ZXING MonoTouch ZxingViewController

ZxingViewController.cs

using System;
using System.Collections;
using System.Runtime.InteropServices;
using MonoTouch.UIKit;
using MonoTouch.CoreFoundation;
using MonoTouch.AVFoundation;
using MonoTouch.CoreVideo;
using MonoTouch.CoreMedia;
using com.google.zxing;
using com.google.zxing.common;

namespace Shield.IPhone
{
	// based on https://github.com/xamarin/monotouch-samples/blob/master/AVCaptureFrames/Main.cs
	public class ZxingViewController : UIViewController
	{

		public event Action<Result> Scan;

		AVCaptureSession session;
		AVCaptureVideoPreviewLayer previewLayer;
		AVCaptureDevice captureDevice;

		UIImageView overlayView;
		UIButton buttonCancel;
		UIButton buttonFlash;

		DispatchQueue queue;
		ZxingScanner scanner;

		public override void LoadView ()
		{
			base.LoadView ();

			if (!SetupCaptureSession ())
				throw new NotSupportedException ("Unable to setup camera for scan");

			previewLayer.Frame = UIScreen.MainScreen.Bounds;
			View.Layer.AddSublayer (previewLayer);
		}

		public override void ViewDidLoad ()
		{
			overlayView = new UIImageView(UIScreen.MainScreen.Bounds);
			//Use your own overlay image here 
			//overlayView.Image = UIImage.FromFile("Images/BarCodeOverlay.png");
			this.View.AddSubview(overlayView);

			buttonCancel = new UIButton(UIButtonType.RoundedRect);
			buttonCancel.Frame = new System.Drawing.RectangleF(20, 20, 130, 30);
			buttonCancel.SetTitle("Cancel", UIControlState.Normal);
			buttonCancel.Alpha = 0.3f;
			buttonCancel.SetTitleColor(UIColor.White, UIControlState.Normal);
			buttonCancel.TintColor = UIColor.Gray;
			buttonCancel.TouchUpInside += (sender, e) => {
				this.Scan(null);
			};

			this.View.AddSubview(buttonCancel);

			buttonFlash = new UIButton(UIButtonType.RoundedRect);
			buttonFlash.Frame = new System.Drawing.RectangleF(170, 20, 130, 30);
			buttonFlash.SetTitle("Flash On", UIControlState.Normal);
			buttonFlash.Alpha = 0.3f;
			buttonFlash.TintColor = UIColor.Gray;
			buttonFlash.SetTitleColor(UIColor.White, UIControlState.Normal);
			//buttonFlash.HorizontalAlignment = UIControlContentHorizontalAlignment.Right;
			buttonFlash.TouchUpInside += (sender, e) => {
				if (captureDevice != null)
				{
					if (captureDevice.TorchAvailable)
					{
						MonoTouch.Foundation.NSError err = null;

						captureDevice.LockForConfiguration(out err);

						if (captureDevice.TorchMode == AVCaptureTorchMode.Auto || captureDevice.TorchMode == AVCaptureTorchMode.Off)
							captureDevice.TorchMode = AVCaptureTorchMode.On;
						else
							captureDevice.TorchMode = AVCaptureTorchMode.Off;

						captureDevice.UnlockForConfiguration();

						this.BeginInvokeOnMainThread(() => {
							if (buttonFlash.CurrentTitle == "Flash On")
								buttonFlash.SetTitle("Flash Off", UIControlState.Normal);
							else
								buttonFlash.SetTitle("Flash On", UIControlState.Normal);
						});
					}
				}
			};
			this.View.AddSubview(buttonFlash);

		}
		bool SetupCaptureSession ()
		{
			// configure the capture session for low resolution, change this if your code
			// can cope with more data or volume
			session = new AVCaptureSession () {
				SessionPreset = AVCaptureSession.PresetMedium
			};

			// create a device input and attach it to the session
			captureDevice = AVCaptureDevice.DefaultDeviceWithMediaType (AVMediaType.Video);
			var input = AVCaptureDeviceInput.FromDevice (captureDevice);
			if (input == null){
				// No input device
				return false;
			}
			session.AddInput (input);

			// create a VideoDataOutput and add it to the sesion
			var output = new AVCaptureVideoDataOutput () {
				VideoSettings = new AVVideoSettings (CVPixelFormatType.CV32BGRA)
			};


			// configure the output
			queue = new DispatchQueue ("myQueue");
			scanner = new ZxingScanner (this);
			output.SetSampleBufferDelegateAndQueue (scanner, queue);
			session.AddOutput (output);
		
			previewLayer = new AVCaptureVideoPreviewLayer (session);
			previewLayer.Orientation = AVCaptureVideoOrientation.Portrait;
			previewLayer.VideoGravity = "AVLayerVideoGravityResizeAspectFill";

			session.StartRunning ();
			return true;
		}
	
		class ZxingScanner : AVCaptureVideoDataOutputSampleBufferDelegate
		{
			bool gotResult = false;
			ZxingViewController parent;
			MultiFormatReader reader;
			byte [] bytes;

			public ZxingScanner (ZxingViewController parent)
			{
				this.parent = parent;
				this.reader = new MultiFormatReader {
					Hints = new Hashtable {
						{ DecodeHintType.POSSIBLE_FORMATS, new ArrayList { 
							BarcodeFormat.UPC_A, BarcodeFormat.UPC_E , BarcodeFormat.CODE_128,
							BarcodeFormat.CODE_39, BarcodeFormat.EAN_13, BarcodeFormat.EAN_8
							} }
					}
				};
			}

			public override void DidOutputSampleBuffer (AVCaptureOutput captureOutput, CMSampleBuffer sampleBuffer, AVCaptureConnection connection)
			{
				try {

					if (!gotResult)
					{
						LuminanceSource luminance;
						connection.VideoOrientation = AVCaptureVideoOrientation.Portrait;

						using (var pixelBuffer = sampleBuffer.GetImageBuffer () as CVPixelBuffer) {
		
							if (bytes == null)
								bytes = new byte [pixelBuffer.Height * pixelBuffer.BytesPerRow];
		
							pixelBuffer.Lock (0);
							Marshal.Copy (pixelBuffer.BaseAddress, bytes, 0, bytes.Length);
		
							luminance = new RGBLuminanceSource (bytes, pixelBuffer.Width, pixelBuffer.Height);


							pixelBuffer.Unlock (0);
						}

						var binarized = new BinaryBitmap (new HybridBinarizer (luminance));
						var result = reader.decodeWithState (binarized);

						//parent.session.StopRunning ();

						gotResult = true;

						if (parent.Scan != null)
						{
							MonoTouch.AudioToolbox.SystemSound.FromFile ("Sounds/beep.wav").PlayAlertSound ();
							parent.Scan (result);
						}
					}

				} catch (ReaderException) {

					// ignore this exception; it happens every time there is a failed scan

				} catch (Exception e) {

					// TODO: this one is unexpected.. log or otherwise handle it

					throw;

				} finally {
					try {
						// lamest thing, but seems that this throws :(
						sampleBuffer.Dispose ();
					} catch { }
				}
			}
		}
	}
}