Narrow scanning area (Android and iOS)

Samples/Sample.Android/MainActivity.cs

@@ -45,7 +45,10 @@ protected override void OnCreate(Bundle bundle)
 				scanner.BottomText = "Wait for the barcode to automatically scan!";
 
 				//Start scanning
-				var result = await scanner.Scan();
+				var result = await scanner.Scan( new MobileBarcodeScanningOptions 
+				{ 
+					ScanningArea = ScanningArea.From(0f, 0.49f, 1f, 0.51f)
+				});
 
 				HandleScanResult(result);
 			};

Samples/Sample.Forms/Sample.Forms/HomePage.cs

@@ -4,6 +4,8 @@
 using System.Text;
 using System.Threading.Tasks;
 using Xamarin.Forms;
+using ZXing;
+using ZXing.Mobile;
 using ZXing.Net.Mobile.Forms;
 
 namespace Sample.Forms
@@ -17,6 +19,7 @@ public class HomePage : ContentPage
 		Button buttonScanContinuousCustomPage;
 		Button buttonScanCustomPage;
 		Button buttonGenerateBarcode;
+		Button buttonScanMiddle1D;
 
 
 		public HomePage() : base()
@@ -130,8 +133,36 @@ public HomePage() : base()
 				await Navigation.PushAsync(new BarcodePage());
 			};
 
+			buttonScanMiddle1D = new Button
+			{
+				Text = "Scan 1D only in the middle (Android and iOS only)",
+				AutomationId = "barcodeMiddleScan1D"
+			};
+			buttonScanMiddle1D.Clicked += async delegate
+			{
+				scanPage = new ZXingScannerPage(new MobileBarcodeScanningOptions
+				{
+					ScanningArea = ScanningArea.From(0f, 0.49f, 1f, 0.51f),
+					PossibleFormats = new List<BarcodeFormat> { BarcodeFormat.All_1D }
+				});
+
+				scanPage.OnScanResult += (result) =>
+				{
+					scanPage.IsScanning = false;
+
+					Device.BeginInvokeOnMainThread(async () =>
+					{
+						await Navigation.PopAsync();
+						await DisplayAlert("Scanned Barcode", result.Text, "OK");
+					});
+				};
+
+				await Navigation.PushAsync(scanPage);
+			};
+
 			var stack = new StackLayout();
 			stack.Children.Add(buttonScanDefaultOverlay);
+			stack.Children.Add(buttonScanMiddle1D);
 			stack.Children.Add(buttonScanCustomOverlay);
 			stack.Children.Add(buttonScanContinuously);
 			stack.Children.Add(buttonScanCustomPage);

Samples/Sample.iOS/HomeViewController.cs

@@ -1,10 +1,6 @@
 using System;
 using MonoTouch.Dialog;
-
-using Foundation;
-using CoreGraphics;
 using UIKit;
-
 using ZXing;
 using ZXing.Mobile;
 using System.Collections.Generic;
@@ -25,18 +21,38 @@ public override void ViewDidLoad()
 			//Create a new instance of our scanner
 			scanner = new MobileBarcodeScanner(this.NavigationController);
 
-			Root = new RootElement("ZXing.Net.Mobile") {
+			Root = new RootElement("ZXing.Net.Mobile")
+			{
 				new Section {
+					new StyledStringElement("Scan with Default View", async () =>
+					{
+						//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 camera up to barcode to scan";
+						scanner.BottomText = "Barcode will automatically scan";
+
+						//Start scanning
+						var result = await scanner.Scan(new MobileBarcodeScanningOptions
+						{
+							ScanningArea = ScanningArea.From(0f, 0.3f, 1f, 0.7f)
+						});
 
-					new StyledStringElement ("Scan with Default View", async () => {
+						HandleScanResult(result);
+					}),
+					new StyledStringElement("Scan with Default View using laser point", async () =>
+					{
 						//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 camera up to barcode to scan";
 						scanner.BottomText = "Barcode will automatically scan";
 
 						//Start scanning
-						var result = await scanner.Scan ();
+						var result = await scanner.Scan(new MobileBarcodeScanningOptions
+						{
+							ScanningArea = ScanningArea.From(0f, 0.49f, 1f, 0.51f)
+						});
 
 						HandleScanResult(result);
 					}),
@@ -145,4 +161,4 @@ public void UITestBackdoorScan(string param)
 			});
 		}
 	}
-}
+}

ZXing.Net.Mobile/Android/CameraAccess/CameraAnalyzer.android.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Generic;
 using System.Threading.Tasks;
 using Android.Views;
 using ApxLabs.FastAndroidCamera;
@@ -112,8 +111,6 @@ void DecodeFrame(FastJavaByteArray fastArray)
 			var width = cameraParameters.PreviewSize.Width;
 			var height = cameraParameters.PreviewSize.Height;
 
-			var barcodeReader = scannerHost.ScanningOptions.BuildBarcodeReader();
-
 			var rotate = false;
 			var newWidth = width;
 			var newHeight = height;
@@ -131,10 +128,33 @@ void DecodeFrame(FastJavaByteArray fastArray)
 			ZXing.Result result = null;
 			var start = PerformanceCounter.Start();
 
-			LuminanceSource fast = new FastJavaByteArrayYUVLuminanceSource(fastArray, width, height, 0, 0, width, height); // _area.Left, _area.Top, _area.Width, _area.Height);
+			var scanningRect = scannerHost.ScanningOptions.ScanningArea;
+			if (rotate)
+			{
+				scanningRect = scanningRect.RotateCounterClockwise();
+			}
+
+			var left = (int) (width * scanningRect.StartX);
+			var top = (int) (height * scanningRect.StartY);
+			var endHeight = (int) (scanningRect.EndY * height) - top;
+			var endWidth = (int) (scanningRect.EndX * width) - left;
+
+			LuminanceSource fast =
+				new FastJavaByteArrayYUVLuminanceSource(
+					fastArray,
+					width,
+					height,
+					left,
+					top,
+					endWidth,
+					endHeight);
+
 			if (rotate)
+			{
 				fast = fast.rotateCounterClockwise();
+			}
 
