onPressed: () {
Navigator.of(ctx).pop();
_controller.resume();
},
child: const Text('OK'),
),
],
),
);
} else {
if (mounted) {
ScaffoldMessenger.of(context).showSnackBar(
const SnackBar(content: Text('No barcodes found in image')),
);
}
await _controller.resume();
}
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: [
// The Full Screen Scanner
FullScreenScanner(
controller: _controller,
options: const ScannerOptions(
allowDuplicate:
true, // Set to true so we get continuous frames for the live overlay
duplicateDelay: 0,
scanWindow: ScanWindow(
widthFactor: 0.8,
heightFactor: 0.3,
), // Ultra-wide rectangle
),
onScan: (result) {
final now = DateTime.now().millisecondsSinceEpoch;
final nowDateTime = DateTime.now();
setState(() {
// Retain imageBytes from previous scan or history if live frame doesn't carry bytes
final existingBytes = result.imageBytes ??
_liveBarcodes[result.value]?['result']?.imageBytes ??
_scannedHistory
.firstWhere((h) => h.value == result.value,
orElse: () => result)
.imageBytes ??
_lastScannedResult?.imageBytes;
final finalResult = ScannerResult(
value: result.value,
type: result.type,
imageBytes: existingBytes,
corners: result.corners,
imageWidth: result.imageWidth,
imageHeight: result.imageHeight,
timestamp: result.timestamp,
);
_liveBarcodes[result.value] = {
'result': finalResult,
'lastSeen': now,
};
// 2-second delay / rate limit for duplicate scans
if (_lastScanTime == null ||
nowDateTime.difference(_lastScanTime!).inMilliseconds >
2000 ||
_lastScannedResult?.value != finalResult.value) {
_lastScannedResult = finalResult;
_lastScanTime = nowDateTime;
final isDuplicate = _scannedHistory.any(
(item) => item.value == finalResult.value,
);
if (!isDuplicate) {
_scannedHistory.insert(0, finalResult);
}
}
});
},
overlayBuilder: (context, state) {
final now = DateTime.now().millisecondsSinceEpoch;
// Clean up barcodes not seen in the last 500ms
_liveBarcodes.removeWhere(
(key, value) => now - (value['lastSeen'] as int) > 500,
);
return Stack(
children: [
Positioned.fill(
child: const ScannerCutoutOverlay(
scanWindow: ScanWindow(
widthFactor: 0.8,
heightFactor: 0.3,
),
borderColor: Colors.greenAccent,
borderWidth: 3.0,
),
),
// Draw live barcodes over the camera
if (_liveBarcodes.isNotEmpty)
Positioned.fill(
child: CustomPaint(
painter: LiveBarcodeOverlayPainter(
liveBarcodes: _liveBarcodes.values
.map((e) => e['result'] as ScannerResult)
.toList(),
history: _scannedHistory,
),
),
),
// Flash screen green on successful scan
if (state.barcodeDetected)
Container(color: Colors.green.withValues(alpha: 0.3)),
],
);
},
),
// Conditional Live Preview Card below overlay cutout
if (_lastScannedResult != null)
Builder(
builder: (context) {
final isAlreadyInList = _scannedHistory
.where((h) => h.value == _lastScannedResult!.value)
.length >
1 ||
(_scannedHistory
.any((h) => h.value == _lastScannedResult!.value) &&
_scannedHistory.first.value !=
_lastScannedResult!.value);
return Positioned(
bottom: 90,
left: 16,
right: 16,
child: Container(
padding: const EdgeInsets.all(12),
decoration: BoxDecoration(
color: Colors.black87,
borderRadius: BorderRadius.circular(16),
border: Border.all(
color: isAlreadyInList
? Colors.amberAccent
: Colors.greenAccent,
width: 1.5,
),
boxShadow: const [
BoxShadow(
color: Colors.black45,
blurRadius: 10,
spreadRadius: 2,
)
],
),
child: Row(
children: [
if (_lastScannedResult!.imageBytes != null)
ClipRRect(
borderRadius: BorderRadius.circular(8),
child: SizedBox(
width: 48,
height: 48,
child: Image.memory(
_lastScannedResult!.imageBytes!,
fit: BoxFit.cover,
filterQuality: FilterQuality.high,
isAntiAlias: true,
),
),
)
else
Container(
width: 48,
height: 48,
decoration: BoxDecoration(
color: Colors.grey[800],
borderRadius: BorderRadius.circular(8),
),
child: Icon(Icons.qr_code,
color: isAlreadyInList
? Colors.amberAccent
: Colors.greenAccent),
),
const SizedBox(width: 12),
Expanded(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
