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flutter_zxing
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Severals fix 

Hi,

Made several improvement on the reader_widget.dart :
1- Fix WidgetsBindingObserver not working on app after injecting reader_widget du to SystemChannels.lifecycle.setMessageHandler
2- Avoid memory leak by removing removeListener
3- Replace method _flashIcon by widget _FlashIcon
4- pass a widget argument for the loader to give more customisation
5- pass a duration argument to customise duration after successful scan
6- don't instantiate new camera if the old one not disposed
 
Hope you like it. Don't hesitate contact me if needed.

Regards,
pull/35/head
Jérémy Favier 2 years ago committed by GitHub
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1 changed files with 82 additions and 96 deletions
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  1. 154
      lib/src/ui/reader_widget.dart

154
lib/src/ui/reader_widget.dart
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@ -4,13 +4,12 @@ import 'dart:math';
import 'package:camera/camera.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
// import 'package:flutter_beep/flutter_beep.dart';
import '../../generated_bindings.dart';
import '../logic/zxing.dart';
import '../utils/extentions.dart';
import '../utils/isolate_utils.dart';
import 'scanner_overlay.dart';
class ReaderWidget extends StatefulWidget {
@ -24,8 +23,10 @@ class ReaderWidget extends StatefulWidget {
this.showFlashlight = true,
this.allowPinchZoom = true,
this.scanDelay = const Duration(milliseconds: 1000), // 1000ms delay
this.scanDelaySuccess = const Duration(milliseconds: 1000), // 1000ms delay
this.cropPercent = 0.5, // 50% of the screen
this.resolution = ResolutionPreset.high,
this.loading = const DecoratedBox(decoration: BoxDecoration(color: Colors.black)),
});
final Function(CodeResult) onScan;
@ -38,14 +39,15 @@ class ReaderWidget extends StatefulWidget {
final Duration scanDelay;
final double cropPercent;
final ResolutionPreset resolution;
final Duration scanDelaySuccess;
final Widget loading;
@override
State<ReaderWidget> createState() => _ReaderWidgetState();
}
class _ReaderWidgetState extends State<ReaderWidget>
with TickerProviderStateMixin {
List<CameraDescription>? cameras;
class _ReaderWidgetState extends State<ReaderWidget> with TickerProviderStateMixin, WidgetsBindingObserver {
List<CameraDescription> cameras = <CameraDescription>[];
CameraController? controller;
bool _cameraOn = false;
@ -59,13 +61,10 @@ class _ReaderWidgetState extends State<ReaderWidget>
// true when code detecting is ongoing
bool _isProcessing = false;
/// Instance of [IsolateUtils]
IsolateUtils? isolateUtils;
@override
void initState() {
super.initState();
WidgetsBinding.instance.addObserver(this);
initStateAsync();
}
@ -81,38 +80,50 @@ class _ReaderWidgetState extends State<ReaderWidget>
}
});
});
}
SystemChannels.lifecycle.setMessageHandler((String? message) async {
debugPrint(message);
final CameraController? cameraController = controller;
if (cameraController == null || !cameraController.value.isInitialized) {
return;
@override
void didChangeAppLifecycleState(AppLifecycleState state) {
switch (state) {
case AppLifecycleState.resumed:
if (cameras.isNotEmpty && !_cameraOn) {
onNewCameraSelected(cameras.first);
}
if (mounted) {
if (message == AppLifecycleState.paused.toString()) {
await cameraController.stopImageStream();
await cameraController.dispose();
break;
case AppLifecycleState.inactive:
break;
case AppLifecycleState.paused:
controller?.stopImageStream().then((_) => controller?.dispose());
setState(() {
_cameraOn = false;
setState(() {});
}
if (message == AppLifecycleState.resumed.toString()) {
_cameraOn = true;
onNewCameraSelected(cameraController.description);
}
}
return null;
});
break;
case AppLifecycleState.detached:
break;
}
}
@override
void dispose() {
stopCameraProcessing();
controller?.removeListener(rebuildOnMount);
controller?.dispose();
WidgetsBinding.instance.removeObserver(this);
super.dispose();
}
void rebuildOnMount() {
if (mounted) {
setState(() {
_cameraOn = true;
});
}
}
Future<void> onNewCameraSelected(CameraDescription cameraDescription) async {
if (controller != null) {
controller?.removeListener(rebuildOnMount);
await controller!.dispose();
}
@ -120,35 +131,24 @@ class _ReaderWidgetState extends State<ReaderWidget>
cameraDescription,
widget.resolution,
enableAudio: false,
imageFormatGroup:
isAndroid() ? ImageFormatGroup.yuv420 : ImageFormatGroup.bgra8888,
