MainActivity.cs

using Android.Content.PM;
using Android.Views;
using AndroidX.Fragment.App;
using Xamarin.Essentials;
using ZXing.Mobile;

namespace Sample.NetAndroid
{
	[Activity(
		Label = "@string/app_name",
		MainLauncher = true,
		Theme = "@style/Theme.AppCompat.Light",
		ConfigurationChanges = ConfigChanges.Orientation | ConfigChanges.KeyboardHidden)]
	public class MainActivity : Activity
	{
		MobileBarcodeScanner scanner;
		Button buttonScanCustomView;
		Button buttonScanDefaultView;
		Button buttonContinuousScan;
		Button buttonFragmentScanner;
		Button buttonGenerate;

		protected override void OnCreate(Bundle? savedInstanceState)
		{
			base.OnCreate(savedInstanceState);

			Platform.Init(Application);

			// Set our view from the "main" layout resource
			SetContentView(Resource.Layout.activity_main);

			//Create a new instance of our Scanner
			scanner = new MobileBarcodeScanner();

			buttonScanDefaultView = FindViewById<Button>(Resource.Id.buttonScanDefaultView);
			buttonScanDefaultView.Click +=
				async delegate
				{
					//Tell our scanner to use the default overlay
					scanner.UseCustomOverlay = false;

					//We can customize the top and bottom text of the default overlay
					scanner.TopText = "Hold the camera up to the barcode\nAbout 6 inches away";
					scanner.BottomText = "Wait for the barcode to automatically scan!";

					//Start scanning
					var result = await scanner.Scan();

					HandleScanResult(result);
				};

			buttonContinuousScan = FindViewById<Button>(Resource.Id.buttonScanContinuous);
			buttonContinuousScan.Click +=
				delegate
				{
					scanner.UseCustomOverlay = false;

					//We can customize the top and bottom text of the default overlay
					scanner.TopText = "Hold the camera up to the barcode\nAbout 6 inches away";
					scanner.BottomText = "Wait for the barcode to automatically scan!";

					var opt = new MobileBarcodeScanningOptions();
					opt.DelayBetweenContinuousScans = 3000;

					//Start scanning
					scanner.ScanContinuously(opt, HandleScanResult);
				};

			Button flashButton;
			View zxingOverlay;

			buttonScanCustomView = this.FindViewById<Button>(Resource.Id.buttonScanCustomView);
			buttonScanCustomView.Click +=
				async delegate
				{
					//Tell our scanner we want to use a custom overlay instead of the default
					scanner.UseCustomOverlay = true;

					//Inflate our custom overlay from a resource layout
					zxingOverlay = LayoutInflater.FromContext(this).Inflate(Resource.Layout.ZxingOverlay, null);

					//Find the button from our resource layout and wire up the click event
					flashButton = zxingOverlay.FindViewById<Button>(Resource.Id.buttonZxingFlash);
					flashButton.Click += (sender, e) => scanner.ToggleTorch();

					//Set our custom overlay
					scanner.CustomOverlay = zxingOverlay;

					//Start scanning!
					var result = await scanner.Scan(new MobileBarcodeScanningOptions { AutoRotate = true });

					HandleScanResult(result);
				};

			buttonFragmentScanner = FindViewById<Button>(Resource.Id.buttonFragment);
			buttonFragmentScanner.Click += delegate { StartActivity(typeof(FragmentActivity)); };

			buttonGenerate = FindViewById<Button>(Resource.Id.buttonGenerate);
			buttonGenerate.Click += delegate { StartActivity(typeof(ImageActivity)); };
		}

		void HandleScanResult(ZXing.Result result)
		{
			var msg = "";

			if (result != null && !string.IsNullOrEmpty(result.Text))
				msg = "Found Barcode: " + result.Text;
			else
				msg = "Scanning Canceled!";

			RunOnUiThread(() => Toast.MakeText(this, msg, ToastLength.Short).Show());
		}
	}
}