The idea of this pull is to make decoding capability as a plugin.

Camera.MAUI.Plugin.MLKit/Camera.MAUI.Plugin.MLKit.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFrameworks>net7.0-android;net7.0-ios;</TargetFrameworks>
+		<TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('windows'))">$(TargetFrameworks);net7.0-windows10.0.19041.0</TargetFrameworks>
+		<!-- Uncomment to also build the tizen app. You will need to install tizen by following this: https://github.com/Samsung/Tizen.NET -->
+		<!-- <TargetFrameworks>$(TargetFrameworks);net7.0-tizen</TargetFrameworks> -->
+		<UseMaui>true</UseMaui>
+		<SingleProject>true</SingleProject>
+		<ImplicitUsings>enable</ImplicitUsings>
+
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'ios'">11.0</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'maccatalyst'">13.1</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'android'">26.0</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows'">10.0.17763.0</SupportedOSPlatformVersion>
+		<TargetPlatformMinVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows'">10.0.17763.0</TargetPlatformMinVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'tizen'">6.5</SupportedOSPlatformVersion>
+
+		<Authors>programatix</Authors>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<PackageReference Include="Xamarin.Build.Download" Version="0.11.4" />
+	</ItemGroup>
+
+	<ItemGroup Condition="'$(TargetFramework)' == 'net7.0-ios'">
+		<PackageReference Include="Xamarin.Firebase.iOS.Core" Version="8.10.0.3" />
+		<PackageReference Include="Xamarin.MLKit.iOS.BarcodeScanning.JimmyPun610" Version="1.6.0.1" />
+		<PackageReference Include="Xamarin.MLKit.iOS.Core.JimmyPun610" Version="5.0.0.1" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<ProjectReference Include="..\Camera.MAUI.Plugin\Camera.MAUI.Plugin.csproj" />
+	</ItemGroup>
+
+	<ItemGroup Condition="'$(TargetFramework)' == 'net7.0-android'">
+		<PackageReference Include="Xamarin.AndroidX.Activity">
+			<Version>1.8.1.1</Version>
+		</PackageReference>
+		<PackageReference Include="Xamarin.AndroidX.Activity.Ktx">
+			<Version>1.8.1.1</Version>
+		</PackageReference>
+		<PackageReference Include="Xamarin.AndroidX.Collection.Jvm">
+			<Version>1.3.0.2</Version>
+		</PackageReference>
+		<PackageReference Include="Xamarin.AndroidX.Collection.Ktx">
+			<Version>1.3.0.2</Version>
+		</PackageReference>
+		<PackageReference Include="Xamarin.AndroidX.Lifecycle.Common">
+			<Version>2.6.2.3</Version>
+		</PackageReference>
+		<PackageReference Include="Xamarin.Google.MLKit.BarcodeScanning">
+			<Version>117.2.0.2</Version>
+		</PackageReference>
+		<PackageReference Include="Xamarin.Google.MLKit.BarcodeScanning.Common">
+			<Version>117.0.0.7</Version>
+		</PackageReference>
+		<PackageReference Include="Xamarin.GooglePlayServices.MLKit.BarcodeScanning">
+			<Version>118.3.0.2</Version>
+		</PackageReference>
+	</ItemGroup>
+</Project>

Camera.MAUI.Plugin.MLKit/Extensions.cs

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+namespace Camera.MAUI.Plugin.MLKit
+{
+    internal static class Extensions
+    {
+    }
+}

