https://www.b4x.com/android/forum/threads/b4x-b4xpages-barcode-reader-with-torch.123781/
Sub btnTorch_Click
If Capturing Then
#If B4i
If scanner.TorchMode = scanner.TORCH_OFF Then
scanner.TorchMode = scanner.TORCH_ON
btnTorch.Text = "Torch Off"
Else
scanner.TorchMode = scanner.TORCH_OFF
btnTorch.Text = "Torch On"
End If
#Else If B4A
If camEx.GetFlashMode <> "torch" Then
camEx.SetFlashMode("torch")
camEx.CommitParameters
btnTorch.Text = "Torch Off"
Else
camEx.SetFlashMode("off")
camEx.CommitParameters
btnTorch.Text = "Torch On"
End If
#End If
End If
End Sub