mainAxisSize: MainAxisSize.min,
children: [
Row(
children: [
Container(
padding: const EdgeInsets.symmetric(
horizontal: 6, vertical: 2),
decoration: BoxDecoration(
color: isAlreadyInList
? Colors.amber.withValues(alpha: 0.2)
: Colors.greenAccent
.withValues(alpha: 0.2),
borderRadius: BorderRadius.circular(4),
),
child: Text(
isAlreadyInList
? 'ALREADY IN LIST'
: '✓ SCANNED',
style: TextStyle(
color: isAlreadyInList
? Colors.amberAccent
: Colors.greenAccent,
fontSize: 10,
fontWeight: FontWeight.bold,
),
),
),
const SizedBox(width: 6),
Text(
_lastScannedResult!.type,
style: TextStyle(
color: Colors.grey[400], fontSize: 11),
),
],
),
const SizedBox(height: 4),
Text(
_lastScannedResult!.value,
style: const TextStyle(
color: Colors.white,
fontSize: 15,
fontWeight: FontWeight.bold,
),
maxLines: 1,
overflow: TextOverflow.ellipsis,
),
],
),
),
IconButton(
icon: const Icon(Icons.close,
color: Colors.grey, size: 20),
onPressed: () {
setState(() {
_lastScannedResult = null;
});
},
),
],
),
),
);
},
),
// Top AppBar Controls
Positioned(
top: 50,
left: 20,
right: 20,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
const Text(
'Scanner SDK',
style: TextStyle(
fontSize: 24,
fontWeight: FontWeight.bold,
color: Colors.white,
shadows: [Shadow(color: Colors.black, blurRadius: 4)],
),
),
Row(
children: [
IconButton(
icon: const Icon(
Icons.photo_library,
color: Colors.white,
size: 30,
),
onPressed: _scanFromGallery,
),
IconButton(
icon: const Icon(
Icons.flip_camera_ios,
color: Colors.white,
size: 30,
),
onPressed: _controller.switchCamera,
),
IconButton(
icon: Icon(
_controller.flashEnabled
? Icons.flash_on
: Icons.flash_off,
color: _controller.flashEnabled
? Colors.yellow
: Colors.white,
size: 30,
),
onPressed: () {
_controller.toggleFlash();
setState(() {}); // Update icon
},
),
],
),
],
),
),
],
),
floatingActionButton: FloatingActionButton(
onPressed: _showHistoryBottomSheet,
backgroundColor: Colors.blueAccent,
child: const Icon(Icons.history, color: Colors.white),
),
floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
);
}
void _showHistoryBottomSheet() {
showModalBottomSheet(
context: context,
backgroundColor: Colors.grey[900],
shape: const RoundedRectangleBorder(
borderRadius: BorderRadius.vertical(top: Radius.circular(20)),
),
builder: (context) {
return Column(
children: [
const Padding(
padding: EdgeInsets.all(16.0),
child: Text(
'Continuous Scan History',
style: TextStyle(
color: Colors.white,
fontSize: 18,
fontWeight: FontWeight.bold,
),
),
),
Expanded(
child: ListView.builder(
padding: EdgeInsets.zero,
itemCount: _scannedHistory.length,
itemBuilder: (context, index) {
final item = _scannedHistory[index];
return Material(
color: Colors.transparent,
child: ListTile(
leading: SizedBox(
width: 50,
height: 50,
child: item.imageBytes != null
? ClipRRect(
borderRadius: BorderRadius.circular(8),
child: CustomPaint(
foregroundPainter: BarcodeLinePainter(
corners: item.corners,
imageWidth:
item.imageWidth?.toDouble() ?? 1080,
imageHeight:
item.imageHeight?.toDouble() ?? 1920,
),
child: Image.memory(
item.imageBytes!,
fit: BoxFit.contain,
filterQuality: FilterQuality.high,
isAntiAlias: true,
),
),
)
: Container(
color: Colors.grey[800],
child: const Icon(
Icons.qr_code,
color: Colors.white,
),
),
),
title: Text(
item.value,
style: const TextStyle(
color: Colors.white,
fontWeight: FontWeight.w600,
),
),
subtitle: Text(
'Type: ${item.type}',
style: const TextStyle(
color: Colors.grey,
fontSize: 12,
),
),
onTap: () {
if (item.imageBytes != null) {
showDialog(
context: context,
builder: (context) {
return Dialog(
backgroundColor: Colors.transparent,
child: Stack(
alignment: Alignment.topRight,
children: [
ClipRRect(
borderRadius: BorderRadius.circular(12),
child: AspectRatio(
aspectRatio: (item.imageWidth ?? 1) /
(item.imageHeight ?? 1),
child: CustomPaint(
foregroundPainter: BarcodeLinePainter(
corners: item.corners,
imageWidth:
item.imageWidth?.toDouble() ??
