Fix #134 - Ability to scale camera preview horizontally and vertically on Android

BarcodeScanning.Native.Maui/CameraView.cs

@@ -321,6 +321,34 @@ public float[] DeviceSwitchZoomFactor
         set => SetValue(DeviceSwitchZoomFactorProperty, value);
     }
 
+    public static readonly BindableProperty CameraPreviewScaleYProperty = BindableProperty.Create(nameof(CameraPreviewScaleY)
+        , typeof(float)
+        , typeof(CameraView)
+        , 1f
+        , BindingMode.OneWayToSource);
+    /// <summary>
+    /// /// Returns the scale factor of the camera preview in Y axis.
+    /// </summary>
+    public float CameraPreviewScaleY
+    {
+        get => (float)GetValue(CameraPreviewScaleYProperty);
+        set => SetValue(CameraPreviewScaleYProperty, value);
+    }
+
+    public static readonly BindableProperty CameraPreviewScaleXProperty = BindableProperty.Create(nameof(CameraPreviewScaleX)
+        , typeof(float)
+        , typeof(CameraView)
+        , 1f
+        , BindingMode.OneWayToSource);
+    /// <summary>
+    /// /// Returns the scale factor of the camera preview in X axis.
+    /// </summary>
+    public float CameraPreviewScaleX
+    {
+        get => (float)GetValue(CameraPreviewScaleXProperty);
+        set => SetValue(CameraPreviewScaleXProperty, value);
+    }
+
     public event EventHandler<OnDetectionFinishedEventArg>? OnDetectionFinished;
     public event EventHandler<OnImageCapturedEventArg>? OnImageCaptured;
 

BarcodeScanning.Native.Maui/CameraViewHandler.cs

@@ -17,7 +17,9 @@ public partial class CameraViewHandler : ViewHandler<CameraView, BarcodeView>
         [nameof(CameraView.AimMode)] = (handler, virtualView) => handler._cameraManager?.UpdateAimMode(),
         [nameof(CameraView.TapToFocusEnabled)] = (handler, virtualView) => handler?._cameraManager?.UpdateTapToFocus(),
         [nameof(CameraView.RequestZoomFactor)] = (handler, virtualView) => handler?._cameraManager?.UpdateZoomFactor(),
-        [nameof(CameraView.VibrationOnDetected)] = (handler, virtualView) => handler?._cameraManager?.UpdateVibration()
+        [nameof(CameraView.VibrationOnDetected)] = (handler, virtualView) => handler?._cameraManager?.UpdateVibration(),
+        [nameof(CameraView.CameraPreviewScaleY)] = (handler, virtualView) => handler?._cameraManager?.UpdatePreviewScale(),
+        [nameof(CameraView.CameraPreviewScaleX)] = (handler, virtualView) => handler?._cameraManager?.UpdatePreviewScale(),
     };
 
     public static readonly CommandMapper<CameraView, CameraViewHandler> CameraCommandMapper = new()

BarcodeScanning.Native.Maui/Platform/Android/CameraManager.cs

@@ -91,7 +91,7 @@ internal CameraManager(CameraView cameraView, Context context)
         _previewView.SetBackgroundColor(_cameraView?.BackgroundColor?.ToPlatform() ?? Color.Transparent);
         _previewView.SetImplementationMode(PreviewView.ImplementationMode.Compatible);
         _previewView.SetScaleType(PreviewView.ScaleType.FillCenter);
-        
+
         using var layoutParams = new RelativeLayout.LayoutParams(LayoutParams.WrapContent, LayoutParams.WrapContent);
         layoutParams.AddRule(LayoutRules.CenterInParent);
         using var circleBitmap = Bitmap.CreateBitmap(2 * aimRadius, 2 * aimRadius, Bitmap.Config.Argb8888);
@@ -136,6 +136,7 @@ internal void Start()
         UpdateCamera();
         UpdateSymbologies();
         UpdateTorch();
+        UpdatePreviewScale();
 
         if (_lifecycleOwner is not null)
             _cameraController?.BindToLifecycle(_lifecycleOwner);
@@ -236,6 +237,15 @@ internal void UpdateZoomFactor()
         }
     }
 
