toggleTorch() is out of sync with the actual torch state

[edwintsai]

I had upgrade to mobile_scanner 3.5.1, If I set torchEnabled : true, it's working in start the camera, but can't stop torch if I call toggleTorch.

IconButton( color: Colors.white, icon: ValueListenableBuilder( valueListenable: cameraController.torchState, builder: (context, state, child) { switch (state) { case TorchState.off: return const Icon(Icons.flash_off, color: Colors.grey); case TorchState.on: return const Icon(Icons.flash_on, color: Colors.yellow); } }, ), iconSize: 32.0, onPressed: () =>cameraController.toggleTorch(), ) ... controller: MobileScannerController( formats: [BarcodeFormat.qrCode], detectionSpeed: DetectionSpeed.noDuplicates, //DetectionSpeed.normal, facing: CameraFacing.back, detectionTimeoutMs: 1000, returnImage: false, torchEnabled: false, ),

[navaronbracke]

I think I know what the problem might be here.

We turn on the torch if torchEnabled is true. However, we do not forward the torch state to the notifier. And in toggleTorch() we do not check the current state either.

As a workaround you could try to set the torch after the controller was started.

[navaronbracke]

What we should do is the following:

• instead of blindly trying to turn the torch on on the native side, check if the torch is available & on before turning it on
• forward the result of the torch being set to on to the notifier, so the state is in sync
• fix the MacOS implementation to match the iOS one (they both use a slightly different setup)

[navaronbracke]

@edwintsai This should have been fixed on master now. I'm currently looking into a small MLKit related issue on Android, but there should be a hotfix later today with this bug fixed.