imageFormatGroup: isAndroid() ? ImageFormatGroup.yuv420 : ImageFormatGroup.bgra8888,
);
final CameraController? cameraController = controller;
if (cameraController == null) {
if (controller == null) {
return;
}
try {
await cameraController.initialize();
await cameraController.setFlashMode(FlashMode.off);
_maxZoomLevel = await cameraController.getMaxZoomLevel();
_minZoomLevel = await cameraController.getMinZoomLevel();
cameraController.startImageStream(processImageStream);
await controller!.initialize();
await controller!.setFlashMode(FlashMode.off);
_maxZoomLevel = await controller!.getMaxZoomLevel();
_minZoomLevel = await controller!.getMinZoomLevel();
controller!.startImageStream(processImageStream);
} on CameraException catch (e) {
debugPrint('${e.code}: ${e.description}');
}
cameraController.addListener(() {
if (mounted) {
setState(() {});
}
});
if (mounted) {
_cameraOn = true;
setState(() {});
}
widget.onControllerCreated?.call(cameraController);
controller!.addListener(rebuildOnMount);
rebuildOnMount();
widget.onControllerCreated?.call(controller);
}
Future<void> processImageStream(CameraImage image) async {
@ -163,7 +163,7 @@ class _ReaderWidgetState extends State<ReaderWidget>
if (result.isValidBool) {
widget.onScan(result);
setState(() {});
await Future<void>.delayed(const Duration(seconds: 1));
await Future<void>.delayed(widget.scanDelaySuccess);
}
} on FileSystemException catch (e) {
debugPrint(e.message);
@ -179,30 +179,13 @@ class _ReaderWidgetState extends State<ReaderWidget>
@override
Widget build(BuildContext context) {
final Size size = MediaQuery.of(context).size;
final double cropSize = min(size.width, size.height) * widget.cropPercent;
return Stack(
children: <Widget>[
// Camera preview
Center(
child: _cameraPreviewWidget(cropSize),
),
],
);
}
// Display the preview from the camera.
Widget _cameraPreviewWidget(double cropSize) {
final CameraController? cameraController = controller;
final bool isCameraReady = cameras != null &&
(cameras?.isNotEmpty ?? false) &&
_cameraOn &&
!(cameraController == null || !cameraController.value.isInitialized);
final bool isCameraReady = cameras.isNotEmpty && _cameraOn && controller != null && controller!.value.isInitialized;
final Size size = MediaQuery.of(context).size;
final double cameraMaxSize = max(size.width, size.height);
final double cropSize = min(size.width, size.height) * widget.cropPercent;
return Stack(
children: <Widget>[
if (!isCameraReady) Container(color: Colors.black),
if (!isCameraReady) widget.loading,
if (isCameraReady)
SizedBox(
width: cameraMaxSize,
@ -214,7 +197,7 @@ class _ReaderWidgetState extends State<ReaderWidget>
child: SizedBox(
width: cameraMaxSize,
child: CameraPreview(
cameraController,
controller!,
),
),
),
@ -241,9 +224,8 @@ class _ReaderWidgetState extends State<ReaderWidget>
_zoom = _scaleFactor;
},
onScaleUpdate: (ScaleUpdateDetails details) {
_scaleFactor =
(_zoom * details.scale).clamp(_minZoomLevel, _maxZoomLevel);
cameraController?.setZoomLevel(_scaleFactor);
_scaleFactor = (_zoom * details.scale).clamp(_minZoomLevel, _maxZoomLevel);
controller?.setZoomLevel(_scaleFactor);
},
),
if (widget.showFlashlight)
@ -252,36 +234,40 @@ class _ReaderWidgetState extends State<ReaderWidget>
left: 20,
child: FloatingActionButton(
onPressed: () {
if (cameraController != null) {
FlashMode mode = cameraController.value.flashMode;
if (controller != null) {
FlashMode mode = controller!.value.flashMode;
if (mode == FlashMode.torch) {
mode = FlashMode.off;
} else {
mode = FlashMode.torch;
}
cameraController.setFlashMode(mode);
controller!.setFlashMode(mode);
setState(() {});
}
},
backgroundColor: Colors.black26,
child: Icon(_flashIcon(cameraController)),
child: _FlashIcon(flashMode: controller!.value.flashMode)),
),
)
],
);
}
}
IconData _flashIcon(CameraController? cameraController) {
final FlashMode mode = cameraController?.value.flashMode ?? FlashMode.torch;
switch (mode) {
class _FlashIcon extends StatelessWidget {
const _FlashIcon({required this.flashMode});
final FlashMode flashMode;
@override
Widget build(BuildContext context) {
switch (flashMode) {
case FlashMode.torch:
return Icons.flash_on;
return const Icon(Icons.flash_on);
case FlashMode.off:
return Icons.flash_off;
return const Icon(Icons.flash_off);
case FlashMode.always:
return Icons.flash_on;
return const Icon(Icons.flash_on);
case FlashMode.auto:
return Icons.flash_auto;
return const Icon(Icons.flash_auto);
}
}
}

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