Camera.MAUI.Plugin.MLKit/MLKitBarcodeDecoder.cs

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+#if IOS || MACCATALYST
+using Foundation;
+using global::MLKit.BarcodeScanning;
+using global::MLKit.Core;
+using DecodeDataType = UIKit.UIImage;
+#elif ANDROID
+
+using Xamarin.Google.MLKit.Vision.BarCode;
+using Xamarin.Google.MLKit.Vision.Common;
+using static Xamarin.Google.MLKit.Vision.Barcode.Common.Barcode;
+using BarcodeScanner = Xamarin.Google.MLKit.Vision.BarCode.IBarcodeScanner;
+using DecodeDataType = Android.Graphics.Bitmap;
+
+#elif WINDOWS
+using BarcodeScanner = System.Object;
+using DecodeDataType = Windows.Graphics.Imaging.SoftwareBitmap;
+#endif
+
+namespace Camera.MAUI.Plugin.MLKit
+{
+    public class MLKitBarcodeDecoder : PluginDecoder<MLKitBarcodeDecoderOptions, BarcodeResult>
+    {
+        #region Private Fields
+
+        private BarcodeScanner barcodeScanner;
+
+        #endregion Private Fields
+
+        #region Public Methods
+
+        public override void ClearResults()
+        {
+        }
+
+        public
+#if ANDROID
+            async
+#endif
+            override void Decode(DecodeDataType data)
+        {
+            try
+            {
+#if ANDROID
+                var image = InputImage.FromBitmap(data, 0);
+                var result = await barcodeScanner.Process(image).ToAwaitableTask();
+                var results = Methods.ProcessBarcodeResult(result);
+                if (results?.Count > 0)
+                {
+                    OnDecoded(new PluginDecodedEventArgs { Results = results.ToArray() });
+                }
+                image.Dispose();
+#elif IOS
+                var image = new MLImage(data) { Orientation = UIKit.UIImageOrientation.Up };
+                barcodeScanner.ProcessImage(image, (barcodes, error) =>
+                {
+                    var results = new List<BarcodeResult>();
+                    foreach (var barcode in barcodes)
+                        results.Add(Methods.ProcessBarcodeResult(barcode));
+
+                    if (results.Count > 0)
+                    {
+                        OnDecoded(new PluginDecodedEventArgs { Results = results.ToArray() });
+                    }
+
+                    image.Dispose();
+                });
+#else
+                throw new NotImplementedException();
+#endif
+            }
+            catch { }
+            finally
+            {
+            }
+        }
+
+        #endregion Public Methods
+
+        #region Protected Methods
+
+        protected override void OnOptionsChanged(object oldValue, object newValue)
+        {
+            if (newValue is BarcodeDecoderOptions barcodeOptions)
+            {
+#if ANDROID || IOS
+                var platformFormats = barcodeOptions.PossibleFormats?.Count > 0
+                    ? barcodeOptions.PossibleFormats.Select(x => x.ToPlatform()).Aggregate((r, x) => r |= x)
+                    : default;
+#if ANDROID
+                barcodeScanner = BarcodeScanning.GetClient(new BarcodeScannerOptions.Builder()
+                    .SetBarcodeFormats(platformFormats == default ? FormatAllFormats : platformFormats)
+                    .Build()
+                );
+#elif IOS
+                var scannerOptions = new BarcodeScannerOptions(platformFormats == default ? global::MLKit.BarcodeScanning.BarcodeFormat.Unknown : platformFormats);
+                barcodeScanner = BarcodeScanner.BarcodeScannerWithOptions(scannerOptions);
+#endif
+#endif
+            }
+            if (newValue is MLKitBarcodeDecoderOptions mlkitOptions)
+            {
+            }
+        }
+
+        #endregion Protected Methods
+    }
+}

Camera.MAUI.Plugin.MLKit/MLKitBarcodeDecoderOptions.cs

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+namespace Camera.MAUI.Plugin.MLKit
+{
+    public record MLKitBarcodeDecoderOptions : BarcodeDecoderOptions
+    {
+    }
+}

