Flutter camera 0.8.1 flash on while streaming

Question

Is there a way in flutter with camera 0.8.1 to stream from my camera to process the frames and keep the flash on while streaming? Working on windows and running on android

The example with camera 0.8.1 do not really give me a idea how to set the flashmode state. But I am still a novice so missing it most probably. Thank you. Get this error ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════ The following NoSuchMethodError was thrown attaching to the render tree: The method 'setFlashMode' was called on null. Receiver: null Tried calling: setFlashMode(Instance of 'FlashMode')

When the exception was thrown, this was the stack: #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5) #1 _CameraAppState.initState (package:cameratest/main.dart:26:13) #2 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4632:57) #3 ComponentElement.mount (package:flutter/src/widgets/framework.dart:4469:5) #4 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3541:14) #5 Element.updateChild (package:flutter/src/widgets/framework.dart:3306:18) #6 RenderObjectToWidgetElement._rebuild (package:flutter/src/widgets/binding.dart:1182:16) #7 RenderObjectToWidgetElement.mount (package:flutter/src/widgets/binding.dart:1153:5) #8 RenderObjectToWidgetAdapter.attachToRenderTree. (package:flutter/src/widgets/binding.dart:1095:18) #9 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2647:19) #10 RenderObjectToWidgetAdapter.attachToRenderTree (package:flutter/src/widgets/binding.dart:1094:13) #11 WidgetsBinding.attachRootWidget (package:flutter/src/widgets/binding.dart:934:7) #12 WidgetsBinding.scheduleAttachRootWidget. (package:flutter/src/widgets/binding.dart:915:7) (elided 11 frames from class _RawReceivePortImpl, class _Timer, dart:async, and dart:async-patch) The code I have is for a preview at this time and want the flash to start when the app start.

    import 'dart:async';
    import 'dart:io';

    import 'package:flutter/material.dart';
    import 'package:camera/camera.dart';

    List<CameraDescription> cameras;

    Future<void> main() async {
      WidgetsFlutterBinding.ensureInitialized();

      cameras = await availableCameras();
         _cameraController.setFlashMode(FlashMode.always);

      runApp(CameraApp());
    }

    class CameraApp extends StatefulWidget {
      @override
      _CameraAppState createState() => _CameraAppState();
    }

    class _CameraAppState extends State<CameraApp> {
     CameraController controller;
 
      @override
      void initState() {

        super.initState();
        controller = CameraController(cameras[0],                         ResolutionPreset.max);

        controller.initialize().then((_) {

          if (!mounted) {
            return;
          }
          setState(() { 
    });

        });
      }

      @override
      void dispose() {
        controller?.dispose();
        super.dispose();
      }

      @override
      Widget build(BuildContext context) {
        if (!controller.value.isInitialized) {

          return Container();
        }
        return MaterialApp(
          home: CameraPreview(controller),
        );
      }
    }

Answer 1

you can set flashmode using the camera controller use it like this

CameraController  _cameraController;
List<CameraDescription> cameras=await availableCameras();
controller = CameraController(cameras[0], ResolutionPreset.max);
_cameraController.setFlashMode(FlashMode.always);
     _cameraController.setFlashMode(FlashMode.always);

and assign the controller to the camera preview

CameraPreview(_cameraController)

Answer 2

To keep the flash on while streaming the only way I could do it was using controller.setFlashMode(FlashMode.torch);

Answer 3

According to the official documentation:

/// The possible flash modes that can be set for a camera
enum FlashMode {
  /// Do not use the flash when taking a picture.
  off,

  /// Let the device decide whether to flash the camera when taking a picture.
  auto,

  /// Always use the flash when taking a picture.
  always,

  /// Turns on the flashlight and keeps it on until switched off.
  torch,
}

While streaming and videoing make sure to set the flash mode to torch:

_cameraController.setFlashMode(FlashMode.torch)