+    internal void UpdatePreviewScale()
+    {
+        if (_cameraView is not null && _previewView is not null)
+        {
+            _previewView.ScaleY = _cameraView.CameraPreviewScaleY;
+            _previewView.ScaleX = _cameraView.CameraPreviewScaleX;
+        }
+    }
+
     internal CoordinateTransform? GetCoordinateTransform(IImageProxy proxy)
     {
         var imageOutputTransform = new ImageProxyTransformFactory().GetOutputTransform(proxy);

BarcodeScanning.Native.Maui/Platform/MaciOS/CameraManager.cs

@@ -243,6 +243,11 @@ internal void UpdateZoomFactor()
         }
     }
 
+    internal void UpdatePreviewScale()
+    {
+        // not supported yet
+    }
+
     private void DeviceLock(Action action)
     {
         DispatchQueue.MainQueue.DispatchBarrierAsync(() =>

BarcodeScanning.Native.Maui/Platform/NET/CameraManager.cs

@@ -14,6 +14,7 @@ internal class CameraManager : IDisposable
     internal void UpdateTorch() => throw new NotImplementedException();
     internal void UpdateVibration() => throw new NotImplementedException();
     internal void UpdateZoomFactor() => throw new NotImplementedException();
+    internal void UpdatePreviewScale() => throw new NotImplementedException();
 
     public void Dispose() => throw new NotImplementedException();
 }

BarcodeScanning.Test/ScanPage.xaml

@@ -23,7 +23,7 @@
                       x:Name="Graphics"
                       InputTransparent="True"/>
 
-        <Grid ColumnDefinitions="*, *, *, *, *, *" AbsoluteLayout.LayoutFlags="All" AbsoluteLayout.LayoutBounds="0,0,1,0.1">
+        <Grid ColumnDefinitions="*, *, *, *, *, *, *" AbsoluteLayout.LayoutFlags="All" AbsoluteLayout.LayoutBounds="0,0,1,0.1">
             <Picker x:Name="Quality" Grid.Column="3" BackgroundColor="Transparent"  WidthRequest="45" HeightRequest="45" SelectedIndexChanged="Quality_SelectedIndexChanged"/>
 
             <Button x:Name="BackButton" Grid.Column="0" WidthRequest="50" HeightRequest="50" CornerRadius="25" Clicked="BackButton_Clicked"/>
@@ -32,6 +32,7 @@
             <Button Text="Q" Grid.Column="3" WidthRequest="50" HeightRequest="50" CornerRadius="25" InputTransparent="True"/>
             <Button Text="V" Grid.Column="4" WidthRequest="50" HeightRequest="50" CornerRadius="25" Clicked="VibrateButton_Clicked"/>
             <Button Text="P" Grid.Column="5" WidthRequest="50" HeightRequest="50" CornerRadius="25" Clicked="PauseButton_Clicked"/>
+            <Button Text="R" Grid.Column="6" WidthRequest="50" HeightRequest="50" CornerRadius="25" Clicked="RotateButton_Clicked" />
         </Grid>
     </AbsoluteLayout>
 

BarcodeScanning.Test/ScanPage.xaml.cs

@@ -84,6 +84,12 @@ private void PauseButton_Clicked(object sender, EventArgs e)
                 Barcode.PauseScanning = true;
         }
 
+        private void RotateButton_Clicked(object sender, EventArgs e)
+        {
+            Barcode.CameraPreviewScaleY = Barcode.CameraPreviewScaleY * -1;
+            Barcode.CameraPreviewScaleX = Barcode.CameraPreviewScaleX * -1;
+        }
+
         private void Quality_SelectedIndexChanged(object sender, EventArgs e)
         {
             var picker = (Picker)sender;