Camera.MAUI.Plugin.MLKit/Platforms/Android/Methods.cs

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+using Android.Runtime;
+using Java.Util;
+using Xamarin.Google.MLKit.Vision.Barcode.Common;
+
+namespace Camera.MAUI.Plugin.MLKit
+{
+    internal static class Methods
+    {
+        internal static int ToPlatform(this BarcodeFormat format)
+        {
+            return format switch
+            {
+                BarcodeFormat.AZTEC => Barcode.FormatAztec,
+                BarcodeFormat.CODABAR => Barcode.FormatCodabar,
+                BarcodeFormat.CODE_128 => Barcode.FormatCode128,
+                BarcodeFormat.CODE_39 => Barcode.FormatCode39,
+                BarcodeFormat.CODE_93 => Barcode.FormatCode93,
+                BarcodeFormat.DATA_MATRIX => Barcode.FormatDataMatrix,
+                BarcodeFormat.EAN_13 => Barcode.FormatEan13,
+                BarcodeFormat.EAN_8 => Barcode.FormatEan8,
+                BarcodeFormat.ITF => Barcode.FormatItf,
+                BarcodeFormat.PDF_417 => Barcode.FormatPdf417,
+                BarcodeFormat.QR_CODE => Barcode.FormatQrCode,
+                BarcodeFormat.UPC_A => Barcode.FormatUpcA,
+                BarcodeFormat.UPC_E => Barcode.FormatUpcE,
+                _ => Barcode.FormatUnknown,
+            };
+        }
+
+        internal static BarcodeFormat BarcodeFormatToNative(this int format)
+        {
+            return format switch
+            {
+                Barcode.FormatAztec => BarcodeFormat.AZTEC,
+                Barcode.FormatCodabar => BarcodeFormat.CODABAR,
+                Barcode.FormatCode128 => BarcodeFormat.CODE_128,
+                Barcode.FormatCode39 => BarcodeFormat.CODE_39,
+                Barcode.FormatCode93 => BarcodeFormat.CODE_93,
+                Barcode.FormatDataMatrix => BarcodeFormat.DATA_MATRIX,
+                Barcode.FormatEan13 => BarcodeFormat.EAN_13,
+                Barcode.FormatEan8 => BarcodeFormat.EAN_8,
+                Barcode.FormatItf => BarcodeFormat.ITF,
+                Barcode.FormatPdf417 => BarcodeFormat.PDF_417,
+                Barcode.FormatQrCode => BarcodeFormat.QR_CODE,
+                Barcode.FormatUpcA => BarcodeFormat.UPC_A,
+                Barcode.FormatUpcE => BarcodeFormat.UPC_E,
+                _ => throw new NotSupportedException()
+            };
+        }
+
+        internal static List<BarcodeResult> ProcessBarcodeResult(Java.Lang.Object result)
+        {
+            if (result == null)
+                return null;
+            var javaList = result.JavaCast<ArrayList>();
+            if (javaList.IsEmpty)
+                return null;
+            var resultList = new List<BarcodeResult>();
+
+            foreach (var barcode in javaList.ToArray())
+            {
+                var mapped = barcode.JavaCast<Barcode>();
+                var cornerPoints = new List<Point>();
+
+                foreach (var cornerPoint in mapped.GetCornerPoints())
+                    cornerPoints.Add(new Point(cornerPoint.X, cornerPoint.Y));
+
+                resultList.Add(new BarcodeResult(mapped.DisplayValue, mapped.GetRawBytes(), cornerPoints.ToArray(), mapped.Format.BarcodeFormatToNative()));
+            }
+
+            return resultList;
+        }
+
+        internal static Task<Java.Lang.Object> ToAwaitableTask(this global::Android.Gms.Tasks.Task task)
+        {
+            var taskCompletionSource = new TaskCompletionSource<Java.Lang.Object>();
+            var taskCompleteListener = new TaskCompleteListener(taskCompletionSource);
+            task.AddOnCompleteListener(taskCompleteListener);
+
+            return taskCompletionSource.Task;
+        }
+    }
+}

Camera.MAUI.Plugin.MLKit/Platforms/Android/TaskCompleteListener.cs

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+using Android.Gms.Tasks;
+
+namespace Camera.MAUI.Plugin.MLKit
+{
+    internal class TaskCompleteListener : Java.Lang.Object, IOnCompleteListener
+    {
+        private readonly TaskCompletionSource<Java.Lang.Object> _taskCompletionSource;
+
+        public TaskCompleteListener(TaskCompletionSource<Java.Lang.Object> tcs)
+        {
+            _taskCompletionSource = tcs;
+        }
+
+        public void OnComplete(global::Android.Gms.Tasks.Task task)
+        {
+            if (task.IsCanceled)
+            {
+                _taskCompletionSource.SetCanceled();
+            }
+            else if (task.IsSuccessful)
+            {
+                _taskCompletionSource.SetResult(task.Result);
+            }
+            else
+            {
+                _taskCompletionSource.SetException(task.Exception);
+            }
+        }
+    }
+}

