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I'm trying to capture an image from camera and save it in cache(i.e., Directory.systemTemp available from dart.io package). It is working fine in debug mode. But when I build the release apk and install, it is not working. This is the code:
import 'dart:async';
import 'dart:io';
import 'package:camera/camera.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
class CameraExampleHome extends StatefulWidget {
@override
_CameraExampleHomeState createState() {
return new _CameraExampleHomeState();
/// Returns a suitable camera icon for [direction].
IconData getCameraLensIcon(CameraLensDirection direction) {
switch (direction) {
case CameraLensDirection.back:
return Icons.camera_rear;
case CameraLensDirection.front:
return Icons.camera_front;
case CameraLensDirection.external:
return Icons.camera;
throw new ArgumentError('Unknown lens direction');
void logError(String code, String message) =>
print('Error: $code\nError Message: $message');
class _CameraExampleHomeState extends State<CameraExampleHome> {
CameraController controller;
String imagePath;
final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
Future<List<CameraDescription>> getCameras() async {
return await availableCameras();
@override
Widget build(BuildContext context) {
return new Scaffold(
key: _scaffoldKey,
appBar: new AppBar(
title: const Text('Camera example'),
body: FutureBuilder(
future: getCameras(),
builder: (BuildContext context, AsyncSnapshot snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.none:
case ConnectionState.waiting:
return new Text('loading...');
default:
if (snapshot.hasError)
return new Text('Error: ${snapshot.error}');
else {
if (snapshot.hasData)
return createCameraView(context, snapshot);
return new Text('Null');
/// Display the preview from the camera (or a message if the preview is not available).
Widget _cameraPreviewWidget() {
if (controller == null || !controller.value.isInitialized) {
return const Text(
'Tap a camera',
style: const TextStyle(
color: Colors.white,
fontSize: 24.0,
fontWeight: FontWeight.w900,
} else {
return new AspectRatio(
aspectRatio: controller.value.aspectRatio,
child: new CameraPreview(controller),
/// Display the thumbnail of the captured image or video
/// Display the control bar with buttons to take pictures and record videos.
Widget _captureControlRowWidget() {
return new Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
mainAxisSize: MainAxisSize.max,
children: <Widget>[
new IconButton(
icon: const Icon(Icons.camera_alt),
color: Colors.blue,
onPressed: controller != null &&
controller.value.isInitialized &&
!controller.value.isRecordingVideo
? onTakePictureButtonPressed
: null,
/// Display a row of toggle to select the camera (or a message if no camera is available).
Widget _cameraTogglesRowWidget(var cameras) {
final List<Widget> toggles = <Widget>[];
if (cameras.isEmpty) {
return const Text('No camera found');
} else {
for (CameraDescription cameraDescription in cameras) {
toggles.add(
new SizedBox(
width: 90.0,
child: new RadioListTile<CameraDescription>(
title:
new Icon(getCameraLensIcon(cameraDescription.lensDirection)),
groupValue: controller?.description,
value: cameraDescription,
onChanged: controller != null && controller.value.isRecordingVideo
? null
: onNewCameraSelected,
return new Row(children: toggles);
String timestamp() => new DateTime.now().millisecondsSinceEpoch.toString();
void showInSnackBar(String message) {
_scaffoldKey.currentState
.showSnackBar(new SnackBar(content: new Text(message)));
void onNewCameraSelected(CameraDescription cameraDescription) async {
if (controller != null) {
await controller.dispose();
controller = new CameraController(cameraDescription, ResolutionPreset.high);
// If the controller is updated then update the UI.
controller.addListener(() {
if (mounted) setState(() {});
if (controller.value.hasError) {
showInSnackBar('Camera error ${controller.value.errorDescription}');
try {
await controller.initialize();
} on CameraException catch (e) {
_showCameraException(e);
if (mounted) {
setState(() {});
void onTakePictureButtonPressed() {
takePicture().then((String filePath) {
if (mounted) {
setState(() {
imagePath = filePath;
// videoController?.dispose();
// videoController = null;
if (filePath != null) showInSnackBar('Picture saved to $filePath');
Future<String> takePicture() async {
if (!controller.value.isInitialized) {
showInSnackBar('Error: select a camera first.');
return null;
//final Directory extDir = await getApplicationDocumentsDirectory();
final Directory extDir = Directory.systemTemp;
final String dirPath = '${extDir.path}/Pictures/flutter_test';
await new Directory(dirPath).create(recursive: true);
final String filePath = '$dirPath/${timestamp()}.jpg';
if (controller.value.isTakingPicture) {
// A capture is already pending, do nothing.
return null;
try {
await controller.takePicture(filePath);
} on CameraException catch (e) {
_showCameraException(e);
return null;
return filePath;
void _showCameraException(CameraException e) {
logError(e.code, e.description);
showInSnackBar('Error: ${e.code}\n${e.description}');
Widget createCameraView(BuildContext context, AsyncSnapshot snapshot) {
return new Column(
children: <Widget>[
new Expanded(
child: new Container(
width: MediaQuery.of(context).size.width,
child: _cameraPreviewWidget(),
_captureControlRowWidget(),
new Padding(
padding: const EdgeInsets.all(5.0),
child: new Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
_cameraTogglesRowWidget(snapshot.data),
//_thumbnailWidget(),
class CameraApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
home: new CameraExampleHome(),
List<CameraDescription> cameras;
void main() {
// Fetch the available cameras before initializing the app.
runApp(new CameraApp());
I've tried setting the directory to await getApplicationDocumentsDirectory() like this:
final Directory extDir = await getApplicationDocumentsDirectory();
//final Directory extDir = Directory.systemTemp;
final String dirPath = '${extDir.path}/Pictures/flutter_test';
await new Directory(dirPath).create(recursive: true);
final String filePath = '$dirPath/${timestamp()}.jpg';
Then the pictures are being saved both in debug mode and the release apk. But the pictures are lost once I relaunch the app. I want them to accessible even after the app is relaunched(that is the main reason why I want to use cache).
So what's going wrong when I try to save to cache in release build of the app?
use the path_provider package instead to get the temp path https://pub.dartlang.org/packages/path_provider
Directory tempDir = await getTemporaryDirectory();
String tempPath = tempDir.path;
Directory.systemTemp is only supposed to be used on the server/console.
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