Camera preview not matching device | flutter - flutter

Question

My camera preview is distorted. It appears far too zoomed in, and also stretched.
What am I doing wrong? How can I fix?
final size = MediaQuery.of(context).size;
final deviceRatio = size.width / size.height;
return Stack(children: <Widget>[
Center(
child: Transform.scale(
scale: controller.value.aspectRatio / deviceRatio,
child: new AspectRatio(
aspectRatio: controller.value.aspectRatio,
child: new CameraPreview(controller),
),
),
),
]);
}
Note: Should work for iOS and Android.
I am using camera package: camera: ^0.7.0+2
Here full page
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:camera/camera.dart';
import 'dart:io';
class Camera extends StatefulWidget {
Function setData;
Camera({Key key, this.setData}) : super(key: key);
#override
_CameraScreenState createState() => _CameraScreenState();
}
class _CameraScreenState extends State<Camera> {
CameraController controller;
List cameras;
int selectedCameraIndex;
String imgPath;
var image;
Future _openGallery() async {
image = await controller.takePicture();
if (widget.setData != null) {
widget.setData(File(image.path));
}
}
#override
void initState() {
super.initState();
availableCameras().then((availableCameras) {
cameras = availableCameras;
if (cameras.length > 0) {
setState(() {
selectedCameraIndex = 0;
});
_initCameraController(cameras[selectedCameraIndex]).then((void v) {});
} else {
print('No camera available');
}
}).catchError((err) {
print('Error :${err.code}Error message : ${err.message}');
});
}
Future _initCameraController(CameraDescription cameraDescription) async {
if (controller != null) {
await controller.dispose();
}
controller = CameraController(cameraDescription, ResolutionPreset.high);
controller.addListener(() {
if (mounted) {
setState(() {});
}
if (controller.value.hasError) {
print('Camera error ${controller.value.errorDescription}');
}
});
try {
await controller.initialize();
} on CameraException catch (e) {}
if (mounted) {
setState(() {});
}
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: SafeArea(
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Expanded(
flex: 1,
child: _cameraPreviewWidget(),
),
Align(
alignment: Alignment.bottomCenter,
child: Container(
height: 120,
width: double.infinity,
child: Row(
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[_cameraControlWidget(context), Spacer()],
),
),
)
],
),
),
),
);
}
Widget _cameraPreviewWidget() {
if (controller == null || !controller.value.isInitialized) {
return const Text(
'Loading',
style: TextStyle(
color: Colors.white,
fontSize: 20.0,
fontWeight: FontWeight.w900,
),
);
}
final size = MediaQuery.of(context).size;
final deviceRatio = size.width / size.height;
return Stack(children: <Widget>[
Center(
child: Transform.scale(
scale: controller.value.aspectRatio / deviceRatio,
child: new AspectRatio(
aspectRatio: controller.value.aspectRatio,
child: new CameraPreview(controller),
),
),
),
]);
}
Widget _cameraControlWidget(context) {
return Expanded(
child: Align(
alignment: Alignment.center,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
mainAxisSize: MainAxisSize.max,
children: <Widget>[
FloatingActionButton(
child: Icon(
Icons.camera,
color: Colors.black,
),
backgroundColor: Colors.white,
onPressed: () {
_openGallery();
Navigator.pop(context);
},
)
],
),
),
);
}
}
Edit based on answer:
final size = MediaQuery.of(context).size;
final deviceRatio = size.width / size.height;
return Stack(children: <Widget>[
Center(
child: Transform.scale(
scale: 16 / 9,
child: Center(
child: AspectRatio(
aspectRatio: 1,
child: Camera(),
),
),
),
),
]);
}

Answer 1

Had the same problem using camerawesome some times ago.
Had to use Transform and an Aspect Ratio:
Transform.scale(
scale: 16 / 9,
child: Center(
child: AspectRatio(
aspectRatio: 1,
child: Camera(),
),
),
),

Answer 2

Use Matrix4.diagonal3Values for scaling, as we can then control the X, Y, Z axis. X is the horizontal, Y is the vertical and Z is for the ones that want to go into other dimensions 🚀.
final size = MediaQuery.of(context).size;
final deviceRatio = size.width / size.height;
final xScale = cameraController.value.aspectRatio / deviceRatio;
// Modify the yScale if you are in Landscape
final yScale = 1;
return Container(
child: AspectRatio(
aspectRatio: deviceRatio,
child: Transform(
alignment: Alignment.center,
transform: Matrix4.diagonal3Values(xScale, yScale, 1),
child: CameraPreview(cameraController),
),
),
);
If you are working with a camera that rotates and supports Landscape, you will most likely need to scale up the Y axis, and skip the X.
The Lightsnap app is locked in Portrait so we don’t need to re-scale the camera preview when the phone rotates. Just a note that you may need to do this if you are supporting landscape.
Thanks to Lightsnap(More Details here)