return null instead of exception (#1339)

Author: VladislavAntonyuk

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/DrawingView/Service/DrawingViewService.android.cs

@@ -48,7 +48,7 @@ public static Stream GetImageStream(IList<Point> points,
 			return stream;
 		}
 
-		static Bitmap GetImageInternal(IList<Point> points,
+		static Bitmap? GetImageInternal(IList<Point> points,
 			float lineWidth,
 			Color strokeColor,
 			Color backgroundColor)
@@ -59,7 +59,7 @@ static Bitmap GetImageInternal(IList<Point> points,
 			var drawingHeight = points.Max(p => p.Y) - minPointY;
 			const int minSize = 1;
 			if (drawingWidth < minSize || drawingHeight < minSize)
-				throw new Exception($"The image size should be at least {minSize} x {minSize}.");
+				return null;
 
 			var image = Bitmap.CreateBitmap((int)drawingWidth, (int)drawingHeight, Bitmap.Config.Argb8888!)!;
 			using var canvas = new Canvas(image);

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/DrawingView/Service/DrawingViewService.gtk.cs

@@ -50,7 +50,7 @@ public static Stream GetImageStream(IList<Point> points,
 			}
 		}
 
-		static Bitmap GetImageInternal(IList<Point> points,
+		static Bitmap? GetImageInternal(IList<Point> points,
 			float lineWidth,
 			Color strokeColor,
 			Color backgroundColor)
@@ -62,7 +62,7 @@ static Bitmap GetImageInternal(IList<Point> points,
 			const int minSize = 1;
 			if (drawingWidth < minSize || drawingHeight < minSize)
 			{
-				throw new Exception($"The image size should be at least {minSize} x {minSize}.");
+				return null;
 			}
 
 			var bm = new Bitmap((int)drawingWidth, (int)drawingHeight);

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/DrawingView/Service/DrawingViewService.ios.cs

@@ -41,7 +41,7 @@ public static Stream GetImageStream(IList<Point> points,
 			return resizedImage.AsJPEG().AsStream();
 		}
 
-		static UIImage GetImageInternal(IList<Point> points,
+		static UIImage? GetImageInternal(IList<Point> points,
 			float lineWidth,
 			Color strokeColor,
 			Color backgroundColor)
@@ -53,7 +53,7 @@ static UIImage GetImageInternal(IList<Point> points,
 			const int minSize = 1;
 			if (drawingWidth < minSize || drawingHeight < minSize)
 			{
-				throw new Exception($"The image size should be at least {minSize} x {minSize}.");
+				return null;
 			}
 
 			var imageSize = new CGSize(drawingWidth, drawingHeight);

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/DrawingView/Service/DrawingViewService.macos.cs

@@ -32,10 +32,15 @@ public static Stream GetImageStream(IList<Point> points,
 			}
 
 			var image = GetImageInternal(points, lineWidth, strokeColor, backgroundColor);
+			if (image is null)
+			{
+				return Stream.Null;
+			}
+
 			return image.AsTiff().AsStream();
 		}
 
-		static NSImage GetImageInternal(IList<Point> points,
+		static NSImage? GetImageInternal(IList<Point> points,
 			float lineWidth,
 			Color strokeColor,
 			Color backgroundColor)
@@ -47,7 +52,7 @@ static NSImage GetImageInternal(IList<Point> points,
 			const int minSize = 1;
 			if (drawingWidth < minSize || drawingHeight < minSize)
 			{
-				throw new Exception($"The image size should be at least {minSize} x {minSize}.");
+				return null;
 			}
 
 			var imageSize = new CGSize(drawingWidth, drawingHeight);

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/DrawingView/Service/DrawingViewService.tizen.cs

@@ -46,7 +46,7 @@ public static Stream GetImageStream(IList<Point> points,
 			}
 		}
 
-		static SKImage GetImageInternal(IList<Point> points,
+		static SKImage? GetImageInternal(IList<Point> points,
 			float lineWidth,
 			Color strokeColor,
 			Color backgroundColor)
@@ -58,7 +58,7 @@ static SKImage GetImageInternal(IList<Point> points,
 			const int minSize = 1;
 			if (drawingWidth < minSize || drawingHeight < minSize)
 			{
-				throw new Exception($"The image size should be at least {minSize} x {minSize}.");
+				return null;
 			}
 
 			var bm = new SKBitmap((int)drawingWidth, (int)drawingHeight);

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/DrawingView/Service/DrawingViewService.uwp.cs

@@ -50,7 +50,7 @@ public static Stream GetImageStream(IList<Point> points,
 			}
 		}
 
-		static CanvasRenderTarget GetImageInternal(IList<Point> points,
+		static CanvasRenderTarget? GetImageInternal(IList<Point> points,
 			float lineWidth,
 			Color lineColor,
 			Color backgroundColor)
@@ -62,7 +62,7 @@ static CanvasRenderTarget GetImageInternal(IList<Point> points,
 			const int minSize = 1;
 			if (drawingWidth < minSize || drawingHeight < minSize)
 			{
-				throw new Exception($"The image size should be at least {minSize} x {minSize}.");
+				return null;
 			}
 
 			var device = CanvasDevice.GetSharedDevice();

src/CommunityToolkit/Xamarin.CommunityToolkit/Views/DrawingView/Service/DrawingViewService.wpf.cs

@@ -35,6 +35,10 @@ public static Stream GetImageStream(IList<Point> points,
 			}
 
 			var image = GetImageInternal(points, lineWidth, strokeColor, backgroundColor);
+			if (image is null)
+			{
+				return Stream.Null;
+			}
 
 			var resizedImage = MaxResizeImage(image, (float) imageSize.Width, (float) imageSize.Height);
 			using (resizedImage)
@@ -46,7 +50,7 @@ public static Stream GetImageStream(IList<Point> points,
 			}
 		}
 
-		static Bitmap GetImageInternal(ICollection<Point> points,
+		static Bitmap? GetImageInternal(ICollection<Point> points,
 			float lineWidth,
 			Color strokeColor,
 			Color backgroundColor)
@@ -58,7 +62,7 @@ static Bitmap GetImageInternal(ICollection<Point> points,
 			const int minSize = 1;
 			if (drawingWidth < minSize || drawingHeight < minSize)
 			{
-				throw new Exception($"The image size should be at least {minSize} x {minSize}.");
+				return null;
 			}
 
 			var bm = new Bitmap((int) drawingWidth, (int) drawingHeight);