1080,
imageHeight:
item.imageHeight?.toDouble() ??
1920,
),
child: Image.memory(
item.imageBytes!,
fit: BoxFit.contain,
filterQuality: FilterQuality.high,
isAntiAlias: true,
),
),
),
),
IconButton(
icon: const Icon(
Icons.close,
color: Colors.white,
size: 30,
),
onPressed: () => Navigator.pop(context),
),
],
),
);
},
);
}
},
),
);
},
),
),
],
);
},
);
}
}
class LiveBarcodeOverlayPainter extends CustomPainter {
final List<ScannerResult> liveBarcodes;
final List<ScannerResult> history;
LiveBarcodeOverlayPainter({
required this.liveBarcodes,
required this.history,
});
@override
void paint(Canvas canvas, Size size) {
for (final barcode in liveBarcodes) {
if (barcode.corners == null || barcode.corners!.isEmpty) continue;
final imageWidth = barcode.imageWidth?.toDouble() ?? 1080;
final imageHeight = barcode.imageHeight?.toDouble() ?? 1920;
// Calculate BoxFit.cover scaling math to map coordinates to screen
final scaleX = size.width / imageWidth;
final scaleY = size.height / imageHeight;
final scale = scaleX > scaleY ? scaleX : scaleY;
final dxOffset = (imageWidth * scale - size.width) / 2;
final dyOffset = (imageHeight * scale - size.height) / 2;
// Find the center of the barcode
double centerX = 0;
double centerY = 0;
for (final corner in barcode.corners!) {
centerX += (corner.x * scale) - dxOffset;
centerY += (corner.y * scale) - dyOffset;
}
centerX /= barcode.corners!.length;
centerY /= barcode.corners!.length;
// Check if already in history
final inHistory = history.any((h) => h.value == barcode.value);
if (inHistory) {
final textSpan = TextSpan(
text: '✓ Scanned: ${barcode.value}',
style: const TextStyle(
color: Colors.white,
fontSize: 13,
fontWeight: FontWeight.bold,
),
);
final textPainter = TextPainter(
text: textSpan,
textAlign: TextAlign.center,
textDirection: TextDirection.ltr,
);
textPainter.layout();
final bgRect = RRect.fromRectAndRadius(
Rect.fromCenter(
center: Offset(centerX, centerY),
width: textPainter.width + 16,
height: textPainter.height + 10,
),
const Radius.circular(8),
);
final bgPaint = Paint()
..color = const Color(0xE62E7D32); // Vibrant dark green with opacity
canvas.drawRRect(bgRect, bgPaint);
textPainter.paint(
canvas,
Offset(
centerX - textPainter.width / 2,
centerY - textPainter.height / 2,
),
);
}
}
}
@override
bool shouldRepaint(covariant LiveBarcodeOverlayPainter oldDelegate) {
return true;
}
}
class BarcodeLinePainter extends CustomPainter {
final List<Point>? corners;
final double imageWidth;
final double imageHeight;
BarcodeLinePainter({
required this.corners,
required this.imageWidth,
required this.imageHeight,
});
@override
void paint(Canvas canvas, Size size) {
if (corners == null || corners!.length < 4) return;
final paint = Paint()
..color = Colors.greenAccent
..strokeWidth = 1.5
..isAntiAlias = true
..strokeCap = StrokeCap.round
..style = PaintingStyle.stroke;
// Calculate exact BoxFit.contain scaling and translation offsets (dx, dy)
final scale = math.min(
size.width / imageWidth,
size.height / imageHeight,
);
final dx = (size.width - imageWidth * scale) / 2;
final dy = (size.height - imageHeight * scale) / 2;
final rawPoints = corners!