Camera.MAUI.Plugin.MLKit/Platforms/iOS/Methods.cs

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+namespace Camera.MAUI.Plugin.MLKit
+{
+    internal static class Methods
+    {
+        internal static global::MLKit.BarcodeScanning.BarcodeFormat ToPlatform(this BarcodeFormat format)
+        {
+            return format switch
+            {
+                BarcodeFormat.AZTEC => global::MLKit.BarcodeScanning.BarcodeFormat.Aztec,
+                BarcodeFormat.CODABAR => global::MLKit.BarcodeScanning.BarcodeFormat.CodaBar,
+                BarcodeFormat.CODE_128 => global::MLKit.BarcodeScanning.BarcodeFormat.Code128,
+                BarcodeFormat.CODE_39 => global::MLKit.BarcodeScanning.BarcodeFormat.Code39,
+                BarcodeFormat.CODE_93 => global::MLKit.BarcodeScanning.BarcodeFormat.Code93,
+                BarcodeFormat.DATA_MATRIX => global::MLKit.BarcodeScanning.BarcodeFormat.DataMatrix,
+                BarcodeFormat.EAN_13 => global::MLKit.BarcodeScanning.BarcodeFormat.Ean13,
+                BarcodeFormat.EAN_8 => global::MLKit.BarcodeScanning.BarcodeFormat.Ean8,
+                BarcodeFormat.ITF => global::MLKit.BarcodeScanning.BarcodeFormat.Itf,
+                BarcodeFormat.PDF_417 => global::MLKit.BarcodeScanning.BarcodeFormat.Pdf417,
+                BarcodeFormat.QR_CODE => global::MLKit.BarcodeScanning.BarcodeFormat.QrCode,
+                BarcodeFormat.UPC_A => global::MLKit.BarcodeScanning.BarcodeFormat.Upca,
+                BarcodeFormat.UPC_E => global::MLKit.BarcodeScanning.BarcodeFormat.Upce,
+                _ => global::MLKit.BarcodeScanning.BarcodeFormat.Unknown,
+            };
+        }
+
+        internal static BarcodeFormat BarcodeFormatToNative(this global::MLKit.BarcodeScanning.BarcodeFormat format)
+        {
+            return format switch
+            {
+                global::MLKit.BarcodeScanning.BarcodeFormat.Aztec => BarcodeFormat.AZTEC,
+                global::MLKit.BarcodeScanning.BarcodeFormat.CodaBar => BarcodeFormat.CODABAR,
+                global::MLKit.BarcodeScanning.BarcodeFormat.Code128 => BarcodeFormat.CODE_128,
+                global::MLKit.BarcodeScanning.BarcodeFormat.Code39 => BarcodeFormat.CODE_39,
+                global::MLKit.BarcodeScanning.BarcodeFormat.Code93 => BarcodeFormat.CODE_93,
+                global::MLKit.BarcodeScanning.BarcodeFormat.DataMatrix => BarcodeFormat.DATA_MATRIX,
+                global::MLKit.BarcodeScanning.BarcodeFormat.Ean13 => BarcodeFormat.EAN_13,
+                global::MLKit.BarcodeScanning.BarcodeFormat.Ean8 => BarcodeFormat.EAN_8,
+                global::MLKit.BarcodeScanning.BarcodeFormat.Itf => BarcodeFormat.ITF,
+                global::MLKit.BarcodeScanning.BarcodeFormat.Pdf417 => BarcodeFormat.PDF_417,
+                global::MLKit.BarcodeScanning.BarcodeFormat.QrCode => BarcodeFormat.QR_CODE,
+                global::MLKit.BarcodeScanning.BarcodeFormat.Upca => BarcodeFormat.UPC_A,
+                global::MLKit.BarcodeScanning.BarcodeFormat.Upce => BarcodeFormat.UPC_E,
+                _ => throw new NotSupportedException()
+            };
+        }
+
+        internal static BarcodeResult ProcessBarcodeResult(global::MLKit.BarcodeScanning.Barcode barcode)
+        {
+            var cornerPoints = new List<Point>();
+
+            foreach (var cornerPoint in barcode.CornerPoints)
+                cornerPoints.Add(new Point(cornerPoint.CGPointValue.X, cornerPoint.CGPointValue.Y));
+
+            return new BarcodeResult(barcode.DisplayValue, barcode.RawData.ToArray(), cornerPoints.ToArray(), barcode.Format.BarcodeFormatToNative());
+        }
+    }
+}

Camera.MAUI.Plugin.ZXing/Camera.MAUI.Plugin.ZXing.csproj

@@ -0,0 +1,35 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFrameworks>net7.0;net7.0-android;net7.0-ios;net7.0-maccatalyst</TargetFrameworks>
+		<TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('windows'))">$(TargetFrameworks);net7.0-windows10.0.19041.0</TargetFrameworks>
+		<!-- Uncomment to also build the tizen app. You will need to install tizen by following this: https://github.com/Samsung/Tizen.NET -->
+		<!-- <TargetFrameworks>$(TargetFrameworks);net7.0-tizen</TargetFrameworks> -->
+		<UseMaui>true</UseMaui>
+		<SingleProject>true</SingleProject>
+		<ImplicitUsings>enable</ImplicitUsings>
+
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'ios'">11.0</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'maccatalyst'">13.1</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'android'">26.0</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows'">10.0.17763.0</SupportedOSPlatformVersion>
+		<TargetPlatformMinVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows'">10.0.17763.0</TargetPlatformMinVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'tizen'">6.5</SupportedOSPlatformVersion>
+
+		<Authors>hjam40,programatix</Authors>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<PackageReference Include="ZXing.Net" Version="0.16.9" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<ProjectReference Include="..\Camera.MAUI.Plugin\Camera.MAUI.Plugin.csproj" />
+	</ItemGroup>
+
+	<!-- Both iOS and Mac Catalyst -->
+	<ItemGroup Condition="$(TargetFramework.StartsWith('net7.0-ios')) != true AND $(TargetFramework.StartsWith('net7.0-maccatalyst')) != true">
+		<Compile Remove="**\MaciOS\**\*.cs" />
+		<None Include="**\MaciOS\**\*.cs" Exclude="$(DefaultItemExcludes);$(DefaultExcludesInProjectFolder)" />
+	</ItemGroup>
+</Project>