Added a way to disable raster canvas scaling for Windows controls

source/SkiaSharp.Views.Forms/SkiaSharp.Views.Forms.UWP/SKCanvasViewRenderer.cs

@@ -1,4 +1,5 @@
 using System;
+using System.ComponentModel;
 using Xamarin.Forms;
 using Xamarin.Forms.Platform.UWP;
 
@@ -28,6 +29,7 @@ namespace SkiaSharp.Views.Forms
 
 				// create the native view
 				var view = new InternalView(newController);
+				view.IgnorePixelScaling = e.NewElement.IgnorePixelScaling;
 				SetNativeControl(view);
 
 				// subscribe to events from the user
@@ -41,6 +43,16 @@ namespace SkiaSharp.Views.Forms
 			base.OnElementChanged(e);
 		}
 
+		protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
+		{
+			base.OnElementPropertyChanged(sender, e);
+
+			if (e.PropertyName == nameof(SKFormsView.IgnorePixelScaling))
+			{
+				Control.IgnorePixelScaling = Element.IgnorePixelScaling;
+			}
+		}
+
 		protected override void Dispose(bool disposing)
 		{
 			// detach all events before disposing

source/SkiaSharp.Views/SkiaSharp.Views.UWP/SKXamlCanvas.cs

@@ -19,6 +19,7 @@ namespace SkiaSharp.Views.UWP
 		private GCHandle buff;
 		private WriteableBitmap bitmap;
 		private double dpi;
+		private bool ignorePixelScaling;
 
 		public SKXamlCanvas()
 		{
@@ -41,6 +42,16 @@ namespace SkiaSharp.Views.UWP
 
 		public SKSize CanvasSize => bitmap == null ? SKSize.Empty : new SKSize(bitmap.PixelWidth, bitmap.PixelHeight);
 
+		public bool IgnorePixelScaling
+		{
+			get { return ignorePixelScaling; }
+			set
+			{
+				ignorePixelScaling = value;
+				Invalidate();
+			}
+		}
+
 		public event EventHandler<SKPaintSurfaceEventArgs> PaintSurface;
 
 		protected virtual void OnPaintSurface(SKPaintSurfaceEventArgs e)
@@ -72,7 +83,19 @@ namespace SkiaSharp.Views.UWP
 			if (ActualWidth == 0 || ActualHeight == 0 || Visibility != Visibility.Visible)
 				return;
 
-			var info = new SKImageInfo((int)(ActualWidth * dpi), (int)(ActualHeight * dpi), SKImageInfo.PlatformColorType, SKAlphaType.Premul);
+			int width, height;
+			if (IgnorePixelScaling)
+			{
+				width = (int)ActualWidth;
+				height = (int)ActualHeight;
+			}
+			else
+			{
+				width = (int)(ActualWidth * dpi);
+				height = (int)(ActualHeight * dpi);
+			}
+
+			var info = new SKImageInfo(width, height, SKImageInfo.PlatformColorType, SKAlphaType.Premul);
 			CreateBitmap(info);
 			using (var surface = SKSurface.Create(info, buff.AddrOfPinnedObject(), info.RowBytes))
 			{
@@ -101,15 +124,23 @@ namespace SkiaSharp.Views.UWP
 				}
 				bitmap = new WriteableBitmap(info.Width, info.Height);
 
-				var scale = 1.0 / dpi;
+				var brush = new ImageBrush
-				Background = new ImageBrush
 				{
 					ImageSource = bitmap,
 					AlignmentX = AlignmentX.Left,
 					AlignmentY = AlignmentY.Top,
-					Stretch = Stretch.None,
+					Stretch = Stretch.None
-					Transform = new ScaleTransform { ScaleX = scale, ScaleY = scale }
 				};
+				if (!IgnorePixelScaling)
+				{
+					var scale = 1.0 / dpi;
+					brush.Transform = new ScaleTransform
+					{
+						ScaleX = scale,
+						ScaleY = scale
+					};
+				}
+				Background = brush;
 			}
 		}
 

source/SkiaSharp.Views/SkiaSharp.Views.WPF/SKElement.cs

@@ -16,6 +16,7 @@ namespace SkiaSharp.Views.WPF
 		private readonly bool designMode;
 
 		private WriteableBitmap bitmap;
+		private bool ignorePixelScaling;
 
 		public SKElement()
 		{
@@ -24,6 +25,16 @@ namespace SkiaSharp.Views.WPF
 
 		public SKSize CanvasSize => bitmap == null ? SKSize.Empty : new SKSize(bitmap.PixelWidth, bitmap.PixelHeight);
 
+		public bool IgnorePixelScaling
+		{
+			get { return ignorePixelScaling; }
+			set
+			{
+				ignorePixelScaling = value;
+				InvalidateVisual();
+			}
+		}
+
 		public event EventHandler<SKPaintSurfaceEventArgs> PaintSurface;
 
 		protected override void OnRender(DrawingContext drawingContext)
@@ -33,11 +44,22 @@ namespace SkiaSharp.Views.WPF
 
 			base.OnRender(drawingContext);
 
-			var m = PresentationSource.FromVisual(this).CompositionTarget.TransformToDevice;
+			int width, height;
-			var dpiX = m.M11;
+			double dpiX = 1.0;
-			var dpiY = m.M22;
+			double dpiY = 1.0;
-			var width = (int)(ActualWidth * dpiX);
+			if (IgnorePixelScaling)
-			var height = (int)(ActualHeight * dpiY);
+			{
+				width = (int)ActualWidth;
+				height = (int)ActualHeight;
+			}
+			else
+			{
+				var m = PresentationSource.FromVisual(this).CompositionTarget.TransformToDevice;
+				dpiX = m.M11;
+				dpiY = m.M22;
+				width = (int)(ActualWidth * dpiX);
+				height = (int)(ActualHeight * dpiY);
+			}
 
 			var info = new SKImageInfo(width, height, SKImageInfo.PlatformColorType, SKAlphaType.Premul);