.map((c) => Offset(c.x * scale + dx, c.y * scale + dy))
.toList();
final linePoints = _calculateCenterLine(rawPoints);
if (linePoints.length == 2) {
canvas.drawLine(linePoints[0], linePoints[1], paint);
}
}
List<Offset> _calculateCenterLine(List<Offset> corners) {
if (corners.isEmpty) {
return [Offset.zero, Offset.zero];
}
if (corners.length < 4) {
double minX = corners.first.dx, maxX = corners.first.dx;
double minY = corners.first.dy, maxY = corners.first.dy;
for (final p in corners) {
if (p.dx < minX) minX = p.dx;
if (p.dx > maxX) maxX = p.dx;
if (p.dy < minY) minY = p.dy;
if (p.dy > maxY) maxY = p.dy;
}
final w = maxX - minX;
final h = maxY - minY;
final cx = (minX + maxX) / 2.0;
final cy = (minY + maxY) / 2.0;
if (w >= h) {
return [Offset(minX, cy), Offset(maxX, cy)];
} else {
return [Offset(cx, minY), Offset(cx, maxY)];
}
}
// Calculate centroid
double cx = 0;
double cy = 0;
for (final p in corners) {
cx += p.dx;
cy += p.dy;
}
cx /= 4.0;
cy /= 4.0;
// Sort corners clockwise around centroid
final sorted = List<Offset>.from(corners);
sorted.sort((a, b) {
final angleA = math.atan2(a.dy - cy, a.dx - cx);
final angleB = math.atan2(b.dy - cy, b.dx - cx);
return angleA.compareTo(angleB);
});
final q0 = sorted[0];
final q1 = sorted[1];
final q2 = sorted[2];
final q3 = sorted[3];
// Compute side lengths
final d0 = (q0 - q1).distance;
final d1 = (q1 - q2).distance;
final d2 = (q2 - q3).distance;
final d3 = (q3 - q0).distance;
// Compare opposite pairs of sides to find short vs long
final sum02 = d0 + d2;
final sum13 = d1 + d3;
if (sum02 > sum13) {
// q0-q1 and q2-q3 are long edges, q1-q2 and q3-q0 are short edges.
final mid12 = Offset((q1.dx + q2.dx) / 2.0, (q1.dy + q2.dy) / 2.0);
final mid30 = Offset((q3.dx + q0.dx) / 2.0, (q3.dy + q0.dy) / 2.0);
return [mid12, mid30];
} else {
// q1-q2 and q3-q0 are long edges, q0-q1 and q2-q3 are short edges.
final mid01 = Offset((q0.dx + q1.dx) / 2.0, (q0.dy + q1.dy) / 2.0);
final mid23 = Offset((q2.dx + q3.dx) / 2.0, (q2.dy + q3.dy) / 2.0);
return [mid01, mid23];
}
}
@override
bool shouldRepaint(covariant BarcodeLinePainter oldDelegate) {
return oldDelegate.corners != corners;
}
}Metadata
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Metadata
A production-ready, federated Flutter plugin for high-performance, full-screen continuous barcode and QR code scanning.
Repository (GitHub)
View/report issues
Topics
#scanner #qr-code #barcode #camera #ml-kit
License
unknown (license)
Dependencies
flutter, flutter_full_screen_scanner_android, flutter_full_screen_scanner_ios, flutter_full_screen_scanner_platform_interface, plugin_platform_interface
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