From 02096e1a0448bb204e0cfbd9958f0bb1388f9a64 Mon Sep 17 00:00:00 2001
From: Stephane Delcroix <stephane@delcroix.org>
Date: Thu, 20 Sep 2018 19:05:33 +0200
Subject: [PATCH 1/2] [A] do not draw gradient for empty CornerRadius (#3786)

Drawing CornerRadius (introduce by #1998) when the CornerRadii are
actually 0 causes scaling artifacts on API < 25.

This fixes the regression when no CornerRadius is set. Expect blurry
border scaling with CornerRadius not empty and API < 25

- fixes #3781
---
 .../Renderers/BoxRenderer.cs                  | 63 +++++++++++--------
 1 file changed, 37 insertions(+), 26 deletions(-)

diff --git a/Xamarin.Forms.Platform.Android/Renderers/BoxRenderer.cs b/Xamarin.Forms.Platform.Android/Renderers/BoxRenderer.cs
index c9a023da9..8415db592 100644
--- a/Xamarin.Forms.Platform.Android/Renderers/BoxRenderer.cs
+++ b/Xamarin.Forms.Platform.Android/Renderers/BoxRenderer.cs
@@ -59,15 +59,20 @@ namespace Xamarin.Forms.Platform.Android
 			if (colorToSet == Color.Default)
 				colorToSet = Element.BackgroundColor;
 
-			if (_backgroundDrawable == null)
-				_backgroundDrawable = new GradientDrawable();
+			if (_backgroundDrawable != null) {
 
-			if (colorToSet != Color.Default)
-				_backgroundDrawable.SetColor(colorToSet.ToAndroid());
-			else
-				_backgroundDrawable.SetColor(colorToSet.ToAndroid(Color.Transparent));
+				if (colorToSet != Color.Default)
+					_backgroundDrawable.SetColor(colorToSet.ToAndroid());
+				else
+					_backgroundDrawable.SetColor(colorToSet.ToAndroid(Color.Transparent));
 
-			this.SetBackground(_backgroundDrawable);
+				this.SetBackground(_backgroundDrawable);
+			}
+			else {
+				if (colorToSet == Color.Default)
+					colorToSet = Element.BackgroundColor;
+				SetBackgroundColor(colorToSet.ToAndroid(Color.Transparent));
+			}
 		}
 
 		protected override void Dispose(bool disposing)
@@ -101,26 +106,32 @@ namespace Xamarin.Forms.Platform.Android
 		void UpdateCornerRadius()
 		{
 			var cornerRadius = Element.CornerRadius;
-
-			if (Background is GradientDrawable backgroundGradient)
-			{
-				var cornerRadii = new[]
-				{
-					(float)(cornerRadius.TopLeft),
-					(float)(cornerRadius.TopLeft),
-
-					(float)(cornerRadius.TopRight),
-					(float)(cornerRadius.TopRight),
-
-					(float)(cornerRadius.BottomRight),
-					(float)(cornerRadius.BottomRight),
-
-					(float)(cornerRadius.BottomLeft),
-					(float)(cornerRadius.BottomLeft)
-				};
-
-				backgroundGradient.SetCornerRadii(cornerRadii);
+			if (cornerRadius == new CornerRadius(0d)) {
+				_backgroundDrawable?.Dispose();
+				_backgroundDrawable = null;
 			}
+			else {
+				this.SetBackground(_backgroundDrawable = new GradientDrawable());
+				if (Background is GradientDrawable backgroundGradient) {
+					var cornerRadii = new[] {
+						(float)(cornerRadius.TopLeft),
+						(float)(cornerRadius.TopLeft),
+
+						(float)(cornerRadius.TopRight),
+						(float)(cornerRadius.TopRight),
+
+						(float)(cornerRadius.BottomRight),
+						(float)(cornerRadius.BottomRight),
+
+						(float)(cornerRadius.BottomLeft),
+						(float)(cornerRadius.BottomLeft)
+					};
+
+					backgroundGradient.SetCornerRadii(cornerRadii);
+				}
+			}
+
+			UpdateBackgroundColor();
 		}
 	}
 }
\ No newline at end of file

From aeca07c097e5dfaa1ec06949b8641a079676af64 Mon Sep 17 00:00:00 2001
From: Matthew Richardson <matthew@velocitysystems.co.nz>
Date: Wed, 27 Jun 2018 11:30:27 +0100
Subject: [PATCH 2/2] Fix #3097 swipe gesture not being handled in
 VisualElementTracker. (#3098) Fixes #3097

---
 Xamarin.Forms.Platform.UAP/VisualElementTracker.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Xamarin.Forms.Platform.UAP/VisualElementTracker.cs b/Xamarin.Forms.Platform.UAP/VisualElementTracker.cs
index be662ffe6..a6a5a47c0 100644
--- a/Xamarin.Forms.Platform.UAP/VisualElementTracker.cs
+++ b/Xamarin.Forms.Platform.UAP/VisualElementTracker.cs
@@ -624,7 +624,7 @@ namespace Xamarin.Forms.Platform.UWP
 			bool hasSwipeGesture = gestures.GetGesturesFor<SwipeGestureRecognizer>().GetEnumerator().MoveNext();
 			bool hasPinchGesture = gestures.GetGesturesFor<PinchGestureRecognizer>().GetEnumerator().MoveNext();
 			bool hasPanGesture = gestures.GetGesturesFor<PanGestureRecognizer>().GetEnumerator().MoveNext();
-			if (!hasPinchGesture && !hasPanGesture)
+			if (!hasSwipeGesture && !hasPinchGesture && !hasPanGesture)
 				return;
 
 			//We can't handle ManipulationMode.Scale and System , so we don't support pinch/pan on a scrollview