+			var barcodeReader = scannerHost.ScanningOptions.BuildBarcodeReader();
 			result = barcodeReader.Decode(fast);
 
 			fastArray.Dispose();

ZXing.Net.Mobile/MobileBarcodeScanningOptions.shared.cs

@@ -21,12 +21,19 @@ public MobileBarcodeScanningOptions()
 			InitialDelayBeforeAnalyzingFrames = 300;
 			DelayBetweenContinuousScans = 1000;
 			UseNativeScanning = false;
+			ScanningArea = ScanningArea.Default;
 		}
 
 		public CameraResolutionSelectorDelegate CameraResolutionSelector { get; set; }
 
 		public IEnumerable<BarcodeFormat> PossibleFormats { get; set; }
 
+		/// <summary>
+		/// Narrow chosen scanning area.<br/>
+		/// <b>Works only on iOS and Android</b>
+		/// </summary>
+		public ScanningArea ScanningArea { get; set; }
+
 		public bool? TryHarder { get; set; }
 
 		public bool? PureBarcode { get; set; }
@@ -118,4 +125,4 @@ public CameraResolution GetResolution(List<CameraResolution> availableResolution
 			return r;
 		}
 	}
-}
+}

ZXing.Net.Mobile/ScanningArea.cs

@@ -0,0 +1,107 @@
+using System;
+
+namespace ZXing.Mobile
+{
+	/// <summary>
+	/// Representation of restricted scanning area in PERCENTAGE. 
+	/// Allowed values: 0 <= value <= 1 AND startY != endY
+	/// Values of startY and endY are ABSOLUTE to image that means if use values of
+	/// startY:0.49 and endY:0.51 we will scan only 2% of the whole image
+	/// starting at 49% and finishing at 51% of the image height.
+	/// </summary>
+	public class ScanningArea
+	{
+		public float StartX { get; }
+		public float StartY { get; }
+		public float EndX { get; }
+		public float EndY { get; }
+
+		ScanningArea(float startX, float startY, float endX, float endY)
+		{
+			//if difference between parameters is less than 1% we assume those are equal
+			if (Math.Abs(startY - endY) < 0.01f)
+			{
+				throw new ArgumentException($"Values of {nameof(startY)} and {nameof(endY)} cannot be the same");
+			}
+
+			//if difference between parameters is less than 1% we assume those are equal
+			if (Math.Abs(startX - endX) < 0.01f)
+			{
+				throw new ArgumentException($"Values of {nameof(startX)} and {nameof(endX)} cannot be the same");
+			}
+
+			//Reverse values instead of throwing argument exception
+			if (startY > endY)
+			{
+				var temp = endY;
+				endY = startY;
+				startY = temp;
+			}
+
+			if (startX > endX)
+			{
+				var temp = endX;
+				endX = startX;
+				startX = temp;
+			}
+
+			if (startY < 0)
+			{
+				startY = 0;
+			}
+
+			if (endY > 1)
+			{
+				endY = 1;
+			}
+
+			if (startX < 0)
+			{
+				startX = 0;
+			}
+
+			if (endX > 1)
+			{
+				endX = 1;
+			}
+
+			StartY = startY;
+			EndY = endY;
+			StartX = startX;
+			EndX = endX;
+		}
+
+		public ScanningArea RotateCounterClockwise()
+		{
+			var startX = StartY;
+			var startY = EndX;
+			var endX = EndY;
+			var endY = StartX;
+
+			if (startY > endY)
+			{
+				startY = 1f - startY;
+				endY = 1 - endY;
+			}
+
+			if (startX > endX)
+			{
+				startX = 1 - startX;
+				endX = 1 - endX;
+			}
+
+			return new ScanningArea(startX, startY, endX, endY);
+		}
+
+
+		static ScanningArea _default = new ScanningArea(0f, 0f, 1f, 1f);
+
+		/// <summary>
+		/// Returns value that represents whole image.
+		/// </summary>
+		public static ScanningArea Default => _default;
+
+		public static ScanningArea From(float startX, float startY, float endX, float endY) =>
+			new ScanningArea(startX, startY, endX, endY);
+	}
+}

ZXing.Net.Mobile/ZXing.Net.Mobile.csproj

@@ -49,9 +49,13 @@
 		<PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
 	</ItemGroup>
 	<ItemGroup>
+		<Compile Include="ScanningArea.cs" />
 		<None Include="..\Art\ZXing.Net.Mobile-Icon.png" PackagePath="icon.png" Pack="true" />
 		<Compile Include="**\*.shared.cs" />
 		<Compile Include="**\*.shared.*.cs" />
+		<Compile Include="iOS\Helpers\Rect.cs">
+		  <SubType></SubType>
+		</Compile>
 	</ItemGroup>
 	<ItemGroup Condition=" $(TargetFramework.StartsWith('netstandard')) ">
 		<Compile Include="**\*.netstandard.cs" />
@@ -126,4 +130,7 @@
 		<None Include="..\ZXing.Net\zxing.dll" Pack="True" PackagePath="lib\xamarinios10" />
 		<None Include="..\ZXing.Net\zxing.dll" Pack="True" PackagePath="lib\xamarinmac20" />
 	</ItemGroup>
+	<ItemGroup>
+	  <Folder Include="iOS\Helpers\" />
+	</ItemGroup>
 </Project>